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© EWE Consulting Engineers - Presentation of Optimising Anaerobic Digestor Performance dtd 17.12.15
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Environmental | Energy | Analytical Services | Water & Waste Water | Process & Chemicals I Civil & Infra
Optimising Anaerobic Digestor Performance for Enhanced Biogas production.
Presented on
First National Conference on Biogas,
Hotel Holiday Inn Mayur Vihar, Delhi
17th December 2015
By:
Vikrum Kishore : Principal Consultant
M Sharma : Sr Manager (Project & Engineering)

2. EWE Consulting Engineers Private Limited
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© EWE Consulting Engineers - Presentation of Optimising Anaerobic Digestor Performance dtd 17.12.15
Water & Waste WaterEnvironment Energy
Analytical Process & Chemicals Civil & Infra
EWE Operating Horizons

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© EWE Consulting Engineers - Presentation of Optimising Anaerobic Digestor Performance dtd 17.12.15
Basics of Degradation
Carbonaceous Matter (C,H and/or O) degradation in absence of Oxygen.
Anaerobic digesters can be categorized as :
The biomass is fixed to a surface ("attached growth")
freely mix type with the reactor liquid ("suspended growth")
Hybrid Types.
There are about 20 variants of anaerobic digesters.
Anaerobic activated sludge process
CSTR
Anaerobic contact process
Anaerobic expanded-bed reactor
Anaerobic filter
Anaerobic fluidised bed – One format is UASB
Anaerobic lagoon
C6H12O6 ------ > CO2 + CO + H2O + CH4 + H2S + Energy

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© EWE Consulting Engineers - Presentation of Optimising Anaerobic Digestor Performance dtd 17.12.15
Anaerobic Metabolic Pathway
Biogas
Solid
Manure
Liquid
Fertilizer
Carbon
Dioxide•Limit Heavy Metals / Grease
•Temperature
Effluent /
Waste Feed
NB : Treated waste water after further treatment, stablisation & concentration
Pie chart is a representation and the ratio’s vary depending on factors

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© EWE Consulting Engineers - Presentation of Optimising Anaerobic Digestor Performance dtd 17.12.15
Wastes that can be Treated
Breweries and Beverage Industry
Distilleries and fermentation industry
Food & Dairy Industry
Pulp and paper.
Poultry & Cattle Waste.
Chicken & Meat Processing.
Textile.
Landfill Leachate Treatment.
High Capacity municipal plants
Left over degraded flowers, Vegetable & Food Waste.
In short any waste which is high in strength and / or beyond biodegradability limits

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© EWE Consulting Engineers - Presentation of Optimising Anaerobic Digestor Performance dtd 17.12.15
Stage 6 Gas liquid
Sepration
Stage 5 Methnogenisis
Stage 4 Acetogenesis
Stage 3 Acedogenisis
Stage 2 Hydrolysis
Stage 1 Distribution
Anaerobic Metabolic Path
Any Matter having high C & H content.
Objective – Maximum generation of CH4
(upto 76% CH4 has been obtained by us
Greater than 97 % CH4 after purification)
Minimizing Water Carryover.
Estimation of H2S generation.
Steps in Anaerobic Digestion:
Dispersion.
Hydrolysis
Complex Organics ----- Monosacharides, Amino Acids, Fatty Acids & Alcohol
Acidogenesis
Monosacharides, Amino Acids, Fatty Acids & Alcohol ----- to Volatile Acids
Acetogenesis
Volatile acids ------ Acetates, H2, CO2.
Methanogenesis.
Acetate ----- CH4 & CO2.
Gas Liquid Separation – Reduction in carry over of solids & water.

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© EWE Consulting Engineers - Presentation of Optimising Anaerobic Digestor Performance dtd 17.12.15
Optimising Digestor Performace
Temperature – Cryophilic, Mesophilic, Thermophylic
Presence of Oils & Greases, Pesticides, Oxidising matter etc.
Heavy metals like Cr+3, Lead etc
Presence of micro nutrients, Zinc, Iron etc
Seeding cultures and time of seeding.
Sampling points.
Maintenance of bed / staged condition.
Residence time = F(Reaction kinetics, Geometry, distribution & Collection).
Hold up time can be as low at 12 hours.
Hold up time can be as high as 120 hours.
Continuous monitoring
Being vigilant – It takes just 2 - 4 days to destablise the kinetics
It takes 10 – 20 days to re-establish the kinetics (5X factor)
It takes just 2 - 4 hours to monitor the bed daily
Once stabilised it is easier to drain and restart than restablise.

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