limbah jagung dan beras

Original article

Corn and rice waste: a comparative and critical presentation of

methods and current and potential uses of treated waste

Ioannis S. Arvanitoyannis1* & Persefoni Tserkezou2

1 Department of Animal Production and Aquatic Environment, School of Agricultural Sciences, University of Thessaly, Fytokou Street,

38446 Nea Ionia, Magnesias, Volos, Hellas (Greece)

2 Department of Crop Production and Agricultural Environment, School of Agricultural Sciences, University of Thessaly, Fytokou Street,

38446 Nea Ionia, Magnesias, Volos, Hellas (Greece)

(Received 1 July 2006; Accepted in revised form 12 January 2007)

Summary Although corn and rice waste can be hardly classified among the most hazardous waste, their treatment is

very important in view of the great volume of waste materials involved. In this review article, an update is

provided for most of the waste treatment techniques (composting, pyrolysis, gasification, combustion) used

to alter the physical, chemical or biological character of the waste, to reduce its volume and ⁄or toxicity and

to make the waste safer for disposal. Furthermore, all current and potential uses of treated corn and rice

waste such as fertilisers, biomass and biogas ⁄biofuel are summarised. Four comprehensive tables and six

figures provide a thorough presentation of both waste treatment methods (characteristics, advantages and

disadvantages) and uses of treated corn and rice waste.

Keywords Biogas, biomass, combustion, composting, gasification, pyrolysis, rice waste, uses of treated corn waste, waste treatment

techniques.

Introduction

Cereal crops are mostly grasses cultivated for theiredible seeds (actually a fruit called a caryopsis). Cerealgrains are grown in greater quantities worldwide thanany other type of crop and provide more food energyto the human race than any other crop (http://en.wikipedia.org/wiki/Grains). Cereals have been partof the human diet since prehistoric times (http://www.nutrition.org.uk/upload/Cereals%20pdf.pdf). Insome developing nations, cereal grains constitute prac-tically the entire diet of common folk. In developednations, cereal consumption is more moderate but stillsubstantial. The word cereal has its origin in theRoman goddess of grain, Ceres (http://en.wikipe-dia.org/wiki/Grains). Wheat and rice are the mostimportant crops worldwide as they account for over50% of the world’s cereal production. In the UK,wheat is the cereal, most commonly used for themanufacture of food products, although many othertypes of cereals (e.g. maize and barley) are used. Eachcereal has unique properties which make it suitable fora variety of food products (http://www.nutrition.

org.uk/upload/Cereals%20pdf.pdf). The starchy carbo-hydrates which are provided by cereals are essential inhuman nutrition. Rice is a staple diet for half of theworld’s population, the remaining half cultivate theother cereals depending on climate and soil (http://www.geocities.com/napavalley/6454/cereals.html). To-day cereals provide a very significant proportion ofboth human and animal diets despite the fact that mostgrains are to a greater or lesser extent deficient in anumber of essential nutrients. A primary problem isthe low level of essential amino acids such as lysine,methionine and threonine in the major cereal storageproteins (http://www.agrsci.dk/afdelinger/forskningsafde-linger/gbi/grupper/molekylaer_genetik_og_bioteknologi/cereals).The seven principal cereals grown in the world are

wheat, rice, maize, barley, sorghum, oats, rice and rye.Globally, maize is the first-largest cereal crop, thesecond being wheat and the third being rice (http://en.wikipedia.org/wiki/Wheat).Maize (or corn, Zea mays) is a cereal grain that was

domesticated in Mesoamerica. It is called corn in theUnited States, Canada and Australia, but in othercountries that term may refer to other cereal grains(http://en.wikipedia.org/wiki/Maize). Hybrid maize isfavoured by farmers over conventional varieties for its

*Correspondent: Fax: +302421093157;

e-mail: [email protected]

International Journal of Food Science and Technology 2008, 43, 958–988958

doi:10.1111/j.1365-2621.2007.01545.x

� 2007 The Authors. Journal compilation � 2007 Institute of Food Science and Technology Trust Fund

high grain yield. It may be processed to make manydifferent ingredients (e.g. high fructose corn syrup whichcan be used as an alternative to sucrose derived fromsugar cane and sugar beet) and food products. Its germis rich in oil and can be refined to produce corn oil(http://www.nutrition.org.uk/upload/Cere-als%20pdf.pdf). Finally, maize is one of the first cropsfor which genetically modified varieties make up asignificant proportion of the total harvest.Rice is a dietary staple of more than half of the

world’s human population (most of Asia and LatinAmerica), making it the most consumed cereal grain.Rice cultivation is well suited to countries and regionswith low labour costs and high rainfall, as it is verylabour-intensive to cultivate and requires plenty of waterfor irrigation. However, it can be grown practicallyanywhere, even on steep hillsides. Rice is the world’sthird largest crop, behind maize (corn) and wheat(http://en.wikipedia.org/wiki/Rice). Brown rice has itsouter husk removed, and white rice is milled andpolished further to remove the bran and germ. Thereare many different types of rice, categorised by size,shape and the region where they are grown. Rice can beground to make flour and is used to make Japanese ricewine (http://www.nutrition.org.uk/upload/Cereals%20pdf.pdf).The aim of this work was to make a comparative and

critical presentation of corn and rice waste treatmentmethods in an attempt to disclose the most effective andlow cost methods. The treatment methodologies of cornand rice wastes are summarised in Tables 1 and 2,respectively, whereas the chemical analysis of corn stalk,corn cob and rice straw is given in Table 3. Moreover,other main issues which are the current and potentialuses of treated corn and rice wastes are summarised incomprehensive Table 4.

Waste treatment methods

Waste treatment techniques are used to alter thephysical, chemical or biological character of the waste,to reduce its volume and ⁄or toxicity, and to make thewaste safer for disposal. Waste treatment may berequired for radioactive, hazardous and other Depart-ment of Energy (DOE) wastes. Mixed wastes (whichcontain both hazardous and radioactive components)pose special management challenges as they are difficultto treat with existing treatment technologies (http://web.em.doe.gov/em30/wasttrea.html).The following are examples of waste treatment

technologies or practices. Biological treatment usuallyinvolves treatment of waste by bacteria, fungi or algae toremove and degrade the hazardous constituents. Boileris a type of device that can be used to treat hazardouswaste. Boilers use controlled flame combustion andrecover thermal energy in the form of steam or heated

gases (http://www.epa.gov/epaoswer/osw/treatech.htm).Methods of treatment in which the application ofphysical forces predominate are known as unit opera-tions. Methods of treatment in which the removal ofcontaminants is brought about by chemical or biologicalreactions are known as unit processes (Tchobanoglouset al., 2003). The preferred use for surplus straw is asfuel in a suitable on-farm boiler, providing heat for hotwater, buildings and grain drying and other operations,thus cutting energy bills and avoiding ploughing-incosts (http://www.biffa.co.uk/files/pdfs/MassBalance_Agriwastes_08_Treatment.pdf). Carbon adsorption usesactivated carbon to adsorb hazardous waste constitu-ents. Gaseous and aqueous waste streams can be treatedby carbon adsorption. Chemical oxidation: uses strongoxidising agents (e.g. hypochlorite, peroxides, persul-fates, percholorates, permanganates, etc) to break downhazardous waste constituents to render them less toxicor mobile (http://www.epa.gov/epaoswer/osw/treatech.htm).Treatment methods are selected based on the compo-

sition, quantity, and form of the waste material. Somewaste treatment methods are prescribed by regulationsand DOE Orders; other treatment methods are beingdeveloped for specific wastes. Waste treatment methodsbeing used today include solidification (e.g. calciningand vitrification) and volume reduction (e.g. inciner-ation, compaction and sizing). There are two principaltypes of biological sewage treatment: (a) the percolatingfilter (also referred to as trickling or biological filter, (b)activated sludge treatment. Both types of treatmentutilise two vessels, a reactor containing the micro-organisms which oxidise the BOD and a secondarysedimentation tank, which resembles the circular radialflow primary sedimentation tank, in which the micro-organisms are separated from the final effluent(Harrison, 2001).Solidification processes such as calcining and vitrifi-

cation can be used to treat non-solid radioactive waste.DOE processing plants take liquid waste or semi-solidsludge and convert it to a solid waste form that can besafely disposed in a geologic repository (http://web.em.doe.gov/em30/wasttrea.html). Solidification is a methodfor mixing of cement, fly ash from the incinerator andwaste filter cake from the physico-chemical treatment toform a virtually insoluble mass (http://www.zazemiat-a.org/bw/radnevo/resume_ovos_en.pdf).Extraction is a process that removes hazardous con-

stituents from either gaseous or liquid waste streams bymeans of settling, filtration, adsorption, absorption,solvents or other means. Although the extracted hazard-ous constituents are removed from the waste stream, theyusually must be treated further to render them less toxic.Incineration is the high temperature burning (rapid

oxidation) of a waste, usually at 870–1370 �C. It is alsoknown as controlled-flame combustion or calcination

Current and potential uses of treated waste I. S. Arvanitoyannis and P. Tserkezou 959

� 2007 The Authors. Journal compilation � 2007 Institute of Food Science and Technology Trust Fund International Journal of Food Science and Technology 2008

Tab

le1Treatm

entmethodologiesofcorn

wastes;Parameters,Quality

controlmethodsandResults

Kin

do

fw

aste

Tre

atm

en

tP

ara

mete

rsM

eth

od

olo

gy

Qu

ali

tyco

ntr

ol

meth

od

sR

esu

lts

Refe

ren

ces

Co

rnw

ast

eC

om

po

stin

gC

han

ges

chara

cteri

za-t

ion

inC

an

dN

iso

top

ed

uri

ng

com

po

stin

g

Co

mp

ost

pH

measu

red

ina

1:2

slu

rry

of

25

gco

mp

ost

an

dw

ate

r

Co

mp

ost

ing

Ch

an

ges

inca

rbo

n,

nit

rog

en

,

d13

Can

dd1

4N

con

ten

t

du

rin

gco

mp

ost

ing

Hig

hly

reca

lcit

ran

tco

mp

ost

s

wit

hp

rolo

ng

ed

Cst

ora

ge

in

no

n-m

inera

lso

ilfr

act

ion

s.

Th

ese

nsi

tivit

yo

fth

en

atu

ral

ab

un

dan

ce

trace

rte

chn

iqu

eto

chara

cteri

se

their

fate

inso

ilim

pro

ves

du

rin

g

com

po

stin

g,

as

am

ore

ho

mo

gen

eo

us

Cis

oto

pe

sig

natu

red

evelo

ps,

inad

dit

ion

toth

ere

lati

vely

larg

eam

ou

nts

of

stab

leC

ap

pli

ed

inco

mp

ost

s

Lyn

chet

al.

(2006)

Co

rnco

bw

ast

eC

hem

ical

act

ivati

on

Ch

em

ical

act

ivati

on

wit

hzi

nc

chlo

rid

e(Z

nC

l 2)

Th

ete

mp

era

ture

of

500

�Cw

as

fou

nd

tob

eth

eo

pti

mal

con

dit

ion

for

pro

du

cin

gh

igh

surf

ace

are

a

carb

on

sw

ith

Zn

CI 2

act

ivati

on

Pyro

lysi

s

Zin

kch

lori

de

act

ivati

on

Act

ivate

dca

rbo

ns

yie

ldvari

ed

inth

era

ng

eo

f27–3

0.4

%.

Th

esu

rface

are

as

of

the

resu

ltin

g

act

ivate

dca

rbo

ns,

incr

ease

d

rap

idly

wit

him

pre

gn

ati

on

rati

oo

fZ

nC

I 2

Th

eZ

nC

I 2act

ivati

on

of

corn

cob

was

suit

ab

lefo

rth

eact

ivate

d

carb

on

sp

rep

ara

tio

nm

icro

po

rou

s.

Tsa

iet

al.

(1998)

Co

rnst

alk

wast

eP

yro

lysi

sT

herm

og

ravi-

metr

ic

an

aly

zers

(TG

A)

were

on

eo

fth

em

ain

tech

niq

ues

use

d

inan

aly

zin

gth

e

chara

cteri

stic

s

of

soli

dfu

el

vo

lati

lisa

tio

nat

low

heati

ng

rate

s

Mate

rials

are

rap

idly

heate

dto

hig

hte

mp

era

ture

sin

the

ab

sen

ceo

fair

(oxyg

en

)

Fla

shp

yro

lysi

s

Pla

sma

heate

dla

min

ar

en

train

ed

flo

wre

act

or

Th

erm

oly

sis

Yie

lds

of

vo

lati

lep

yro

lysi

sp

rod

uct

s

dep

en

ded

on

the

fin

al

pyro

lysi

s

tem

pera

ture

an

dre

sid

en

ceti

me

Sh

uan

gn

ing

et

al.

(2005)

Co

rnst

raw

wast

eP

yro

lysi

sT

GA

were

on

eo

fth

e

main

tech

niq

ues

use

din

an

aly

zin

gth

e

chara

cteri

stic

so

fso

lid

fuel

vo

lati

lisa

tio

nat

low

heati

ng

rate

s

Th

eh

eati

ng

pro

cess

con

sist

s

of

fast

sam

ple

heati

ng

(25–7

0K

s)1)

toth

ed

esi

red

tem

pera

ture

Pyro

lysi

ski

neti

csT

he

rati

ob

etw

een

the

con

vers

ion

an

dh

eati

ng

tim

evari

ed

fro

ma

maxim

um

of

ab

ou

t1050

(lo

w

tem

pera

ture

s)to

am

inim

um

of

ab

ou

t65

(hig

hte

mp

era

ture

s)

wit

hth

eco

rresp

on

din

gso

lid

mass

fract

ion

at

the

beg

inn

ing

of

the

tru

eis

oth

erm

al

stag

e

eq

ual

to0.9

9an

d0.7

5.

Th

ew

eig

ht

loss

curv

es

ob

tain

ed

for

corn

stalk

sh

ave

the

sam

e

qu

ali

tati

ve

beh

avio

ur

as

wh

eat

stra

w

Lan

zett

a&

Di

Bla

si(1

998)

Current and potential uses of treated waste I. S. Arvanitoyannis and P. Tserkezou960

International Journal of Food Science and Technology 2008 � 2007 The Authors. Journal compilation � 2007 Institute of Food Science and Technology Trust Fund

Tab

le1(C

ontinued)

Kin

do

fw

aste

Tre

atm

en

tP

ara

mete

rsM

eth

od

olo

gy

Qu

ali

tyco

ntr

ol

meth

od

sR

esu

lts

Refe

ren

ces

Co

rnco

bw

ast

eP

yro

lysi

sH

2,

CH

4,

CO

,C

O2

an

dC

2H

2(f

or

an

aly

sis)

,

CH

4,

C2H

6,

C3H

8an

dC

3H

6(f

or

flam

eio

nd

ete

cto

r,FID

)

Th

eco

rnco

bw

as

firs

tp

lace

din

the

react

or,

then

nit

rog

en

pass

ed

thro

ug

hth

ere

act

or

wit

ha

flo

w

of

80

mL

min

)1.

Th

ere

act

or

ish

eate

dto

110

�Cat

ah

eati

ng

rate

of

10

Km

in)

1an

d

held

the

tem

pera

ture

for

1h

in

ord

er

tore

mo

ve

the

wate

r

Pyro

lysi

s

Gas

chro

mato

gra

ph

y

Mass

spect

rom

etr

y

Th

eexp

eri

men

tssh

ow

ed

the

hig

her

the

tem

pera

ture

,th

e

gre

ate

rth

eyie

ldo

fem

itte

dg

ase

s

an

dle

sser

the

am

ou

nt

of

the

liq

uid

an

dth

eso

lid

resi

du

e

Beyo

nd

400

�C,

on

lya

part

of

the

com

po

nen

tsd

eco

mp

ose

d

an

dexh

ibit

ed

asl

ow

er

weig

ht

loss

Cao

et

al.

(2004)

Co

rnst

over

wast

eP

yro

lysi

sA

naly

tica

lsy

stem

toth

e

dete

rmin

ati

on

of

yie

ldp

ara

mete

rsap

art

fro

mH

2O

,C

O,

CO

2an

dH

2,

the

pro

du

cts

were

div

ided

into

fam

ily

gro

up

s,

e.g

.p

ara

ffin

s,o

lefi

ns,

alc

oh

ols

,

aro

mati

csetc

.

Co

rnst

over,

the

leaves

an

dst

alk

s

that

are

usu

all

yle

ftin

the

field

aft

er

corn

harv

est

,ca

nse

rve

as

are

pre

sen

tati

ve

bio

mass

feed

sto

ck

Pyro

lysi

sT

he

an

aly

tic

sem

i-em

pir

ical

mo

del

pro

vid

es

asi

mp

lean

du

sefu

l

way

of

dis

till

ing

the

ess

en

ceo

f

the

ob

serv

ed

therm

o-c

hem

ical

resp

on

seo

fco

rnst

over

to

tem

pera

ture

an

dh

eati

ng

rate

Gre

en

&Fen

g(2

006)

Co

rnco

bw

ast

eG

asi

fica

tio

nU

nd

er

the

exp

eri

men

tal

con

dit

ion

sin

the

act

ivati

on

tem

pera

ture

ran

ges

of

500–8

00

�Cw

ith

less

po

llu

tio

n

chara

cteri

stic

so

fK

OH

:

K2C

O3)

as

chem

ical

ag

en

ts

Tru

ed

en

sity

an

dp

oro

sity

incr

ease

wit

hin

crease

inth

eact

ivati

on

tem

pera

ture

Gasi

fica

tio

no

fco

rnco

bC

om

pari

son

of

ph

ysi

cal

chara

cteri

sati

on

so

fth

e

carb

on

pro

du

cts

wit

hth

ose

of

com

merc

ial

act

ivate

d

carb

on

sin

dic

ate

sth

at

the

act

ivate

dca

rbo

ns

pre

pare

dfr

om

ag

ricu

ltu

ral

wast

eco

rnco

bb

y

usi

ng

acl

ean

er

pro

cess

isan

avail

ab

lero

ute

for

the

bio

mass

uti

lisa

tio

nan

db

iore

sou

rce

recy

clin

g.

Th

eh

igh

-su

rface

-are

aca

rbo

np

rod

uct

s

ob

tain

ed

were

very

pro

mis

ing

ad

sorb

en

tsfo

rp

oll

uti

on

con

tro

l

an

dfo

ro

ther

ap

pli

cati

on

s

Tsa

iet

al.

(2001a)

Co

rnst

arc

hw

ast

eG

asi

fica

tio

nK

HC

O3

was

ad

ded

toth

e

mix

ture

of

starc

han

d

wate

rb

efo

reth

efo

rmati

on

of

the

gel

Th

ein

flu

en

ceo

fp

ress

ure

,

tem

pera

ture

,re

sid

en

ceti

me

an

d

alk

ali

ad

dit

ion

on

the

gasi

fica

tio

n

of

corn

starc

h

Gasi

fica

tio

no

f

corn

starc

h

An

incr

ease

inte

mp

era

ture

imp

roved

the

bio

mass

con

vers

ion

.

Lo

ng

er

resi

den

ceti

me

sho

wed

an

imp

rovem

en

tin

gasi

fica

tio

nyie

ld

un

til

am

axim

um

was

reach

ed

.

Gas

com

po

siti

on

chan

ged

wit

h

resi

den

ceti

me

an

dte

mp

era

ture

.

Po

tass

ium

ad

dit

ion

aff

ect

ed

the

gasi

fica

tio

nyie

ldo

fco

rnst

arc

h.

D’J

esu

set

al.

(2006)

Co

rnco

bw

ast

eC

hem

ical

an

d

ph

ysi

cal

act

ivati

on

KO

Han

dK

2C

O3

were

eff

ect

ive

act

ivati

ng

ag

en

ts

or

chem

ical

act

ivati

on

du

rin

ga

peri

od

of

10

�Cm

in)

1.

Su

bse

qu

en

tg

asi

fica

tio

nat

a

soaki

ng

peri

od

of

800

�CG

asi

fica

tio

n

Pyro

lysi

s

Th

ep

oro

sity

create

din

the

aci

d-

un

wash

ed

carb

on

pro

du

cts

is

sub

stan

tiall

ylo

wer

than

that

of

aci

d-w

ash

ed

carb

on

pro

du

cts

beca

use

of

po

tass

ium

salt

sle

ft

inth

ep

ore

stru

ctu

re

Tsa

iet

al.

(2001a)



Tab

le1(C

ontinued)

Kin

do

fw

aste

Tre

atm

en

tP

ara

mete

rsM

eth

od

olo

gy

Qu

ali

tyco

ntr

ol

meth

od

sR

esu

lts

Refe

ren

ces

Co

rnw

ast

eC

om

bu

stio

nan

d

gasi

fica

tio

n

Rem

oval

of

carb

on

fro

m

foss

ilfu

els

pri

or

tou

sein

nerg

yp

rod

uct

ion

isli

kely

to

be

far

less

cost

lyth

an

att

em

pti

ng

tore

mo

ve

CO

fro

md

isp

ers

ed

sou

rces

Co

rnre

fin

ery

ind

ust

ryp

rod

uce

s

aw

ide

ran

ge

of

pro

du

cts

incl

ud

ing

starc

h-b

ase

deth

an

ol

fuels

for

tran

spo

rtati

on

Bio

mass

com

bu

stio

n

Gasi

fica

tio

nco

mb

ust

ion

Gre

en

pla

nts

develo

ped

to

pro

du

ced

esi

red

pro

du

cts

an

d

en

erg

yco

uld

be

po

ssib

lein

the

futu

re.

Bio

log

ical

syst

em

sca

nalr

ead

y

be

tail

ore

dto

pro

du

cefu

els

such

as

hyd

rog

en

.

Po

licy

dri

vers

for

incr

ease

du

se

of

bio

mass

for

en

erg

yan

d

bio

base

dp

rod

uct

sare

revie

wed

for

their

po

ten

tial

con

trib

uti

on

s

for

aca

rbo

nco

nst

rain

ed

wo

rld

Ch

um

&O

vere

nd

(2001)

Co

rnco

ban

d

corn

tar

wast

e

Co

mb

ust

ion

En

gin

ep

ow

er

perf

orm

an

ce,

fuel

con

sum

pti

on

an

d

em

issi

on

s(C

O2,

CO

,H

Can

d

NO

)h

ave

been

stu

die

d

Tem

pera

ture

ran

ge

fro

m110

to220

�CC

om

bu

stio

nN

osi

gn

ifica

nt

dif

fere

nce

in

perf

orm

an

ceb

etw

een

die

sel

fuel

an

dm

ixed

fuel.

Th

em

ixed

fuel

op

era

tio

n

pro

du

ced

low

fuel

con

sum

pti

on

at

the

vari

ou

slo

ad

ing

.

Mix

ed

fuel

wit

h11.7

%an

d6.6

%

oil

-eco

no

mis

ing

rate

,h

ad

bett

er

oil

-eco

no

mis

ing

com

pare

to

die

sel

fuel,

resp

ect

ively

.

Th

em

ixed

fuel

sho

wed

sig

nifi

can

t

imp

rovem

en

tat

CO

2em

issi

on

s

Zh

an

g&

Wan

g(2

006)

Co

rnw

ast

eC

om

bu

stio

nC

alc

ium

,C

u,

K,

Mg

,

Na,

P,

San

dZ

nw

ere

reco

vere

dw

ith

the

bo

mb

wash

ing

s

Th

ep

roce

du

rein

vo

lves

sam

ple

com

bu

stio

nin

aco

mm

erc

ial

stain

less

steel

oxyg

en

bo

mb

op

era

tin

gat

twen

ty-fi

ve

bar

Co

mb

ust

ion

Ind

uct

ively

cou

ple

d

pla

sma

op

tica

l

em

issi

on

spect

rom

etr

y

Mo

sto

fth

eele

men

tre

coveri

es

in

the

sam

ple

svari

ed

betw

een

91%

an

d105%

an

dth

ece

rtifi

ed

an

d

dete

rmin

ed

con

ten

tsexh

ibit

ed

a

fair

ag

reem

en

tat

a95%

con

fid

en

cele

vel.

So

uza

et

al.

(2002)

Co

rnst

over

wast

eC

om

bu

stio

nT

he

fert

ilis

ati

on

con

sist

ed

of

168

kgN

,

an

d90

kgeach

of

P2O

5

an

dK

2O

eq

uiv

ale

nts

To

min

imis

eth

eeff

ect

of

wate

r

inth

eb

iom

ass

spect

ra,

each

sam

ple

was

air

-dri

ed

tole

ss

than

10%

mo

istu

rep

rio

rto

NIR

spect

rosc

op

ican

aly

sis

NIR

spect

rosc

op

y

Co

mb

ust

ion

NIR

spect

rosc

op

ysh

ow

ed

(a)

a

rap

idd

rop

inso

lub

leg

luca

n,

(b)

incr

ease

inli

gn

inan

d(c

)in

crease

inxyla

n.

As

pro

du

ctyie

ldin

ferm

en

tati

on

-base

d

bio

mass

con

vers

ion

pro

cess

es

is

pro

po

rtio

nal

toth

est

ruct

ura

l

carb

oh

yd

rate

con

ten

to

fth

e

feed

sto

ck,

tim

ing

of

sto

ver

coll

ect

ion

an

dth

ep

rop

ort

ion

of

an

ato

mic

al

fract

ion

sco

llect

ed

aff

ect

the

qu

ali

tyo

fco

rnst

over

as

ferm

en

tati

on

feed

sto

ck

Po

rdesi

mo

et

al.

(2005)



Tab

le1(C

ontinued)

Kin

do

fw

aste

Tre

atm

en

tP

ara

mete

rsM

eth

od

olo

gy

Qu

ality

co

ntr

ol

meth

od

sR

esu

lts

Refe

ren

ces

Co

rno

ilB

iod

iese

lC

on

tro

lo

fH

C,

CO

,N

Ox

Th

een

gin

ew

as

fuell

ed

wit

h

pu

rem

ari

ne

die

sel

fuel

an

d

ble

nd

sco

nta

inin

gtw

oty

pes

of

bio

die

sel,

at

pro

po

rtio

ns

up

to50%

.

Bio

die

sel

Th

etw

oty

pes

of

bio

die

sel

ap

peare

dto

have

eq

ual

perf

orm

an

cean

dir

resp

ect

ive

of

the

raw

mate

rial

use

dfo

r

their

pro

du

ctio

n,

their

ad

dit

ion

toth

em

ari

ne

die

sel

fuel

imp

roved

the

part

icu

late

matt

er,

un

bu

rnt

hyd

roca

rbo

ns,

nit

rog

en

oxid

e

an

dca

rbo

nm

on

oxid

eem

issi

on

s.

Th

eN

Ox

em

issi

on

sw

ere

red

uce

d

inall

case

sw

hen

the

two

bio

die

sel

con

tain

ing

fuels

were

use

d.

Kall

igero

set

al.

(2003)

Co

rnw

ast

eE

than

ol

an

d

bio

die

sel

pro

du

ctio

n

Pro

du

ctio

no

f1000

Lo

f

eth

an

ol

fro

mco

rn

Un

der

rela

tively

hig

hp

rice

sfo

r

gaso

lin

eth

eco

sts

for

usi

ng

eth

an

ol

an

db

iod

iese

lare

mu

ch

hig

her

per

eq

uiv

ale

nt

litr

eo

fg

aso

lin

e

Bio

die

sel

Eth

an

ol

pro

du

ctio

n

Eit

her

the

cost

sfo

rg

en

era

tin

g

eth

an

ol

or

bio

die

sel

have

to

be

red

uce

dsu

bst

an

tiall

y,

by

e.g

.te

chn

ical

chan

ge

or

the

pri

cefo

ro

ilh

as

toin

crease

furt

her

befo

reeth

an

ol

an

d

bio

die

sel

wil

lb

eco

me

eco

no

mic

ally

com

peti

tive

Wess

ele

r(2

007)

Co

rnst

over

wast

eB

iod

iese

lan

d

bio

eth

an

ol

So

iln

itro

gen

-rela

ted

bu

rden

s(e

.g.

N2O

,N

Ox,

NiO

3)

wo

uld

be

red

uce

db

y

harv

est

ing

corn

sto

ver

Wh

en

corn

sto

ver

ish

arv

est

ed

,

eth

an

ol

isp

rod

uce

dfr

om

bo

th

corn

sto

ver

an

dco

rng

rain

an

d

lig

nin

rich

ferm

en

tati

on

resi

du

es

fro

mco

rnst

over

are

uti

lise

dto

gen

era

teele

ctri

city

an

dst

eam

,

wh

ich

are

use

din

the

eth

an

ol

pro

du

ctio

nsy

stem

Bio

die

sel

Bio

eth

an

ol

Co

rnst

over

rem

oval

wo

uld

red

uce

soil

org

an

icca

rbo

nacc

um

ula

tio

n

rate

s,b

ut

cult

ivati

on

of

win

ter

cover

cro

ps,

even

wit

hco

rnst

over

rem

oval,

cou

ldin

crease

soil

org

an

ic

carb

on

acc

um

ula

tio

nra

tes

beca

use

of

incr

ease

dca

rbo

nin

pu

tsfr

om

win

ter

cover

cro

ps.

Uti

lisa

tio

no

fco

rnst

over

an

dw

inte

r

cover

cro

ps

can

imp

rove

the

eco

-effi

cien

cyo

fth

ecr

op

pin

gsy

stem

s

Kim

&D

ale

(2005)

Co

rnco

bw

ast

eP

yro

lysi

sT

he

gas

pro

du

cts

were

an

aly

zed

by

gas

chro

mato

-gra

ph

y

(GC

)as

CO

2,

CO

,H

2,

CH

4,

C2H

4,

C3H

6,

C3H

8,

etc

.

Th

ete

mp

era

ture

was

350–4

00

�CP

yro

lysi

s

Gas

chro

mato

gra

ph

y

Mass

spect

rom

etr

y

Dif

fere

nti

al

therm

og

ravim

etr

ic

an

aly

sis

sho

wed

that

therm

al

deco

mp

osi

tio

np

roce

ssin

vo

lves

two

step

s.

Th

eh

eati

ng

rate

aff

ect

sb

oth

the

act

ivati

on

en

erg

yo

fth

e

deco

mp

osi

tio

nre

act

ion

,b

ut

als

oth

ep

ath

of

the

react

ion

.

Th

em

axim

um

rate

tem

pera

ture

of

the

deco

mp

osi

tio

nre

act

ion

shif

ted

toa

hig

her

tem

pera

ture

,

an

dth

eo

rder

an

dact

ivati

on

en

erg

yo

fth

eto

tal

deco

mp

osi

tio

n

react

ion

decr

ease

d.

Cao

et

al.

(2004)



Tab

le1(C

ontinued)

Kin

do

fw

aste

Tre

atm

en

tP

ara

mete

rsM

eth

od

olo

gy

Qu

ali

tyco

ntr

ol

meth

od

sR

esu

lts

Refe

ren

ces

Co

rno

ilC

hem

ical

meth

od

Die

ne

hyd

ro-p

ero

xid

e

con

-cen

trati

on

an

da-t

oco

ph

ero

l

con

cen

trati

on

as

an

aly

tica

lin

dic

ato

rs

Co

rno

ilst

ore

dat

60

�CA

nti

oxid

ati

ve

extr

act

Gas

chro

mato

gra

ph

y

Th

est

ab

ilis

ati

on

of

stri

pp

ed

corn

oil,

free

fro

man

yg

en

uin

ean

tio

xid

an

t,

pro

ves

the

occ

urr

en

ceo

fcl

ass

I

an

tio

xid

an

tsg

en

era

ted

du

rin

gro

ast

ing

.

Pro

tect

ion

of

gen

uin

ea-t

oco

ph

ero

l

inco

rno

ilin

dic

ate

sth

ep

rese

nce

of

class

IIan

tio

xid

an

tsw

hic

hare

ab

leto

pro

tect

or

tore

gen

era

te

a-t

oco

ph

ero

l

Kri

ng

set

al.

(2000)

Co

rnw

ast

eB

iore

med

ati

on

pH

was

main

tain

ed

aro

un

d

7.2

–7.5

for

ab

ou

t40

days

Myco

bact

eri

um

smeg

mati

s

an

dM

.p

hle

i

An

aero

bic

ferm

en

tati

on

s

Meth

an

og

en

esi

s

Insi

ture

med

iati

on

Bio

rem

ed

iati

on

that

incl

ud

es

an

aero

bic

ferm

en

tati

on

so

f

wast

es

top

rod

uce

meth

an

e

an

dh

yd

rog

en

,th

eg

en

eti

cs

of

meth

an

og

en

esi

san

din

situ

rem

ed

iati

on

of

con

tam

inate

d

aq

uif

er

syst

em

s,la

nd

fill

leach

ate

s

an

din

du

stri

al

effl

uen

ts

Lan

dap

pli

cati

on

of

ferm

en

tati

on

byp

rod

uct

san

dth

eir

use

inan

imal

feed

s.

Bio

cata

lyti

cst

ud

ies

of

tran

sfo

rmati

on

so

fco

mp

on

en

tso

fco

rn

Bio

chem

ical

react

ion

sfo

rth

e

pro

du

ctio

no

fd

e-i

cers

fro

m

ind

ust

rial

wate

rst

ream

s,

bio

die

sel

pro

du

ctio

nfr

om

fats

an

dg

rease

s,b

iod

eg

rad

ab

lep

last

ics

fro

mp

oly

meri

zab

lesu

gar

deri

vati

ves,

sin

gle

cell

foo

ds

deri

ved

fro

mfu

ng

al

gro

wth

on

wast

est

ream

s,an

d

bact

eri

al

po

lysa

cch

ari

des

fro

mE

rwin

iasp

eci

es

Sep

ara

tio

nan

dre

covery

of

com

po

nen

tsb

ym

em

bra

ne

tech

no

log

ies

Mo

ntg

om

ery

(2004)

Co

rnco

b

ag

row

ast

e

Ch

em

ical

act

ivati

on

Inch

em

ical

act

ivati

on

,th

ep

recu

rso

r

mate

rials

are

imp

reg

nate

dw

ith

chem

ical

ag

en

tssu

chas

Zn

Cl 2

an

dH

3P

O4

toin

hib

itth

efo

rmati

on

of

chars

an

den

han

ceth

eyie

ldo

f

the

resu

ltin

gact

ivate

dca

rbo

n

Th

eh

igh

er

act

ivati

on

tem

pera

ture

can

overc

om

eth

ed

raw

back

so

f

alo

ng

er

peri

od

of

act

ivati

on

req

uir

ed

toatt

ain

larg

er

surf

ace

are

aan

dca

no

ffer

hig

her

po

ten

tial

top

rod

uce

act

ivate

d

carb

on

of

gre

ate

rad

sorp

tio

n

cap

aci

tyfr

om

ag

ricu

ltu

re

wast

es

such

as

corn

cob

s

Bu

rn-o

ffin

gasi

fyin

g

ag

en

tsan

dat

800

an

d900

�C.

Ste

am

act

ivati

on

BE

Tsu

rface

are

as

of

act

ivate

d

carb

on

saft

er

ab

ou

t71

an

d59

wt%

bu

rn-o

ffo

fC

O2

an

dst

eam

act

ivati

on

sat

900

�Cw

ere

1705

an

d1315

m2

g)

1,

resp

ect

ively

,

ind

icati

ng

hig

had

sorp

tio

nca

paci

ties.

Pro

du

ctio

no

fh

igh

-qu

ali

ty

mic

rop

oro

us

act

ivate

dca

rbo

n

fro

mco

rnco

bag

row

ast

eu

sin

g

N2

carb

on

isati

on

foll

ow

ed

by

ph

ysi

cal

act

ivati

on

wit

hC

O2

or

steam

Ch

an

get

al.

(2000)



Tab

le1(C

ontinued)

Kin

do

fw

aste

Tre

atm

en

tP

ara

mete

rsM

eth

od

olo

gy

Qu

ali

tyco

ntr

ol

meth

od

sR

esu

lts

Refe

ren

ces

Co

rnh

usk

s

wast

e

En

zym

e

pre

para

tio

n

Th

eco

rnh

usk

sw

ere

pass

ed

thro

ug

h

aH

ob

art

cho

pp

er,

ble

nd

ed

wit

h1.2

5M

NaO

H(2

0g

per

100

mL)

An

en

zym

ep

rep

ara

tio

nd

eri

ved

fro

mA

sperg

illu

sn

iger

an

d

Tri

cho

derm

are

ese

i

En

zym

ati

c

sacc

hari

fica

tio

no

f

corn

hu

sks

Th

ep

rod

uct

so

fth

een

zym

ati

c

react

ion

were

iden

tifi

ed

as

glu

cose

,

cell

ob

iose

,xylo

bio

se,

ara

bin

ose

an

dxylo

se

Incr

easi

ng

the

con

cen

trati

on

of

corn

hu

sks

inth

ere

act

ion

mix

ture

ad

vers

ely

aff

ect

ed

the

pro

du

ctio

n

of

tota

lan

din

div

idu

al

solu

ble

sug

ars

Han

g&

Wo

od

am

s(1

999)

Co

rnco

bs

wast

e

En

zym

e

pre

para

tio

n

Pre

treate

dw

ith

NaO

H,

foll

ow

ed

by

48

ho

fre

act

ion

at

50

�Can

dp

H5

An

en

zym

ep

rep

ara

tio

n

deri

ved

fro

mA

sperg

illu

sn

iger

an

dT

rich

od

erm

a

reese

i.

En

zym

ati

c

sacc

hari

fica

tio

no

f

corn

cob

s

Th

ep

rod

uct

so

fth

een

zym

ati

c

react

ion

were

iden

tifi

ed

as

glu

cose

,

cell

ob

iose

,xylo

bio

se,

ara

bin

ose

an

dxylo

se.

Incr

easi

ng

the

con

cen

trati

on

of

corn

hu

sks

inth

ere

act

ion

mix

ture

ad

vers

ely

aff

ect

ed

the

pro

du

ctio

no

fto

tal

an

d

ind

ivid

ual

solu

ble

sug

ars

Han

g&

Wo

od

am

s(2

001)

Co

rnco

b

wast

e

Bio

deg

rad

ati

on

Th

eo

pti

mu

mp

Hfo

rce

llu

lase

pro

du

ctio

nw

as

fou

nd

tob

e5.5

Ph

an

ero

chaete

chry

sosp

ori

um

NR

RL

6359,

P.

chry

sosp

ori

um

NR

RL

6361

an

dC

ori

olu

s

vers

ico

lor

NR

RL

6102

En

zym

ed

ete

rmin

ati

on

Pro

tein

dete

rmin

ati

on

Ph

an

ero

chaete

chry

sosp

ori

um

NR

RL

6359

was

sele

cted

as

a

bett

er

pro

du

cer

for

rele

ase

red

uci

ng

sug

ars

Th

eh

igh

est

levels

of

xyla

nase

,

glu

can

ase

an

dce

llu

lase

were

dete

cted

incu

ltu

reP

.ch

ryso

spo

riu

m

NR

RL

6359

aft

er

48

h

Ab

dE

l-N

ass

er

et

al.

(1997)

Co

rnst

over

wast

e

Ch

em

ical

act

ivati

on

Co

rnst

over

tran

spo

rted

by

pip

eli

ne

at

20%

soli

ds

con

cen

trati

on

(wet

basi

s)

or

hig

her

cou

ldd

irect

lyen

ter

an

eth

an

ol

ferm

en

tati

on

pla

nt

Heat

loss

ina

1.2

6m

pip

eli

ne

carr

yin

g2

Md

ryto

nn

es

year)

1is

ab

ou

t5

�Cat

ad

ista

nce

of

400

kmin

typ

ical

pra

irie

clay

soil

s

Sacc

hari

fica

tio

no

f

corn

sto

ver

Tra

nsp

ort

of

corn

sto

ver

inm

ult

iple

pip

eli

nes

off

ers

the

op

po

rtu

nit

yto

develo

pa

larg

eeth

an

ol

ferm

en

tati

on

pla

nt,

avo

idin

gso

me

of

the

dis

eco

no

mie

so

fsc

ale

that

ari

se

fro

msm

aller

pla

nts

wh

ose

cap

aci

ties

are

lim

ited

by

issu

es

of

tru

ckco

ng

est

ion

.

Sacc

hari

fica

tio

nin

the

pip

eli

ne

wo

uld

red

uce

the

need

for

invest

men

tin

the

ferm

en

tati

on

pla

nt,

savin

g

ab

ou

t0.2

cen

ts⁄L

of

eth

an

ol.

Ku

mar

et

al.

(2005)

Co

rnco

b

wast

e

Hyd

roly

sis

Th

een

zym

ati

ch

yd

roly

sis

was

carr

ied

ou

tu

sin

gci

trate

bu

ffer

(50

raM

,p

H4.5

)

at

52–5

3�C

for

dif

fere

nt

tim

ein

terv

als

.

Use

of

Ap

erg

illu

ssp

.E

nzy

mati

ch

yd

roly

sis

Th

eh

yd

roly

sis

pro

du

cts

were

an

aly

sed

by

HP

LC

Xylo

sew

as

fou

nd

tob

eth

em

ajo

r

en

dp

rod

uct

wit

htr

ace

so

fxylo

bio

se

an

dxylo

trio

seat

the

beg

inn

ing

of

hyd

roly

sis.

Co

rnco

bp

ow

der

sho

wed

low

er

exte

nt

of

hyd

roly

sis

wh

en

treate

d

wit

hh

igh

er

en

zym

eco

nce

ntr

ati

on

s

for

lon

ger

peri

od

so

fti

me.

Go

khale

et

al.

(1998)

Co

rnst

over

wast

e

Rad

iati

on

Gam

ma

irra

dia

tio

no

fco

rnst

over

in

com

bin

ati

on

wit

hso

diu

mh

yd

roxid

e

for

bio

con

vers

ion

of

po

lysa

c-ch

ari

de

into

pro

tein

by

Ple

uro

tus

sp.

Ple

uro

tus

ost

reatu

san

dP

.eo

us

are

macr

ofu

ng

iw

hic

hu

tili

se

po

lysa

cch

ari

des

Gam

ma

rad

iati

on

Aft

er

the

heat

⁄rad

iati

on

treatm

en

t,

succ

ess

ion

of

the

resi

du

al

mic

roo

rgan

ism

inth

eco

mp

ost

cou

ldin

flu

en

ceth

eb

ioco

nvers

ion

of

the

sub

stra

teto

uti

liza

ble

nu

trie

nts

for

the

mu

shro

om

develo

pm

en

t.

Gb

ed

em

ah

et

al.

(1998)



Tab

le1(C

ontinued)

Kin

do

fw

aste

Tre

atm

en

tP

ara

mete

rsM

eth

od

olo

gy

Qu

ali

tyco

ntr

ol

meth

od

sR

esu

lts

Refe

ren

ces

Co

rnh

ull

an

dco

rn

sto

ver

wast

e

Ph

ysi

cal

act

ivati

on

Th

eu

sual

com

merc

ial

cho

ices

of

act

ivati

on

gas

are

steam

,C

O2,

air

or

their

mix

ture

sC

O2

an

dO

2

Tem

pera

ture

con

tro

lfo

rth

ere

act

or

con

sist

ed

of

ath

ree-z

on

e

tem

pera

ture

con

tro

lsy

stem

Ph

ysi

cal

act

ivati

on

Bo

thth

esu

rface

are

aan

dth

en

atu

re

of

po

rosi

tyw

ere

sig

nifi

can

tly

aff

ect

ed

by

the

con

dit

ion

so

fact

ivati

on

,th

e

exte

nt

of

wh

ich

dep

en

ded

on

the

natu

reo

fth

ep

recu

rso

rs.

Th

eh

igh

er

the

act

ivati

on

tem

pera

ture

,

the

gre

ate

rare

the

surf

ace

are

as

an

dm

icro

po

revo

lum

es

of

the

resu

ltan

tact

ivate

dca

rbo

ns.

Vari

ou

sp

recu

rso

rsw

ere

aff

ect

ed

dif

fere

ntl

yb

yth

ed

ura

tio

no

fact

ivati

on

.

Fo

ro

ak,

the

lon

ger

the

du

rati

on

of

act

ivati

on

,th

eg

reate

rth

e

ad

sorp

tio

nca

paci

tyo

fre

sult

an

t

act

ivate

dca

rbo

ns,

an

dvic

evers

a

for

corn

hu

lls

an

dco

rnst

over.

Zh

an

get

al.

(2004)

Co

rnco

bw

ast

eC

hem

ical

act

ivati

on

Ch

em

ically

act

ivate

dm

eth

od

wit

h

solu

tio

no

fK

OH

an

dso

ap

wh

ich

act

ed

as

surf

act

an

t

Th

ete

mp

era

ture

isb

etw

een

450

an

d850

�CC

hem

ical

meth

od

Th

esp

eci

fic

surf

ace

are

ao

f

act

ivate

dca

rbo

nfr

om

corn

cob

sre

ach

ed

2700

m2

g)

1.

An

dth

ead

dit

ion

of

the

soap

as

surf

act

an

tm

ay

sho

rten

the

soaki

ng

tim

e.

Th

est

ruct

ure

of

the

act

ivate

d

carb

on

pre

pare

dh

ad

narr

ow

dis

trib

uti

on

of

po

resi

zean

d

the

mic

ro-p

ore

sacc

ou

nte

d

for

78%

.

Easy

an

dfe

asi

ble

meth

od

Cao

et

al.

(2006)



Tab

le2Treatm

entmethodologiesofrice

wastes;parameters,quality

controlmethodsandresults

Kin

do

f

waste

Tre

atm

en

tP

ara

mete

rsM

eth

od

olo

gy

Qu

ali

tyco

ntr

ol

meth

od

sR

esu

lts

Refe

ren

ces

Ric

e stra

w

Co

mp

ost

ing

pH

7,

the

ad

dit

ion

of

com

po

st

(20–2

00

gp

ot)

1)

imp

roved

sele

cted

soil

chem

ical

(in

crease

dto

tal

N,

tota

lC

an

dC

EC

)

Th

eco

mp

ost

sre

ach

ed

matu

rity

in90

days.

Co

mp

ost

ing

Ben

efi

to

fco

mp

ost

wit

ho

ut

chem

ical

fert

ilis

er

dem

on

stra

ted

the

vali

dit

y

an

dp

oss

ibil

ity

of

sust

ain

ab

leag

ro-

no

mic

perf

orm

an

ceo

ffa

ba

bean

usi

ng

loca

lly

avail

ab

lere

cycl

ed

or-

gan

icm

ate

rials

.T

he

tota

lo

rgan

icC

con

cen

trati

on

decl

ined

slig

htl

yfo

r

all

mix

ture

sd

uri

ng

com

po

stin

g.

Co

mp

ost

Nin

crease

dw

ith

incr

eas-

ing

am

ou

nts

of

oil

seed

rap

eca

ke

an

dp

ou

ltry

man

ure

inth

efe

ed

-

sto

cks.

Ab

delh

am

idet

al.

(2004)

Ric

e stra

w

Co

mp

ost

ing

To

tal

Kje

ldah

ln

itro

gen

(TK

N),

tota

l

org

an

icca

rbo

n(T

OC

)an

do

rgan

ic

matt

er

(OM

)an

dh

um

icsu

b-

stan

ce(H

S)

Psy

chro

ph

ilic

an

dm

eso

ph

ilic

mic

roo

rgan

ism

s

An

aero

bic

com

po

stin

gA

sa

resu

lto

fb

iod

eg

rad

ati

on

of

org

an

icco

mp

ou

nd

s,th

ete

mp

era

-

ture

incr

ease

dan

dre

ach

ed

40–5

0�C

.p

Hte

nd

ed

tob

est

ab

le

an

dap

peare

dto

be

con

sist

en

tin

all

the

com

po

sts.

Zh

u(2

007)

Ric

e flake

s

Co

mp

ost

ing

Th

ep

rod

uct

ion

med

iaco

nta

ined

5g

of

soli

dsu

bst

rate

an

d10

mL

min

era

l

solu

tio

nco

nta

inin

g

(mg

⁄gd

s)(N

H4) 2

SO

44,

Mg

SO

4Æ7

H2O

1,

FeS

O4Æ7

H2O

0.0

2,K

2H

PO

41.4

an

d

KH

2P

O4

0.6

,in

250

ml

Erl

en

meyer

flask

sin

itia

lly

main

tain

ed

at

pH

7.

Asp

erg

illu

ssp

.C

om

po

stin

gO

rgan

icn

itro

gen

sup

ple

men

tati

on

sho

wed

ah

igh

er

en

zym

ep

rod

uc-

tio

nco

mp

are

dw

ith

ino

rgan

ic

sou

rce.

Op

tim

um

en

zym

eact

ivit

y

was

ob

serv

ed

at

55

�C,

pH

5.

En

zym

eact

ivit

yw

as

en

han

ced

in

the

pre

sen

ceo

fca

lciu

mw

here

as

pre

sen

ceo

fE

DT

Ag

ave

revers

eeff

ect

.

An

toet

al.

(2006)

Ric

e stra

w

Co

mp

ost

ing

Th

em

ois

ture

con

ten

t(o

ven

dri

ed

at

105

�Cfo

r24

h),

tota

lo

rgan

icm

att

er

(weig

ht

loss

on

ign

itio

nat

550

�Cfo

r

72

h),

oxid

izab

leo

rgan

icca

rbo

n

(Walk

ley–B

lack

meth

od

)an

dto

tal

nit

rog

en

(Kje

ldah

lm

eth

od

)w

ere

dete

rmin

ed

.

Th

ere

spir

ati

on

act

ivit

yo

fm

icro

or-

gan

ism

was

dete

rmin

ed

on

dif

fere

nt

init

ial

C⁄N

(17,

24

an

d40)

raw

mate

rials

Co

mp

ost

ing

Str

aw

resi

du

es

fro

mri

cecu

ltiv

ati

on

are

rich

ino

rgan

icm

att

er

con

ten

t

(80%

)an

do

xid

izab

leo

rgan

icC

(34%

)an

dh

ave

ah

igh

C⁄N

rati

o

(very

vari

ab

lean

dn

ear

the

avera

ge

of

50),

wh

ich

mean

sa

feasi

ble

carb

on

sou

rce

for

the

mic

ro-

org

an

ism

sw

hic

hab

leto

surv

ive

the

com

po

stin

gco

nd

itio

ns.

Iran

zoet

al.

(2004)

Ric

e stra

w

Pyro

lysi

sO

xyg

en

con

ten

to

fth

eb

io-o

ils

was

sig

nifi

can

tly

red

uce

db

eca

use

of

the

evo

luti

on

of

cata

lyti

cg

ase

ssu

chas

H2O

,C

Oan

dC

O2

Pyro

lysi

ste

mp

era

ture

,h

eati

ng

rate

an

dh

old

ing

tim

eo

nth

eyie

lds

of

pyro

lysi

sp

rod

uct

san

dth

eir

chem

-

ical

com

po

siti

on

s

Fast

pyro

lysi

sG

as

chro

-

mato

gra

ph

yM

ass

spect

rom

etr

y

Th

eto

tal

yie

ldo

fli

qu

idp

rod

uct

s

sig

nifi

can

tly

incr

ease

das

the

pyro

-

lysi

ste

mp

era

ture

was

rais

ed

fro

m

400

to500

�C.

Th

eh

igh

wate

rco

n-

ten

tin

the

pyro

lysi

sli

qu

idp

rod

uct

may

be

du

eto

the

hig

hm

ois

ture

con

ten

tin

the

feed

ing

bio

mass

es

an

dth

ere

lease

of

vo

lati

leo

rgan

ic

pro

du

cts

du

rin

gth

ep

rep

ara

tio

no

f

con

den

sed

liq

uid

sam

ple

.

Tsa

iet

al.

(2006)



Tab

le2(C

ontinued)

Kin

do

f

waste

Tre

atm

en

tP

ara

mete

rsM

eth

od

olo

gy

Qu

ali

tyco

ntr

ol

meth

od

sR

esu

lts

Refe

ren

ces

Ric

e hu

sk

Pyro

lysi

sW

eig

ht

loss

curv

es

for

the

pyro

lysi

so

f

rice

hu

skg

rain

inN

2an

dC

O2

atm

osp

here

su

nd

er

no

n-i

soth

erm

al

con

dit

ion

s

Dif

fere

nt

levels

of

tem

pera

ture

Ric

eh

usk

pyro

lysi

sT

he

meth

od

was

fou

nd

top

red

ict

sati

sfact

ori

lyth

ep

yro

lysi

sd

ata

at

dif

fere

nt

heati

ng

rate

so

fri

ceh

usk

.

Sh

arm

a&

Rao

(1999)

Ric

e hu

sk

Pyro

lysi

sT

he

con

ten

to

fS

iO2

inth

eso

lid

resi

du

ew

as

dete

rmin

ed

gra

vim

etr

i-

call

yaft

er

treatm

en

tw

ith

hyd

ro-

flu

ori

caci

dan

dth

eco

nte

nt

of

carb

on

No

n-i

soth

erm

al

heati

ng

inair

Pyro

lysi

sT

he

bu

rnin

go

fri

ceh

usk

pro

du

ces

SiO

2w

ith

glo

bu

lar

stru

ctu

rean

d

well

develo

ped

speci

fic

are

a.

Th

e

pyro

lysi

sin

nit

rog

en

med

ium

giv

es

SiO

2m

ixed

wit

hca

rbo

n.

Vla

ev

et

al.

(2003)

Ric

e hu

sk

Pyro

lysi

sT

he

spect

rum

of

cata

lyze

dsa

mp

les

wit

hFeC

l 2Æ4

H2O

.

Tem

pera

ture

,p

yro

lysi

sti

me,

typ

eo

f

cata

lyst

,an

dp

roce

ssatm

osp

here

Pyro

lysi

sT

he

op

tim

ised

pro

du

ctio

np

roce

ssw

as

develo

ped

usi

ng

as

aFeC

l 2.4

H2O

-

cata

lyze

r,1370

�Cas

pro

cess

tem

-

pera

ture

,1.5

Lm

in)

1arg

on

flo

w

an

d40

min

resi

den

ceti

me.

Alt

er-

nati

ve

use

sfo

rth

eri

ceh

usk

are

gen

era

ted

as

new

pro

du

cts

that

are

man

ufa

ctu

red

fro

ma

rem

ain

der

mate

rial.

Mart

inez

et

al.

(2005)

Ric

e stra

w

Pyro

lysi

sN

itro

gen

was

use

das

the

sweep

ing

gas

wit

hth

efl

ow

rate

so

feit

her

50,

100,

200

an

d400m

Lm

in)

1an

dth

e

hig

hest

bio

-oil

yie

ldw

as

ob

tain

ed

wh

en

flo

wra

tew

as

200

mL

min

)1.

Pyro

lysi

ste

mp

era

ture

,p

art

icle

size

,

sweep

ing

gas

flo

wra

tean

dst

eam

velo

city

Pyro

lysi

sG

as

chro

ma-

tog

rap

hyM

ass

spect

r-

om

etr

y

Th

ep

yro

lysi

so

ils

were

con

du

cted

wit

hH

-NM

R,

oil

san

dali

ph

ati

csu

b-

fract

ion

sw

ith

FT

-IR

.T

he

chem

ical

chara

cteri

sati

on

has

sho

wn

that

the

oil

ob

tain

ed

fro

mri

cest

raw

may

be

po

ten

tially

valu

ab

leas

fuel

an

d

chem

icals

feed

sto

cks.

Pu

tun

et

al.

(2004)

Ric

e hu

sk

an

d

stra

w

Co

mb

ust

ion

Th

em

ain

ele

men

tin

rice

hu

skash

is

sili

con

(87.7

%as

SiO

2),

follo

wed

by

po

tass

ium

(5.4

%as

K2O

)an

dp

ho

s-

ph

oro

us

(3.7

%as

P2O

5)

No

rmal

tem

pera

ture

Co

mb

ust

ion

Th

eco

mb

ust

ion

test

su

sin

gri

ceh

usk

as

fuel

were

do

ne

usi

ng

dif

fere

nt

furn

ace

tem

pera

ture

san

dfl

uid

isa-

tio

nvelo

citi

es.

Th

eeff

ect

of

these

vari

ab

les

on

com

bu

stio

neffi

cien

cy,

CO

em

issi

on

san

dash

chara

cteri

s-

tics

were

stu

die

d.

Th

eco

mb

ust

ion

test

sw

ere

op

era

ted

inth

ete

mp

era

-

ture

ran

ge

of

840–8

80

�Can

din

the

flu

idis

ati

on

velo

city

ran

ge

of

1–1

.2m

⁄s.

Arm

est

oet

al.

(2002)

Ric

e hu

sk

Co

mb

ust

ion

CO

em

issi

on

svari

es

fro

m200

to

800p

pm

,S

O2

ran

ges

fro

m50

to

100

pp

man

dN

Ox

ran

ges

fro

m150

to220

pp

m

Th

ete

mp

era

ture

measu

rin

gan

dg

as

sam

pli

ng

po

rts

are

inst

all

ed

at

dif

-

fere

nt

heig

hts

.

Co

mb

ust

ion

Th

eexp

eri

men

tssh

ow

that

CO

em

is-

sio

ns

vari

es

fro

m200

to800

pp

m,

wh

ere

as

SO

2ra

ng

es

fro

m50

to

100

pp

man

dN

Ox

ran

ges

fro

m150

to220

pp

m.

Ifth

efl

uid

isin

gvelo

city

gro

ws

furt

her,

the

stro

ng

com

bu

s-

tio

nin

ten

sity

zon

ew

ill

mo

ve

to

theto

po

fth

efr

eeb

oard

an

din

crea-

ses

the

loss

es

inu

nb

urn

ed

com

-

bu

stib

les.

Fan

get

al.

(2004)



Tab

le2(C

ontinued)

Kin

do

f

waste

Tre

atm

en

tP

ara

mete

rsM

eth

od

olo

gy

Qu

ali

tyco

ntr

ol

meth

od

sR

esu

lts

Refe

ren

ces

Ric

e stra

w

Co

mb

ust

ion

Kan

dC

lco

nte

nt

of

Mis

can

thu

san

d

dete

rmin

ed

that

asu

bst

an

tial

de-

clin

ein

Kan

dC

lo

ccu

rred

as

are

sult

of

over-

win

teri

ng

Th

eavail

ab

lep

eri

od

for

mech

an

ised

coll

ect

ion

of

rice

stra

waft

er

the

win

ter

peri

od

ran

ges

fro

m0

to

45

days.

Th

erm

al

con

vers

ion

Th

em

ois

ture

con

ten

tsare

sim

ilar

to

tho

seo

fri

cep

lan

tsju

stp

rio

rto

harv

est

.R

esu

lts

for

the

sub

treat-

men

tssh

ow

that

shie

lded

stu

bb

le

has

sig

nifi

can

tly

hig

her

con

cen

tra-

tio

ns

of

Kan

dC

lth

an

exp

ose

d

stu

bb

lean

dlo

ose

stra

w,su

gg

est

ing

that

the

thatc

hin

geff

ect

of

stra

w

do

es

red

uce

leach

ing

rate

.

Bakk

er

&Jen

kin

s(2

003)

Ric

e hu

sk

Pyro

lysi

sU

sin

gso

me

carb

on

ate

sli

kem

ixtu

reo

f

sod

ium

carb

on

ate

an

db

i-ca

rbo

nate

,

mag

nesi

um

carb

on

ate

an

dzi

nc

car-

bo

nate

Hig

hte

mp

era

ture

Pyro

lysi

sT

he

dra

stic

weig

ht

loss

patt

ern

ob

-

serv

ed

betw

een

350

an

d400

�Cw

as

du

eto

the

dest

ruct

ion

of

cell

ulo

se

an

dh

em

icellu

lose

inth

eo

rig

inal

bio

mass

.P

yro

lysi

sap

pare

ntl

yst

ar-

ted

at

aro

un

d350

�Cw

here

the

vo

lati

lem

att

er

inth

eb

iom

ass

beg

an

tovap

ori

se.

Th

eyie

ldb

eca

me

al-

mo

stco

nst

an

taft

er

this

stag

e,

wh

ich

mark

ed

the

maxim

um

char

yie

ld.

Mait

iet

al.

(2006)

Ric

e hu

sk

Co

mb

ust

ion

Bo

thfi

ne

carb

on

⁄si

lica

an

dp

ure

sili

cap

ow

ders

can

be

ob

tain

ed

by

carb

on

isati

on

an

dco

mb

ust

ion

of

rice

hu

sku

nd

er

no

n-i

soth

erm

alc

on

-

dit

ion

s

Usi

ng

heati

ng

rate

so

f5,

10,

15,

20

�Cm

in)

1.

Co

mb

ust

ion

Carb

on

isati

on

Aft

er

heati

ng

the

rice

hu

skin

N2

or

air

,

the

imp

uri

tyco

nte

nt

islo

wer

than

that

inaci

d-l

each

ed

sam

ple

,in

dic

a-

tin

gth

at

the

meta

lsare

als

op

rob

-

ab

lyca

rrie

do

ut

fro

mth

evo

lati

les

du

rin

gth

erm

al

deco

mp

osi

tio

n.

By

com

pari

ng

the

carb

on

⁄si

lica

mo

lar

rati

oin

the

carb

on

ised

hu

sk,

itw

as

fou

nd

that

the

carb

on

⁄sil

ica

mo

lar

rati

oin

crease

dw

ith

incr

easi

ng

the

heati

ng

rate

.

Lio

u(2

004)

Ric

e hu

sk

Co

mb

ust

ion

Su

lph

ur

an

dn

itro

gen

con

tain

ed

inth

e

liq

uid

fuel

are

test

ed

tob

e0.1

%an

d

0.2

%fo

rri

ceh

usk

s

Tem

pera

ture

sb

etw

een

420

an

d

540

�CC

om

bu

stio

nG

as

chro

-

mato

gra

ph

yM

ass

spect

rom

etr

y

Exp

eri

men

tssh

ow

that

ate

mp

era

ture

belo

w420

�Cis

no

tsu

ffici

en

tfo

r

pyro

lysi

sas

som

eri

ceh

usk

so

r

saw

du

stw

ere

fou

nd

inth

ech

arc

oal

an

dash

.T

he

data

sho

ws

that:

(a)

the

en

erg

yca

scad

eis

ab

ou

t49%

for

liq

uid

fuel

an

dab

ou

t86%

for

all

pro

du

cts,

(b)

the

therm

al

en

erg

y

con

tain

ed

inth

ech

arc

oal

ism

ore

than

the

en

erg

yco

nsu

med

by

ele

ctri

ch

eati

ng

.

Zh

en

get

al.

(2006)

Ric

e stra

w

Bio

gasi

fica

-

tio

n

Am

mo

nia

isu

sed

as

asu

pp

lem

en

tal

nit

rog

en

sou

rce

for

rice

stra

w

dig

est

ion

.

Mech

an

ical,

therm

al

an

dch

em

ical

(am

mo

nia

)tr

eatm

en

t

Bio

gasi

fica

tio

n

An

aero

bic

dig

est

ion

Aco

mb

inati

on

of

gri

nd

ing

(10

mm

len

gth

),h

eati

ng

(110

�C),

an

d

am

mo

nia

treatm

en

t(2

%)

resu

lted

in

the

hig

hest

bio

gas

yie

ld,

0.4

7Lg

gl

VS

-fed

,w

hic

his

17.5

%h

igh

er

than

the

bio

gas

yie

ldo

fu

ntr

eate

dw

ho

le

stra

w.

Pre

treatm

en

tte

mp

era

ture

has

asi

gn

ifica

nt

eff

ect

on

the

dig

est

ibilit

yo

fst

raw

Zh

an

g&

Zh

an

g(1

999)



Tab

le2(C

ontinued)

Kin

do

f

waste

Tre

atm

en

tP

ara

mete

rsM

eth

od

olo

gy

Qu

ality

co

ntr

ol

meth

od

sR

esu

lts

Refe

ren

ces

Ric

e stra

w

Bio

gas

Dis

infe

ctio

no

fst

raw

an

dm

an

ure

by

mean

so

f0.1

%K

Mn

O4

plu

s2%

form

alin

solu

tio

nin

ho

tw

ate

r

Ple

uro

tus

sajo

rca

juB

iog

as

Su

pp

lem

en

tati

on

of

rice

stra

ww

ith

bio

gas

resi

du

al

slu

rry

man

ure

has

stro

ng

imp

act

inim

pro

vin

gth

eyie

ld

po

ten

tial,

pro

tein

an

dm

inera

l

nu

trie

nt

con

ten

tso

fP

leu

rotu

ssa

jor

caju

mu

shro

om

inIn

dia

nsu

bco

n-

tin

en

to

rsi

mil

ar

clim

ati

cco

nd

itio

ns.

Ban

ik&

Nan

di

(2004)

Ric

e hu

sk

Gasi

fica

tio

nT

he

infr

are

db

an

din

ten

sity

of

CO

2g

as

was

start

ing

tog

row

at

200–3

00

�C,

ind

icati

ng

an

oxid

ati

on

react

ion

oc-

curr

ed

wh

ile

CO

gas

was

dete

cted

at

450

�C.

Tem

pera

ture

belo

w730

�Cto

pro

du

ce

syn

gase

sfo

rp

ow

er

gen

era

tio

nan

d

tore

cover

valu

ab

leam

orp

ho

us

sil-

ica

mate

rials

.

Pyro

lysi

sGasi

fica

-

tio

nS

team

gasi

fica

tio

n

Gasi

fica

tio

no

fri

ceh

usk

was

acc

om

-

pan

ied

by

asu

bst

an

tial

pro

du

ctio

n

of

syn

gas

at

450–6

30

�C.

Itap

pears

that

ino

rder

tog

en

era

te10

kW

ele

ctri

cp

ow

er,

ap

pro

xim

ate

ly

28

kgh

of

rice

hu

skm

ust

be

gasi

-

fied

.T

he

rice

hu

skg

asi

fica

tio

np

ro-

cess

,in

term

so

fh

eat

req

uir

em

en

ts,

can

be

self

-su

stain

ing

.

Lin

et

al.

(1999)

Ric

e hu

sk

Gasi

fica

tio

nU

sin

ga

gasi

fyin

gm

ed

ium

such

as

air

,

oxyg

en

,st

eam

Hig

hte

mp

era

ture

Air

gasi

fica

tio

nT

he

hig

her

heati

ng

valu

eo

fth

eg

as

ob

tain

ed

at

this

flu

idis

ati

on

velo

city

an

deq

uiv

ale

nce

rati

o(3

.09

±5.0

3

MJ

Nm

)3)

com

pare

dvery

well

wit

h

pu

bli

shed

data

fro

mair

-blo

wn

bio

-

mass

gasi

fiers

of

sim

ilar

scale

of

op

era

tio

n.

Th

eg

as

yie

ldan

dca

rbo

n

con

vers

ion

were

inth

era

ng

eo

f

1.3

0–1

.98

Nm

3kg

)1

an

d55–8

1%

,

resp

ect

ively

.

Man

sara

yet

al.

(1999)

Ric

e hu

sk

Gasi

fica

tio

nC

O2

isin

tro

du

ced

by

rep

laci

ng

N2

gas

Dif

fere

nt

levels

of

tem

pera

ture

Ste

am

gasi

fica

tio

nA

tth

eh

igh

er

tem

pera

ture

of

900

�C,

the

react

ion

mech

an

ism

isn

ot

on

ly

chem

icall

yco

ntr

oll

ed

bu

tals

ob

e

infl

uen

ced

by

dif

fusi

on

al

resi

stan

ce.

Bh

at

et

al.

(2001)



and is a technology that destroys organic constituents inwaste materials (http://www.epa.gov/epaoswer/osw/treatech.htm). Incineration of some commercial andindustrial wastes which are hazardous and have lowthroughputs, use incineration as a means of disposal,and energy recovery is often a secondary objective.Sewage sludge incineration generates heat which is oftenused to dry the input sewage sludge to levels where thecombustion is self-sustaining (Williams, 2005). Theactivated sludge process may have up to four phases:(a) clarification, by flocculation of suspended andcolloidal matter, (b) oxidation of carbonaceous matter,(c) oxidation of nitrogenous matter and (d) auto-digestion of the activated sludge (Harrison, 2001).Neutralisation is a process used to treat corrosive

hazardous waste streams. Low pH acidic corrosivewaste streams are usually neutralised by containingbases. High pH corrosive waste streams are usuallyneutralised by adding acids (http://www.epa.gov/epao-swer/osw/treatech.htm).Vitrification is a solidification process that combines

semi-liquid waste with glass, resulting in a stable glassform. In this process, highly radioactive liquid andsludge is mixed with glass particles and heated to veryhigh temperatures to produce a molten glass (http://web.em.doe.gov/em30/wasttrea.html).The physicochemical treatment plant will neutralise

inorganic hazardous waste, including cyanides, chro-mium waste, waste acids, waste alkalis, heavy-metalcontaining waste. The main methods used will becyanide oxidation, chromium reduction with subsequentsettling, settling of heavy metals, neutralisation of acidsand alkalis (http://www.zazemiata.org/bw/radnevo/re-sume_ovos_en.pdf). Physical removal is a process thatremoves the hazardous constituents from waste streamsby separation techniques such as ion exchange, adsorp-tion, reverse osmosis, chelation, solvent extraction,crystallisation, precipitation, distillation, filtration, eva-poration, etc. The removed hazardous constituents mayrequire further treatment to make them less toxic.Smelting is a technology employing high temperature

heating in order to recover metals from waste streams(e.g. lead, zinc). Steam stripping is a treatment

technology mainly applied towards removal of organiccompounds from liquid waste streams (http://www.e-pa.gov/epaoswer/osw/treatech.htm). Solid WasteReduction By reducing the volume of waste thatrequires disposal, DOE can use the existing storageand disposal sites for a longer period of time. Solidwaste reduction includes treatment methods that reducethe volume of solid waste such as incineration, com-paction and sizing (http://web.em.doe.gov/em30/wasttrea.html).

Composting

Composting is the most popular technology for treat-ment of organic wastes, as it can be applied to processwastes of widely varying origin, including animalmanures and mortalities, sewage sludges and municipaland industrial wastes (Lynch et al., 2006).Over the past few years, the dialogue between

compost producers and the agricultural communityhas increased reflective of the interest in determiningcompost’s many applications. Generally, compost as asoil amendment is known to provide many benefitsincluding improved soil structure, increased water-holding capacity, improved root and plant growth andreduced wind and water erosion (http://www.compost.org/pdf/ccc.rs.testing.compost.PDF).Composting is a decomposition of the organic,

biodegradable fraction of waste to produce a stableproduct such as soil conditioners and growing materialfor plants. Composting of garden and food waste hasbeen encouraged for home owners as a direct way ofrecycling. It has been extended to the larger scale forgreen waste from parks and gardens and also tomunicipal solid waste and to sewage sludge. The qualityof the compost produced from waste, compared withnon-waste sources, has been an issue for waste com-posting, particularly in the area of contamination(Williams, 2005). At the time the composting operationswere started, little trial data for agricultural cropsexisted for biowaste compost, and it was felt necessaryto investigate the performance of the material under soiland climate conditions, which are typical for theprospective compost market area (Erhart et al., 2005).The composting process is aerobic and consequently

relies on a plentiful supply of oxygen. Regular aerationis required to maintain aerobic conditions. The com-posting process may be characterised by three stages(Swan et al., 2002). The first stage is characterised byincreasing temperatures and involves a high rate ofmicrobiological activity. Simple carbohydrates andproteins are readily biologically degraded by mesophilicmicroorganisms, followed by thermotolerant and ther-mophilic microorganisms as the temperature rises above45 �C (Swan et al., 2002). The second stabilisation stageinvolves biodegradation of the waste by thermophilic

Table 3 Chemical analysis of corn stalk, corn cob and rice straw

(adapted from Demirbas & Sahin, 1998; Zhang & Zhang, 1999; Tsai

et al., 2001a,b; Singh & Sharma, 2002; Shuangning et al., 2005)

Parameter Corn stalk Corn cob Rice straw

Carbon 43.6 ± 0.5 45.8 ± 0.9 38.8 ± 0.4

Hydrogen 5.4 ± 0.2 5.5 ± 0.5 4.6 ± 0.05

Oxygen 42.3 ± 0.9 45.3 ± 0.9 43.7 ± 1.1

Nitrogen 0.6 ± 0.1 0.9 ± 0.3 0.46 ± 0.02

Cellulose 50.4 ± 7 50.2 ± 2.7 41.2 ± 3

Lignin 13.7 ± 1.1 14.5 ± 1.5 12.7 ± 2.1

Ash 0.9 ± 0.1 0.9 ± 0.2 20.5 ± 0.2



Table 4 Treatment methods, physicochemical characteristics, substrate to be applied and final product ⁄ uses

Substrate to

be applied

Treatment

methods Physicochemical characteristics Final products ⁄ uses Reference

Wheat straw, corn

cobs, barley husks

Adsorption Use of chemical (NaOH and NH4OH)

and physical treatments

(steam and milling)

to help break down the complex

lignin complex in order to improve

the performance of the substrates.

Soil conditioner

or fertiliser

Robinson

et al. (2002)

Corn cob, barley husk

and wheat straw

Adsorption Experiments were carried out statically

at room temperature, 20 ± 2 �CSoil fertiliser. Robinson et al. (2002)

Corn Composting The temperature of the

mixture rose to >40 �C within

1 week of the onset of composting

of CSC, and thermophilic phase

(>40 �C) temperatures were

sustained for the first 7

months of the 9 months

composting period.

Composting has long

been used

for management

of manure on farm

Lynch et al. (2006)

Corn cob Chemical activation

and pyrolysis

Impregnation ratio of 20–200 wt%

Heating rate of 10 K min)1

Pyrolysis temperature of 673–1073 K

Soaking time of 0.5–4.0 h

Raw materials for

preparing activated

carbons or

adsorbents to apply in the

removal of some

organic and inorganic

compounds from

liquid and gas phases

Tsai et al. (1998)

Corn stalk and

fresh wheat straw

Pyrolysis Pyrolysis temperature

Residence time

Bio-oil Shuangning

et al. (2005)

Corn straw and

wheat straw

Pyrolysis At low temperatures (400 K),

only equilibrium moisture

content and presumably

extractives are released, even

for very long residence

times of the solid.

Gas and volatile Lanzetta &

Di Blasi (1998)

Corn cob Pyrolysis The temperature was at 350–400 �C. Xylan from corn cob

is an additive in

papermaking, textile

printing and the

pharmaceutical industry.

Low-grade fuels

Cao et al. (2004)

Corn stover Pyrolysis High levels of temperature Biomass feedstock Green & Feng (2006)

Corn cob Gasification Temperature ranges of

500–800�C with less pollution

characteristics of potassium hydroxide:

potassium carbonate

(KOH:K2CO3) as chemical agents

and subsequent gasification

at the soaking time of 1 h.

Raw material for the

preparation

of activated carbon

Tsai et al. (2001a)

Corn starch Gasification The influence of process

variables like temperature

pressure, residence time and catalyst

on supercritical water

gasification of model compounds has

been investigated.

Feedstock D’Jesus et al. (2006)

Corn cob Chemical and

physical activation

Chemical activation with

potassium salts

Physical activation with CO2

Renewable source for

energy production

Tsai et al. (2001a)



Table 4 (Continued)

Substrate to

be applied

Treatment


Corn Combustion and

gasification

Carbon, hydrogen and mixed alcohols Renewable fuels Chum & Overend (2001)

Corn cob and

corn tar

Combustion Temperature range from 110 to 220 �C Burning oil of biomass (BOB) Zhang & Wang (2006)

Corn Combustion Combustion was carried out in a

high pressure stainless

steel oxygen bomb

with a capacity of 340 mL.

Renewable fuels Souza et al. (2002)

Corn stover Combustion To minimise the effect of water in the

biomass spectra, each

sample was air-dried to less

than 10% moisture prior to

NIR spectroscopic analysis.

Fuel or industrial feedstock Pordesimo et al. (2005)

Corn oil Biodiesel The engine was fuelled with

pure marine diesel fuel

and blends containing two types of

biodiesel, at proportions up to 50%.

Alternative fuels Kalligeros et al. (2003)

Corn Ethanol and biodiesel

production

Under relatively high prices for

gasoline the costs for

using ethanol and biodiesel are

much higher per

equivalent litre of gasoline.

Alternative liquid fuels

and ethanol production

Wesseler (2007)

Corn stover Biodiesel and

bioethanol

When corn stover is harvested,

ethanol is produced from both

corn stover and corn grain.

Biofuels Kim & Dale (2005)

Corn cob Pyrolysis Pyrolytic temperatures below 600 �C at

the heating rate of 30 K ⁄ rain.

Liquid products of biomass Cao et al. (2004)

Corn oil and

wheat germs

Chemical method Use of different antioxidants

Ascorbyl palmitate (0.02% w ⁄ w)

BHA

Tert-butyl-4-hydroxyanisole (0.02% w ⁄ w)

Different amounts of solvent extracts, to

25 g of stripped corn oil or plant oils.

Edible products as corn oil Krings et al. (2000)

Corn Bioremedation Varying pH (4.5–7.5)

Temperature between 35 and 55 �CMethane and hydrogen

Biofuels

Montgomery (2004)

Corn cob

agrowaste

Chemical activation Physical activation involves the

carbonisation of a carbonaceous

precursor followed by the

gasification of the resulting

char in the presence of suitable

oxidising gasifying

agents such as CO2 and steam

at high temperatures.

Chemical preparation with ZnCl2.

Renewable source for

energy production

Chang et al. (2000)

Corn husks Enzyme preparation pH 5.0

Temperature 50 �CEnzymatic production

of soluble sugars

Hang & Woodams (1999)

Corn cobs Enzyme preparation Pretreated with NaOH

Followed by 48 h of reaction

Temperature 50 �CpH 5.0

Enzymatic production

of reducing sugars

Hang & Woodams (2001)

Corn cob and

wheat straw

Biodegradation Xylanase, glucanase, cellulase,

Phanerochaete

chrysosporium NRRL 6359,

P. chrysosporium

NRRL 6361 and Coriolus

versicolor NRRL 6102

Production of enzymes Abd El-Nasser et al. (1997)



Table 4 (Continued)

Substrate to

be applied

Treatment


Corn stover Chemical activation Heat loss in a 1.26 m

pipeline carrying 2M dry

tonnes per year is about 5 �C

Production of ethanol

and sugars

Kumar et al. (2005)

Corn stover Radiation Gamma irradiation of corn

stover in combination

with sodium hydroxide

for bioconversion

of polysaccharide.

Fertiliser for the production

of Pleurotus spp.

Gbedemah et al. (1998)

Corn hull

and orn

stover

Physical activation Temperatures around 800 �C Activated carbon Zhang et al. (2004)

Corn cob Chemical activation Many chemicals can be used

as activators such as ZnCl2,

H3PO4, KOH, K2CO3,

water vapour, CO2.

Renewable fuels Cao et al. (2006)

Rice straw Composting EC, pH were measured in

the aqueous extracts

of rice straw, oilseed rape

cake, poultry manure

and compost in a solid:

distilled water of 1:20

(w ⁄ v dry weight basis).

Composting of rice straw with

oilseed rape cake and poultry

manure effects faba bean

(Vicia faba L.) growth

and soil properties.

Abdelhamid et al. (2004)

Rice straw Composting Temperature, aeration,

moisture and nutrients

should be appropriately

controlled.

It is considered C ⁄ Nratio at 25–30 as the

initial optimum ratio for composting.

The mixture of swine

manure with rice

straw is used as fertiliser

Zhu (2007)

Rice flakes Composting (NH4)2SO4 4 mg gds)1

MgSO4 Æ7H2O 1 mg ⁄ gds

FeSO4 Æ 7H2O 0.02 mg ⁄ gds

K2HPO4 1.4 mg ⁄ gds

KH2PO4 0.6 mg ⁄gds. pH 7

Edible products Anto et al. (2006)

Rice straw Composting The C ⁄ N ratios were

the lowest (17–24)

A temperature of 62 �Cduring 48 h removed

pathogenic microorganisms

from rice straw

Paper production, construction

materials, incorporation in soil,

compost, energy source,

animal feed, etc.

Iranzo et al. (2004)

Rice straw Pyrolysis Moisture 13.61% wt.

Pyrolysis temperature of 400–800 �CFuel gases, liquids and solids Tsai et al. (2006)

Rice husk Pyrolysis Temperature 250–550 �C Source of thermal energy. Sharma & Rao (1999)

Rice husk Pyrolysis Temperature 1300–1500 �C Fuel gases Martinez et al. (2005)

Rice straw Pyrolysis Moisture 7.16%wt Raw material for paper industry,

or as animal feed sources.

Bio-oils

Putun et al. (2004)

Rice husk

and straw

Combustion The influence of different variables

such as temperature,

fluidisation velocity on the

combustion efficiency

and CO emissions was investigated.

Fuels Armesto et al. (2002)

Rice husk Combustion Moisture 16.92%wt

Temperature is 340 �CRenewable fuels Fang et al. (2004)



microorganisms and is an exothermic process so thattemperature in the compost pile can reach up to 70 �C.The high temperature stage involves the thermaldestruction of weed seeds and pathogenic microorgan-isms. The compost also includes a third maturationstage and is characterised by lower temperatures(Williams, 2005). The final stages of composting wouldbe processes such as sieving and grading to removenon-composted materials and contaminants.Composting is commonly used to improve the prop-

erties of manures for organic farming. Available N inraw manure is immobilised during optimal compostingallowing more stable slow release of N forms for crops(Vuorinen & Saharinen, 1997). High quality compost isincreasingly available and it offers farmers considerablebenefit when used on land – in a way that othermaterials, whether conventional fertilisers or wastessuch as sludges, do not. Users of compost should ensurethat material complies with an accredited standard,most commonly UK BSI PAS1002. Good qualitycompost is a valuable and safe resource, not a wasteproduct. As a general principle, all material such ascompost that has significant fertiliser value should beapplied only up to the level of crop requirements.However, the way in which compost can be used isdifferent when compared with mineral fertilisers. Toidentify the use-thresholds it is important to understandthe nature of compost (http://www.remade.org.uk/organics/organics_documents/compostbenefitsscottishcrops.pdf).During composting, putrescible material is progres-

sively broken down by microorganisms in a series ofdistinct stages. In the mesophilic stage, microorganismsbegin to actively break down the organic material, thetemperature of the composting material rising to around50 �C in about 2 days. During the second or thermo-philic stage, temperatures begin to rise so that only themost temperature resistant microorganisms survive. Inthe third stage, the material continues to cool and

microorganisms begin to complete for the remainingorganic material, in turn leading to breakdown ofcellulose and lignin in the waste. During the final levelsof microbial activity continue to fall as the remainingorganic material is broken down and the microorgan-isms die as their food sources deplete (Harrison, 2001).Turning compost is important as it ensures proper

mixing, wetting, aeration and decomposition. The com-post heap is allowed to settle for 1 month, and thenturned using pitch forks. Material on the top of the heapand along the edges is laid on the ground first, followedby the materials in the middle of the heap. Materialsat the bottom are then placed at the top of the heap(http://www.formatkenya.org/ormbook/Chapters/chapter9.htm).Because much C from plant residues such as straw

materials is only slowly available to micro-organisms,leading to low growth efficiency, a limited amount of Nmay be required during decomposition, and recycling ofN may then be adequate to meet the N requirements.Micro-organisms, especially fungi, have a considerablecapacity to adapt to N deficient conditions. A largeamount of N initially could consequently result inimmobilisation. This greater N immobilisation maydepend on (a) synthesis of microbial biomass with alower C ⁄N ratio; (b) higher N losses; or (c) reduced Nmineralisation or re-mineralisation, which may havebeen related to reduced microbial activity (Dresbøll &Thorup-Kristensen, 2005).Composting of urban waste has emerged as a valuable

alternative because of the high proportion of organicmatter in urban waste. The bio-degradable fraction isestimated at about 25% (fresh weight) in France, alongwith an additional 25% made up of paper andcardboard. Composts have long been used in agricultureand urban waste composts may be applied in arablefields as organic amendment to maintain soil organicmatter (SOM) as well as supply nutrients to crops(Gabrielle et al., 2005). Organic wastes make up a large

Table 4 (Continued)

Substrate to

be applied

Treatment


Rice straw Combustion Temperature 575 �C Fuel Bakker & Jenkins (2003)

Rice husk Pyrolysis The optimum temperature is 400 �C Fodder for livestock

and industrial

fuel for boilers

Maiti et al. (2006)

Rice husk Combustion Temperature ranging between 300 and 700 �CpH about 7

Renewable source of

thermal energy

Liou (2004)

Rice husk Combustion Temperature range of 450-550 �C Liquid fuel Zheng et al. (2006)

Rice straw Biogas 2% formalin

0.1% KMnO4

Fertiliser for the production

of Pleurotus sajor caju

Banik & Nandi (2004)

Rice husk Gasification High moisture content (10.0% wt)

Low heating value (HHV 3450 kcal kg)1)

Renewable source of energy Lin et al. (1999)

Rice husk Gasification Temperature range of 200 ± 1372 �C Fuel gas Mansaray et al. (1999)



part up to 40%- of the municipal solid waste stream.Therefore, organic wastes should be recycled from anecological as well as from an economical point of view.In the late 1980s, composting of separately collectedorganic household wastes was introduced in Vienna andsubsequently a municipal composting plant was set up.As a result of extensive quality control measures, allcompost lots produced were suitable for agriculture and22% even for organic farming. With wheat, a wide rangeof yield responses to compost fertilisation has beenrecorded. Non-significant wheat yield increases followedthe application of 6.9 t ha)1 biowaste compost on aparabrown soil in Germany (Erhart et al., 2005).Control of a composting process and the properties of

the end product can be achieved by at least two differentstrategies. One strategy is to adjust process parameters,such as moisture level, temperature or oxygen content.Another is to alter the starting conditions by changingthe composition or type of material used so that C ⁄Nratio or fibre composition is changed (Dresbøll &Thorup-Kristensen, 2005). Compost is likely also tocontain a wide range of minor plant nutrients andbeneficial microbes not normally present in mineralfertilisers. Together these are likely to have an additivepositive effect on general soil ‘health’. Composts derivedfrom segregated wastes are generally acceptably low inheavy metals and compost complying with an appro-priate standard will have data to confirm this(http://www.remade.org.uk/organics/organics_documents/compostbenefitsscottishcrops.pdf). Composted solidsare usually dark brown to black, but the colour mayvary if bulking agents such as recycled compost or woodchips have been used in the composting process. Theodour of well-composted solids is inoffensive andresembles that of commercial garden-type soil condi-tioners (Tchobanoglous et al., 2003).The remaining nutrient rich material should be added

later in the process when the turnover of the wheat strawwould already be proceeding. Decomposition of thenewly added material would then result in less Nimmobilisation compared with compost produced by asingle addition at the beginning of the process (Dresbøll& Thorup-Kristensen, 2005).Decomposition of plant tissue depends on various

factors including temperature, moisture content, oxygencontent and residue quality. In general, both resourcequality and physiochemical parameters affect thecomposition and activity of the decomposer commu-nities conducting the mineralisation ⁄ immobilisationprocesses of decomposition. Thus, when producingplant based compost to be used as growing medium inhorticultural productions choice of plant material is akey factor, as root proliferation and developmentdepend heavily on the physical structure and stabilityof the medium. The physical properties are mainlydependent on the starting material and are difficult to

alter during strongly affected by production (Catonet al., 1999). Nitrogen was often recognised as a limitingfactor for microbial growth and activity during thedecomposition of plant residues, especially in materialswith a high C ⁄N ratio such as wheat straw. However,experiments on the effect of additional N supply on thedecomposition of plant residues showed differentresults, ranging from positive to negative effects on thedecomposition rate (Dresbøll & Thorup-Kristensen,2005).Organic compost from waste may be used for various

purposes, among which are soil recovery, commercialproduction, pastures, lawns and reforestry and agricul-ture. However, the quality of compost determines theplant growth and development of plants. The effect ofcompost made from urban waste on corn plant (Zeamays L.) growth was investigated. Two types of compostwere used: the selected compost, produced from organicwaste selectively collected; and the non-selected com-post. Chemical analyses of the compost and growthproperties of the plant like chlorophyll content; heightand stem diameter; aerial and radicular dry biomasseswere used to evaluate compost quality (Lima et al.,2004).However, a technical difficulty was the lack of a

reliable and inexpensive methodology to examine thefate of compost in soil and to quantify compost effectson SOM. Organic amendments often supply muchgreater C inputs to soil than are derived from cropresidues. Relatively few studies applied the d13C tech-nique to improve our understanding of the transforma-tion, utilisation and stabilisation of amendment carbonin soil. However, the high degree of microbial processingoccurring during composting of organic amendmentsreduced the inherent variability of their 13C signature,an aspect of composting which had not been examined(Lynch et al., 2006). Composting temperature is influ-enced by moisture content, degree of aeration, size andsize of the pile, and climatic conditions, particularly airtemperature and rainfall. The finished compost is friablehumus with moisture content less than 40%. Althoughtoo low in nutrients to be considered a fertiliser,compost is an excellent soil conditioner. For example,when mixed with soil, the added humus content increa-ses the capacity for retention of water (Hammer &Hammer, 2004).

Pyrolysis

Pyrolysis (PY) is the first and most basic thermo-chemical step to convert biomass into gaseous or liquidfuels. However, despite the fact that PY underlieshumankind’s oldest technology (the use of fire) PY isstill not a predictive science (Green & Feng, 2006). PY isthe decomposition of a complex organic substance toone of a simpler structure by means of heat in the



absence of oxygen or any other reagents, except possiblysteam. Some polymers will depolymerise in the presenceof excessive temperatures either to polymers of lowermolecular weight, or back to the monomers from whichthey were derived (http://composite.about.com).Pyrolysis typically occurs under pressure and at

operating temperatures above 430 �C. In practice, it isnot possible to achieve a completely oxygen-free atmo-sphere. Because some oxygen is present in any PYsystem, a small amount of oxidation occurs. If volatileor semi-volatile materials are present in the waste,thermal desorption will also occur (http://www.cpeo.org/techtree/ttdescript/pyrols.htm). PY isthermal degradation of waste in the absence of air toproduce char, PY oil and syngas, e.g. the conversion ofwood to charcoal (http://www.juniper.co.uk/services/Our_services/P&GFactsheet.html). The manner, inwhich PY works, offers some advantages over conven-tional incineration. Firstly, because no air is fed into thecombustor, far less waste gases are produced andtherefore the gas cleaning system can be smaller andhence less costly. Secondly, the waste itself must be pre-prepared to make it homogeneous and to remove bulkymaterials. Finally, in theory the solid, liquid and gaseousstreams can be further processed into useful productsand hence there should be less material to discard tolandfill (Harrison, 2001).Organic materials are transformed into gases, small

quantities of liquid and a solid residue containingcarbon and ash. The off-gases may also be treated in asecondary thermal oxidation unit. Particulate removalequipment is also required. Several types of PY units areavailable, including the rotary kiln, rotary hearthfurnace or fluidised bed furnace (http://www.cpeo.org/techtree/ttdescript/pyrols.htm). Flash PY gives high oilyields, but because of the technical efforts required toprocess pyrolytic oils this energy generating system doesnot seem to be very promising at the present stage ofdevelopment. However, PY as a first stage in a two-stagegasification plant for straw and other agriculturalfeedstocks posing technical difficulties in gasificationdoes deserve consideration (http://www.tab.fzk.de/en/projekt/zusammenfassung/AB49.htm).Pyrolysis is usually consindered to be anhydrous and

occuring whenever solid organic material is sufficientlyheated, e.g. when frying, roasting, baking, toasting. Theprocess also occurs when burning compact solid fuel,like wood. In fact, the flames of a wood fire are as aresult of combustion of gases released by PY, notcombustion of the wood itself. Thus, the PY of commonmaterials like wood, plastic and clothing is extremelyimportant for fire safety and fire fighting (http://en.wikipedia.org/wiki/Pyrolysis).Pyrolysis is an interesting degradative technique

because it can be easily coupled to gas chromatography(GC), mass spectrometry (MS) or GC ⁄MS thus allowing

the online degradation of polymers and the analysis oftheir fragments by hyphenated techniques such asPY ⁄GC, PY ⁄GC ⁄MS or PY ⁄MS (Rodriguez et al.,1997). The PY products identified were mostly relatedto carbohydrates (furans), proteins (nitriles and pyrrols),chitin (pyridines and pyrazols), lipids (alkanes andderivatives of benzene) and lignin (phenols). The relativeyield of all individual PY products was similar in thesamples from the maize (C4) and control wheat (C3) soil.In detail the 23-year maize cropping added 2-methylfu-ran, pyridine and xylene but, on the contrary, decreasedthe content of furan-3-carboxaldehyde and phenol(http://dbs.clib-jena.mpg.de/dbs-publ/pubi/bgc/BGC0130.pdf).Some of the main objectives were to characterise and

study the preparation of biomass to meet the necessaryspecifications to be used for bio-oil production in therotating cone PY technology. This included selection ofa number of relevant biomass materials based onprimary criteria such as their high availability in theEU and low production costs (http://www.biomat-net.org/secure/Fair/F538.htm).Bio-oil from fast PY is in many ways different from

other liquid fuels (such as rape seed oil or bio ethanolderived) from biomass like. It also differs significantlyfrom diesel fuel in both physical properties and chemicalcomposition. Bio-oil contains water and solids; it isacidic and has a low calorific value (http://www.dynamotive.com/biooil/technology.html).Fast PY process that converts forest and agricultural

residue (including bark) into liquid Bio-oil and char. Bio-oil is a clean burning, greenhouse gas neutral fuel thatwill initially be used to replace fossil fuels to generatepower and heat in stationary gas turbines, diesel enginesand boilers and to replace natural gas in the forestindustry and to replace another product in the coalindustry. The char is a high heating value solid fuel thatcan be used in kilns, boilers and the briquette industry.Three products are produced: Bio-oil (60–75% wt), char(15–25% wt) and non-condensable gases (10–20% wt)(http://www.biomatnet.org/secure/Fair/F538.htm).Fast PY refers to the rapid heating of biomass

(including forest residue such as bark, sawdust andshavings; and agricultural waste such as wheat strawand bagasse) in the absence of oxygen. It useda bubbling fluidised bed reactor (FBR), which isconsidered to be a simpler and more robust processthan other PY technologies under development (http://www.dynamotive.com/biooil/technology.html).Thermogravimetric analyzers (TGA) were one of the

main techniques used in analyzing the characteristics ofsolid fuel volatilisation at lowheating rates. The maxi-mum heating rate of TGA could reach as high as100 LC min-1. For years, PY and combustion reactionsof pulverised biomass were investigated in variousapplications using TGA (Shuangning et al., 2005).



Understanding PY kinetics is important for the effectivedesign and operation of the thermochemical conversionunits given that solid devolatilisation is always afundamental step. The TGA technique has been appliedin several cases for such a purpose. Thermogravimetriccurves for wheat, barley, oats and rye straw have beenmeasured in both inert and oxidising atmospheres. Interms of global kinetics, (for all types of straw), twodistinct reaction zones are detailed, the thermal degra-dation rates of the first zone is higher than the second(Lanzetta & Di Blasi, 1998). The pyrolyser consistsbasically of a rotating, vertically orientated, electricallyheated disk. Solid wood boards with a cross sectionalarea of 10 · 47 mm and a length of approximately350 mm are pressed against the disk by a piston. Thepressure ranges between 30 and 50 bar, and the heateddisk temperature is approximately 700 �C (http://www.pyne2005.inter-base.net/docs/PyNews%2017.pdf).The core of the PY pilot plant is the rotating cone

reactor which is a compact high intensity reactor inwhich biomass of ambient temperature is mixed with hotsand. Upon mixing with the hot sand at 550 �C thebiomass decomposes providing 70 weight per centcondensable vapours, 15 weight per cent non-conden-sable gases and 15 weight per cent char. During theBiomass Technology Group (BTG) and KARA projectsa fully automated PY plant with a capacity of260 kg h)1 was successfully designed and constructed.This was operated over a number of trial periods, duringwhich the following conditions were established as thosethat gave the highest oil yield and produced the bestquality bio-oil: (a) reactor temperature of 470 �C, (b)vapour residence time<one second and (c) biomassparticles<4 mm (http://www.biomatnet.org/secure/Fair/F538.htm).Based on the differences in isotopic enrichment of

chemical structures after vegetation change the PYproducts could be divided into three groups: (a) PYproducts with a nearly complete C4 signal, e.g. phenol,derived from lignin degradation products, (b) PYproducts with an intermediate isotopic enrichment of6–8 per thousand, most likely to be a composite ofremaining fragments derived from both maize andnative wheat and (c) PY products showing only lowenrichments in 13C of 1–3 per thousand. Most of theirprecursors were found to be proteinaceaous materials.This indicated that proteins or peptides were indeedpreserved during decomposition and humification pro-cesses occurring in the soil. Our study highlights thepotential of Py–GC ⁄MS-C-IRMS to further novelinsights into the dynamics of soil organic constituents(Gleixner et al., 1999).Insight at the chemical structure of complex biomac-

romolecules can be obtained via pyrolytic studies andthis technique has been applied to a large range ofnatural compounds. Among the various methods used

for isolating lignin-containing materials from biomass,the one affording the so-called ‘ligno-cellulosic sub-strate’. This material was obtained from wheat straw bysuccessive acid and base treatments (Gauthier et al.,2003). PY in the presence of tetramethylammoniumhydroxide (TMAH) has been used to analyse phenolicacids, natural resins, resinites, humic acids, asphaltenes,kerogens, lignins and organic matter in nearshoremarine sediments. PY of lignin in the presence ofTMAH induces cleavage of propylaryl ether bonds andmethylation of hydroxyl (OH) groups located on bothalkyl side chains and aromatic rings. The techniqueavoids decarboxylation of polar moieties and yieldsphenolic derivatives, which are not observed duringconventional analytical PY (Vane et al., 2001). Com-bined Py ⁄GC ⁄MS of complex macromolecular materialscan provide detailed structural information but sufferslimitations for the identification of compounds compri-sing polar functional groups like carboxylic and OHgroups. This technique is improved by introducingthermochemolysis with telramethylammonium hydrox-ide, TMAH thermochemolysis corresponds to a therm-ally-assisted chemolytic degradation rather thandegradation simply induced by thermal bond cleavage.In addition, in situ methylation occurs so that a numberof polar products become volatile enough for gaschromatographic analysis (Gauthier et al., 2003).Analytical PY is one of the many tools utilised for the

study of natural organic polymers. Analytical PYmethodology covers two distinct subjects, the instru-mentation used for PY and the analytical methods thatare applied for the analysis of the PY products. Avariety of pyrolytic techniques and of analytical instru-ments commonly coupled with PY devices are given(http://www.elsevier.com/wps/find/bookdescription.cws_home/600279/description#description). The term PY issometimes used to encompass also thermolysis in thepresence of water, such as steam cracking of oil, or moregenerally hydrous PY. An example of the latter isthermal depolymerisation of organic waste into lighcrude oil (http://en.wikipedia.org/wiki/Pyrolysis).The applications of analytical PY included topics such

as polymer detection used for example in forensicscience, structure elucidation of specific polymers, andidentification of small molecules present in polymers(anti-oxidants, plasticisers, etc.). In addition, the degra-dation during heating is a subject of major interest inmany practical applications regarding the physicalproperties of polymers (http://www.elsevier.com/wps/find/bookdescription.cws_home/600279/description#description). Analytical methods based on PY-GCcoupled to MS present great potential because of thesmall amount of sample necessary for analysis and thetype of information provided (Camarero et al., 2001).Analytical PY was shown to be very effective in thecharacterisation of lignins, where most of the pyrolytic



fragments are not secondary rearrangement products,but diagnostic compounds in which the structure of themain building blocks of the macromolecule is preserved.In this way, a semiquantitative assessment of themonomer composition for the different lignin typescan be made: in fact, PY combined with GC and MSproved to be a valuable tool for the analysis of pulpsamples (Galletti et al., 1997).Pyrolysis was carried out at 600 �C for 5 s. Py–GC

interface was set at 200 �C. The GC column was a SPB-5 and was operated from 50 to 290 �C at 5 �C min)1,holding the initial temperature for 10 min. The injectorwas set at 250 �C in the split mode. Mass spectra wererecorded under electron ionisation at 70 eV, spectralrange from 40 to 450 m:z, 1 scan per s. To optimise Py–GC:MS quantitation of lignin and polysaccharide PYproducts correction factors for the use of 1,3,5-tri-tert-butylbenzene as internal standard were obtained fordifferent phenolic standards (Martinez et al., 2001). PYand gasification are thermal processes that usehigh temperatures to break down any waste contain-ing carbon (http://www.foe.co.uk/resource/triefings/gasifications_pyrolysis.pdf).Pyrolysis yields of carbon products prepared from

agricultural waste corn cob by chemical physical acti-vation are presented in Fig. 1 and element analysis ofrice husk heat treated under pyrolytic conditions atdifferent temperature is given in Figs 2 and 3. A systemboundary in the various cropping and alternativeproduction systems is presented in Fig. 4. Materialand energy balances of the rice husk gasification processand flow sheet of rice husk fluidised bed fast PY andfluidised bed fast PY catalytic treatment processes aregiven in Figs 5 and 6, respectively.

Gasification

The gasification process breaks down the hydrocarbonsleft into a syngas using a controlled amount of oxygen.Gasification and PY typically rely on carbon-basedwaste such as paper, petroleum based wastes like

plastics, and organic materials such as food scraps.Gasification involves a small amount of oxygen whereasPY uses none (http://www.foe.co.uk/resource/triefings/gasifications_pyrolysis.pdf).Gasification can be used in conjunction with gas

engines (and potentially gas turbines) to obtain higherconversion efficiency than conventional fossil-fuel en-ergy generation (http://www.juniper.co.uk/services/Our_services/P&GFactsheet.html). Gasification in-volves subjecting solid biomass to hot steam and air toproduce a gaseous biofuel. This gas, often known as‘synthesis gas’ may be burnt directly for heating and ⁄orelectricity production, or may be further converted toact as a substitute for almost any fossil fuel. Theadvantage of gas, over biomass, is that it is a ‘better’fuel, having a higher calorific value, and being moreeasily stored and transported (http://www.ecocentre.org.uk/biomass.html).The gasification process was originally developed in

the 1800s to produce town gas for lighting and cooking.Natural gas and electricity soon replaced town gas forthese applications, but the gasification process wereutilised for the production of synthetic chemicals andfuels since the 1920s. Gasification relies on chemicalprocesses at elevated temperatures >700 �C, contraryto biological processes such as anaerobic fermentation(digestion) which releases biogas (http://en.wilipedia.org/wiki/Gasification).

05

10152025303540

500 600 700 750 800Activation temperature

Pyr

oly

sis

yiel

ds

Figure 1 Pyrolysis yields of carbon products prepared from agricul-

tural waste corn cob ( for KOH activating agent, ; for K2CO3

activating agent) by chemical physical activation (adapted from Tsai

et al., 2001a,b).

01020304050607080

150 350 450 550 650 750Temperature

Ele

men

ts

Figure 2 Elemental analysis of rice husk heat treated (¤ for C, for H

and m for N) under pyrolytic conditions at different temperatures

(adapted from Maiti et al., 2006).

010203040506070

150 350 450 550 650 750Temperature

Ele

men

ts

Figure 3 Elemental analysis of rice husk heat treated (¤ for O-dry ash

free and for dry ash) under pyrolytic conditions at different

temperatures (adapted from Maiti et al., 2006).



The gasification of herbaceous biomass is still at anearly stage of research and development. Intensifieddevelopment efforts on gasification technologies forherbaceous biomass feedstocks are desirable as thepotential supply of this group of fuels is comparativelylarge (http://www.tab.fzk.de/en/projekt/zusammenfas-sung/AB49.htm). A wide range of biomass fuels suchas wood, charcoal, wood waste (branches, roots, bark,saw dust) as well agricultural residues- maize cobs,coconut shells, cereal straws, rice husks, were used asfuel for biomass gasification. Theoretically, almost allkinds of biomass with moisture content of 5–30% can begasified; however, not every biomass fuel lead to thesuccessful gasification. Most of the development workwas carried out with common fuels such as coal,charcoal and wood (http://mitglied.lycos.de/cturare/fue.htm).The gasification technologies developed by competing

suppliers of gasification power plants, are based eitheron fixed bed gasification or fluidised bed gasification. Inboth cases, a limited number of commercial runningplants is present. In fixed bed gasification reactors, thefuel is fed into the top of a vertical reactor. The fuel istransported downwards by gravity while undergoing thegasification reactions (http://www.ecn.nl/docs/library/report/2000/c00080.pdf).Compared with other biomass energy conversion

technologies, supercritical water gasification (SWG) isthe most efficient one for biomass with a high moisturecontent (40%). In spite of the high pressure and hightemperature required for biomass conversion withsupercritical water the process is technically feasible,because tubular or slim vessel type reactors can be used(D’Jesus et al., 2006). The fuel size affects substantiallythe pressure drop across the gasifier and power thatmust be supplied to draw the air and gas throughgasifier. Large pressure drops will lead to reduction ofthe gas load in downdraft gasifier thus resulting in lowtemperature and tar production. Excessively large sizes

of particles give rise to reduced reactivity of fuel, causingstart-up problem and poor gas quality. In general, woodgasifiers work well on wood blocks and wood chips

Downdraftgasifier

Electric power10 KW

Internal combustionengine

Tar/waterabsorbent

Tar (108 g h–1)

Carbon (7.84 kg h–1)

Syngas (54 000 L h–1)

Carbon3.11 kg h–1

Ash4.67 kg h–1

Water2.8 kg h–1

Carbon10.95 kg h–1

Air

Rice husk28 kg h–1

Water (14.77 kg h–1)

Figure 5 Material and energy balances of the rice husk gasification

process (adapted form Lin et al., 1999).

Corn culture

Corn stover processCorn stover

Edible oil

Liquid fuel

Ethanol

Corn oilCorn gluten mealCorn gluten feed

Wet milling

Export to power grid

Liquid fuel

Ethanol electricity

Corn grain

Figure 4 System boundaries in the various

cropping and alternative production systems

(adapted from Seungdo et al., 2005a, b).



ranging from 80 · 40 · 40 mm to 10 · 5 · 5 mm. Forcharcoal gasifier, charcoal with size ranging from10 · 10 · 10 mm to 30 · 30 · 30 mm is quite suitable(http://mitglied.lycos.de/cturare/fue.htm#size).The electric efficiency of a gasification plant is directly

related to the cold gas efficiency of the gasifier. Thisparameter is mainly determined by the carbon conver-sion, the heat loss of the reactor and the fuel gastemperature leaving the reactor. Fixed bed reactorsgenerally show a lower carbon conversion but also havea lower exit temperature of the gas. The heat loss shouldbe lower as the specific surface (m2 ⁄m3) is lower (http://www.ecn.nl/docs/library/report/2000/c00080.pdf).The influence of process variables like temperature

pressure, residence time, and catalyst on SWG of modelcompounds was investigated. The best hydrogen yieldfor the SWG of sawdust and different starches wasreached at high temperatures. The same important effect

of the temperature has been reported in other publica-tions (D’Jesus et al., 2006).One of the major advantages of BIVKIN-technology

over fixed bed technology involves the superior fuelflexibility. BIVKIN-technology was demonstrated to besuitable to handle a broad range of feedstocks withvarying moisture content and physical shape. Fixed bedgasifiers do require properly sized wood chips, bri-quettes or pellets with a defined moisture content. Incase of pellets, high quality standards were set regardingthe mechanical strength of pellets at high temperatures.This mechanical strength would probably not be realisedfor all kinds of feedstock. Not only expensive pre-treatment steps can be omitted in the case of fluidisedbed compared with fixed bed processes, but long-termcontracts with fuel suppliers may not be necessaryanymore as the fuel input is flexible (http://www.ecn.nl/docs/library/report/2000/c00080.pdf).

Rice husk

Catalyst

Pyrolysis oil

Liquidcollector

Condenser

CatalyticReactor

Liquidcollector

Condenser

Cyclone

Char

Char collector

Fluidized bed reactor Feeder

DrierSieveGrinder

Cokedcatalyst

GAS

Cyclone

Regeneration

Figure 6 Flow sheet of rice husk fluidised

bed fast pyrolysis and fluidised bed fast

pyrolysis catalytic treatment processes

(adapted from Islam et al., 2004a, b).



The moisture content of the most biomass fueldepends on the type of fuel, it’s origin and treatmentbefore it is used for gasification. Moisture content of thefuel is usually referred to inherent moisture plus surfacemoisture. The moisture content below 15% by weight isdesirable for trouble free and economical operation ofthe gasifier (http://mitglied.lycos.de/cturare/fue.htm#moisture). The form in which fuel is fed to gasifier hasan economical impact on gasification. Densifying bio-mass has been practiced in the US for the past 40 years.Cupers and Pelletisers densify all kinds of biomass andmunicipal waste into ‘energy cubes’. These cubes wereavailable in cylindrical or cubic form and had a highdensity of 600–1000 kg m-3. The specific volumetriccontent of cubes was much higher than the raw materialthey were made from (http://mitglied.lycos.de/cturare/fue.htm#form).Corn has a high energy content and high organic

matter yield (per hectare). Corn silage is chemicallystable because it does not degrade and maintains itsproperties over long period of time. Corn silage isavailable all year through thereby preventing shortagesin the continuous production of hydrogen from bio-mass. As a result of all these advantages, corn silage is afeedstock suitable for an industrial SWG process. Tooptimise the process of SWG of biomass, the influenceof the process variables on the gasification of realbiomass feedstock like corn were studied. A down-flowreactor (1000 mm long and 8 mm inner diameter) withpreheater (250 mm long and 8 mm inner diameter) wasused for investigating the influence of temperature oncorn silage the gasification with the aim of improvinggasification yield and reducing the problems of solidformation (D’Jesus et al., 2006).Energy content of fuel is determined in most cases in

an adiabatic, constant volume bomb calorimeter. Usingthis method higher heating values were obtained becausethe condensation heat from water formed in thecombustion of fuel was included. Heating values arealso reported on moisture and ash basis. Fuel of higherenergy content is always better for gasification. Mostbiomass fuels (wood, straw) have heating values in therange of 10–16 MJ kg-1, whereas liquid fuel (diesel,gasoline) display higher heating value (http://mitglied.lycos.de/cturare/fue.htm#energy).

Combustion

The combustion of biomass is considered a three stepprocess; devolatilisation to char and volatiles, andcombustion of volatiles and char. A number of param-eters are required as inputs to existing computationalfluid dynamics (CFD) particle combustion models, suchas devolatilisation yields and rates, composition ofvolatiles, amount of char formed and char burningrates (Jones et al., 2000).

Although combustion involves complicated chemicalreactions and fluid dynamical processes, including thedevelopment of instabilities, the team had a high degreeof experimental control over combustion and couldstudy it in detail by using a two-dimensional chamberthat prevented convection (http://www.esam.northwest-ern.edu/~matkowsky/fingering.html).The combustion gases typically pass though a boiler

system to recover energy. The most flexible means ofrecovering energy from the hot gases is to produce steamfor direct use or for electricity generation. To generateelectricity, superheated steam is passed from the boilersystem to a turbine generator (Harrison, 2001). Duringcombustion, all fuel is converted to a hot gas (flue gas),which can be used to generate steam in a boiler andsubsequently generate electricity in a steam turbine ⁄gen-erator. The electric efficiency is mainly the result of theefficiency of the steam turbine. Fuel gasification resultedin production of a combustible fuel gas (http://www.ecn.nl/docs/library/report/2000/c00080.pdf).The use of an elevated pressure of oxygen inside a

closed metal container in the form of oxygen bombcombustion is an alternative procedure for completeoxidation of biological samples. Combustion with oxy-gen in sealed bomb was used to convert solid and liquidcombustible samples into soluble forms for chemicalanalysis. In this system, the organic matter was oxidisedto carbon dioxide and water by the combustionreaction, and the volatile components, formed byburning, are trapped in an absorption solution (Souzaet al., 2002).The off-gases containing volatile organic compounds

(VOCs) from covered treatment facilities will have to betreated before they can be discharge to the atmosphere.Options for the off-gas treatment include: (a) vapour-phase adsorption on granular activated carbon or otherVOC selective resins, (b) thermal incineration, (c)catalytic incineration, (d) combustion in a flare, (e)biofiltration and (f) combustion in a boiler or processheater (Tchobanoglous et al., 2003). Nitrogen freed bycombustion at high temperature in pure oxygen wasmeasured with thermal conductivity detection andconverted to equivalent protein by appropriate numer-ical factor. Any instrument or device designed todetermine nitrogen by combustion may be used provi-ded it is equipped as follows: (a) furnace to maintainminimum operating temperature of 950 �C for PY ofsample in pure (99.9%) oxygen, (b) system to isolateliberated nitrogen gas from other combustion productsfor subsequent determination with thermal conductivitydetector, (c) detection system to interpret detectorresponse as % nitrogen (weight ⁄weight). Other featurestentatively included are calibration on standard mater-ial, blank determination and barometric pressure com-pensation (http://www.foragetesting.org/lab_procedure/sectionB/3/part3.3htm).



The world has for sometime witnessed growing con-cern over the environmental impact and ⁄or exhaust ofconventional fossil fuel energy sources. The concern hashighlighted the need for diversification and promptedresearch world-wide into potential alternative sources offuel energy for internal combustion engine. Environ-mental well-being requires a modified mix of energysources to emit less carbon dioxide, starting with a moveto wards alternative fuels (Zhang & Wang, 2006).Such propagation of combustion waves is called

filtration combustion. The latter is of great importancebecause it occurs not only in natural processes such assmoldering and underground fires, but also in coalgasification, the self-propagating high-temperaturesynthesis of materials, regeneration of coked catalysts,calcination and agglomeration of ores, oil extractionand waste incineration (http://www.esam.northwester-n.edu/~matkowsky/fingering.html).Problems faced in the combustion procedure were

discussed and tentative solutions were evaluated. Thereliability of the oxygen bomb IC procedures wasestablished by testing the recoveries of a large groupof organic compounds containing various heteroatoms.Combustion was carried out at thirty bar of oxygen(Souza et al., 2002). Miscanthus can be used as fuel forcombustion in heating systems. Investigations weremade in Denmark regarding combustion of Miscan-thus · Giganteus in farm heating plants. Full scale testswere carried out concerning combustion of Miscan-thus · Giganteus in the type of farm heating plantwhich is conventionally used for straw combustion. Thecombustion qualities were determined by means of fuelanalyses and measurements of heating plant efficiencies.In general, high softening, hemispherical and flowtemperatures are considered to be advantageous(http://www.eeci.net/archive/biobase/B10367.html).

Biogas

Biogas technology is a complete system in itself with itsset objectives (cost effective production of energy andsoil nutrients), factors such as microbes, plant design,construction materials, climate, chemical and microbialcharacteristics of inputs, and the inter-relationshipsamong these factors. Biogas is about 20% lighter thanair and has an ignition temperature in the range of 650–750 �C. It is an odourless and colourless gas that burnswith clear blue flame similar to that of LPG gas. Itscalorific value is 20 Mega Joules (MJ) per m3 and burnswith 60% efficiency in a conventional biogas stove(http://www.fao.org/sd/EGdirect/EGre0022.htm).High energy yields were obtained from the production

of upgraded biogas used for vehicle refuelling purposes.Comparisons indicate that energy yields from biogasderived from wheat are twice as high as wheat whenused for ethanol production. As well as economic and

air quality benefits, studies also indicated that usingbiogas for transport, CO2 emissions could be reduced ona life cycle basis by between 65% and 85% on currentfuels, depending on the feedstock used (http://www.ngv-global.com/index.php?option=com-content&task=view&id=83&Itemid=2&lang=en).Compressed natural gas (CNG) comes primarily from

fossil sources; although ‘biogas’, which is very similar toCNG, is produced from renewable sources. Biogas isexamined in a separate entry, below. Three submissionswere received that specifically focused on promotingCNG, with a number of other submissions alsomentioning its benefits. Air quality benefits are partic-ularly significant compared with heavy-duty dieselvehicles, and it is in these vehicles that CNG tends tobe used. CNG engines are also significantly less noisythan diesel engines. Again, this is a particular benefitwhen CNG is used in heavy-duty vehicles (http://www.defra.gov.uk/ENVIRONMENT/consult/greenfuel/response/03.htm).In addition to the animal and human wastes, plant

materials can also be effectively used for biogas and bio-manure production. For example, 1 kg of pre-treatedcrop waste and water hyacinth have the potential ofproducing 0.037 and 0.045 m3 of biogas, respectively. Asdifferent organic materials have different bio-chemicalcharacteristics, their potential for gas production alsovaries. Two or more of such materials can be usedtogether provided that some basic requirements for gasproduction or for normal growth of methanogens aremet (http://www.fao.org/sd/EGdirect/EGre0022.htm).

Current and potential uses of corn and rice wastes

Biomass is considered to be a potential for the renewableenergy sources in the future. It already supplies 14% ofworld’s total energy consumption. Biomass is also asource of a large variety of chemicals and materials.Biomass resources that can be used for energy produc-tion cover a wide range of materials such as forestryresidues, energy crops, organic wastes, agriculturalresidues, etc. Agricultural waste, a readily availablebiomass, is produced annually worldwide and is vastlyunder utilised (Putun et al., 2004). Biomass is also asource of a large variety of chemicals and materials, andof electricity and fuels. About 60% of the needed processenergy in pulp, paper and forest products is provided bybiomass combustion. These processes could be improvedto the point of energy self-sufficiency of these industries(Chum & Overend, 2001). Biomass fuels are the firstenergy source harnessed by mankind. They remain theprimary source of energy for more than half the world’spopulation and account for 14% of the total energyconsumption in the world. Biomass is the most commonform of renewable energy. The use of renewable energysources is becoming increasingly important when it is



considered to assist to alleviate global warming andprovide fuel supply (Cuiping et al., 2004). Modelling andanalysis of energy conversion processes require adequatefuel characteristics especially average and variations inelemental compositions. Knowledge of the concentrationand speciation of alkali elements in fuels is useful forstudies of Biomass Integrated Gasification CombinedCycle (BIGCC) or other biomass power generationtopics (Cuiping et al., 2004). Development of biomassand other renewable power generation has distincteconomic and environmental advantages. Despite this,the situation today in California is such that herbaceousfuels are virtually unusable by many existing biomasspower generators using direct-combustion technologies(Thy et al., 2006). Using biomass as a source of fuel haslittle adverse environmental impact. The combustion ofbiomass produces significantly less nitrogen oxide andsulphur dioxide than the burning of fossil fuels. Unlikefossil fuel combustions, the use of biomass fuels will notcontribute to CO2 levels that cause global warming(Cuiping et al., 2004).Fuel ethanol plants are being commissioned and

constructed at an unprecedented rate based on thisdemand, although a need for a more efficient and cost-effective plant still exists (Kwiatkowski et al., 2006). Inrecent years, research and development efforts directedtowards commercial production of fuel ethanol fromrenewable resources as an alternative transportation fuelhave increased. Currently, fuel ethanol is producedalmost exclusively from corn starch. The economics offuel ethanol production is significantly influenced by thecost of raw materials, which accounts for more than halfof the cost (Krishnan et al., 2000). Even the reduction incost of a few cents per litre of ethanol produced, issignificant when dealing with the dry-grind process, andthe ability to accurately predict the costs of productionprior to incorporating new technologies is highly desir-able (Kwiatkowski et al., 2006).Today’s corn refinery industry produces a wide range

of products including starch-based ethanol fuels fortransportation. The biomass industry can produce addi-tional ethanol by fermenting some by-product sugarstreams. Lignocellulosic biomass is a potential source forethanol that is not directly linked to food production.Moreover, through gasification biomass can lead tomethanol, mixed alcohols and Fischer–Tropsch liquids.The life science revolution we are witnessing has thepotential to radically change the green plants andproducts we obtain from them. Green plants developedto produce desired products and energy could be possiblein the future. Biological systems can already be tailoredto produce fuels such as hydrogen (Chum & Overend,2001). Ethanol is a renewable, bio-based oxygenatedfuel. In the USA, the production of fuel ethanol fromcorn starch reached about 2.81 billion gallons in 2003.Developing ethanol as fuel, beyond its current role as

fuel oxygenate, will require developing lignocellulosicbiomass as a feedstock because of its abundance and lowcost. Previously, corn fibre (obtained from corn wet-milling industries) was targeted as a model substrate foruse as lignocellulosic biomass because of its highcarbohydrate content (70%) containing 20% residualstarch, 15% cellulose and 35% hemicellulose, and lowlignin content (>8%) (Saha et al., 2005). The corn dry-grind process is the most widely used method in the USfor generating fuel ethanol by fermentation of grain.Increasing demand for domestically produced fuel andchanges in the regulations on fuel oxygenates have led toincreased production of ethanol mainly by the dry-grindprocess. Fuel ethanol plants are being commissioned andconstructed at an unprecedented rate based on thisdemand, though a need for a more efficient and cost-effective plant still exists. The models were developedusing software and they handle the composition of rawmaterials and products, sizing of unit operations, utilityconsumptions, estimation of capital and operating costs,and the revenues from products and co-products (Kwi-atkowski et al., 2006).The production of bio-ethanol from corn stover using

simultaneous saccharification and fermentation (SSF) athigh dry matter content addresses both issues. Cornstover is an agricultural by-product and thus has a loweconomic value. SSF at high dry matter content resultsin a high ethanol concentration in the fermented slurry,thereby decreasing the energy demand in the subsequentdistillation step (Ohgren et al., 2006). An economicanalysis for ethanol production from glucose indicatingthat cost savings of 6 cents gal-1 could be achieved byusing technology. These potential cost savings wererealised because of higher ethanol yields, lower oper-ating costs and lower capital costs for the continuousFBR process with an immobilised Z. mobilis biocatalystcompared with those for a conventional batch processusing yeast (Krishnan et al., 2000). A by-product of thecorn wet-milling industry consists of corn hulls andresidual starch not extracted by the milling process.Conversion of the starch along with the lignocellulosiccomponents in the corn fibre would increase ethanolyields from a corn wet mill by 13% and is promising ifthe value of the corn fibre as an animal feed product isnot severely affected. Corn fibre was obtained from alocal corn wet mill and stored in a refrigerated trailer forno longer than a month. Usually multiple shipments (orlots) were required to supply the pilot plant with enoughfeedstock for operation during an extended run. Thecorn fibre moisture content was 55–60% (w ⁄w) asreceived (Schell et al., 2004).Rice (Oryza sativa L.) is an important crop in many

areas of the world, and yields a large amount of ricestraw residue. A major portion of this agricultural wasteis disposed by burning or is mulched in rice fields(Abdelhamid et al., 2004). Rice straw has been described



some potential uses. It is a marginal feed that wouldhave to compete with other cereal grain straws such aswheat and barley. Most of the rice straw harvested wentto animal feed. It has been reviewed with the use ofagricultural residues, including rice straw, as a source ofnon-wood fibres. It is most suitable for the productionof corrugated medium and newsprint; however, the onlycommercial pulp mills using straw or bagasse exist indeveloping countries like India and China. It can beconverted through bioconversion to ethanol, which is aclean-burning transportation-fuel oxygenate. Directcombustion of rice straw in a utility boiler of a biomasspower plant is also an alternative for utilising rice straw,but leaching is required to avoid slagging and fouling(Kadam et al., 2000). Preparing compost from rice strawenriched with rock phosphate using cellulose degradingmicro-organisms and phosphate dissolving ones maynot only compensate for the higher cost of manufactur-ing fertilisers in industry but also provide the growingplants in alkaline soils with available phosphorous. Useof phosphate dissolving fungi in production of compostoffers a solution to the waning interest of farmers in theuse of organic phosphatic fertilisers in alkaline soils. Thecomposts obtained were evaluated as organic phos-phatic fertilisers in pots cultivated with cowpea plants.The effect of the composts on the microbial communitystructure of rhizosphere soils was also studied (Zayed &Abdel-Motaal, 2005). However, an attractive alternativeusage of rice straw is composting. This process has manyadvantages including sanitation, mass and bulk reduc-tion, and decrease of carbon (C) to nitrogen (N) ratio(C ⁄N). Rice straw is rich in C and poor in N. Its C ⁄Ncan vary from 50 to 150, which limits seriously thecomposting process. This high C ⁄N can be decreased byincreasing the basal N content of rice straw by addingoilseed rape cake and poultry manure. The employedmixtures of Rice straw and N materials (cowdung + soybean plants) ranged at ratios from 70% to100% rice straw. The mixture containing 70% rice strawproduced the most suitable compost in terms of matur-ity and nutrients (Abdelhamid et al., 2004).Rice straw is commonly burnt in many of the

developing countries. Burning rice straw has harmfulenvironmental implications through global addition ofcarbon dioxide, a gas contributing to the greenhouseeffect, and likely high health costs through increase inrespiratory problems in the local population. Theconversion of rice straw into value-added compostmay have the potential to improve productivity of thecrops and reduce environmental pollution. However,rice straw is among certain organic materials which areresistant to microbial attack (Zayed & Abdel-Motaal,2005). The PY of rice straw was studied to estimate theeffect of PY conditions on product yields and bio-oilcomposition when the heating rate was 5 K min-1.Liquid products obtained from PY, inert atmosphere

PY and steam PY were then fractionated into aspalth-anes and maltanes. The chemical characterisation hasshown that the oil obtained from rice straw may bepotentially valuable as fuel and chemicals feedstocks(Putun et al., 2004).The addition of rice straw to wood fuels is expected to

decrease both solidus and liquidus temperatures (i.e. theclassic freezing point depression), but the magnitude ofthe depression cannot be predicted based on theavailable experimental data. In addition to the strongcompositional effects on melting temperatures, theseverity of slag formation and its ease of removal willdepend on the amount of melt present as well as itscomposition and polymerisation. It is plausible thattypical boiler conditions during combustion are withinthe melting temperature of slag from blended wood andstraw fuel and, therefore, that melt will be present in theslag (Zayed & Abdel-Motaal, 2005). The traditionaldisposal method for rice and wheat straw in many partsof the world is burning. The burning of wheat straw ispopular in China because of the short turnaround timebetween the wheat harvest and rice transplanting inrice–wheat rotations. Estimated losses are up to 80% ofN, 25% of P and 21% of K in addition to the problemof air pollution. Furthermore, declining or stagnatingyield have been observed in rice-based cropping systems.Improvements are, therefore, required in the manage-ment of soil, water and straw (Fan et al., 2005). Achange from traditional flooding (anaerobic) to non-flooded mulching (aerobic) and the effects of non-flooded mulching cultivation on soil temperature arelikely to exert large influence on N forms and availab-ility and N cycling. Return of straw can also lead totemporary nutrient limitation because of microbialimmobilisation. It is therefore important to test inter-actions between varying N inputs and non-floodedmulching cultivation and their effects on productivityand N cycling in rice–wheat systems. As part of ourevaluation of non-flooded mulching cultivation, theobjectives of the present study were to determine theeffects of non-flooded mulching cultivation and fertiliserN application rate on crop yield, N uptake, residual soilNmin and the net N balance (Fan et al., 2005).Treatment methods, physicochemical characteristics,

substrate to be applied and final product ⁄uses of cornand rice wastes are given in Table 4.

Conclusions

The traditional disposal method for rice and corn strawin many parts of the world is burning which involvesharmful environmental implications through globaladdition of CO2. A change from traditional flooding(anaerobic) to non-flooded mulching (aerobic) and theeffects of non-flooded mulching cultivation on soiltemperature are likely to exert large influence on N



forms and availability and N cycling. However, anattractive alternative usage of rice straw is composting.This process has many advantages including sanitation,mass and bulk reduction, and decrease of carbon (C) tonitrogen (N) ratio (C ⁄N). Using biomass (properlytreated rice and corn waste) as a source of fuel has littleadverse environmental impact. The combustion ofbiomass produces significantly less nitrogen oxide andsulphur dioxide than the burning of fossil fuels. Unlikefossil fuel combustions, the use of biomass fuels will notcontribute to carbon dioxide levels. Therefore, the threemain axes of potential uses of treated corn and rice arebiomass, composting, and biofuel in order of increasingpotential.

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