Pretreated Palm Oil Mill Effluent (POME) Digestion in an Up-Flow Anaerobic Sludge Fixed Film Bioreactor: a Comparative Study

An up-flow anaerobic sludge fixed film (UASFF) bioreactor was used to treat the pretreated palm oil mill effluent (POME). In physical pretreatment, POME was pre-settled for ۲ h and the supernatant was fed into the reactor. In chemical pretreatment, optimum dosages of cationic and anionic polymers were used. Experiments of pretreated POME digestion were conducted based on a central composite face-centered design (CCFD) with two independent operating variables, feed flow rate (QF) and up-flow velocity (Vup). The operating variables were varied to cover a wide range of organic loading rate (OLR) from ۳.۸ to ۲۹ g COD/l.d. A stable TCOD removal efficiency of ۸۳.۵% was achieved at the highest QF (۳.۳۱ l/d, corresponding to OLR of ۲۶ g COD/l.d) for pre-settled POME whereas only ۶۲.۲% TCOD removal was achieved with chemically pretreated POME at QF of ۷.۶۳ l/d (corresponding to OLR of ۲۹ g COD/l.d) and that too was coupled with process instability. At comparable OLRs i.e. ۱۶.۹۵ g COD/l.d (QF=۲.۱۶ l/d) for pre-settled POME and ۱۶.۴۲ g COD/l.d (QF=۴.۳۲ l/d) for chemically pretreated POME, the VFA concentrations for the two cases were also similar.

Keywords:

Pome , Pretreatment , UASFF Reactor , Central Composite Face , Centered Design (CCFD)