Chemical and biological effects of zero-valent iron (ZVI) concentration on in-situ production of H from ZVI and bioconversion of CO into CH under anaerobic conditions.

The conversion of carbon dioxide (CO) to methane (CH) is a strategy for sequestering CO. Zero-valent iron (ZVI) has been proposed as an alternative electron donor for the CO reduction to CH. In this study, the effects of ZVI concentrations on the abiotic production of H (without the action of microorganisms) in the first part and on the biological conversion of CO to CH using ZVI as a direct electron donor in the second part were examined.

Efficient removal of tannins from anaerobically-treated palm oil mill effluent using protein-tannin complexation in conjunction with electrocoagulation.

Despite the significant removal of chemical oxygen demand (COD) by anaerobic digestion, anaerobically-treated palm oil mill effluent (POME) still contains tannins and other phenolic compounds, resulting in residual COD and a brownish color. In this study, we investigated the removal of tannins from anaerobically treated POME using protein-tannin complexation in conjunction with electrocoagulation. The amino acid composition of the protein, aqueous pH, and protein: tannin ratios were found to be important parameters affecting the tannin removal efficiency.

Effect of freeze-thaw process on physical properties, microbial activities and population structures of anaerobic sludge.

Effects of the freeze-thaw process on physical properties, cell viability, microbial activities and population structures of anaerobic sludge were investigated. It was found that the sludge volume index was greatly reduced from 16.4 mL/g in the original sludge to 4.

Comparative biochemical methane potential of paragrass using an unacclimated and an acclimated microbial consortium.

The effect of inoculum sources on the anaerobic digestion of paragrass was investigated. Two types of sludge were used as the inoculums: an anaerobic sludge obtained from a domestic wastewater treatment plant (OS) and a sludge acclimated to fibrous substrates in raw palm oil mill effluent (AMC). Microbial activity assays showed that the AMC had hydrolytic and acetogenic activities two times greater than the activities of the OS.

Simultaneous treatment of raw palm oil mill effluent and biodegradation of palm fiber in a high-rate CSTR.

A high-rate continuous stirred tank reactor (CSTR) was used to produce biogas from raw palm oil mill effluent (POME) at 55°C at a highest organic loading rate (OLR) of 19 g COD/ld. Physical and chemical pretreatments were not performed on the raw POME. In order to promote retention of suspended solids, the CSTR was installed with a deflector at its upper section.

Comparative mesophilic and thermophilic anaerobic digestion of palm oil mill effluent using upflow anaerobic sludge blanket.

The effects of organic loading rate and operating temperature on the microbial diversity and performances of upflow anaerobic sludge blanket (UASB) reactors treating palm oil mill effluent (POME) were investigated. The following two UASB reactors were run in parallel for comparison: (1) under a mesophilic condition (37 degrees C) and (2) under a mesophilic condition in transition to a thermophilic condition (57 degrees C). A polymerase chain reaction (PCR)-based denaturing gradient gel electrophoresis (DGGE) analysis showed that the microbial population profiles significantly changed with the organic loading rate (OLR) and the temperature transition from the mesophilic to the thermophilic condition.

UASB performance and microbial adaptation during a transition from mesophilic to thermophilic treatment of palm oil mill effluent.

The treatment of palm oil mill effluent (POME) by an upflow anaerobic sludge bed (UASB) at organic loading rates (OLR) between 2.2 and 9.5 g COD l(-1) day(-1) was achieved by acclimatizing the mesophilic (37 °C) microbial seed to the thermophilic temperature (57 °C) by a series of stepwise temperature shifts.

Effect of chitosan on UASB treating POME during a transition from mesophilic to thermophilic conditions.

The effects of chitosan addition on treatment of palm oil mill effluent were investigated using two lab-scale upflow anaerobic sludge bed (UASB) reactors: (1) with chitosan addition at the dosage of 2 mg chitosan per g volatile suspended solids on the first day of the operation (R1), (2) without chitosan addition (the control, R2). The reactors were inoculated with mesophilic anaerobic sludge which was acclimatized to a thermophilic condition with a stepwise temperature increase of 5 °C from 37 to 57 °C. The OLR ranged from 2.