32.4 Microbiology and Physico-Chemical Process in AD

493

application. Government needs to promote participation of the Industry in R&D and

technology development including transfer of know-how to the Industry. Encourag-

ing international collaboration for advanced biofuel research and capacity building

is the need of the hour. Skill development to ensure availability of trained and skilled

manpower is essential to meet the new demands of the biofuel industry. Manufac-

turing of equipment that are compatible with biofuels needs to be accomplished.

It is vital for the leading companies to participate in distribution and marketing of

biofuels certifying quality standards, consumer awareness about blending percent-

ages, warranty requirements, etc. The pricing of biofuels can be encouraged with

incentives. Coordination between states and urban local bodies (ULB) is necessary

to track the availability of MSW feedstock for biofuels including urban areas.

32.3

Significances of Anaerobic Microbiology in Biogas

Process

Anaerobically transforming the agro-industrial waste, agro-residuces, and both ter-

restrial and aquatic weeds into biogas and bio-compost results in sustainable energy

security to a large population of a nation. There exists vast knowledge and experience

regarding animal waste-fed biogas plants. However, low availability of animal waste

can enable accessibility of biogas to only about 12–17 million homes in India. Hence,

there is a need to explore agro-residues and agro-industrial residues as resources for

the production of biogas. The inadequate scientific knowledge and technologies for

the production of biogas from plant-based feedstock are the limiting criteria. This

can be accomplished with better understanding of fundamentals of anaerobic micro-

biology, biochemical, and physico-chemical concepts of the entire process resulting

in sustainable energy production. With growing population, there is a surge in gen-

eration of food waste. Disposal of food waste by means of landfilling, incineration,

and composting results in the emission of GHG. Hence, anaerobic digestion (AD) of

food waste by means of co-digestion with animal dung resulting in the production

of biogas and by-products such as CO2 and nutrient-rich manure is a sustainable

management approach [3, 4].

32.4

Microbiology and Physico-Chemical Process in AD

The conversion of organic components in biomass feedstock by consortia of bacteria

in the absence of oxygen to methane (biogas), carbon dioxide, and anaerobic com-

post takes place during anaerobic digestion. It is imperative to analyze the complex

microbial biochemistry involved in anaerobic digestion to harness enhanced pro-

duction of biogas. The production of biogas in anaerobic digestion is carried out by

the following four key steps: (i) hydrolysis, (ii) acidogenesis, (iii) acetogenesis, and

(iv) methanogenesis.

32.4.1

Hydrolysis and Acidogenesis

In the hydrolytic process, bacterial fermentation breaks down the plant-based

biomass feedstock, rich in macromolecules such as carbohydrates (pectins,