world wide perspective of anaerobic digestion

7/28/2019 World Wide Perspective of Anaerobic Digestion

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WORLD WIDE PERSPECTIVEOF ANAEROBIC DIGESTION


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INTRODUCTION

Biogas is nothing but anaerobic digestion of organic

materials Developing countries is more interest in biogas

technology because of escalating fossil fuel cost

Renewable energy technology such as solar, wind and

biomass based technologies reduce deforestation andimportation of fossil fuels

Biogas needs lowest financial inputs per kwh of output

NPK conserve via slurry by recycle process Potential to reduce plant, animal and human pathogens

Domestic use-reduce lungs and eye problem


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DESSEMINATION OF BIOGAS

TECHNOLOGY IN DEVELOPING

COUNTRIES China, India and South Korea have installed morenumbers

CHINA

More than 7 million digesters of family size units(6-

10 m3) for cooking and lighting

50,000 medium size units (50 m3)

1100 larger size units (100 m3) and the output is

8000 kw


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INDIA

1 lakh digesters

Primary objective is to provide fuel for cooking and

lighting

Community biogas plants for using night soil as

feedstock

Various organic feed stocks

SOUTH KOREA

29,000 units

Reduced in numbers due to colder weather operation


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VARIOUS DESIGNS

Fixed dome digester- Chinese model

Floating cover digester-Indian KVIC model

Bag digester

Plug flow digester Anaerobic filter

Anaerobic baffle reactor

UASB reactor

Ganesh model biogas plant

Pragathi model biogas plant

Deenbandhu model biogas plant


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SPECIFIC PROBLEMS

Lack of understanding of fundamentals

Lack of rigorous field data studies

Optimization

Carbon-Nitrogen ratios


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LACK OF UNDERSTANDING OF

FUNDAMENTALS

Multi disciplinary technology which includes

microbiology, chemistry and engineering

Total gas production and methane production is theimportant measure of process performance


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LACK OF RIGOROUS FIELD DATA

STUDIES

On actual process performance under a variety of

operating conditions and with various feed stocks

Over and under designed biogas plants leads to waste

of resources or mismatch with the user need Needs to closely monitor the number of existing units

to provide the substantive data base


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OPTIMIZATION

Optimize existing designs to reduce capital cost and

improve performance

Capital cost reduced by 27 % for small plant and 41.2

% for larger plant Larger plants under identical conditions the lower

cost design improved gas yields by 14 % compare to

KVIC


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C/N Ratio

30: 1 is optimal

High nitrogen levels with low C/N ratios cause

toxicity

Low levels (high C/N ratios) can inhibit the

rate of digestion

world wide perspective of anaerobic digestion

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