Holistic determination of suitable conditions for biogas production from Pennisetum purpureum x Pennisetum americanum liquor in anaerobic baffled reactor.

Holistic approach had been undertaken to determine the suitable conditions for biogas production from Pennisetum purpureum x Pennisetum americanum (Napier Pak Chong1) liquor using the anaerobic baffled reactor (ABR). Effects of factors, i.e. organic loading rates (OLRs), feeding schemes, trace element additions and effluent recirculation rates, on ABR performance were systematically investigated. Increase of OLRs and effluent recirculation rates adversely affected methane yields when capability of ABR in containing microorganisms was deteriorated. High stability of ABR performance was detected under the semi-continuous feeding scheme with trace element additions. The suitable condition for ABR was found at the OLR of 4.0 kg COD/m3.d under the semi-continuous feeding scheme with trace element additions at the effluent recirculation rate of 0.5 (QR/Q). At this condition, high methane yield (0.49 ± 0.05 Nm3/kg VSadded) could be achieved using the economical ABR at relatively high OLR of 4.0 kg COD/m3.d.