The Effect of Mixing on Methane Production in a Semi-commercial Closed Digester Tank Treating Palm Oil Mill Effluent

The performance of a semi-commercial closed digester tank treating palm oil mill effluent (POME) was studied at four different mixing regimes i.e natural mixing (NM), minimal horizontal mixing (MHM), minimal horizontal and vertical mixing (MHVM) and vigorous mixing (VM). The chemical oxygen demand (COD) removal efficiency recorded satisfactory result at higher than 90% when subjected to the first three mixing regimes but reduced to the lowest of 85% when VM was applied. In the NM, MHM and MHVM experiments, the maximum total volatile fatty acids (VFA) concentration in the digester was recorded below the critical level of 1000 mg L . The MHM gave -1 the highest methane productivity at 1.4 m m d in comparison to NM at 1.0 m m d and MHVM 3 -3 -1 3 -3 -1 at 1.1 m m d. This indicates minimal mixing was required to provide good contact between 3 -3 -1 substrate and microorganisms inside the digester and to release the entrapped biogas at the bottom of the digester. The VM on the other hand was discovered to inhibit the methane production process as methane was not produced at the end of the experiment and total VFA concentration was also recorded high at 3700 mg L . The high total VFA concentration in the system may have disrupted -1 the syntrophic relationship between acidogens and methanogens and inhibited the methanogenesis

The Effect of Higher Sludge Recycling Rate on Anaerobic Treatment of Palm Oil Mill Effluent in a Semi-Commercial Closed Digester for Renewable Energy

Problem statement: A 500 m3 semi-commercial closed anaerobic digester was constructed for Palm Oil Mill Effluent (POME) treatment and methane gas capture for renewable energy. During the start-up operation period, the Volatile Fatty Acids (VFA) accumulation could not be controlled and caused instability on the system.Approach: A settling tank was installed and sludge was recycled as to provide a balanced microorganisms population for the treatment of POME and methane gas production. The effect of sludge recycling rate was studied by applying Organic Loading Rates (OLR) (between 1.0 and 10.0 kgCOD m-3 day-1) at different sludge recycling rates (6, 12 and 18 m3 day-1).Results: At sludge recycling rate of 18 m3 day-1, the maximum OLR was 10.0 kgCOD m-3 day-1 with biogas and methane productivity of 1.5 and 0.9 m3 m-3 day-1, respectively. By increasing the sludge recycling rate the VFA concentration was controlled below its inhibitory limit (1000 mg L-1) and the COD removal efficiency recorded was above 95% which indicated good treatment performance for the digester. Two methanogens species (Methanosarcina sp. and Methanosaeta concilii) had been identified from sludge samples obtained from the digester and recycled stream.Conclusion: By increasing the sludge recycling rate upon higher application of OLR, the treatment process was kept stable with high COD removal efficiency. The biogas and methane productivity were initially improved but reduced once OLR and recycling rate were increased to 10.0 kg COD m3 day-1 and 18 m3 day-1 respectively

Improved anaerobic treatment of palm oil mill effluent in a semi-commercial closed digester tank with sludge recycling and appropriate feeding strategy

Anaerobic treatment of palm oil mill effluent (POME) in a semi-commercial closed digester tank with sludge recycling was studied using different feeding strategies; one fixed at every three hour and another at every six hour. The organic loading rate (OLR) was increased step-wise and stopped once inhibition on methane production occurred. The chemical oxygen demand (COD), feeding rate, hydraulic retention time (HRT),OLR, and sludge recycling ratio were measured. Performance was based on the COD removal efficiency and methane yield, while stability was assessed in terms of total volatile fatty acids (VFA) accumulation, total VFA-to-alkalinity ratio (VFA:Alk) and food-to-microorganisms ratio (F/M ratio). The feeding strategies, at every three hour and six hour, gave satisfactory COD removal efficiency of higher than 90%, but the latter feeding strategy gave a more stable process with total VFA concentration recorded below 500 mg L-1 and VFA:Alk ratio of less than 0.3 at maximum OLR of 6.0 kgCOD m-3 d-1. The treatment period could also be extended up to 100 days without any obvious problems

Improved economic viability of integrated biogas energy and compost production for sustainable palm oil mill management

This paper proposes a new approach for integrated technology of biogas energy and compost production for a palm oil mill. This study evaluated the economic viability based on the changes of materials flow and energy balance when a palm oil mill introduces this approach. A palm oil mill processing 54 tonnes fresh fruit bunch (FFB) per hour has the potential to produce 8.2 GWh per year of electricity using biogas captured during anaerobic treatment of palm oil mill effluent (POME). Compost production using shredded empty fruit bunch (EFB) and POME anaerobic sludge obtained from the anaerobic digester is equivalent of 579 tonnes, 151 tonnes and 761 tonnes per year of nitrogen, phosphorus and potassium respectively. The integrated technology is a more attractive solution compared to the case when the palm oil mill installs either biogas energy or compost technology individually. The result of economic analysis suggests that this integrated approach is the most economically effective in comparison to the other two cases. Interestingly, even without Clean Development Mechanism (CDM), the integrated technology can still be economically viable, which can be a good solution for sustainable palm oil industry management in the near future

Recovery of residual crude palm oil from the empty fruit bunch spikelets using environmentally friendly process

The development of new, low-cost technology to increase the oil recovery in the palm oil mill especially from the palm oil wastes has been an important goal for the industry to increase OER. According to preliminary oil detection, the residual oil is mainly located on the surface of spikelet, about 73.73 ± 0.05% from total residual oil. The combined water-steam shows the best oil extraction process, indicating 82 ± 0.13% of oil may be removed from the EFB spikelet. Thus, this method is chemical free and environmentally friendly residual CPO recovery process using EFB

Study on residual oil recovery from empty fruit bunch by combination of water and steam process

In this study, the recovery of residual oil from the spikelet of oil palm empty fruit bunches (OPEFB) was conducted. Residual oil was present in the OPEFB due to mechanical processes such as the loading of fruit into the sterilizer cage, sterilization and threshing, in which a certain portion of the oil from the fruitlet was impregnated mainly on the surface of the spikelet rather than on the stalk of OPEFB. The highest residual oil content was found mainly in the small OPEFB (28.49 ± 5.20% dry basis). The oil extraction process was introduced as hydro solvent-assisted steam extraction, which comprises of four main steps, i.e., flooding, injection, soaking and draining. The overall process resulted in above 83% residual oil removal from the spikelet. The proposed method can be an option to be implemented in the palm oil mill because it is a chemical-free, environment-friendly and novel process

Recovery of residual crude palm oil (RCPO) from oil palm decanter cake (OPDC) using D-limonene

In this study, d-limonene as green solvent was used as an alternative to n-hexane to recover the residual crude palm oil (RCPO) from the OPDC. The OPDC obtained from the palm oil mill contained about 12.55±3.15% (dry basis) of RCPO. Similar as n-hexane, the results proved that d-limonene as solvent was able to recover 100% of the RCPO from the OPDC successfully. The recyclable of d-limonene was 90%, higher than n-hexane (70%) and not much variation on fatty acids composition of extracted RCPO were observed. To ensure complete RCPO recovery, microscopic observation and FTIR spectra analysis on OPDC before and after the extraction were performed. This study concludes that d-limonene is comparable to n-hexane. However, the residual oil is classified as non-edible as it is not extracted via mechanical method. Therefore, further analysis is necessary in order to determine the potential use of the residual oils in other industries such as pharmaceutical, food packaging, fiberboard manufacturing and others

The effect of mixing on methane production in a semi-commercial closed digester tank treating palm oil mill effluent

The performance of a semi-commercial closed digester tank treating palm oil mill effluent (POME) was studied at four different mixing regimes i.e natural mixing (NM), minimal horizontal mixing (MHM), minimal horizontal and vertical mixing (MHVM) and vigorous mixing (VM). The chemical oxygen demand (COD) removal efficiency recorded satisfactory result at higher than 90% when subjected to the first three mixing regimes but reduced to the lowest of 85% when VM was applied. In the NM, MHM and MHVM experiments, the maximum total volatile fatty acids (VFA) concentration in the digester was recorded below the critical level of 1000 mg L-1. The MHM gave the highest methane productivity at 1.4 m3 m-3 d-1 in comparison to NM at 1.0 m3 m-3 d-1 and MHVM at 1.1 m3 m-3 d-1. This indicates minimal mixing was required to provide good contact between substrate and microorganisms inside the digester and to release the entrapped biogas at the bottom of the digester. The VM on the other hand was discovered to inhibit the methane production process as methane was not produced at the end of the experiment and total VFA concentration was also recorded high at 3700 mg L-1. The high total VFA concentration in the system may have disrupted the syntrophic relationship between acidogens and methanogens and inhibited the methanogenesis

Characterization of Waste Clay from Palm Oil Mill Effluent and Enzyme Immobilization Study for Cassava Saccharification Process

Waste clay recovered from palm oil mill effluent (POME) was characterized and used as an enzyme-supporting material for the cassava saccharification process. The clay was treated by the Soxhlet extraction method to remove the residual oil and then characterized using a BET surface area analyser, XRF, XRD, FTIR, TGA, and FESEM. The chemical analysis showed that the sample had a high amount of CaO (93%) with a minor content of SiO2 (1.378%) and Al2O3 (0.707%), with a surface area of 1.15 m2/g. The XRD analysis revealed the major mineral presence to be calcite, as confirmed by FESEM analysis. The FTIR results also attested to the presence of a calcite phase and carbonate groups. To study the performance of the waste clay for enzyme immobilization application, the recovered waste clay was further used as an enzyme supporting material for enzyme immobilization in the cassava saccharification process. Results showed that the enzymes were successfully encapsulated and gave the highest immobilization yield of 70% with 2% clay concentration. In addition, the encapsulated enzymes also enhanced the reusability, where the enzyme retained 32% of its activity after seven cycles of saccharification processing

Physicochemical Characterization of Oil Palm Decanter Cake (OPDC) for Residual Oil Recovery

A characterization study on oil palm decanter cakes (OPDC) was performed to gain an in-depth understanding of the material’s characteristics to aid in potential residual oil recovery. The OPDC was characterized by a high moisture content, high biodegradability, high organic content, and a nutrient-rich composition. Microscopic observation showed that the oil attachments in OPDC, and a vast majority of the droplets, were less than 50 μm in size. Furthermore, contact angle measurement revealed the hydrophilic and oleophilic characteristics of OPDC. Specifically, the contact angles of water and crude palm oil (CPO) with OPDC were both less than 45° with absorption rates of 0.0265 0.003 µL/s and 0.1042 0.05 µL/s, respectively. The OPDC is a fibrous material, and the surface area and pore size measured were 7.103 m2/g and 481.7 Å, respectively. Fourier transform infrared spectroscopy (FTIR) and thermogravimetric (TG) analysis results showed the functional groups and degradation properties of OPDC, respectively