Palm Oil Mill Effluent Treatment Research Articles

Review of techniques for biohydrogen production from palm oil mill effluent

Due to rapid growth in population and societal development, the demand for energy is on the increase. The production of palm oil as one of the major edible oils consumed in the world has increased tremendously. Palm oil mill effluent (POME), a wastewater from the most significant agricultural industry is produced in tremendous amounts that requires proper management to mitigate its negative environmental effects. Studies have shown that Palm oil mill effluent (POME) possesses the properties of a good carbon feedstock for hydrogen generation in fermentation processes. In this study, several methods for biohydrogen production from Palm oil mill effluent (POME) were discussed. An apprehension into the different pre-treatment methods on POME including physicochemical, chemical and biological and their effects on the characteristics of POME including pH, temperature, sugar content, solid content, viscosity, nutrients and by-product toxicity on the biohydrogen production and effluent quality were reviewed. Various bioreactor designs were used for biohydrogen from POME, the modifications applied on the system design to increase the stability and productivity of POME treatment have been examined. The individual and interactive effects of pH, different temperatures of heat treatment, different inoculum sizes and substrate concentrations on biohydrogen production were discussed. Moreover, higher biohydrogen productivity could be obtained with the addition of nanoparticle nutrients and introducing genetically modified H2-producing bacteria. Finally, further investigation in the future shall focus on the development of a more inclusive and efficient POME treatment via DF process that favours biohydrogen production, environmental benign and economically viable.

Enhancing palm oil mill effluent treatment through initial granulation of fruit and vegetable eco-enzymes

Enhancing palm oil mill effluent treatment through initial granulation of fruit and vegetable eco-enzymes

A Hybrid Ultrasonic Membrane Anaerobic System (UMAS) Development for Palm Oil Mill Effluent (POME) Treatment

The high chemical oxygen demand (COD) and biochemical oxygen demand (BOD) levels in palm oil mill effluent (POME) wastewater make it an environmental contaminant. Moreover, conventional POME wastewater treatment approaches pose economic and environmental risks. The present study employed an ultrasonic membrane anaerobic system (UMAS) to treat POME. Resultantly, six steady states were procured when a kinetic assessment involving 11,800–21,700 mg·L−1 of mixed liquor suspended solids (MLSS) and 9800–16,800 mg·L−1 of mixed liquor volatile suspended solids (MLVSS) was conducted. The POME treatment kinetics were explained with kinetic equations derived by Monod, Contois and Chen and Hashimoto for organic at loading rates within the 1–11 kg·COD·m−3·d−1 range. The UMAS proposed successfully removed 96.6–98.4% COD with a 7.5 day hydraulic retention time. The Y value was 0.67 g·VSS/g·COD, while the specific micro-organism decay rate, b was 0.24 day−1. Methane (CH4) gas production ranged from 0.24 to 0.59 litres per gram of COD daily. Once the initial steady state was achieved, the incoming COD concentrations increased to 88,100 mg·L−1. The three kinetic models recorded a minimum calculated solids retention time of 12.1 days with maximum substrate utilization rate, K values ranging from 0.340 to 0.527 COD·g−1·VSS·d−1 and maximum specific growth rate, µmax from 0.248 to 0.474 d−1. Furthermore, the solids retention time (SRT) was reduced from 500 to 12.1 days, resulting in a 98.4% COD level reduction to 1400 mg·L−1.

Treatment of diluted palm oil mill effluent (POME) synchronous with electricity production in a persulfate oxidant-promoted photocatalytic fuel cell.

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 740.0mV, short circuit current density (Jsc) of 146.7 μA cm-2, and power density (Pmax) of 35.6μWcm-2. The pre-eminent PFC/PS system performance was yielded under optimal conditions of 2.5mM 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.

Comparative analysis in the performances of four in‐ground lagoon anaerobic digesters treating palm oil mill effluent (POME)

AbstractWhile 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.

Fabrication of novel Z-scheme BaFe2O4/BiOCl nanocomposite with promoted visible light photocatalytic palm oil mill effluent treatment and pathogens destruction

Fabrication of novel Z-scheme BaFe2O4/BiOCl nanocomposite with promoted visible light photocatalytic palm oil mill effluent treatment and pathogens destruction

Palm oil mill effluent (POME) treatment using a combined anaerobic-microalgae down-flow hanging sponge (DHS) reactor

Palm oil mill effluent (POME) generated from the production of palm oil contains organic and inorganic contaminants that can be a nutrient source for microorganisms such as bacteria, fungi, and microalgae. In this study, POME was treated using a combined anaerobic (R1) and microalgae (R2) in down-flow hanging sponge (DHS) reactor. Chlorella pyrenoidosa was immobilized in sponge carriers of R2 and LED lights were used for 12 hours per day to support microalgae growth. The DHS reactors were continuously operated for 165 days in three phases with different COD loading rates, namely 3, 6, and 12 kg-COD/m³·day in Phase 1, Phase 2, and Phase 3, respectively. The hydraulic retention time (HRT) was set at 46 min and 52 min in R1 and R2, respectively. The highest COD removal rate was achieved at 6.93 kg-COD/m³·day and 4.85 kg-COD/m³·day in R1 and R2, respectively. In addition, maximum phosphate removal was 68% in both reactors. Increased concentration of nitrate in R-2 indicated that nitrification may occur in the reactor. The pH of R1 effluent was relatively stable at neutral conditions, while the pH value of R2 effluent slightly increased. Based on visual observation, bacteria biofilm also grew in the microalgae reactor (R2). Synergistic bacteria-microalgae may play an important role in pollutant removal. The results of this study show that a combined anaerobic and microalgae DHS reactor can be used as an alternative for POME treatment because they have a shorter HRT and can be applied in a small area.

A series anaerobic-aerobic down-flow hanging sponge (DHS) reactor for the treatment of palm oil mill effluent (POME)

Palm oil mill effluent (POME) contains very high organic compounds that must be treated before being discharged into the environment. Pond technology has been widely used for the treatment of POME; however, it requires a huge area of land. Down-flow hanging sponge (DHS) reactor has shown a high pollutant removal efficiency, less energy, and land area requirement. This study aimed to investigate the performance of a series of anaerobic (R3) and aerobic (R4) DHS reactors in treating POME. The reactor was continuously supplied with POME in three different phases for 165 days. The COD loading rate was set at 3.06, 6.12, and 12.24 kg-COD/m³·day in Phase 1, Phase 2, and Phase 3, respectively. Hydraulic retention time (HRT) was set at 47 min and 50 min, in R3 and R4, respectively. The reactors showed good performance for pollutant removal efficiency, especially COD. In Phase 1, the average COD removal rate was 2.68 and 0.27 kg-COD/m³·d in R3 and R4, respectively. In Phase 2, when the COD loading rate was increased, the average COD removal rate achieved 4.12 and 1.53 kg-COD/m³·d in R3 and R4, respectively. In Phase 3, the COD loading rate was doubled to 12.24 kg-COD/m³·day and the average COD removal rate of 5.81 and 2.90 kg-COD/m³·d was achieved in R3 and R4, respectively. During operation, the concentration of nitrate fluctuated in R4, which indicated that nitrification had occurred. Phosphate could be reduced in R3, but only a small portion could be removed in R4. Total suspended solids (TSS) could be effectively removed in R4. These results revealed that a combination of anaerobic-aerobic DHS reactors showed good performance in removing pollutants such as COD and TSS. Therefore, DHS technology can be used as a polishing treatment for treated POME.

ELECTROCHEMICAL OZONE GENERATION FOR PALM OIL MILL WASTEWATER TREATMENT USING NICKEL/ANTIMONY DOPED TIN OXIDE ANODES

Ozonation have been employed in organic matter degradation and discoloration process of wastewater. In this study, nickel-antimony doped tin oxide (NATO) anode was employed to generate ozone for palm oil mill effluent (POME) wastewater treatment. NATO was synthesized varying Ni concentrations and calcination temperatures. The materials were characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX) and X-ray Photoelectron Spectroscopy (XPS) techniques. All materials showed rutile structure. The electrode displayed a smooth cracked mud surface morphology. Regarding the oxidation state, the binding energies of the Sb 3d3/2 peak were observed at 540.62 eV and 541.51 eV corresponding to Sb3+ and Sb5+, respectively. The key findings show that increasing calcination temperature increases ozone current efficiency obtained from the absorbances of dissolved ozone in liquid phase and current density, which decreases with increasing Ni content. The highest current efficiency and current density (i.e. ca. 30% and 0.18 Acm-2 in 1 M H2SO4 at 2.7V) was achieved at 2%mole ratio Ni content calcined at 650°C. Regarding POME treatment, discoloration and degradation efficiency increased with electrolysis time from the initial chemical oxygen demand (COD) and total organic carbon (TOC) of 1,780 and 96 mgL-1, respectively under the aforementioned conditions. The highest removal efficiency of 80% was achieved within 10 min discoloration and 15 min for TOC and COD. The electrochemical ozone generation using NATO anode have shown high efficiency in the POME treatment due to •OH radicals and O3. NATO is a promising electrocatalyst candidate for wastewater treatment.

Enhancing Physiochemical Substrate Properties of Thin-Film Composite Membranes for Water and Wastewater Treatment via Engineered Osmosis Process

The commercial thin-film composite (TFC) nanofiltration (NF) membrane is unsuitable for engineered osmosis processes because of its thick non-woven fabric and semi-hydrophilic substrate that could lead to severe internal concentration polarization (ICP). Hence, we fabricated a new type of NF-like TFC membrane using a hydrophilic coated polyacrylonitrile/polyphenylsulfone (PAN/PPSU) substrate in the absence of non-woven fabric, aiming to improve membrane performance for water and wastewater treatment via the engineered osmosis process. Our results showed that the substrate made of a PAN/PPSU weight ratio of 1:5 could produce the TFC membrane with the highest water flux and divalent salt rejection compared to the membranes made of different PAN/PPSU substrates owing to the relatively good compatibility between PAN and PPSU at this ratio. The water flux of the TFC membrane was further improved without compromising salt rejection upon the introduction of a hydrophilic polydopamine (PDA) coating layer containing 0.5 g/L of graphene oxide (PDA/GO0.5) onto the bottom surface of the substrate. When tested using aerobically treated palm oil mill effluent (AT-POME) as a feed solution and 4 M MgCl2 as a draw solution, the best performing TFC membrane with the hydrophilic coating layer achieved a 67% and 41% higher forward osmosis (FO) and pressure retarded osmosis (PRO) water flux, respectively, compared to the TFC membrane without the coating layer. More importantly, the coated TFC membrane attained a very high color rejection (>97%) during AT-POME treatment, while its water flux and reverse solute flux were even better compared to the commercial NF90 and NF270 membranes. The promising outcomes were attributed to the excellent properties of the PAN/PPSU substrate that was coated with a hydrophilic PDA/GO coating and the elimination of the thick non-woven fabric during TFC membrane fabrication.

Synergetic Effect of Chemical Coagulation and Electroflotation on Synthetic Palm Oil Mill Effluent Treatment

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.

Single-Step Surface Hydrophilization on Ultrafiltration Membrane with Enhanced Antifouling Property for Pome Wastewater Treatment

High organic materials in palm oil mill effluent (POME) can result in serious water pollution. To date, biological treatment has been used to reduce the environmental risks of these effluents prior of their discharge into water streams. However, the effluents’ dark brownish colour remains as a significant issue that must be addressed, as it affects the overall quality of water. Although membrane technology has been frequently used to address these difficulties, membrane fouling has become a serious limitation in POME treatment. On the other hand, zwitterions with balanced charge groups have received growing interest in the fabrication of antifouling membranes due to their hydrated nature. The development of a simple and efficient covalent bonding technique to improve the stability of zwitterions on membrane surfaces remains a challenge. By grafting and co-depositing polyethylenimine (PEI)-based zwitterion (Z-PEI) with super hydrophilic polydopamine (PDA) on the surface of a commercial polysulfone (PSf) ultrafiltration membrane at ambient temperature, a new zwitterionic surface with a neutral surface charge was created (PDA/Z-PEI). This study aims to investigate the effect of different loading ratios of PDA/Z-PEI (1:1, 1:2, and 1:3) and evaluate their performance on treating brownish coloured anaerobically treated POME (AT-POME). SEM and FTIR analysis showed the successful incorporation of the PDA/Z-PEI membrane while the zwitterionic feature is indicated by zeta potential analysis. Water flux analysis demonstrated that a lower water flux was achieved for M-ZPEI membranes as compared to the PSf and PSf-MDPA membranes, attributed by the tight skin layer of PDA-ZPEI. In the development of a tight hydration layer on the membrane surface by zwitterions, zwitterionic membranes demonstrated excellent antifouling capabilities, particularly PDA/Z-PEI with a loading ratio of (1:2) with a flux recovery ratio of around 84% and colour rejection of 81.75%. Overall, this research contributes to the development of a unique coating with improved stability and antifouling properties by altering the membrane surface in a simple and reliable manner.

Anaerobic acetogenic treatment of palm oil mill effluent for COD removal

Palm oil mill effluent (POME) is a form of wastewater that is dark brownish and contains a high concentration of contaminants such as chemical oxygen demand (COD). Conventional biological treatments, such as ponding, are widely utilized and require large amounts of land to be occupied for extended periods to cure POME efficiently. The goal of this research is to examine the effect of 5, 7, and 9-day hydraulic retention times on the COD removal of POME in a batch mode utilizing anaerobic acetogenic treatment followed by anaerobic polishing. The findings indicate that increasing HRT improves the removal efficiency of POME treatment. COD had a removal efficiency of 53%, 63%, and 62% for 5,7, and 9 days, respectively. Seven and nine HRT days performed better than five HRT days. This study establishes the suitability of the anaerobic acetogenic process for the treatment of POME.

A mini review and bibliometric analysis of palm oil mill effluent in past five years

Indonesia and Malaysia are countries with the highest palm oil production globally. Indonesia is leading the list, followed by Malaysia and Thailand. Palm oil production generates countless benefits to the economy, environment, and society of the contributed countries. This industry provides high income and collection of methane gas for biogas generation and economy of the local community. However, despite the benefits, this industry has some difficulties, including treating the Palm Oil Mill Effluent (POME). POME contains a complex microbial structure and a high amount of oil, grease, and suspended solids. The existing treatment of POME consists of many drawbacks that lead to poor quality of the effluent and failure to meet the minimum requirement from the Department of Environment (DOE). Advance Oxidization Process (AOP), bio granulation, and ponding system are among the research that have been tried to treat POME. The local government still uses old-style treatment types such as Conventional Activated Sludge (CAS), ponding system, and anaerobic digester tank. This review paper presents a mini review of positive and negative consequences the palm oil industry as well as examine a bibliometric study towards the modern research development of the POME. This mini review concludes that the palm oil industry encourages the positive impact in economy, environment and social to the many parties especially country and local community. Besides that, the existing treatment of the POME have to be improved appropriate with the increment of the demand and era.

Polishing of Treated Palm Oil Mill Effluent Using Azolla pinnata

Phytoremediation was used in this study to polish treated palm oil mill effluent using Azolla pinnata. The effectiveness of phytoremediation using A. pinnata can be proved through the reduction of the contamination concentration of wastewater before and after treatment. Preliminary study was made to determine the range of variables that are required for Response Surface Methodology (RSM) software. The variables for this study are the quantity of A. pinnata (20-30 grams), the concentration of palm oil mill effluent (60% -10%), and retention time (1-5 days). Characterization of palm oil mill effluent showed the BOD concentration (285 mg/L), and oil and grease (68.1 mg/L) above the emission standards, the Environment Quality Act 1974, (2005). The highest percentage of effectiveness to eliminate contamination after treatment is ammonia nitrate with an average efficiency of 93%. Meanwhile, the process of BOD removal efficiency percentage is the lowest at 46%. The optimization process has been done using the software Design Expert®. Through Variance analysis, the percentage of effectiveness to eliminate the BOD is not significant for the quadratic equation. Optimum conditions for phytoremediation of the palm oil mill effluent using A. pinnata are quantity of A. pinnata (30 g), the concentration of palm oil mill effluent (10%) and retention time (4.7 days) with the reliability or desirability at 0.9. Maximum percentage of effectiveness removal for BOD, COD, TS, TSS, oil and grease, NH3-H and phosphate are 63.67%, 80.02%, 85.89%, 80.58%, 81.50%, 98.44%, 92.92% and 0.90%, respectively.

Optimisation and performance evaluation of response surface methodology (RSM), artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS) in the prediction of biogas production from palm oil mill effluent (POME)

In recent years, machine learning (ML) techniques have been developed to predict the performance of anaerobic digestion (AD) processes including methane potential and reactor stability. However, their practical applications to industrial-scale palm oil mill effluent (POME) treatment plant are limited. In this study, ML algorithms such as response surface methodology (RSM), adaptive neuro-fuzzy inference system (ANFIS) and artificial neural network (ANN) are employed to model the biogas production and methane yield from the AD of POME in a local industry-scale anaerobic covered lagoon. Results demonstrated that these models were well aligned with two years of operational data with high coefficient of determination (R2) of up to 0.98. ANFIS yields the highest prediction accuracy, with R2 of 0.9791 along with the lowest mean absolute error (MAE) of 0.0730 and root mean squared error (RMSE) of 0.1438. Subsequently, ANFIS is used in the multi-objective optimisation to maximise the biogas production and methane yield. Optimal conditions for the temperature of the anaerobic digester, pH and recirculation ratio are 38.9 °C, 7.03 and 1.89 respectively which could enhance the biogas production and methane yield by 19.4% and 12.2% respectively. Confirmatory experiments were carried out in the biogas plant under this set of optimised variables for a period of two months. The predicted biogas production and methane yield are highly correlated to the actual data with small percentage difference of 1.25% and 5.09% respectively, indicating that ANFIS model was accurate and reliable. Sensitivity analysis shows that pH has the most dominant effect on the methane yield.

Treatment of Palm Oil Mill Effluent Using Fenugreek Coagulant and Aloe-Vera Gel Flocculant

POME is regarded as the largest pollution contributor to the nation’s rivers. Plant based coagulant and flocculant can be utilised to treat POME. In this study, fenugreek seeds and aloe vera gel were utilized as a natural coagulant and flocculant respectively for the treatment of palm oil mill effluent (POME). Jar tests were carried out to study the effects of pH and coagulant-flocculant dosage on the removal efficiencies of turbidity, total suspended solids (TSS) and chemical oxygen demand (COD). Optimum conditions obtained for maximum removals were pH 4, 30 g coagulant dosage and 20 mL flocculant dosage. It was found that the highest removal efficiencies of turbidity, TSS and COD are 82.78, 83.08 and 32.06 %, respectively. Results of the study shows that fenugreek and aloe vera gel are effective natural substitutes for the treatment of POME.

Polymeric materials used for immobilization of microalgae for the bioremediation of palm oil mill effluent

The immobilization of microalgae on polymeric materials such as polyurethane foam (PUF) has shown distinct advantages over non-immobilized technique with significant pollutants degradation efficiency. However, the effect of volume and pore size of PUF on the microalgae performance to remove organics and ammonium has not been extensively investigated. In this study, a down flow hanging sponge (DHS) reactor packed with PUF carrier for the immobilization of microalgae was utilized in treating palm oil mill effluent. The result of chemical oxygen demand (COD) degradation indicates that smaller pore size (0.56 mm) and higher PUF volume (38.0 %) increased the total performance of DHS reactor. In addition, this study also found that the growth of microalgae was greatly influenced by different pore sizes and volumes of PUF.

Characterization and morphological study of microbes in treated palm oil mill effluents

Palm oil mill effluent (POME) is wastewater generated by palm oil milling. Due to its extremely polluting qualities, it must be treated before being discharged into the water course. This study was aimed to evaluate the bacterial growth of raw and treated POME as well as identifying indigenous microorganisms by determining the morphological characteristics of bacteria that were found in the POME. The bacterial growth was identified by bacterial enumeration of colony forming units (CFU). Besides, the morphological identification of bacteria was determined by using gram staining. The results show the best bacterial growth curve is from serial dilution factor of 10-6 with a total of 2.24 x 10-6 CFU/mL in raw POME and optimum growth on day seven. While for the treated POME, the total is 1.97 x 10-6 CFU/mL and recorded the optimum growth on day ten of incubation. The growth curve indicates the number of colonies in raw POME is higher than treated POME. It concluded that treated POME still has the bacteria although it has been treated. Apart from that, from the morphological identification by gram staining, the bacteria were Bacillus cereus, Bacillus subtilis, Staphylococcus aureus and Micrococcus luteus. From a gram staining, this research obtained all gram positive in purple colour from the POME samples. Two of them in treated POME were in Bacillus shape while the other two from raw and treated POME were in coccus shape, respectively.

Removal of Nutrients by Using Green Microalgae from Lab-Scale Treated Palm Oil Mill Effluent

The use of microalgae for the removal of contaminants such as total phosphorus (TP), total nitrogen (TN), chemical oxygen demand (COD), and other pollutants from palm oil mill effluent (POME) has recently received much attention. This study aimed to investigate the impact of POME as a nutrient on microalgal growth and the rate at which nutrients were removed. Three green microalgae species were isolated from Penang, Malaysia’s palm oil mill. The polyphasic approach, which combines morphological and molecular observations, was used for species identification. The three green microalgae were identified as Chlorella sorokiniana, Scenedesmus quadricauda, and Chlorococcum oleofaciens. All three green microalgae were cultivated in 25%, 50%, and 75% (v/v) of lab-scale palm oil mill effluent (LABT-POME) to investigate the growth of these three green microalgae in 100 mL of BBM. Under a light microscope and a scanning electron microscope (SEM), the morphological changes of those three green microalgae (before and after cultivation in 25%, 50%, and 75% dilution of (LABT-POME)) were observed. When cultivated in LABT-POME, C. oleofaciens showed the highest growth rate compared to the other two species of green microalgae. C. oleofaciens was able to remove more than 90% of total phosphorus (TP), total nitrogen (TN), and ammonia nitrogen from LABT-POME, as well as minimise soluble chemical oxygen demand (SCOD) by about 65%. The growth of C. oleofaciens was well fitted to the Verhulst growth kinetic model with an R2 value of 0.99 and a growth rate of 0.3195 day−1 (d−1). The results of this study show the ability of newly isolated green microalgae to remove nutrients (TP, TN, NH3–N, and SCOD) from POME, which could be used as an effective and environmentally friendly method to remove pollutants.