Valorization of palm oil mill effluent via enhanced oil recovery as an alternative feedstock for biodiesel production.

Residual oil from palm oil mill effluent (POME) can be valorized into value-added products like biofuel. However, the complex structure in POME limits the full recovery of intracellular lipids. To address this challenge, low-frequency ultrasonication was used as a pre-treatment prior to oil recovery to improve the yield by liberating the entrapped oil via the cell disruption technique. This study focused on optimizing the ultrasound conditions (i.e., ultrasonication amplitude, ultrasonication duration, and probe immersion depth) to maximize the improvement of oil recovery yield using response surface methodology. The optimized conditions were 30.074% ultrasonication amplitude, 0.167 min ultrasonication duration, and 2 cm probe immersion depth. This resulted in an additional 42.50% improvement in oil recovery yield over non-ultrasonicated POME, which is in close agreement with the model prediction. Additionally, a cost-benefit analysis was incorporated to determine the feasibility of ultrasonication for enhancing oil recovery. The study also explored the synthesis of biodiesel from POME-recovered oil and characterized the fuel attributes according to American Society for Testing and Materials- and European Standards-prescribed procedures. The attributes of biodiesel produced from POME-recovered oil are comparable to those of palm-based biodiesel in Malaysia, demonstrating its potential as an alternative source for biodiesel production.

Recent advancements in the treatment of palm oil mill effluent (POME) using anaerobic biofilm reactors: Challenges and future perspectives.

Palm oil is the most utilized vegetable globally which is mostly produced in countries such as Malaysia, Indonesia and Thailand. The great amount of POME generation from palm oil mills is now a threat to the environment and require a suitable treatment of POME to reduce the organic strength in accordance with the standard discharge limit before releasing to the environment. Currently, the technology to combine the anaerobic process and biofilm system in bioreactors have produced a fresh idea in treatments of high strength wastewater like POME. Anaerobic biofilm reactor is a convincing method for POME treatment due to its significant advantages over the conventional biological treatments consisting of anaerobic, aerobic and facultative pond systems. Overall, integrated anaerobic-aerobic bioreactor (IAAB) can remove more than 99% of chemical oxygen demand (COD), biochemical oxygen demand (BOD) and total suspended solids (TSS) with the combination of anaerobic and aerobic digestion for POME treatment. It has better performance as compared to up-flow anaerobic sludge blanket (UASB) and up-flow anaerobic filter (UAF) with 80% and 88-94% COD removal efficiency respectively. Anaerobic pond was found to perform well also by removing 97.8% of COD in POME but require long retention time and larger land. Hence, this study aims to provide intensive review of the performance of the anaerobic biofilm reactor in treating POME and the recent advancements in this technology. The limitations and future perspectives in utilization of anaerobic biofilm reactor during its operation in treating POME are discussed.

Fuel cell virus sensor using virus capture within antibody-coated nanochannels.

We report a unique fuel cell sensor system for the first time direct detection of unlabeled virus particles based on the formation of antibody-virus complexes within the sensor's membrane nanochannels. This strategy exploits the change in the membrane resistance of the powered system, comprising a Prussian blue nanotubes (PB-nt) membrane cathode and a platinum mesh anode. The method reports an impressive shortest response time of ∼5 min toward the specific virus target, at low concentration values of 3-45 plaque-forming units per milliliter (pfu mL(-1)) with detection limit of 0.04 pfu mL(-1), comparable to state-of-the-art polymerase chain reaction (PCR)-based methods. The sensor can clearly differentiate dengue virus serotype 2 from serotype 3. When filled with Nafion perfluorinated resin, the PB-nt membrane demonstrates powerful utilization as a stand-alone fuel cell based virus sensor, and thus offers the outstanding promise of a sustainable, low-cost, and rapid low-power virus detection tool.

Anaerobic treatment of ultrasound pretreated palm oil mill effluent (POME): microbial diversity and enhancement of biogas production.

In this study, palm oil mill effluent (POME) treated by ultrasonication at optimum conditions (sonication power: 0.88 W/mL, sonication duration: 16.2 min and total solids: 6% w/v) obtained from a previous study was anaerobically digested at different hydraulic retention times (HRTs). The reactor biomass was subjected to metagenomic study to investigate the impact on the anaerobic community dynamics. Experiments were conducted in two 5 L continuously stirred fill-and-draw reactors R1 and R2 operated at 30 ± 2 °C. Reactor R1 serving as control reactor was fed with unsonicated POME with HRT of 15 and 20 days (R1-15 and R1-20), whereas reactor R2 was fed with sonicated POME with the same HRTs (R2-15 and R2-20). The most distinct archaea community shift was observed among Methanosaeta (R1-15: 26.6%, R2-15: 34.4%) and Methanobacterium (R1-15: 7.4%, R2-15: 3.2%). The genus Methanosaeta was identified from all reactors with the highest abundance from the reactors R2. Mean daily biogas production was 6.79 L from R2-15 and 4.5 L from R1-15, with relative methane gas abundance of 85% and 73%, respectively. Knowledge of anaerobic community dynamics allows process optimization for maximum biogas production.

Improved anaerobic digestion of palm oil mill effluent and biogas production by ultrasonication pretreatment.

Palm oil mill effluent (POME) is a highly polluted wastewater that consists of a high organic content of 4-5% total solids; a potential renewable energy source. A waste to energy study was conducted to improve biogas production using POME as substrate by ultrasonication pretreatment at mesophilic temperatures. The effect of temperature on the specific growth rate of anaerobes and methanogenic activity was investigated. Five sets of assays were carried out at operating temperatures between 25 °C and 45 °C. Each set consisted of two experiments using identical anaerobic sequencing batch reactors (AnSBR); fed with raw POME (control) and sonicated POME, respectively. The ultrasonication was set at 16.2 min ultrasonication time and 0.88 W mL-1 ultrasonication density with substrate total solids concentration of 6% (w/v). At 25 °C, biogas production rate and organic matter removal exhibited lowest values for both reactors. The maximum organic degradation was 96% from AnSBR operated at 30 °C fed with sonicated POME and 91% from AnSBR operated at 35 °C fed with unsonicated POME. In addition, the methane yield from AnSBR operated at 30 °C was enhanced by 21.5% after ultrasonication pretreatment. A few normality tests and a t-test were carried out. Both tests indicated that the residuals of the experimental data were normality distributed with mean equals to zero. The results demonstrated that ultrasonication treatment was a promising pretreatment to positively affect the organic degradation and biogas production rates at 30-35 °C.