32.7 Factors Influencing Biogas Production

499

Fibrobacteres

Chloroflexi

Bacteroidetes

Acidiobacteria

Actinobacteria

Other

Euryarchaeota

Verrucomicrobia

Tenericutes

Synergistetes

Spirochaetes

Proteobacteria

Planctomycetes

Firmicutes

Figure 32.2

Microbial community in a typical biogas digestion system treating Sewage

sludge, lignocellulosic biomass, and household food wastes.

highest volume of biogas (21 cm³). This enhanced yield could be attributed to the

availability of adequate moisture and nutritive content from fruit waste that is

necessary for the metabolic processes of the microorganisms. It is reported that

co-digestion of cattle dung feedstock in combination with cheese whey enhanced

the production of biogas. Use of rumen fluid as inoculum in co-digestion of cattle

manure with food waste increased the biogas yield by 24–47% over the control [9].

Enhanced production of biogas from lignocellulosic material can be brought about

by phylum Neocallimastigomycota, an anaerobic fungus commonly present in rumi-

nants [5].

32.7.5

Recirculation of Leachate

In a solid-state-stratified bed (SSB) reactor developed by Centre for Sustainable Tech-

nologies (CST), recirculation of leachate of the digester fed with dry biomass feed-

stock is necessary as the microbial consortia is low in the newly fed biomass. This

facilitates initiation of hydrolysis and acidogenesis of the freshly fed feedstock and

circulates the accumulated VFA to lower portion of the digester for transformation

into biogas [3].

32.7.6

Ammonia

Protein digestion in an AD results in the generation of ammonia which could be

inhibitory to methanogens when liberated in high concentration. Methanosarcina

barkeri, Methanobacterium thermoautotrophicum, Methanobacterium formicicum,

and Methanospirillum hungatei were the most sensitive. With favorable ambient