biomethanation of organic waste, anaerobic degradation,degradation of organic waste

BIOMETHANATION

MUNICIPAL SOLID WASTE

Presented by,

Salin Kumar Sasi

URBAN WASTE SCENARIO

• Urban India generates about 1.4 lakh MT/day of MSW

• Requires 1750 acres of land for land filling/year

Courtesy-MNRE

PHASES

• PHASE I – MSW SCENARIO IN INDIA

• PHASE II – BIOMETHANATION

• PHASE III – FACTORS AFFECTING

BIOMETHANATION

• PHASE IV – BIOMETHANATION PROCESS

• PHASE V – BIOMETHANATION OF MSW IN INDIA

• PHASE VI – BIOMETHANATION PLANT IN

ABROAD AND INDIA

• PHASE VII – RESULTS AND DISCUSSIONS

PHASE I

MSW SCENARIO IN INDIA

Courtesy-MNRE

TECHNOLOGICAL OPTIONS FOR

ENERGY RECOVERY FROM URBAN WASTES

Courtesy-MNRE

POTENTIAL OF ENERGY FROM

URBAN WASTES

2007 2017

(lakh tpd)1.48 2.15 3.03

MW 2550 3670 5200

(mcd)17.75 20.70 24.75

MW 330 390 460

Courtesy-MNRE

INDIAN SCENARIO

• As per MSW Rule 2000, biodegradable material

should not be deposited in the sanitary landfill

• Therefore there is almost no scope of generation of

biogas in the form of landfill gas from new sanitary

landfills

• However, there is a huge potential of trapping the

landfill gas generated in the old dump-sites across

the country, particularly the large ones with more

than 5 meter thickness (height plus depth)

Courtesy-MNES

Courtesy-NEERI

WTE TECHNOLOGIES

• Bio-methanation

• Incineration

• RDF

• Gasification

• Integrated systems

MERITS OF BIOMETHANATION

• Reduction in land requirement for MSW disposal.

• Preservation of environmental quality.

• Production of stabilized sludge can be used as

soil conditioner in the agricultural field.

• Energy generation which will reduce operational

• Supplement national actions to achieve real, long

term, measurable and cost effective GHG’s

reductions in accordance with Kyoto Protocol.

PHASE II

BIOMETHANATION

Courtesy-MNRE

PRINCIPLES

• Complex process leading to generation of methane and carbon dioxide.

• Process involves three steps (Barlaz et al 1990) Hydrolysis Acidification Methanogenesis

• Process can be carried out in Single step Two step

HYDROLYSIS

• Anaerobic bacteria breakdown complex organic molecules (proteins, cellulose, lignin and lipids) into soluble monomer molecules such as amino acids, glucose, fatty acids and glycerol.

• Monomers are available to the next group of bacteria.

• Hydrolysis of complex molecules is catalyzed by extra cellular enzymes (cellulose, proteases and lipases).

• Hydrolytic phase is relatively slow ,can be limiting in anaerobic digestion.

ACIDOGENESIS

• Acidogenic bacteria converts sugar, aminoacids and fatty acids to organic acids (acetic, propionic, formic, lactic, butyric acids), alcohols and ketones (ethanol, methanol, glycerol and acetone), acetate, CO2and H2.

• Acetate is the main product of carbohydrate fermentation.

• The products formed vary with type of bacteria as well as with the culture conditions (temperature, pH etc).

ACETOGENESIS

• Acetogenic bacteria converts fatty acids and alcohols into acetate, hydrogen and carbon dioxide .

• Acetogenic bacteria requires low hydrogen for fatty acids conversion .

• Under relatively high hydrogen partial pressure, acetate formation is reduced and the substrate is converted to propionic acid, butyric acid and ethanol rather than methane.

METHANOGENESIS

• Methanogenesis in microbes is a form of anaerobic respiration.

• Methanogens do not use oxygen to breathe, oxygen inhibits the growth of methanogens.

• Terminal electron acceptor in methanogenesis is carbon.

• Two best described pathways involve the use of carbon dioxide and acetic acid as terminal electron acceptors:

CO2+ 4 H2 → CH4 + 2H2O

CH3COOH → CH4 + CO2

Acetate

Short chain fatty acids

Lipase, protease, pectinase

cellulase, amylase produced

by hydrolytic microorganisms

Stage 1 Hydrolysis

Organic matter

(Carbohydrates, lipids, proteins etc)

Stage 2 Acidogenesis

(mainly acetic and formic acid)Stage 3 Acetogenesis

Acetate CO2 and H2

Methane +CO2

ß-oxidation, glycolysis

deamination, ring reduction

and ring cleavage

Carboxylic volatile acids, keto acids,

hyroxy acids, ketones, alcohols,

simple sugars, amino aicds,H2 and CO2

Stage 4 Methanogenesis

Courtesy-Kashyap .D.R et al ,2003

PHASE - III

FACTORS AFFECTING

BIOMETHANATION

Courtesy-MNRE

NUTRIENTS

• Lower nutrient requirement compared to aerobic bacteria.

• COD:N range is 700:5.

• N used in synthesis of Enzymes, RNA, DNA.

• Concentration of various nutrients (Speece et. al ,1996)

N : 50 mg/lP : 10 mg/lS : 5 mg/l

• Most important process control parameter.

• Optimum pH between 6.7 & 7.4 range for methanogenic bacteria (Zehnder et. al. 1982).

• Excess alkalinity or ability to control pH must be present to guard against the accumulation of excess volatile acids.

• The three major sources of the alkalinity are lime, Sodium bicarbonate and sodium hydroxide.

TEMPERATURE

• Constant and Uniform temperature maintenance.

• Three temperature range

Psychrophilic range ; < 200 C.

Mesopholic range ; 200 C to 400C.

Thermophilic range ; >400 C.

• Rates of methane production double for each 100C temperature change in the mesophilic range .

• Loading rates must decrease as temperature decreases to maintain the same extent of treatment.

• Operation in the thermophilic range is not practical because of the high heating energy requirement (Ronald L. Drostle – 1997)

• Study of temperature variation (Alvarez Rene et al 2007).

Forced square-wave temperature variations

(i) 11 0 C and 25 0 C,

(ii) 15 0 C and 29 0 C,

(iii) 19 0 C and 32 0C.

Large cyclic variations in the rate of gas production

and the methane content.

The values for volumetric biogas production rate and

methane yield increased at higher temperatures.

The average volumetric biogas production rate for

cyclic operation between 11 and 25 0C was 0.22 L d -1 L -

1 with a yield of 0.07 m 3CH 4kg -1 VS added (VSadd)

Between 15 and 29 0C the volumetric biogas

production rate increased by 25% (to 0.27 L d -1L-1with

a yield of 0.08 m 3CH 4 kg -1 VSadd).

Between 19 and 32 0C, 7% in biogas production was

found and the methane yield was 0.089 m3 CH4 kg-1

VSadd.

Digester showed an immediate response when the

temperature was elevated, which indicates a well-

maintained metabolic capacity of the methanogenic

bacteria during the period of low temperature.

Periodic temperature variations appear to give less

decrease in process performance than as prior

anticipated.

Courtesy- Alvarez Rene et al 2007

SOLID RETENTION TIME (SRT) AND

HYDRAULIC RETENTION TIME(HRT)

• SRT is defined as the average time the solid particles

remains in the reactor.

• The anaerobic digestion is typically performed in

Continuously Stirred Tank Reactor (CSTR).

• The performance of CSTR is dependent on hydraulic

retention time (HRT) of the substrate and the degree of

contact between the incoming substrate and a viable

bacterial population (Karim et al.,2005).

• An increase or decrease in SRT results in an increase or

decrease of the reaction extent.

MIXING

• Mixing creates a homogeneous substrate preventing

stratification and formation of a surface crust, and

ensures solids remain in suspension.

• Mixing enables heat transfer and particle size reduction

as digestion progresses .

• Mixing can be performed in two different ways(Kaparaju

P et al,2007):

Continuous mixing – SRT is equal to HRT

Non-continuous mixing – SRT is more than HRT

• The effect of continuous , minimal (mixing for 10 min

prior to extraction / feeding) and intermittent mixing

(withholding mixing for 2 hr prior to extraction/feeding)

on methane production was investigated in lab-scale

CSTR (kaparaju P. et. al ,2007) .

• On comparison to continuous mixing, intermittent and

minimal mixing strategies improved methane

productions by 1.3% and 12.5%, respectively.

ALKALINITY

• Calcium, magnesium, and ammonium

bicarbonate are examples of buffering substances

found in a digester .

• A well established digester has a total alkalinity

of 2000 to 5000 mg/L.

• The principal consumer of alkalinity in a reactor

is carbon dioxide .

TOXICITY

• Toxicity depends upon the nature of the substance

, concentration and acclimatization .

• NH 4-N concentration of 1500-3000 mg/L at 200C

and pH 7.4 and above is considered stimulatory .

• Anaerobic process is highly sensitive to toxicants

due to slow growth rate.

PHASE-IV

BIOMETHANATION PROCESS

Courtesy-MNRE

BIOMETHANATION INCLUDES FOUR

MAJOR ELEMENTS

1. Pretreatment.

2. Digestion.

3. Gas purification

4. Residue treatment.

PRETREATMENT

• Separate out inorganic matter and materials which disrupt mechanical operation of the digester

• Increase the biodegradability of the substrate.

• Classification of the refuse by either wet or dry separation processes

• Provides the feedstock with a high concentration of digestible matter, relatively free of metals, glass and grit

• Dry separation processes offer the advantage of flexibility in selecting the desired water content

• Wet separation processes operate at low solids concentrations, and have the disadvantage of requiring a dewatering step

DIGESTION

• Organic feedstock is mixed with nutrients and control chemicals.

• Lime and ferrous salts are added for pH and hydrogen sulfide control.

• Digester operates at mesophilic conditions ( 370C ).

• The conversion occurs in two steps firstly solids are solubilized or digested by enzymic action, secondly the soluble products are fermented in a series of reactions resulting in the production of methane and carbon dioxide.

PRODUCTS OF DIGESTION

• Consist of two streams

The gas stream is composed of approximately equal

volumes of methane and carbon dioxide.

The slurry stream is composed of an aqueous

suspension of undigested organic matter.

SINGLE-STAGE HIGH RATE

DIGESTION

• Process done in single digester

• Uniform feed is very important

• Digester fed on daily cycle of 8 or 24 hours.

• Digester tank may have fixed roof or floating

TWO-STAGE DIGESTION

• Seldom used in modern digester design.

• High rate digester coupled with second tank in

series.

• Second tank not provided with mixing

contraption.

• Less than 10% of the gas generated comes from

second tank

GAS TREATMENT AND HANDLING

• Gas from digester contains methane, carbon dioxide and trace quantities of hydrogen sulfide.

• CO2 and H2S must be removed if the methane gas is to be pumped for combustion purpose.

• Standard method of removing acid gases from natural gas is by absorption with monoethanolamine (MEA), the MEA is then regenerated and recirculated.

• Methane must also be dried, accomplished by a glycol dehydration process in which the moisture is absorbed in dry glycol, which is also regenerated and recirculated.

PHASE V

BIOMETHANATION OF MSW IN

Project for generation of 5 MW power from Municipal Solid

Waste at Lucknow (Courtesy MNRE)

Courtesy-MNRE

ENERGY RECOVERY POTENTIAL

Courtesy-Ambulkar.A.R et al 2003

Energy ResourcesMaterial Resources

Commercial

sources

Non-conventional

sources

Industrial

Utilization

Agricultural

Consumption

Waste Generation

Manure

Biomethanation

TechnologyBiogas

Processing

of waste

Degradable

organic matterInerts

Municipal

Solid waste

Energy Generation-Consumption in System

Role of Biomethanation Technology

in the system

Energy ResourcesEnergy ResourcesMaterial ResourcesMaterial Resources

Commercial

sources

Commercial

sources

Non-conventional

sources

Non-conventional

sources

Industrial

Utilization

Industrial

Utilization

Agricultural

Consumption

Agricultural

Consumption

Waste GenerationWaste Generation

ManureManure

Biomethanation

Technology

Biomethanation

TechnologyBiogasBiogas

Processing

of waste

Processing

of waste

Degradable

organic matter

Degradable

organic matterInertsInerts

Municipal

Solid waste

Municipal

Solid waste

Energy Generation-Consumption in System

Role of Biomethanation Technology

in the system

ENERGY GENERATION/CONSUMPTION IN

SYSTEM

Parameters related with Technical

Feasibility

Need for obtaining waste

with desired composition

addressing the following

issues:

• Annual seasonal

variation in waste

composition.

• Identification of

points for collection

of waste.

• Source specific

collection of waste.

Ensuring process kinetics

to be fast enough for

implementation at plant

scale addressing the

following parameters with

optimum conditions:

• pH

• Digester Temperature

(Thermophilic,

mesophilic conditions)

• Carbon to Nitrogen ratio

• Maintenance of

COD/BOD values of the

reactor feed.

Ensuring the

conditioning of waste

at processing site with

respect to the

following points:

• Removal of non-

biodegradables

• Removal of

binders like soil

particles, stones,

• Adjustment of

water content in

the feed to the

reactor.

Feasibility

issues:

• Annual seasonal

variation in waste

composition.

of waste.

• Source specific

issues:

• Annual seasonal

variation in waste

composition.

of waste.

• Source specific

optimum conditions:

• pH

(Thermophilic,

• Maintenance of

reactor feed.

optimum conditions:

• pH

(Thermophilic,

• Maintenance of

reactor feed.

Ensuring the

respect to the

following points:

• Removal of non-

biodegradables

• Removal of

binders like soil

particles, stones,

• Adjustment of

water content in

the feed to the

reactor.

Ensuring the

respect to the

following points:

• Removal of non-

biodegradables

• Removal of

binders like soil

particles, stones,

• Adjustment of

water content in

the feed to the

reactor.

PARAMETERS RESPONSIBLE FOR TECHNICAL

FEASIBILITY OF BIOMETHANATION PLANT

Factors affecting the

economy of plant

Compromise with the

quality of raw material as

energy generation

source

•MSW being a

heterogeneous

mixture has a

remarkable seasonal

variation which

hampers the quality

of product

Energy inefficiency associated

with the plant

• Biological processing is a time

consuming process and hence

energy generation rates are

• Net energy generation rate is

low as it involves the

efficiencies associated with

both biogas generation and

biogas combustion.

• The calorific value of biogas is

comparatively less as it

contains about 50% CO2 along

with methane.

Costs associated with

Pre- and Post- treatment

of the feed

• Raw material being a

heterogeneous

mixture with

considerable amount

of inerts and needs

pre-treatment.

• Large amount of

wastewater is

generated with

needs an efficient

method for treatment.

Problems associated with

marketing of products

• Uncertainty in markets

for the digestate

represents a

commercial risk, which

impacts on the

technology’s costs.

• Other energy

generation sources

will have to competitive

edge over the biogas.

• Compost is not yet

established as a

product marketable.

economy of plant

Compromise with the

energy generation

source

•MSW being a

heterogeneous

mixture has a

remarkable seasonal

variation which

hampers the quality

of product

Compromise with the

energy generation

source

•MSW being a

heterogeneous

mixture has a

remarkable seasonal

variation which

hampers the quality

of product

with the plant

biogas combustion.

with methane.

with the plant

biogas combustion.

with methane.

of the feed

heterogeneous

mixture with

considerable amount

of inerts and needs

pre-treatment.

• Large amount of

wastewater is

generated with

needs an efficient

of the feed

heterogeneous

mixture with

considerable amount

of inerts and needs

pre-treatment.

• Large amount of

wastewater is

generated with

needs an efficient

for the digestate

represents a

impacts on the

• Other energy

generation sources

established as a

product marketable.

for the digestate

represents a

impacts on the

• Other energy

generation sources

established as a

product marketable.

PARAMETERS AFFECTING THE COMMERCIAL

VIABILITY OF BIOMETHANATION PLANT

Factors enhancing the

economy of plant

Reduction in costs

• Reduction in raw

material transportation

• The feed MSW is very

cheap and so less raw

material cost.

Financial Incentives from

government

• Financial and fiscal

incentives offered by the

Ministry of Non

Conventional Energy

Sources.

• Constitutional Amendment

Act and emphasis on

privatization has led to the

creation of this market in

India.

economy of plant

Reduction in costs

material cost.

Reduction in costs

material cost.

government

Ministry of Non

Conventional Energy

Sources.

Act and emphasis on

India.

government

Ministry of Non

Conventional Energy

Sources.

Act and emphasis on

India.

PARAMETERS FAVORING THE COMMERCIAL

VIABILITY OF BIOMETHANATION PLANT

PHASE VI

BIOMETHANATION PLANT IN

ABROAD AND INDIA

VALORGATM PLANT AT FRANCE

• PrincipleThe Valorga process is an anaerobic biological treatment process for waste organic fraction .

• Advantages

Adapted to the treatment of organic municipal solid waste

The process operates under anaerobic conditions with a high dry solid content of 25 - 35 %, owing to a specific process design.

Anaerobic digestion leads to the production of a high methane content gas: the biogas.

Does not require a large land area.

VALORGATM PROCESS

SPRERI PLANT AT ANAND Courtesy- SPRERI

SPRERI PLANT AT ANAND

SARDAR PATEL RENEWABLE ENERGY RESEARCH INSTITUTE

APPROPRIATE RURAL TECHNOLOGY

INSTITUTE (ARTI), PUNE

Schematic description of the small ARTI compact

biogas plant. Courtesy-ARTI

APPROPRIATE RURAL TECHNOLOGY INSTITUTE

(ARTI), PUNE

Construction of an ARTI compact

biogas plant.

ARTI biogas plant for treatment of

kitchen waste at household level.

The design, has won the Ashden Award for Sustainable Energy 2006

Bhabha Atomic Research Centre (BARC), Mumbai

Courtesy-MNES

Biogas Plant at Trombay

Courtesy-MNES

Parameters of BARC technology

Courtesy-MNES

The Energy and Resources Institute (TERI), New Delhi

Courtesy-TERI

Waste is fed into the acidification module. UASB unit

The Energy and Resources Institute (TERI), New Delhi

Courtesy-TERI

PROJECTS INSTALLED FOR

ENERGY FROM URBAN WASTES

• 6.6 MW project based on MSW at Hyderabad

• 6 MW project based on MSW at Vijayawada

• 5 MW project based on MSW at Lucknow

• 1 MW power from Cattle Dung at Ludhiana

• 150 kW plant for Veg. Market, sewage and

slaughterhouse waste at Vijayawada

• 250 kW power from Veg. Market wastes at

Chennai.

PHASE VII

RESULTS ANS DISCUSSIONS

SALIENT POINTS

ULTIMATE GOAL OF BIOMETHANATION

DEVELOPMENT OF NATIONAL POLICY

DEVELOPMENT OF APPROPRIATE TECHNOLOGY

IMPROVEMENTS IN COLLECTION AND

TRANSPORTATION SYSTEMS

MARKETING STRATEGY

ALLOCATION OF FUNDING

PUBLIC AWARENESS

CONCLUSION

Considerable potential for enhancing the biogas

production from the present stock of MSW

generated in the country.

Drastic reduction in the emission of CH4 and

CO2, earning the country precious carbon credits.

Assist in implementation of KYOTO protocol.

REFERENCES

Alvarez Rene and Liden Gunnar (2007), ‘The effect of temperature variation on biomethanation’, Bioresource Technology 99 (2008) pp 7278- 7284.

Ambulkar A.R and Shekdar A.V (2003), ‘Prospects of biomethanation technology in the Indian context: a pragmatic approach’, Resources Conservation and Recycling 40 (2004) pp 111-128.

Bhattacharyya J.K., Kumar S., Devotta S., (2008), ‘Studies on acidification in two-phase biomethanation process of municipal solid waste’, Waste Management 28 (1), 164-169. Bioresource Technology 77 (2000) pp 612-623.

Dhussa A. K and Tiwari R.C (2000), Article on Waste-to-energy in India.http://www.undp.org.in/programme/GEF/march00/page 12-14.

Kaparaju P, Buendia I, Ellegaard L and Angelidakia I (2007), ‘Effect of mixing on methane production during Thermophilic anaerobic digestion of manure: Lab-scale and pilot-scale studies’, Bioresource Technology 99 (2008) pp 4919-4928.

Karim K., Hoffmann R., Klasson K.T., Al-Dahhan M.H.,(2005), ‘Anaerobic digestion of animal waste : effect of mixing’, Science Technology 45, pp 3397-3606.

Kashyap. D.R, Dadhich. K. S, Sharma. S. K (2003), ‘Biomethanation under psychrophilic conditions’, Bioresource Technology 87 (2003) pp 147 - 153.

Kim I.S., Kim D.H., Hyun S.H.,(2002), ‘Effect of particle size and sodium concentration on anaerobic thermophilic food waste digestion’, Science Technology 41,pp 61-73.

Kumar D., Khare M., Alappat B.J.(2001), ‘Leachate generation from municipal landfills in New Delhi, India’.27th WEDC Conference on People and Systems for Water, Sanitation and Health, Lusaka, Zambia.

Mahindrakar AB, Shekdar AV.(2000), ‘ Health risks from open dumps: a perspective’, Bioresource Technology 63 (2000) pp 281 - 293.

Muller Christian., (2007), ‘Anaerobic digestion of biodegradable solid waste in Low and Middle income countries’, Eawag Aquatic Research.

Municipal Solid Waste (Management and Handling) Rules,(2000), MNES, Govt of India, New Delhi.

NEERI Report (2005), ‘Assessment of Status of Municipal Solid Waste Management in Metro Cities, State Capitals, Class I Cities and Class II Towns’.

Parkin G. F,Owen, William F, (1986)*, ‘ Fundamentals of anaerobic digestion of waste water sludges’, J. Env. Engg. Div. ASCE, Vol. 112, No. 5, pp 867-920.

Ronald, L. Drostle, (1997)*, ‘Theory and practice of water and waste water treatment’, John Wiley and sons, Inc USA ( NewYork).

Sawyer, Clair N, Mc Carty, Perry L. and Gene F. Parkin (2003), ‘Chemistry for Environmental Engineering and Sciences (Fifth Edition), Tata McGraw Hill Book Company, pp 689-697.

Solid waste manual (2004), MNES, Govt of India.

Speece R.E. (1983)*, ‘Anaerobic biotechnology for Industrial waste water treatment’. Env. Sci.and Tech Vol.17, No.19, pp 416A.

Vavilin V.A., Angelidaki I., (2005), ‘Anaerobic degradation of solid material: Importance of initiation centers for methanogenesis, mixing intensity and 2D distributed model’, Biotechnology, Bioengineering 89(1), 13-122.

Zehnder, A.J, K. Ingvorsen and T. Marti (1982)*, ‘ Microbiology of methanogen bacteria in anaerobic digestion’, pp 45-68.

* - Papers not referred in original

WISHING A VERY HAPPY

TEACHER’S DAY

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