Ecology, Environment and Conservation Paper

ESTIMATION AND OPTIMIZATION OF METHANE PRODUCTION FROM CATTLE MANURE AND CORN STRAW THROUGH SEMICONTINUOUS DIGESTION IN PILOT-SCALE STUDIES

Jabraeil Taghinazhad, Reza Abdi and Mehrdad Adl

Abstract

In this study, we experimentally investigated the methane production from anaerobic co-digestion of cow manure (CM) and corn straw (CS) in semi-continuously stirred tank reactor (CSTR) that developed to operate under mesophilic conditions. The pilot-scale digester with 180 L in volume was employed. An average OLR of 2 and 3 kg VS. (m-3.d-1) and a HRT of 25 days was examined with respect to two different CM to CS mixing ratios of 100:0 and 75:25, respectively. The results showed both organic loading rates at co-digestion of CM+CS gave better methane yields than single digestion of CM. The biogas yield was obtained 0.243, 0.204, 0.311 and 0.296m3.(kg VS input)-1 for 2 and 3 kg VS.(m-3.d-1) at CM to CS mixing ratios of 100:0 and 75:25, respectively. The reactor showed stable performance with VS reduction between 55-74% during different runs. Modified Gompertz and logistic plot equation showed higher correlation of methane accumulation (R2 over 0.99) than exponential rise to maximum plot for all substrate concentrations.