Hydrogen and Methane Production from Starch Wastewater in a Mesophillic Anaerobic Baffled Reactor

Treatment of starch wastewater was investigated in a 30 l capacity pilot scale anaerobic baffled reactor (ABR) under mesophillic conditions. The reactor was operated at different hydraulic retention times (HRTs) of 72; 48 and 24 h. Corresponding organic loading rates (OLRs) were 8.7; 7.6 and 22 kg COD/m 3 . d. The results showed that COD and BOD5 removals exceeded 40 and 50% respectively at OLR of 22 kgCOD/m 3 .d. The percentage COD recovered as methane in the gas phase was 56.7 and 43% at HRTs of 24 and 72 h, respectively. Methane yield averaged at 0.29 and 0.30 lCH4 /g COD removed of ABR, at HRTs of 24 and 72 h., respectively, Increasing the BOD5/COD ratio from 0.59 to 0.66 improved the removal efficiency of BOD5 from 40 to 54% respectively. Methane yield averaged at 0.29 and 0.30 lCH4 /g COD removed of ABR, respectively. Removal of COD particulate fraction of organics was found to be greater than COD soluble fraction. Sudden drop in pH from 7.8 to 6.7 and generation of volatile fatty acids (VFA) were observed in the first compartment due to acidogenesis and acetogenesis. The pH increased and VFA concentration decreased longitudinally down the reactor.