methodological framework to assess environmental impacts...

Methodological framework to

assess environmental impacts of

various waste management options

Anand Bohra (National Council for Cement & Building Materials)

Dr. Poonam Ahluwalia (MWH India Private Limited)

Dr. Arvind K. Nema (IIT Delhi)

• In India, municipal solid waste (MSW) management has remained one

of the most neglected areas.

• Environment Impacts (EI) associated with the MSW management due

to large quantities of waste generation and inadequate facilities of

treatment and disposal are a cause of serious concern.

• Integrated solid waste management (ISWM) is the selection and

application of suitable techniques, technologies and management

approaches to achieve specific objectives and goals.

• In ISWM rather than accepting a simple hierarchy, alternatives are

examined systematically which is most beneficial from point of view of

resource requirements and environmental concerns.

• Life Cycle assessment (LCA) is an environmental management tool

that allows prediction of the environmental burdens associated with a

product or service over the whole life cycle, i.e. from cradle to grave.

Background and Introduction

• Global warming - Global warming potential (GWP)

Potential EI of Concern

• Global Warming is the increase of Earth's average surface temperature

due to effect of greenhouse gases, such as carbon dioxide emissions from

burning fossil fuels or from deforestation, which trap heat that would

otherwise escape from Earth.

• This is a type of greenhouse effect.

Management

Option GWP

Aerobic

Composting

GWP due to CO2 emissions during electricity production-required

for composting and Negative GWP due to avoidance of

phosphate fertilizer (emissions saved due to avoided production).

• Eutrophication -Eutrophication potential (EP)

Potential EI of Concern…

Management

Option EP

Aerobic

Composting

EP due to NH3 emissions (minor) during composting process.

Negative EP due to NH3 emissions from avoidance of fertilizer.

• Eutrophication or more precisely hypertrophication, is the ecosystem response to

the addition of artificial or natural substances, such as nitrates and phosphates,

through fertilizers or sewage, to an aquatic system [Example- "bloom" of

phytoplankton in a water body as a response to increased levels of nutrients].

• Associated Negative environmental effects include hypoxia, the depletion of

oxygen in the water, which induces reductions in specific fish and other animal

populations.

• Acidification - Acidification potential (AP)


Management

Option AP

Aerobic

Composting

AP due to SO2 and NOx during

electricity production- required for

composting and emissions (NH3)

during composting process.

Negative AP due to avoidance of

phosphate fertilizer (emissions

saved due to avoided production)

• The Acidification Potential is a meter of the disposition of a unit of the mass of a

component i to release H+ protones, expressed in terms of the H+ potential of

the reference substance SO2

Substance Acidification potential

(in kg SO2-equivalent)

SO2 1.00

NO 1.07

N2O 0.70

NOx 0.70

NH3 1.88

HCl 0.88

HF 1.60

• Formation of Photo oxidants- Photo oxidant formation potential (POFP)


• The photochemical oxidation, very often defined as summer smog, is the result

of reactions that take place between nitrogen oxides (NOx) and emissions like

hydrocarbons into air (VOC, NM-VOC) exposed to UV radiation.

• The Photochemical Ozone Creation Potential, POCP or Photo oxidant formation

potential (POFP) of VOC’s is, related to a reference substance, in this case, the

olefine ethylene (H2C=CH2).

ai is the change of ozone concentration due to a

change in the emission of VOC i

bi(t) integrated emission of VOC i up to that time (t)

aC2H4 is the change of ozone concentration due to a

change in the emission of ethylene

bC2H4(t) integrated emission of ethylene up to that time (t)

• Formation of Photo oxidants- Photo oxidant formation potential (POFP)


Substance POCPi

(kg C2H4-equiv./kg)

Alkanes

Methane 0.007

Ethane 0.082

Propane 0.42

Management

Option POFP

Landfilling

POFP due to unrecovered CH4

emissions from landfill

operations

• Toxic Emissions - Human toxicological potential (HTP)


Management Option HTP

Aerobic

Composting

HTP due to Particulate Matter (PM) from emissions

during electricity production-required for composting and

Negative HTP due to avoidance of phosphate fertilizer

(emissions saved due to avoided production)

• The human toxicity potential (HTP), reflects the potential harm of a unit of

chemical released into the environment, is based on both the inherent toxicity of

a compound and its potential dose.

• It is used to weight emissions in terms of a reference compound [kg DCB-

Equivalent] (DCB - Dichlorobenzene) and is mainly due to heavy metal and

chlorinated hydrocarbon emissions

• STEPS

Proposed Methodological Framework

1. Establish system boundary – demarcate foreground and background

systems.

• The principal distinction between foreground and background system lies in the

way the inventory data are compiled

• The foreground should be described by primary data based on actual

processes and their operating conditions and background activities can be

described by generic average industry data

• The production of energy, diesel and fertilizers are included in the background

system

• Other parameters of MSW management system besides waste treatment

process, such as collection, transportation, material recovery facility, recycling

and waste minimization are not included in the system boundary

Syste

m B

ou

nd

ary

Dem

arc

ati

on

• STEPS


2. Make assumptions to simplify analysis consistent with system

requirements.

• For calculating the credits due to electricity produced from MSW management

system, it is assumed that it will replace the electricity unit produced from a

thermal power plant using fossil fuel.

• Upstream processes related to the manufacture and use of products entering

the waste package, are excluded.

• …..

• ….

• STEPS


3. Prepare checklist of impacts applicable to each management option.

Management

Option GWP AP EP POFP HTP

Aerobic

Composting

GWP due to CO2

emissions during

electricity

production-required

for composting and

Negative GWP due

to avoidance of

phosphate fertilizer

(emissions saved

due to avoided

production). CO2

emissions during

composting process

are considered as

biogenic.

AP due to SO2

and NOx during

electricity

production-

required for

composting and

emissions during

composting

process.

Negative AP due

to avoided

production of

phosphate

fertilizer

EP due to

NH3

emissions

during

composting

process.

Negative EP

due to NH3

emissions

from

avoidance of

fertilizer.

Negative

POFP due

to SO2, CO,

CH4 due to

avoidance

of fertilizer.

HTP due to

Particulate

Matter (PM)

from emissions

during electricity

production-

required for

composting and

Negative HTP

due to avoided

production of

phosphate

fertilizer

Management

Option

GWP AP EP POFP HTP

Landfilling

GWP due to

unrecovered CH4

emissions from

landfilling operations

and Negative GWP

due to avoided

emissions from

electricity production

using landfill gas.

The CO2 emissions

during landfilling

process are

considered as

biogenic.

AP due to NH3

emissions

during

landfilling

operations.

Negative AP

due to avoided

SO2 & NOx

emissions from

electricity

production

using landfill

gas.

EP due to

NOx, NH3

emissions

during

landfilling

operations.

POFP due to

unrecovered

CH4 emissions

from landfill

operations

HTP due to

leaching of

various

substances

like benzene &

heavy metals

to the water

table.

Management

Option

GWP AP EP POFP HTP

RDF

Combustion

GWP due to CO2

emissions during

electricity production-

required for RDF

preparation and also

emissions from

combustion of RDF.

Negative GWP due to

avoided emissions

from electricity

production from RDF.

AP due to SO2 &

NOx emissions

during electricity

production required

for RDF preparation

and also emissions

from combustion of

RDF. Negative AP

due to avoided

emissions from

electricity production

from RDF.

Negative

EP due to

avoidance

of NOx

emissions

from

electricity

production

from RDF

Negative

POFP due

to avoided

emissions

from

electricity

production

from RDF

Negative

HTP due to

avoidance

of

particulate

emissions

from

electricity

production

using RDF.

• STEPS


4. Input-Output Analysis for various management options

EXAMPLE: Input-Output Analysis for Landfilling

• The sanitary land filling process requires energy input for compaction and

spreading of the waste and also for putting waste in cells of the landfill

• Diesel consumption data for compactors can be taken from secondary data (such

as Brazilian inventory)

• Volumes and composition of LFG in the short term (100 years) can be estimated

from literature (IPCC report, 2006; McDougall et al., 2001; Williamson, 1991)

• Energy input can be calculated based on the fuel consumption during

consumption process (estimated on basis of hp of compactor) (Source: Velumani

and Meenakshi, 2007)

Energy Input = MSWslf x D x d x (C.V / 1000)

Where:

MSWslf = MSW disposed in Land fill

D = Fuel Consumption rate (1 L / ton of MSW compacted)

d = density of Diesel fuel (= 0.90 kg/L)

C.V. = Calorific Value of Diesel fuel (= 40 MJ/kg)

• Methane Emissions are calculated as follows (source: IPCC):

ME = [MSWg x MSWf x MCF x DOC x DOCf x F x (16/12 –R)] x [1 – OX]

Where:

• MSWg = Total municipal solid waste (MSW) generated (kg).

• MSWf = Fraction of MSW disposed of at the disposal sites.

• MCF= Methane correction factor (fraction). The fraction depends upon the

method of disposal and depth available at landfills. For:

Anaerobic managed solid waste disposal sites, this factor is 1.0

Semi-aerobic managed solid waste disposal sites it is 0.5

Unmanaged solid waste disposal sites – deep and/or with high water

table it is 0.8

Unmanaged-shallow solid waste disposal sites, this factor is 0.4.


• Methane Emissions are calculated as follows (source:IPCC):

• ME = [MSWg x MSWf x MCF x DOC x DOCf x F x (16/12 –R)] x [1 – OX]

Where:

• DOCf = Fraction of Degradable organic carbon (DOC) converted to LFG

• F= Fraction of methane in LFG (default is 0.5).

• R= Recovered methane (kg).

• Recovery of LFG is not adopted for land dumps facility; hence the value of R is

zero for land dumps

• OX= Oxidation factor (default is 0; Source: Kumar et al., 2004)

• It accounts for the methane that is oxidized in the upper layer of waste mass

where oxygen is present.

• DOC= Degradable organic carbon (fraction). Assessed from waste

composition.


Energy Recovery Analysis in Sanitary Land Filling

Energy recovery depends upon the calorific value of LFG and efficiency of collection of LFG and thermal efficiency. Conversion of methane gas into electricity can be estimated as (Velumani and Meenakshi, 2007):

Energy Recovery = (2 x CH4 / d) x C.V. x Ef x Thf

Where

CH4 = Quantity of Methane

d = Density of LFG = generally around 0.72 kg/m3

C.V. = Calorific Value of LFG = generally around 18 MJ/m3

Ef = Collection efficiency of LFG = say 0.5

Thf = Thermal transformation efficiency = reported around 0.30 in literature


Input-Output Analysis for Landfilling

Leachate Emissions from Land fill

• Leachate Tapping efficiency is assumed based on system of collection. For example, 80% of the leachate from land fill will be collected and remaining 20% will leak to aquatic recipients.

• Other assumptions on nitrogen transformation to ammonia and release as leachate and phosphorus content in leachate are made based on secondary data. For example, about 90% of Nitrogen in waste is transformed into ammonium and released from land fill as leachate; Phosphorus emissions in leachate will be equal to 2% of phosphorus in waste land filled; Mercury and Cadmium emissions will be 0.0001% and 0.08% of waste land filled respectively.

• Energy required for treatment of leachate can be estimated from secondary sources. 0.001 MJ/ kg energy is required for treatment of leachate (Finnvedan et al., 2002).

Input-Output Analysis for Landfilling

Leachate Emissions from Land fill…

Quantity of leachate produced can be estimated by:

Leachate produced = (F x R x A x d) / H

Where

F = fraction of rainfall = 0.13 (According to McDougall (2001), 13% of total rainfall emerges as leachate for that landfill)

R = rainfall say 700 mm for Delhi.

d = density of waste land filled = say 1 ton/m3

A = Active period for land fill = 30 years

H = Height of land fill = say 20 m.

• STEPS


4. Input-Output Analysis for various management options…

The various gaseous & other emissions from different MSW management options and

emissions related with the inputs like energy & electricity to the management options are

required to be characterized in terms of reference equivalents using equivalence factors for

various Impact categories. The equivalence factors are detailed below:

• For GWP, CO2 is the equivalence factor (as suggested by IPCC and CML). The different

global warming gases (like CH4, N2O, CO2, etc) are added up and converted to CO2

equivalents using equivalence factors.

• For acidification, SO2 is the reference substance. The emissions of the various acid

producers (HCl, HF, NO2, SO2, H2S, NH4, NH3) from different processes and during

production of various input materials are added and converted to SO2 eq using equivalence

factors.

• STEPS


4. Input-Output Analysis for various management options…

For eutrophication potential, the reference substance is taken as PO4.

PO4 equivalence factors of various substances

1 kg Nitrogen oxides (NOx, air) 0.13 kg eq PO4

1 kg Total nitrogen (water) 0.42 kg eq PO4

1 kg Total phosphorous (water) 3.07 kg eq PO4

1 kg Chemical O2 demand (COD) 0.022 kg eq PO4

1 kg NH3 0.35 kg eq PO4

1 kg NH4+ 0.33 kg eq PO4

1 kg NO3- 0.095 kg eq PO4

1 kg NO2- 0.13 kg eq PO4

• STEPS


4. Input-Output Analysis for various

management options…

For POCP, ethylene C2H4 is chosen as reference. The

POCP value is not a constant, but can very over

distance and time, since formation of oxidants along

the path of an air pocket is determined by the

meteorological conditions, which can also vary

spatially and chronologically. Therefore, the resulting

value for this indicator may be considered as

approximate.

For HTP, the reference substance is 1,4 dichloro

benzene (1,4 DCB).

Emissions Eq. 1,4 DCB

PM 0.82

SPM 0.82

HCl 0.5

Pb 12

Benzene 1900

Toulene 0.33

NO2 1.2

SO2 0.096

Cd 23

Ni 330

The equivalence factors for

various emissions in terms of

1,4 DCB are listed below:

THANKS FOR

YOUR

ATTENTION

methodological framework to assess environmental impacts...

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