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Palm oil mill effluent (POME) can be transformed into biogas. Acidogenesis, as a fermentation process, involves decomposition of hydrolysis products into simpler organic products in the form of acetate, hydrogen and carbon dioxide. Intermediate products from acidogenesis form of volatile fatty acids (VFA), such as propionate, butyrate, valerate, and their isoforms, which require further metabolic processes to produce biogas. The aim of the research was to determine the suitable kinetics model that describes microbial growth (from volatile suspended solid (VSS) values) and production in the acidogenesis process. The reactor used in this acidogenesis process was a stirred tank reactor with a volume of 6 L and operates in a batch system. This research was conducted with a variable agitation rate variation (200; 250; and 300 rpm) at a temperature of 30 °C and 55 °C. The pH was varied, including 5; 5.5; and 6. The kinetic models used in this study were Modified Gompertz, Monod, and Logistic. The best effect of pH on VSS was obtained at pH 5.5, agitation rate on VSS was obtained at agitation rate of 250 rpm and operating conditions for acidogenesis process was achieved under thermophilic conditions (55 °C). Logistic kinetic model is the best kinetic model that can describe VSS and VFA in this study. [ABSTRACT FROM AUTHOR]

The utilization of palm oil mill residues for sustainable biogas production presents a promising avenue to mitigate environmental challenges associated with waste disposal and energy demand in palm oil processing. The study explores the use of palm oil mill residues for sustainable biogas production, focusing on the impact of mixing ratios of POME and three raw milled residues on biogas yield through anaerobic co-digestion. Results indicate that co-digestion significantly enhanced biogas production compared to mono-digestion of POME alone. The highest biogas yield of 370 ml was recorded in the digester with 40% residues followed by 50% with a cumulative biogas of 190 ml. The two digesters were higher than 80 ml recorded for POME alone. The findings underscore the potential of integrating palm oil mill residues into biogas systems to achieve dual objectives of waste management and renewable energy generation. [ABSTRACT FROM AUTHOR]

Palm oil mill effluent (POME), wastewater generated from palm oil production, is known for its extremely high chemical oxygen demand and brownish color. Anaerobic digestion is the primary treatment method for POME in the palm oil industry; however, anaerobically treated POME has high concentrations of residual contaminants and color intensity. This study proposes an approach to treat anaerobically-treated POME in recycled water for industrial applications by integrating preliminary organic precipitation, electrocoagulation, and electrooxidation (EO). The EO process was optimized in terms of the current density, electrolysis time, electrode arrangement, and feed flow rate. At a current density of 60 mA/cm2 and an electrolysis time of 9 min, the EO process with a graphite anode and stainless-steel cathode in the monopolar electrode configuration reduced the phenolic concentration and color in the preliminary-treated POME from 8.95 mg/L and 317.19 ADMI to 0.25 mg/L and 26.10 ADMI, respectively. Additionally, the EO process exhibited a 92.26% efficiency in lowering the ammonium-nitrogen content. [ABSTRACT FROM AUTHOR]

Abstract Palm oil mill effluent (POME), wastewater generated from palm oil production, is known for its extremely high chemical oxygen demand and brownish color. Anaerobic digestion is the primary treatment method for POME in the palm oil industry; however, anaerobically treated POME has high concentrations of residual contaminants and color intensity. This study proposes an approach to treat anaerobically-treated POME in recycled water for industrial applications by integrating preliminary organic precipitation, electrocoagulation, and electrooxidation (EO). The EO process was optimized in terms of the current density, electrolysis time, electrode arrangement, and feed flow rate. At a current density of 60 mA/cm2 and an electrolysis time of 9 min, the EO process with a graphite anode and stainless-steel cathode in the monopolar electrode configuration reduced the phenolic concentration and color in the preliminary-treated POME from 8.95 mg/L and 317.19 ADMI to 0.25 mg/L and 26.10 ADMI, respectively. Additionally, the EO process exhibited a 92.26% efficiency in lowering the ammonium-nitrogen content.

This study investigates the effect of microbial configuration on the electrochemical performance of photosynthetic microbial fuel cells (PMFCs). The PMFC configuration incorporating both bacteria and microalgae exhibited the highest open-circuit voltage (OCV) of 397.95 ± 31.53 mV, significantly higher than that of the OCVs obtained in the sterile control (C1) and the microalgae-only configuration (C2), which were 32.47 ± 22.43 mV and 284.59 ± 12.63 mV, respectively. Furthermore, the PMFC containing only microalgae achieved a current density (CD) of 20.96 ± 0.18 mA/m³ and a power density (PD) of 0.40 ± 0.01 mW/m³ under room temperature conditions. Notably, the combined bacteria and microalgae configuration demonstrated a substantial performance improvement, yielding a significantly higher CD of 49.33 ± 0.36 mA/m³ and PD of 0.78 ± 0.01 mW/m³ at room temperature. This configuration also achieved a maximum decolorization of 93.57 ± 0.10% with a corresponding algal biomass recovery of 134.90 ± 2.69 mg/L. These findings highlighted the critical role of microbial composition in PMFC performance. The combination of bacteria and microalgae yielded superior results compared to other configurations under the investigated conditions.

The utilization of palm oil mill residues for sustainable biogas production presents a promising avenue to mitigate environmental challenges associated with waste disposal and energy demand in palm oil processing. The study explores the use of palm oil mill residues for sustainable biogas production, focusing on the impact of mixing ratios of POME and three raw milled residues on biogas yield through anaerobic co-digestion. Results indicate that co-digestion significantly enhanced biogas production compared to mono-digestion of POME alone. The highest biogas yield of 370 ml was recorded in the digester with 40% residues followed by 50% with a cumulative biogas of 190 ml. The two digesters were higher than 80 ml recorded for POME alone.The findings underscore the potential of integrating palm oil mill residues into biogas systems to achieve dual objectives of waste management and renewable energy generation.

Aim of the study: In our investigation, we used freshwater microalgae Chlorella sp. BF01 to degrade the melanoidin in the palm oil mill effluent, and generate electricity in the photosynthetic microbial fuel cell (PMFC). Material and methods: The freshwater microalgae Chlorella sp. were used in a PMFC consortium for the degradation of melanoidin and electricity generation. The removal (%), electrochemical properties, and biomass recovery were monitored without adding an exogenous medium. Results and conclusions: In this study, lipid-producing microalgae were employed as whole-cell biocatalysts in a PMFC using palm oil mill effluent as a substrate. The maximum melanoidin removal of 79.54 ± 0.45% was gained. The maximum power density reached was 3.98 ± 0.10 W/m3. The paper presents research findings that pave the way for a practical implementation of this innovative approach on an industrial scale.

AbstractThis research performed cellulase production by Aspergillus fumigatus A4112 and evaluated its potential use in palm oil mill effluent (POME) hydrolysis to recover oil simultaneously with the generation of fermentable sugar useful for biofuel production under non-sterilized conditions. Empty fruit bunch (EFB) without pretreatment was used as carbon source. The combination of nitrogen sources facilitated CMCase production. The maximum activity (3.27 U/mL) was obtained by 1.0 g/L peptone and 1.5 g/L (NH4)2SO4 and 20 g/L EFB at 40 °C for 7 days. High level of FPase activity (39.51 U/mL) was also obtained. Interestingly, the enzyme retained its cellulase activities more than 60% at ambient temperature over 15 days. In enzymatic hydrolysis, Triton X-100 was an effective surfactant to increase total oil recovery in the floating form. High yield of reducing sugar (50.13 g/L) and 21% (v/v) of floating oil was recoverable at 65 °C for 48 h. Methane content of the raw POME increased from 41.49 to 64.94% by using de-oiled POME hydrolysate which was higher than using the POME hydrolysate (59.82%). The results demonstrate the feasibility of the constructed process for oil recovery coupled with a subsequent step for methane yield enhancement in biogas production process that benefits the palm oil industry. [ABSTRACT FROM AUTHOR]

Ten species of white-rot fungi were evaluated for their ability to decolorization of palm oil mill effluent. The highest decolorization efficiency was found with Trametes elegans (PP17-06), followed by Ganoderma sp.2 (PW17-06) and Ganoderma sp.2 (PW17-177), respectively. T. elegans was further evaluated for the long-term performance of decolorization for 24 d. The optimal retention time for the decolorization was 8 d, with a color removal efficiency of 47.7%. Beyond 18 d of incubation, decolorization efficiency was reduced due to the autolysis of enzymes. During the biodegradation process, manganese peroxidase enzyme activities reached a maximum of 36.03 U.L-1. However, no significant laccase and lignin peroxidase activities were observed. T. elegans was also assessed for decolorization performance through biosorption on mycelial biomass. The synthesis of the enzyme was prevented by exposing the mycelium to HgCl2. Within an optimal contact time of 2 d, decolorization efficiency reached 12.5% with ADMI reduction from 4259.0 (±20.1) ADMI to 3727 (±104.04) ADMI. Results indicate that the adsorption capacity was reached at this time, and no significant color removal can be achieved by biomass. Results obtained in this study showed the potential of T. elegans in decolorizing palm oil mill effluent. [ABSTRACT FROM AUTHOR]

Palm oil, the main vegetable oil produced globally, serves diverse purposes, ranging from cooking to the production of processed foods, cosmetics, and biodiesel. Despite contributing significantly to the economies of major producing nations, the escalating production of palm oil raises serious environmental concerns, including deforestation, biodiversity loss, and various forms of pollution. Palm oil mill effluent (POME), a byproduct of palm oil extraction, poses a severe environmental threat when left untreated. As an eco-friendly alternative, anaerobic digestion in controlled bioreactors has emerged, offering simultaneous POME treatment and biofuel generation, particularly hydrogen, with high energy efficiency. This review explores the challenges and opportunities associated with biohydrogen production from POME. Key considerations involve optimizing parameters through pretreatments, nanoparticle incorporation, defining optimal bioreactor conditions, determining hydraulic retention times, and integrating multi-stage processes like dark fermentation followed by photofermentation. This review also emphasizes the significance of sustainable practices and economic analyses in shaping the future of hydrogen production from POME, positioning it as a pivotal player in the palm oil industry’s circular economy and the global energy transition. [ABSTRACT FROM AUTHOR]

The present investigation analyzes the influence of water content in a biodiesel blend using palm oil mill effluent: POME (8%). Two water emulsion blends were tested: POME (8%) + H2O (5%) and POME (8%) + H2O (10%). The tests were performed on a stationary diesel engine operating at four load conditions (25%, 50%, 75% and 100%). From the results, it is shown that the blends POME (8%) + H2O (5%) and POME (8%) + H2O (10%) allow a decrease of 2.2% and 4.7% in NOx emissions. In this way, the NOx formation problems of biodiesel are minimized. The evaporation of the water microparticles in the blends POME (8%) + H2O (5%) and POME (8%) + H2O (10%) improves the homogeneity between the air and the fuel. This contributes to a 2.65% decrease in BSFC and a 1.65% increase in BTE compared to POME (8%). Additionally, water emulsions achieve a 14.6%, 7.3%, 13.4%, 1.8%, and 14.1% reduction in CO, CO2, HC, NOx, and smoke opacity emissions compared to conventional diesel. In general, the emulsified blends POME (8%) + H2O (5%) and POME (8%) + H2O (10%) contribute to a greater reduction in engine pollutant emissions, as well as an improvement in engine performance parameters when compared to POME (8%). [ABSTRACT FROM AUTHOR]

Oil palm processing generates substantial waste materials rich in organic content, posing various environmental challenges. Anaerobic digestion (AD), particularly for palm oil mill effluent (POME), offers a sustainable solution, by converting waste into valuable biomethane for thermal energy or electricity generation. The synergistic activities of the AD microbiota directly affect the biomethane production, and the microbial community involved in biomethane production in POME anaerobic digestion has been reported. The composition of bacterial and archaeal communities varies under different substrate and physicochemical conditions. This review discusses the characteristics of POME, explores the microbial members engaged in each stage of AD, and elucidates the impacts of substrate and physicochemical conditions on the microbial community dynamics, with a specific focus on POME. Finally, the review outlines current research needs and provides future perspectives on optimizing the microbial communities for enhanced biomethane production from oil palm wastes. [ABSTRACT FROM AUTHOR]

BACKGROUND AND OBJECTIVES: To improve photocatalytic degradation perfomance, photocatalyst particles with a larger surface area preferred. The effectiveness of titanium dioxide as a photocatalyst depends on the synthesis method used. The method affect the particle size, crystallinity and phase composition of the produced catalyst. This study aims to develop a green synthesis process of nano-titanium dioxide photocatalysts for the advanced treatment of palm oil mill effluent. METHODS: The green synthesis of titanium dioxide nanoparticles used de Man-Rogosa-Sharpe broth media containing Lactobacillus bulgaricus culture and titanium oxyhydroxide metal oxide. The factors investigated were the molarity of titanium oxyhydroxide (0.025 molar; 0.035 molar and 0.045 molar) and temperature (40; 50 and 60 degrees Celsius). The synthesized photocatalyst was characterized using a particle size analyzer to determine the particle size. The produced photocatalyst with a nanoparticle size range of 1-100 nanometer was further characterized using scanning electron microscopy-energy dispersive X-ray and X-ray diffraction. The photocatalyst was tested for advanced treatment of palm oil mill secondary effluent. The factors investigated in this test included the irradiation time and titanium dioxide photocatalyst dosage. The treatment performance was evaluated in terms of effluent quality and pollutant elimination efficiency. FINDINGS: Nano titanium dioxide photocatalysts have been synthesized through titanium oxyhydroxide metal oxide biologically using Lactobacillus bulgaricus. The synthesis process at a temperature of 60 degrees Celsius and a 0.025 molar metal oxide solution produced a titanium dioxide photocatalyst with a size of 33.28 nanometer. The content of titanium and oxygen constituents in the photocatalyst was confirmed to be 39.06 percent and 47.95 percent respectively, with 67.6 percent titanium dioxide crystallinity in a theta degree of 25.4. This indicates that the green synthesis has produced an anatase diffraction nano titanium dioxide photocatalyst. Testing the titanium dioxide photocatalyst to treat palm oil mill secondary effluent yielded in elimination efficiency of 16.16-27.27 percent for chemical oxygen demand and 11.05-21.95 percent for biological oxygen demand. Phenol, which is toxic and difficult to degrade biologically, could eliminated significantly (up to 81.12 percent) using a photocatalyst dose of 1 gram per liter at a time irradiation of 2.5 hour. CONCLUSION: The biological synthesis of nano titanium dioxide photocatalysts is affected by temperatures and metal oxide concentrations. The photocatalytic process for advanced treatment of palm oil mill secondary effluent shows that this synthesis process effectively eliminates phenols. Some compounds such as lignin, amino acids, and pectin are not significantly mineralized using this process. [ABSTRACT FROM AUTHOR]

Palm oil mill effluent (POME) has a high concentration of organic matter and total suspended solids. However, improper disposal of oil refining wastes containing oils, fats, and sludge can cause environmental damage and harm human health due to their toxic, carcinogenic, and polluting effects. This research was carried out to solve the harmful effects caused by the release of POME to the environment. The goal of this study was to isolate a naturally occurring bacterium that could degrade POME and use it as a single carbon source. Bacteria were isolated from POME-contaminated medium using an enrichment technique. Judging by 16S rRNA partial gene sequencing, morphological, biochemical, and molecular identification methods, the isolated bacteria was identified as a novel Bacillus sp. The effects of substrate concentration, inoculum size, pH, temperature, and incubation time on the bacterial growth were investigated using a ''one factor at a time'' (OFAT) approach. The optimal conditions for the bacterium's growth were found to be pH 7.5, 35 °C, 20 % v/v substrate concentration, 6 % v/v inoculum size, and 96 hours of incubation. The isolate is capable of reducing 84 % of COD and 91 % of BOD from a POME sample. The high degradation potential of POME by the isolate suggests it can be used as a good option for bioremediation of POME-polluted areas.

This study has successfully evaluated graphite felt (GF) beads as a solid matrix to immobilize or trap the mixed cultures in an immobilized mixed-cell reactor (IMcR). The anaerobic sludge of palm oil mill effluent was used as an inoculum source in the IMcR with mixed culture. Here, glucose, sucrose, and starch were used as the model substrates to evaluate the performance of IMcR with GF beads for producing bio-hydrogen (BioH2). BioH2, effluent, and surface morphology of GF beads were analyzed by using gas chromatography equipped with a thermal conductivity detector, high-performance liquid chromatography, and scanning electron microscopy, respectively. The highest H2 yield (YH2) and production rates were obtained at 304.0 ± 13.2 mL g?1COD (corresponding to 2.26 mol mol?1glucose) and 1403 ± 61 mL L?1 day?1, respectively. IMcR with GF beads is a new approach for generating high YH2, which can be used for more than two months in an experimental run.

The microbial fuel cell (MFC) is a device that harnesses microbial metabolism to convert chemical energy into bio-electrical energy. Extensive research has demonstrated its efficacy in both wastewater treatment and power generation applications. This study focused on the integration of a microbial fuel cell (MFC) with a biocathode constructed using the oxidoreductase-producing bacterium Bacillus sp. MCO22 and rice straw as a cost-effective substrate. The MFC utilized palm oil mill effluent (POME) as a chemical energy source for electricity generation in the anodic chamber. The ability of the MFC was evaluated by monitoring biochemical oxygen demand (BOD) activity and electrochemical properties. Post-operation, chemical oxygen demand (COD) and color removal were measured. The results revealed that the MFC with the BOD-based cathode achieved a maximum current density and power density of 0.58±0.01 A/m2 and 0.17±0.00 W/m2, respectively. Furthermore, it exhibited high COD and color removal rates of 95.10±0.10% and 98.53±0.33%, respectively, without requiring an external power supply. This study presents novel insights into utilizing a BOD-producing bacterium as a whole-cell biocatalyst on the MFC cathodic surface for both electricity generation and agricultural wastewater treatment.

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. HIGHLIGHTS An optimized study for ultrasound-enhanced oil recovery from palm oil mill effluent (POME) using response surface methodology was conducted.; Cost–benefit analysis revealed that ultrasound pre-treatment is a viable process.; POME-recovered oil was used for biodiesel production via a two-step esterification and transesterification process.; Biodiesel produced from POME-recovered oil met the fuel characteristics requirement of local and international standards.;

BACKGROUND AND OBJECTIVES: To improve photocatalytic degradation perfomance, photocatalyst particles with a larger surface area preferred. The effectiveness of titanium dioxide as a photocatalyst depends on the synthesis method used. The method affect the particle size, crystallinity and phase composition of the produced catalyst. This study aims to develop a green synthesis process of nano- titanium dioxide photocatalysts for the advanced treatment of palm oil mill effluent.METHODS: The green synthesis of titanium dioxide nanoparticles used de Man-Rogosa-Sharpe broth media containing Lactobacillus bulgaricus culture and titanium oxyhydroxide metal oxide. The factors investigated were the molarity of titanium oxyhydroxide (0.025 molar; 0.035 molar and 0.045 molar) and temperature (40; 50 and 60 degrees Celsius). The synthesized photocatalyst was characterized using a particle size analyzer to determine the particle size. The produced photocatalyst with a nanoparticle size range of 1-100 nanometer was further characterized using scanning electron microscopy-energy dispersive X-ray and X-ray diffraction. The photocatalyst was tested for advanced treatment of palm oil mill secondary effluent. The factors investigated in this test included the irradiation time and titanium dioxide photocatalyst dosage. The treatment performance was evaluated in terms of effluent quality and pollutant elimination efficiency.FINDINGS: Nano titanium dioxide photocatalysts have been synthesized through titanium oxyhydroxide metal oxide biologically using Lactobacillus bulgaricus. The synthesis process at a temperature of 60 degrees Celsius and a 0.025 molar metal oxide solution produced a titanium dioxide photocatalyst with a size of 33.28 nanometer. The content of titanium and oxygen constituents in the photocatalyst was confirmed to be 39.06 percent and 47.95 percent respectively, with 67.6 percent titanium dioxide crystallinity in a theta degree of 25.4. This indicates that the green synthesis has produced an anatase diffraction nano titanium dioxide photocatalyst. Testing the titanium dioxide photocatalyst to treat palm oil mill secondary effluent yielded in elimination efficiency of 16.16-27.27 percent for chemical oxygen demand and 11.05-21.95 percent for biological oxygen demand. Phenol, which is toxic and difficult to degrade biologically, could eliminated significantly (up to 81.12 percent) using a photocatalyst dose of 1 gram per liter at a time irradiation of 2.5 hour.CONCLUSION: The biological synthesis of nano titanium dioxide photocatalysts is affected by temperatures and metal oxide concentrations. The photocatalytic process for advanced treatment of palm oil mill secondary effluent shows that this synthesis process effectively eliminates phenols. Some compounds such as lignin, amino acids, and pectin are not significantly mineralized using this process.

This critical review for anaerobic degradation of complex organic compounds like butyrate using reactors has been enormously applied for biogas production. Biogas production rate has a great impact on: reactor granulation methanogenesis, nutrient content, shear velocity, organic loading and loss of nutrients taking place in the reactor continuously. Various technologies have been applied to closed anaerobic reactors to improve biogas production and treatment efficiency. Recent reviews showed that the application of closed anaerobic reactors can accelerate the degradation of organics like volatile fatty acid-butyrate and affect microbial biofilm formation by increasing the number of methanogens and increase methane production 16.5 L−1 CH4 L−1 POME−1. The closed anaerobic reactors with stable microbial biofilm and established organic load were responsible for the improvement of the reactor and methane production. The technology mentioned in this review can be used to monitor biogas concentration, which directly correlates to organic concentrations. This review attempts to evaluate interactions among the: degradation of organics, closed anaerobic reactors system, and microbial granules. This article provides a useful picture for the improvement of the degradation of organic butyrate for COD removal, biogas and methane production in an anaerobic closed reactor. Recent reviews showed that the application of closed anaerobic reactors can accelerate the degradation of organic compounds, such as volatile fatty acid-butyrate, and affect microbial biofilm formation by increasing the number of methanogens, thus enhancing biogas production. The closed anaerobic reactors with stable microbial biofilm established the organic load and improved the performance of the reactor for methane production. The technology used involves monitoring biogas concentrations which correlates with organic concentrations. This review attempts to evaluate interactions among: the degradation of organics, closed anaerobic reactors system, and microbial granules. This review, therefore, provides a useful picture for the improvement of butyrate degradation for COD removal and methane production with the help of various anaerobic closed reactors. The performance of UASBR depends on granulation. The granulation process in UASB reactors can be divided into four steps: (1) Transport of cells to the surface of other cells; (2) Initial reversible adsorption by physicochemical forces; (3) Irreversible adhesion of the cells by microbial appendages and/or polymers; and (4) Multiplication of the cells and development of the granules. Any factor which can complement any one of the four steps will be able to accelerate the granulation process and shorten the startup time of UASB reactors. [ABSTRACT FROM AUTHOR]

While palm oil mill effluent (POME) from different sources will have varying characteristics due to the different process flows in mills, efficient monitoring and performance evaluation of anaerobic digesters in POME treatment are crucial to ensure stable biogas production with minimal operational problems. Therefore, this study aims to evaluate and compare the performances of in‐ground lagoon anaerobic digesters under mesophilic conditions in four different biogas plants (BGPs A, B, C and D) located in Malaysia with respect to total chemical oxygen demand (COD) removal and total biogas produced. Results show that all BGPs are still functioning well with satisfactory methane yields (.135–.364 Nm3 CH4/kgCOD removed) and COD removal efficiencies (67%–85%). ANOVA analysis shows that organic loading rate (OLR), temperature (T) and recirculation ratio (RR) have significant effects on the COD removal and biogas production of all four plants. BGP B has the highest amount of biogas produced (4.12 × 105 Nm3/month) and COD removal rate amongst other BGPs due to its most stable and lowest T (<40°C), high RR, and consistent and high COD load. Conversely, BGP D has the lowest COD removal and biogas production, which are mainly contributed by a high COD inlet (92 000 mg/L) and a high T in the anaerobic digester (48.7°C). Despite having a similar design of an anaerobic digester, this comparative study reveals that different BGPs will have different optimum operating conditions and limitations, depending not only on the operating conditions of the BGP (OLR, T and RR) but also on the raw POME quality stemming from the palm oil milling process. A future study would be focused on the optimisation of four BGPs for maximum biogas removal. [ABSTRACT FROM AUTHOR]

Aims: This study aimed to investigate the effect of palm oil mill effluent (POME) final discharge on the active bacterial composition, gene expression, and metabolite profiles in the receiving rivers to establish a foundation for identifying potential biomarkers for monitoring POME pollution in rivers. Methods and results: The POME final discharge, upstream (unpolluted by POME), and downstream (effluent receiving point) parts of the rivers from two sites were physicochemically characterized. The taxonomic and gene profiles were then evaluated using de novo metatranscriptomics, while the metabolites were detected using qualitative metabolomics. A similar bacterial community structure in the POME final discharge samples from both sites was recorded, but their composition varied. Redundancy analysis showed that several families, particularly Comamonadaceae and Burkholderiaceae [Pr(>F) = 0.028], were positively correlated with biochemical oxygen demand (BOD5) and chemical oxygen demand (COD). The results also showed significant enrichment of genes regulating various metabolisms in the POME-receiving rivers, with methane, carbon fixation pathway, and amino acids among the predominant metabolisms identified (FDR < 0.05, PostFC > 4, and PPDE > 0.95). This was further validated through qualitative metabolomics, whereby amino acids were detected as the predominant metabolites. Conclusions: The results suggest that genes regulating amino acid metabolism have significant potential for developing effective biomonitoring and bioremediation strategies in river water influenced by POME final discharge, fostering a sustainable palm oil industry. [ABSTRACT FROM AUTHOR]

The microbial fuel cell (MFC) is a device that harnesses microbial metabolism to convert chemical energy into bio-electrical energy. Extensive research has demonstrated its efficacy in both wastewater treatment and power generation applications. This study focused on the integration of a microbial fuel cell (MFC) with a biocathode constructed using the oxidoreductase-producing bacterium Bacillus sp. MCO22 and rice straw as a cost-effective substrate. The MFC utilized palm oil mill effluent (POME) as a chemical energy source for electricity generation in the anodic chamber. The ability of the MFC was evaluated by monitoring biochemical oxygen demand (BOD) activity and electrochemical properties. Post-operation, chemical oxygen demand (COD) and color removal were measured. The results revealed that the MFC with the BOD-based cathode achieved a maximum current density and power density of 0.58±0.01 A/m² and 0.17±0.00 W/m², respectively. Furthermore, it exhibited high COD and color removal rates of 95.10±0.10% and 98.53±0.33%, respectively, without requiring an external power supply. This study presents novel insights into utilizing a BOD-producing bacterium as a whole-cell biocatalyst on the MFC cathodic surface for both electricity generation and agricultural wastewater treatment. [ABSTRACT FROM AUTHOR]

Attributable to the prosperous production growth of palm oil in Malaysia, the generated palm oil mill effluent (POME) poses a high threat owing to its highly polluted characteristic. Urged by the escalating concern of environmental conservation, POME pollution abatement and potential energy recovery from the effluent are flagged up as a research topic of interest. In this study, a cutting-edge photocatalytic fuel cell (PFC) system with employment of ZnO/Zn nanorod array (NRA) photoanode, CuO/Cu cathode, and persulfate (PS) oxidant was successfully designed to improve the treatment of POME and simultaneous energy production. The photoelectrodes were fabricated and characterized by field emission scanning electron microscopy with energy (FESEM), X-ray diffraction (XRD), energy-dispersive X-ray (EDX), and Brunauer, Emmett, and Teller analysis (BET). Owing to the properties of strong oxidant of PS, the proposed PFC/PS system has exhibited exceptional performance, attaining chemical oxygen demand (COD) removal efficiency of 96.2%, open circuit voltage (Voc) of 740.0 mV, short circuit current density (Jsc) of 146.7 μA cm−2, and power density (Pmax) of 35.6 μW cm−2. The pre-eminent PFC/PS system performance was yielded under optimal conditions of 2.5 mM of persulfate oxidant, POME dilution factor of 1:20, and natural solution pH of 8.51. Subsequently, the postulated photoelectrocatalytic POME treatment mechanism was elucidated by the radical scavenging study and Mott–Schottky (M-S) analysis. The following recycling test affirmed the stability and durability of the photoanode after four continuous repetition usages while the assessed electrical energy efficiency revealed the economic viability of PFC system serving as a post-treatment for abatement of POME. These findings contributed toward enhancing the sustainability criteria and economic viability of palm oil by adopting sustainable and efficient POME post-treatment technology. [ABSTRACT FROM AUTHOR]

The present study focuses on bio-hydrogen production using palm oil mill effluent (POME) at a semi-pilot scale of an "up-flow anaerobic sludge blanket fixed-film (UASFF) reactor". The reactor was operated in the palm oil mill industry for over 180 days of operation at ambient temperature through dark fermentation process with different organic loading rates (OLR) of 22–36 g-COD/l.d, depending on the COD concentration of POME. By acclimatizing the sludge, the semi-pilot scale UASFF reactor achieved hydrogen content, and hydrogen production rate (HPR) of 20%–68%, and 12 L H 2 /d to 39 L H 2 /d, respectively with a maximum COD removal of 35%. Moreover, from high through pyrosequencing analysis, hydrogen fermentation was attributed to Clostridium sensu stricto , Lactobacillus , and thermoanaerobium spp. This study offers an extensive approach to developing a semi-pilot scale bio-hydrogen production and, provides further prospects for profitable exploitation which could be a promising approach for reaching sustainability and economic feasibility (using wastewater as a low-cost feedstock) in commercial applications for future studies. [Display omitted] [ABSTRACT FROM AUTHOR]

Two bacterial and six yeast strains capable of lipase production were investigated for their extracellular lipase (ECL), cell-bound lipase (CBL), and growth profile in basal standard medium (BSM) and the low-cost palm oil mill effluent (POME) media. The yeast Magnusiomyces spicifer AW2 and bacteria Staphylococcus hominis AUP19 were selected and further employed to explore their survivability, lipase activity, and cell biomass production in various POME concentrations. It was revealed that diluted POME 1:1 at pH 7.0 was suitable for yeast and bacterial performance. Furthermore, the development of co-culture between yeast and bacteria was performed by mixing them at a ratio of 1:1. The synthetic co-culture system was successful in improving CBL activity to 3860 U/L. The bioremediation parameter, i.e., oil and grease (O&G) removal, was efficiently achieved 1.1-fold higher than yeast alone and bacterial monoculture at 80.1 ± 1.3%. At the same time, COD removal was highest with the co-culture treatment of 75.9 ± 2.8%, indicating 1.3-fold more effective than yeast monoculture and 1.4-fold better than single bacterial form. The mixed cells of two strains effectively improved biodiesel production from oleic acid of 73.5 ± 3.3% and palm oil of 82.5 ± 0.3% under solvent-free conditions for 72-h reactions at room temperature (30 ± 2 °C), indicating a promising prospect of a combined approach of POME treatment and valorization. [ABSTRACT FROM AUTHOR]

The palm oil industry produces a high amount of palm oil mill effluent (POME) every year, which can potentially cause catastrophic contamination to the environment if not treated properly. Due to strict regulation by the Department of Environment Malaysia, POME final discharge must be treated until the pollutants and colour level are below the regulated standard. Therefore, a batch adsorption study has been conducted using activated carbon (AC) produced from oil palm kernel shells (OPKS) to treat the POME final discharge. The OPKS-AC was generated by using the double-insulated carbonisation–activation reactor. The treated OPKS showed excellence characteristics as bioadsorbent with surface area of 730.91 m2 g−1 and microporous pore size distribution of 2.67 nm. The treatment of POME final discharge by using OPKS-AC had successfully reduced the level of pollutants and colour by up to 91% of biochemical oxygen demand (BOD), 87% of chemical oxygen demand (COD), 74% of total suspended solids (TSS), and 97% colour. The equilibrium points were reached after 480 min of contact time for COD, TSS and colour and 540 min for BOD using OPKS-AC dosage of 250 g L−1. The isotherm modelling showed that the adsorption behaviour onto OPKS-AC fitted the Langmuir isotherm model. Overall, the OPKS-AC can significantly remove the pollutants and colour of POME final discharge, which fit the kinetic model tested. [ABSTRACT FROM AUTHOR]

Melanoidin is the main cause of the dark brown color of the palm oil mill effluent (POME) that form under the Maillard reaction. In this study, the constructed wetland integrated with microbial fuel cell (CWMFC) has been developed for melanoidin removal from the POME and simultaneously electricity generation as a by-product. The macrophyte Dieffenbachia sp. has been used as a biocatalyst on the cathode electrode and the oxidoreductase-producing bacterium Bacillus lichenformis with laccase and manganese peroxidase activity has been used as an anodic biocatalyst. The maximal melanoidin removal, chemical oxygen demand (COD) removal, enzyme activity, and power output were monitored. The maximal laccase and manganese peroxidase activities of 1.60 - 0.10 U/mL and 1.45 - 0.05 U/mL were found during melanoidin degradation. In addition, the maximal melanoidin removal of 93.59 - 0.10% and 95.12 - 0.15% were achieved respectively. When the maximal power density of 0.18 - 0.01 mW/m³ was generated. This study gained new knowledge about using the CW-MFC system as a biological treatment process of the melanoidin content in the POME and simultaneously generated electrical energy as a by-product. [ABSTRACT FROM AUTHOR]

Anaerobic co-digestion (co-AD) of agro-industrial waste, namely, palm oil mill effluent (POME) and sugarcane vinasse (Vn), with water hyacinth (WH) as co-substrate was carried out in two separate Anaerobic Suspended Growth Closed Bioreactors (ASGCBs) under thermophilic (55 °C) conditions. The highest chemical oxygen demand (COD) and soluble COD reduction in co-AD of POME-WH (78.61%, 78.86%) is slightly higher than co-AD of Vn-WH (75.75%, 78.24%). However, VFA reduction in co-AD of POME-WH (96.41%) is higher compared to co-AD of Vn-WH (85.94%). Subsequently, biogas production peaked at 13438 mL/day values and 16122 mL/day for co-AD of POME-WH and Vn-WH, respectively. However, the methane content was higher in the co-AD of POME-WH (72.04%) than in the co-AD of Vn-WH (69.86%). Growth yield (YG), maximum specific substrate utilization rate (rx,max) and maximum specific biomass growth rate (μmax) are higher in co-AD of POME-WH, as supported by the higher mixed liquor volatile suspended solids (MLVSS) and COD reduction efficiency compared to co-AD of Vn-WH. However, methane yield ( Y CH 4 ) reported in the co-AD of POME-WH and Vn-WH are 0.2748 and 0.3112 L CH4/g CODreduction, respectively, which suggests that WH is a more suitable co-substrate for Vn compared to POME. [ABSTRACT FROM AUTHOR]

Palm oil mill effluent (POME) is considered the most environmentally harmful when discharged without proper treatment. In addition to conventional biological treatment methods, physicochemical treatment techniques are considered alternative methods to treat POME as polishing or post-treatment techniques to meet the discharge water quality standards set by authorities. Recently, electroflotation (EF) has gained popularity in wastewater treatment owing to its high efficiency, no harmful by-products, and ease of operation. However, EF has limitations on energy consumption because high current density and long electrolysis time are often used to increase the density of gas bubbles and metallic ions produced in the EF system used in pollutant removal. Polyaluminum chloride (PAC) and cationic polyacrylamide (CPAM) are used as alternative options for the production of coagulants instead of using a sacrificial anode in EF. In this study, we hypothesized that PAC and CPAM could enhance the efficiency and reduce the specific energy consumption of EF by minimizing the electrolysis time used in POME treatment. The effects of electrolysis time, current density, and coagulant dosage on POME treatment were investigated. EF treatment at a current density of 2.5 mA/cm2 has achieved 82% of turbidity and 47% of chemical oxygen demand (COD) removal after 45 min electrolysis time, consuming 0.014 kWh of specific energy for the treatment of one gram of COD. There was no improvement in terms of turbidity removal when the current density was increased from 2.5 to 5 mA/cm2; however, the COD removal efficiency was increased up to 52% at 5 mA/cm2. When EF was performed at 1 A combined with PAC at a dosage of 40 mg/L and CPAM at a dosage of 20 mg/L, it was noticed that turbidity and COD removal increased up to 96% and 54%, respectively, within 15 min electrolysis. Subsequently, the specific energy consumption was reduced to 0.004 kWh (by 71%) per one gram of COD treatment. Results confirmed that the chemical coagulants could increase the POME treatment efficiency and reduce the specific energy consumption of EF. However, this method can be improved aiming at further reduction of COD by mineralizing the dissolved organic compounds to fulfill the POME discharge quality standards.

The goal of this study was to investigate the effect of the type and dose of coagulants on the color removal of POME through the coagulation process. The coagulants used in this study were alum and poly aluminium chloride (PAC). The dose of coagulants was varied to 2, 4, 6, and 8 g/L. The results of this study showed that the optimum dose for coagulant of alum was 6 g/L and the optimum dose for coagulant of PAC was 8 g/L, in which these doses resulted in color removal efficiencies of 80.65±10.30% and 94.12±1.00%, respectively. The PAC coagulant was more effective than the alum coagulant. The kinetic models used to predict the color removal efficiencies were the first- and second-order kinetic models. Based on the kinetic analysis, the MAPE of the first and second-order kinetic models was 9.17-28.28% and 5.48-21.62%, respectively. It means that the second-order kinetic model can predict with higher accuracy than the first-order kinetic model. By the second order kinetic model, the reaction kinetic constant of the coagulation process at alum coagulant of 6/L and PAC coagulant of 0.021 and 0.057 /min, respectively.

Palm oil mill effluent (POME) is considered the most environmentally harmful when discharged without proper treatment. In addition to conventional biological treatment methods, physicochemical treatment techniques are considered alternative methods to treat POME as polishing or post-treatment techniques to meet the discharge water quality standards set by authorities. Recently, electroflotation (EF) has gained popularity in wastewater treatment owing to its high efficiency, no harmful by-products, and ease of operation. However, EF has limitations on energy consumption because high current density and long electrolysis time are often used to increase the density of gas bubbles and metallic ions produced in the EF system used in pollutant removal. Polyaluminum chloride (PAC) and cationic polyacrylamide (CPAM) are used as alternative options for the production of coagulants instead of using a sacrificial anode in EF. In this study, we hypothesized that PAC and CPAM could enhance the efficiency and reduce the specific energy consumption of EF by minimizing the electrolysis time used in POME treatment. The effects of electrolysis time, current density, and coagulant dosage on POME treatment were investigated. EF treatment at a current density of 2.5 mA/cm2 has achieved 82% of turbidity and 47% of chemical oxygen demand (COD) removal after 45 min electrolysis time, consuming 0.014 kWh of specific energy for the treatment of one gram of COD. There was no improvement in terms of turbidity removal when the current density was increased from 2.5 to 5 mA/cm2; however, the COD removal efficiency was increased up to 52% at 5 mA/cm2. When EF was performed at 1 A combined with PAC at a dosage of 40 mg/L and CPAM at a dosage of 20 mg/L, it was noticed that turbidity and COD removal increased up to 96% and 54%, respectively, within 15 min electrolysis. Subsequently, the specific energy consumption was reduced to 0.004 kWh (by 71%) per one gram of COD treatment. Results confirmed that the chemical coagulants could increase the POME treatment efficiency and reduce the specific energy consumption of EF. However, this method can be improved aiming at further reduction of COD by mineralizing the dissolved organic compounds to fulfill the POME discharge quality standards. [ABSTRACT FROM AUTHOR]

The use of cyanobacteria for intracellular polyhydroxybutyrate (PHB) accumulation for bioplastic production offers a cost-saving opportunity. Because of their short generation cycles, cyanobacteria have a high potential as a source of PHB. This research aimed to screen the best cyanobacteria strain growing on palm oil mill effluent (POME) and optimize the environmental and nutritional factors by using Box-Behnken RSM. Results showed that Synechocystis sp. produced the highest PHB compared to Nostoc sp., Synechococcus sp., and Chroococcus sp. Further optimization revealed that the interaction of glycerol and UV-C irradiation, or glycerol and iron addition increased PHB production of Synechocystis sp.. The highest PHB production was found at 670 mg L−1 glycerol, 70 min UV-C irradiation time, and 20 mg L−1 iron. It was confirmed by FT-IR, GC-MS and NMR H1 that PHB was dominated by butyric esters with 284 °C thermal stability. [ABSTRACT FROM AUTHOR]

The development of the palm oil industry has induced the generation of palm oil mill effluent (POME) together with its waste activated sludge (WAS) in recent years. This study aims to discover new opportunities in treating POME WAS that has high organic content with low degradability but having potential in converting waste into energy. The optimized electrochemical oxidation (EO) of pre-treated WAS was applied prior to anaerobic digestion (AD) to improve the POME WAS digestibility (by assessing its solids minimization and biogas production) under mesophilic conditions at 30 ± 0.5 °C and solids retention time of 15 days. The enhancement in sludge minimization was verified, with 1.6-fold over the control at steady-state. Promising results were obtained with a total chemical oxygen demand (COD) removal of 68.8% with 11.47 mL CH4/g CODadded in pre-treat digester, compared with 37.1% and 3.9 mL CH4/g CODadded in control digester. It is also worth noting that the specific energy (SE) obtained for this EO pre-treated AD system is 2505 kJ/kg TS with about 94% increment in methane production. It is evident that this system was applicable on POME WAS in ameliorating solids minimization as well as enhancing biogas production. [ABSTRACT FROM AUTHOR]

The rapid increase in demand for renewable energy has led to a need for more efficient and effective ways to produce biogas from palm oil mill effluent (POME), which is rich in biological and chemical oxygen demand (BOD and COD). Despite its potential as a source of biogas, POME is not always effectively utilized in biogas production due to a lack of optimization of the treatment process. This study aims to address this issue by identifying the critical parameters affecting biogas production from POME and optimizing the process for maximum biogas yield and COD removal. This study employed comparative analysis and response surface methodology to optimize the performance of palm oil mill effluent (POME)-based biogas plants in Malaysia. Historical data from three commercial POME-based biogas plants in Malaysia were analyzed to identify the most critical parameters for biogas yield and COD removal. Response surface methodology, using Box–Behnken design and Design-Expert software, was then used to optimize these parameters. Sensitivity analysis was performed to interpret the impact of parameters on biogas production, with Organic Loading Rate (OLR) found to be the most critical factor for methane yield. The results showed that the optimum conditions for maximum methane production were OLR of 1.23 kg/m3·day, inlet Total Solids (TS) of 46,370 mg/L, pH of 4.5, and temperature of 45.4 °C, resulting in a 39.6% increase in methane yield (0.335 m3 CH4/kgCODremoved) and a 1.1% increase in COD removal (93.4%). [ABSTRACT FROM AUTHOR]

Biomass wastes originating from palm oil milling activities can be characterized by their high biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solid (TSS), and oil and grease content. The utilization of oil palm wastes such as palm oil mill effluent (POME) and empty fruit bunch (EFB) has great potential for a sustainable energy biomass pellet as it reduces the reliance on conventional materials for energy production. A mixture of POME and EFB in various ratios ranging between 7:3, 8:2, 9:1, and 10:0 was fermented in the presence of Lysinibacillus sp. LC 556247 for 120 h at 37 ± 2 °C and 180 rpm with the aim of elucidating the biodegradation of complex organic material in terms of BOD, COD, TSS, total organic carbon, inorganic carbon, and total carbon content. After fermentation, the mixtures were oven dried at 105 °C overnight and then subjected to calorific energy value (CEV) determination. The highest CEV of 20.26 MJ/kg was achieved for a ratio of 10:0 (slightly higher than the control experiment with the value of 18.67 MJ/kg), with maximum removal efficiencies of COD (12.19%), BOD (11.72%), TSS (93.94%), and oil reduction of 17.43%. The addition of EFB did not positively increase the CEV. [ABSTRACT FROM AUTHOR]

Palm oil, the main vegetable oil produced globally, serves diverse purposes, ranging from cooking to the production of processed foods, cosmetics, and biodiesel. Despite contributing significantly to the economies of major producing nations, the escalating production of palm oil raises serious environmental concerns, including deforestation, biodiversity loss, and various forms of pollution. Palm oil mill effluent (POME), a byproduct of palm oil extraction, poses a severe environmental threat when left untreated. As an eco-friendly alternative, anaerobic digestion in controlled bioreactors has emerged, offering simultaneous POME treatment and biofuel generation, particularly hydrogen, with high energy efficiency. This review explores the challenges and opportunities associated with biohydrogen production from POME. Key considerations involve optimizing parameters through pretreatments, nanoparticle incorporation, defining optimal bioreactor conditions, determining hydraulic retention times, and integrating multi-stage processes like dark fermentation followed by photofermentation. This review also emphasizes the significance of sustainable practices and economic analyses in shaping the future of hydrogen production from POME, positioning it as a pivotal player in the palm oil industry’s circular economy and the global energy transition.

Biomass fuel is one of the renewable energy sources that can be produced by valorization of palm oil mill effluent (POME) and empty fruit bunch (EFB). POME and EFB are available abundantly in Malaysia and only small portion is utilized to produce other value-added products. The objective of this study is to: (1) utilize the wastes from agro-industrial sector especially palm oil wastes and bio-valorize into value-added product of biomass fuel with high CEV, and simultaneously (2) reduce the waste accumulated in the palm oil factory. In this study, co-fermentation of bacteria (Lysinibacillus sp.) and fungus (Aspergillus flavus) at 37 °C, 180 rpm for 5 days, followed by overnight oven-dry at 85 °C was conducted utilizing a mixture of POME and EFB with the ratio of 7:3 at laboratory scale. Three fermentation medium conditions were performed, namely: (1) Group 1: autoclaved POME and EFB without addition of any microorganisms, (2) Group 2: autoclaved POME and EFB with the addition of Lysinibacillus sp. LC 556247 and Aspergillus flavus, and (3) Group 3: POME and EFB as it is (non-sterile). Among all condition, Group 2 with co-fermentation evinced the highest calorific energy value (CEV) of 26.71 MJ/kg, highest biochemical oxygen demand (BOD) removal efficiency of 61.11%, chemical oxygen demand (COD) removal efficiency at 48.47%, and total suspended solid (TSS) reduction of 37.12%. Overall, this study successfully utilized abundant POME and EFB waste and turn into value added product of renewable biomass fuel with high CEV percentage and simultaneously able to reduce abundant liquid waste.