Strategies for recovery of imbalanced full-scale biogas reactor feeding with palm oil mill effluent

Background Full-scale biogas production from palm oil mill effluent (POME) was inhibited by low pH and highly volatile fatty acid (VFA) accumulation. Three strategies were investigated for recovering the anaerobic digestion (AD) imbalance on biogas production, namely the dilution method (tap water vs. biogas effluent), pH adjustment method (NaOH, NaHCO3, Ca(OH)2, oil palm ash), and bioaugmentation (active methane-producing sludge) method. The highly economical and feasible method was selected and validated in a full-scale application. Results The inhibited sludge from a full-scale biogas reactor could be recovered within 30–36 days by employing various strategies. Dilution of the inhibited sludge with biogas effluent at a ratio of 8:2, pH adjustment with 0.14% w/v NaOH, and 8.0% w/v oil palm ash were considered to be more economically feasible than other strategies tested (dilution with tap water, or pH adjustment with 0.50% w/v Ca(OH)2, or 1.25% NaHCO3 and bioaugmentation) with a recovery time of 30–36 days. The recovered biogas reactor exhibited a 35–83% higher methane yield than self-recovery, with a significantly increased hydrolysis constant (kH) and specific methanogenic activity (SMA). The population of Clostridium sp., Bacillus sp., and Methanosarcina sp. increased in the recovered sludge. The imbalanced full-scale hybrid cover lagoon reactor was recovered within 15 days by dilution with biogas effluent at a ratio of 8:2 and a better result than the lab-scale test (36 days). Conclusion Dilution of the inhibited sludge with biogas effluent could recover the imbalance of the full-scale POME-biogas reactor with economically feasible and high biogas production performance.

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Enhancement of Thermophilic Biogas Production from Palm Oil Mill Effluent by pH Adjustment and Effluent Recycling

Processes ◽

10.3390/pr9050878 ◽

2021 ◽

Vol 9 (5) ◽

pp. 878

Author(s):

Apinya Singkhala ◽

Chonticha Mamimin ◽

Alissara Reungsang ◽

Sompong O-Thong

Keyword(s):

Palm Oil ◽

Oil Palm ◽

Biogas Production ◽

Optimal Dose ◽

Methane Yield ◽

Ph Adjustment ◽

Oil Palm Ash ◽

Palm Oil Mill ◽

Archaea Community ◽

Effluent Recycling

A sudden pH drops always inhibits the anaerobic digestion (AD) reactor for biogas production from palm oil mill effluent (POME). The pH adjustment of POME by oil palm ash addition and the biogas effluent recycling effect on the preventing of pH drop and change of the archaea community was investigated. The pH adjustment of POME to 7.5 increased the methane yield two times more than raw POME (pH 4.3). The optimal dose for pH adjustment by oil palm ash addition was 5% w/v with a methane yield of 440 mL-CH4/gVS. The optimal dose for pH adjustment by biogas effluent recycling was 20% v/v with a methane yield of 351 mL-CH4/gVS. Methane production from POME in a continuous reactor with pH adjustment by 5% w/v oil palm ash and 20% v/v biogas effluent recycling was 19.1 ± 0.25 and 13.8 ± 0.3 m3 CH4/m3-POME, respectively. The pH adjustment by oil palm ash enhanced methane production for the long-term operation with the stability of pH, alkalinity, and archaea community. Oil palm ash increased the number of Methanosarcina mazei and Methanothermobacter defluvii. Oil palm ash is a cost-effective alkali material as a source of buffer and trace metals for preventing the pH drop and the increased methanogen population in the AD process.

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Monitoring of Ammoniacal Nitrogen and Phosphate in the Leachates When Diluted Palm Oil Mill Effluent was Used as a Fertilizer

Borneo Journal of Resource Science and Technology ◽

10.33736/bjrst.1586.2019 ◽

2019 ◽

Vol 9 (1) ◽

pp. 56-64 ◽

Cited By ~ 1

Author(s):

Nurul Iylia Salleh ◽

Tze-Pei Phan ◽

Seng Lau ◽

Chee-Bee Yeoh ◽

Meng-Guan Tay

Keyword(s):

Palm Oil ◽

Growth Rates ◽

Oil Palm ◽

Tap Water ◽

Palm Oil Mill Effluent ◽

Ammoniacal Nitrogen ◽

Leaching Rate ◽

Liquid Fertilizer ◽

Ground Water Pollution ◽

Palm Oil Mill

Palm oil mill effluent (POME) contains a high amount of nutrients and organic matter; therefore, it has been considered as an alternative liquid fertilizer (LF). However, the studies on the reuse of POME as fertilizer have been mostly limited to nutrients absorption but the leachates were neglected. Such approach caused potential impacts on ground water pollution. Thus, this research aimed to compare the leachabilities of ammoniacal nitrogen (NH3-N) and phosphate (PO43-), as well as the growth rates of oil palm seedlings in three different watering conditions. Six oil palm seedlings were watered with either POME, LF or tap water. The leachates from each seedling pot were collected weekly and analyzed for their NH3-N and PO43- concentrations. The pots which were watered with tap water showed the highest leaching rate of 0.0251 mg.L-1.week-1 for NH3-N and 0.0392 mg.L-1.week-1 for PO43-. The average concentrations of NH3-N in the leachates from the POME, LF and tap water potswere 0.45, 0.38 and 0.36 mg/L, respectively, whereas for PO43-, the average concentrations were 1.09 (POME), 0.96 (LF) and 0.66 (tap water) mg/L. The quickest plant growth rates were recorded in tap water (0.56 cm/day), followed by LF (0.51 cm/day) and POME (0.42 cm/day).

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