Biogas production from palm oil mill effluent and empty fruit bunches by coupled liquid and solid-state anaerobic digestion

Malaysia is one of the largest palm oil producers worldwide and its most abundant waste, palm oil mill effluent (POME), can be used as a feedstock to produce methane. Anaerobic digestion is ideal for treating POME in methane production due to its tolerance to high-strength chemical oxygen demand (COD). In this work, we compared the culture conditions during the start-up of anaerobic digestion of acidified POME between thermophilic (55 °C) and mesophilic (37 °C) temperatures. The pH of the digester was maintained throughout the experiment at 7.30 ± 0.2 in a working volume of 1000 mL. This study revealed that the thermophilic temperature stabilized faster on the 44th day compared to the 52nd day for the mesophilic temperature. Furthermore, the thermophilic temperature indicated higher biogas production at 0.60 L- CH 4 /L·d compared to the mesophilic temperature at 0.26 L- CH 4 /L·d. Results from this study were consistent with the COD removal of thermophilic temperature which was also higher than the mesophilic temperature.

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Inoculum Selection and Micro-Aeration for Biogas Production in Two-Stage Anaerobic Digestion of Palm Oil Mill Effluent (POME)

Jurnal Bahan Alam Terbarukan ◽

10.15294/jbat.v8i1.16318 ◽

2019 ◽

Vol 8 (1) ◽

pp. 14-21

Author(s):

Sri Ismiyati Damayanti ◽

Dian Fitriani Astiti ◽

Chandra Wahyu Purnomo ◽

Sarto Sarto ◽

Wiratni Budhijanto

Keyword(s):

Anaerobic Digestion ◽

Palm Oil ◽

Volatile Fatty Acids ◽

Biogas Production ◽

Liquid Waste ◽

Palm Oil Mill Effluent ◽

Cow Manure ◽

Two Stage ◽

Second Stage ◽

Palm Oil Mill

Two-stage anaerobic fluidized bed is an innovation in anaerobic digestion technology intended to handle liquid waste with high organic loading and complex substrate. The process is based on separation between acidogenic/acetogenic and methanogenic processes. The first stage is anaerobic process to convert substrate (represented as soluble chemical oxygen demand/sCOD) into volatile fatty acids (VFA). The second stage is methanogenic process to convert VFA into biogas. This study aimed to separate acidogenic/acetogenic and methanogenic processes by means of limited injection of air (micro-aeration) and inoculum selection. Micro-aeration was introduced in acidogenic/acetogenic stage because the relevant microbes were facultative so that the obligate anaerobic methanogens will be suppressed. On the other hand, the methanogenic reactor was kept completely anaerobic to ensure methanogenic dominance over acidogenic/acetogenic ones. Two sources of inoculums were used in this study, i.e. anaerobically digested biodiesel waste and anaerobically digested cow manure. Both inoculums were taken from active biogas reactor treating biodiesel waste and cow manure, respectively. Experiments were run in batch reactors treating palm oil mill effluent (POME) as the substrate for the acidogenic/acetogenic reactor. After the reaction in the first stage reached the minimum substrate concentration, the content of the reactor was used as the substrate for the methanogenic reactor as the second stage. Routine measurements were taken for sCOD and VFA concentrations, biogas production, and methane concentration in the biogas. Results confirmed that micro-aeration maintained good performance of acidogenic/acetogenic process, which was indicated by peaks in VFA accumulation, while suppressing methanogenic activities as no methane produced in this stage. Digested biodiesel waste was superior inoculum to be compared to digested cow manure with respect to sCOD removal. In the methanogenic stage, digested biodiesel waste also performed better as inoculum as it led to higher VFA conversion, higher biogas production rate, and higher methane content in the biogas.

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Thermophilic solid-state anaerobic digestion of solid waste residues from palm oil mill industry for biogas production

Industrial Crops and Products ◽

10.1016/j.indcrop.2016.11.002 ◽

2017 ◽

Vol 95 ◽

pp. 502-511 ◽

Cited By ~ 23

Author(s):

Wantanasak Suksong ◽

Aminee Jehlee ◽

Apinya Singkhala ◽

Prawit Kongjan ◽

Poonsuk Prasertsan ◽

...

Keyword(s):

Anaerobic Digestion ◽

Solid State ◽

Solid Waste ◽

Palm Oil ◽

Biogas Production ◽

Palm Oil Mill

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MODELING OF BATCH AND CONTINUOUS ANAEROBIC DIGESTION OF PALM OIL MILL EFFLUENT: THE EFFECT OF WASTEWATER-SLUDGE RATIO

Jurnal Teknologi ◽

10.11113/jt.v78.8649 ◽

2016 ◽

Vol 78 (5-6) ◽

Author(s):

Hathaikarn Thongpan ◽

Rachadaporn Thongnan ◽

Nirattisai Rakmak ◽

Chairat Siripatana

Keyword(s):

Anaerobic Digestion ◽

Palm Oil ◽

Production Efficiency ◽

Biogas Production ◽

Wastewater Sludge ◽

Palm Oil Mill Effluent ◽

Lag Phase ◽

Type Model ◽

Initial Ph ◽

Palm Oil Mill

In this work, both models for batch and continuous anaerobic digestion of palm oil mill effluent were developed based on Monod’s kinetics. Then the authors attempt to understand the effect of wastewater-sludge (WW:S) ratio on the biogas production efficiency in batch digesters. The experiments were carried out at a controlled temperature of 35±0.5 °C. Two series of the experiment were conducted. In the first series, the wastewater-sludge ratios covered 1:1 (add sodium bi-carbonate), 1:1, 1:2 and 2:1. It was found that the ratio of 1:2 gave the highest biogas producing efficiency followed by the ratio 1:1 (add sodium bi-carbonate). At 1:1 ratio, sodium bi-carbonate addition was required to start anaerobic digestion at a workable pH range whereas at 1:2 ratio the initial pH is in the workable range without the need of its addition. However, at the ratio of 2:1 the starting pH was too low to adjust pH economically by adding sodium bi-carbonate. The second series was to confine experiments to a narrower ratio range, namely: 1:1 (add sodium bi-carbonate), 1:1.5, 1:2, 1:2.5. In both sets of experiment, the ratio 1:2 gave the best biogas production potential of 76.62 and 78.52 ml of biogas/g COD removed respectively. In all treatments, the process was able to remove more than 80% of wastewater initial COD. The modified Gompertz equation was used to estimate the maximum specific biogas production rate (MBPR or Rm/S0). It was also found that the ratio of 1:2 gave the best MBPR in both experimental series (26.87 ml biogas/g COD-day). A modified Monod-type Model was also developed to describe the microbial growth, substrate consumption and biogas production in continuous operation. In general, sludge recycle provided active biomass which can use the substrate in the wastewater instantly without significant lag phase or delay. Furthermore, continuous-flow model developed, with parameters estimated from batch experiments, predicted the experimental kinetics of the actual continuous experiments satisfactory.

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