Effect of various pretreatment methods on anaerobic mixed microflora to enhance biohydrogen production utilizing dairy wastewater as substrate

Influence of different pretreatment methods applied on anaerobic mixed inoculum was evaluated for selectively enriching the hydrogen (H2) producing mixed culture using dairy wastewater as substrate. The experimental data showed the feasibility of molecular biohydrogen generation utilizing dairy wastewater as primary carbon source through metabolic participation. However, the efficiency of H2 evolution and substrate removal efficiency were found to be dependent on the type of pretreatment procedure adopted on the parent inoculum. Among the studied pretreatment methods, chemical pretreatment (2-bromoethane sulphonic acid sodium salt (0.2 g/l); 24 h) procedure enabled higher H2 yield along with concurrent substrate removal efficiency. On the contrary, heat-shock pretreatment (100 °C; 1 h) procedure resulted in relatively low H2 yield. Compared to control experiments all the adopted pretreatment methods documented higher H2 generation efficiency. In the case of combination experiments, integration of pH (pH 3; adjusted with ortho-phosphoric acid; 24 h) and chemical pretreatment evidenced higher H2 production. Data envelopment analysis (DEA), a frontier analysis technique model was successfully applied to enumerate the relative efficiency of different pretreatment methods studied by considered pretreatment procedures as input and cumulative H2 production rate and substrate degradation rate as corresponding two outputs.