Evaluation of different consortia for biomethanation under psychrophilic conditions: Laboratory and field studies

Biomethanation with different consortia under psychrophilic conditions was studied under laboratory and field conditions. Under laboratory conditions, it was studied in batch digesters at 15 ± 10°C for 30 days hydraulic retention time (HRT) using different consortia viz. simple consortium, microbial consortium of Central Institute for Research on Cotton Technology (CIRCOT), Mumbai (India) and consortium of Antarctica supplied by Defence Research and Development Establishment, Gwalior (India). The microbial consortium of CIRCOT, Mumbai, activated in fresh cattle dung slurry and simple consortium yielded 1.025 and 0.865 L biogas, respectively, with maximum number of methanogens (45 ×106 ml⁻¹). The microbial consortium of CIRCOT, Mumbai, activated in autoclaved cattle dung slurry and consortium of Antarctica resulted in biogas production of only 0.570 and 0.445 L, respectively. The methanogenic counts in these digesters were low whereas sulphate reducing bacteria were high. The counts of proteolytic bacteria were high (105 ml⁻¹) in digesters inoculated with CIRCOT, Mumbai consortium. The field studies were carried out in 1 m³ Deenbandhu biogas plants with CIRCOT, Mumbai consortium activated in fresh cattle dung slurry which increased biogas production by 16-18% in the first year during winter months. However, this increase became negligible in the subsequent year.