Microbial hydrogen production from sewage sludge bioaugmented with a constructed microbial consortium

A constructed microbial consortium was formulated from three facultative H2-producing anaerobic bacteria, Enterobacter cloacae IIT-BT 08, Citrobacter freundii IIT-BT L139 and Bacillus coagulans IIT-BT S1. This consortium was tested as the seed culture for H2 production. In the initial studies with defined medium (MYG), E. cloacae produced more H2 than the other two strains and it also was found to be the dominant member when consortium was used. On the other hand, B. coagulans as a pure culture gave better H2 yield (37.16 ml H2/g CODconsumed) than the other two strains using sewage sludge as substrate. The pretreatment of sludge included sterilization (15% v/v), dilution and supplementation with 0.5% w/v glucose, which was found to be essential to screen out the H2 consuming bacteria and ameliorate the H2 production. Considering (1:1:1) defined consortium as inoculum, COD reduction was higher and yield of H2 was recorded to be 41.23 ml H2/g CODreduced. Microbial profiling of the spent sludge showed that B. coagulans was the dominant member in the constructed consortium contributing towards H2 production. Increase in H2 yield indicated that in consortium, the substrate utilization was significantly higher. The H2 yield from pretreated sludge (35.54 ml H2/g sludge) was comparatively higher than that reported in literature (8.1–16.9 ml H2/g sludge). Employing formulated microbial consortium for biohydrogen production is a successful attempt to augment the H2 yield from sewage sludge.