Zero discharge performance of an industrial pilot-scale plant treating palm oil mill effluent

Co-digestion of palm oil mill effluent with chicken manure and crude glycerol: biochemical methane potential by monod kinetics

In Thailand, the palm oil industry produces a huge amount of palm oil mill effluent (POME), mostly used for electricity generation through biogas production. Co-digestion with other waste can further improve biogas yield and solve waste management problems. Most previous studies relied on biochemical methane potential (BMP) assay or batch co-digestion to obtain the optimal mixing ratio, ignoring the kinetic part or treat it for sole discussion of the results. This work directly uses mechanistic models based on Monod kinetics to describe the experimental results obtained from the co-digestion of POME (40 ml, BMP = 281.2 mlCH₄/gCODadded)) with chicken manure (CM) (0–50 g) and crude glycerol (Gly) (0–10 ml). The best mixing ratio between CM and POME was 5 gCM: 40 mlPOME (BMP = 276.9 mlCH₄/gCODadded). The best ratio for Gly and POME was 2 mlGly: 40 mlPOME (BMP = 211.9 mlCH₄/gCODadded). Adding Gly only 2 mlGly/40 mlPOME doubled the amount of biogas. Hence, crude glycerol is a good substrate for on-demand biogas output. The co-digestion increases the methane output but with a decreased yield. A multi-substrate Monod model was developed based on the levels of digestion difficulty. A partial-least squared fitting was used to estimate its main parameters. All parameters included in the model passed the significant tests at a 95% confidence level. The model can describe the experimental results very well, predict observable state variables of batch co-digestion, and allow a simple extension for continuous co-digestion dynamics. A limited continuous experiment was conducted to confirm the applicability of the model parameters of POME digestion obtained from BMP tests to predict a continuous AD. The results show good potential but must be carefully interpreted. It is generally possible and practical to directly obtain design and operational parameters from BMP assays based on only accumulated biogas curves and initial and final COD/VS.

Efficiency of pollutants removal in treated palm oil mill effluent (TPOME) using different concentrations of sodium alginate-immobilized Nannochloropsis sp. cells

Palm oil mill effluent (POME) has high chemical oxygen demand (COD), thus requires effective treatments to environmentally benign levels before discharge. In this study, immobilized microalgae cells are used for removing pollutants in treated palm oil mill effluent (TPOME). Different ratios of microalgae beads to TPOME concentration were examined at 1:2.5, 1:5, and 1:10. The biomass concentration and COD removal were measured through a standard method. The color of the cultivated microalgae beads changed from light green to darker green after the POME treatment for 9 days, hence demonstrating that microalgae cells were successfully grown inside the beads with pH up to 9.84. The immobilized cells cultivated in the POME at 1:10 achieved a higher biomass concentration of 1.268 g/L and a COD removal percentage of 72% than other treatment ratios. The increment of the ratio of microalgae cells beads to POME concentration did not cause any improvement in COD removal efficiency. This was due to the inhibitory effect of self-shading resulting in the slow growth rate of microalgae cells which responsible for low COD removal. Therefore, this system could be a viable technology for simultaneous biomass production and POME treatment. This will contribute to research efforts toward the development of new and improved technologies in treating POME.

Toxicity of palm oil mill effluent on the early life stages of Nile tilapia (Oreochromis niloticus, Linnaeus 1758)

Harmful effects of several pollutants have been reported on early life stages of fish. However, the effects of palm oil mill effluent (POME) on fish early life stages are still unexplored. Therefore, the objective of this present study was to elucidate the impact of POME on the early life stages of Nile tilapia (Oreochromis niloticus). Fertilized eggs of Nile tilapia were exposed to four concentrations of POME (0, 1.565, 2.347, and 3.130 mg/L) in 20 plastic funnels. Each of the control and treatment groups was maintained in five replicates. The cumulative hatching rate, malformation rate, body length, and deformities of larvae were analyzed. Results showed that hatching rate and survival rate of Nile tilapia larvae significantly decreased with increasing concentrations of POME. In contrast to, malformation rate and heart rate were significantly increased. Furthermore, results showed several malformations of Nile tilapia larvae including lordosis, kyphosis, and curved tail when exposed to 1.565 mg/L, 2.347 mg/L, and 3.130 mg/L of POME concentrations. Further research is required to understand the physiological mechanisms of different endpoints in the early stages of Nile tilapia induced by the toxicity of POME.

Bioenergy for a Cleaner Future: A Case Study of Sustainable Biogas Supply Chain in the Malaysian Energy Sector

A life cycle assessment (LCA)-based environmental sustainability evaluation conceptual framework of biogas production has been proposed to improve the sustainability of biogas supply chains. The conceptual framework developed in this study can be used as a guideline for the related stakeholders and decision makers to improve the quality and enhance the sustainability of biogas production in Malaysia as well as promoting biogas as a clean, reliable and secure energy. A case study on an LCA analysis of a zero waste discharge treatment process has been conducted. In the zero discharge treatment system, biogas can be produced with a maximum water recycle and reuse. It was indicated that the biogas production and zero discharge treatment of a palm oil mill effluent were environmentally sustainable as the system utilized organic waste to produce bioenergy and achieved zero discharge. However, there were other aspects that should be taken into consideration, particularly regarding the sources of electricity and upstream activity, to ensure the sustainability of the system holistically.

Integrated System Technology of POME Treatment for Biohydrogen and Biomethane Production in Malaysia

In recent years, production of biohydrogen and biomethane (or a mixture of these; biohythane) from organic wastes using two-stage bioreactor have been implemented by developing countries such as Germany, USA and the United Kingdom using the anaerobic digestion (AD) process. In Thailand, biohythane production in a two-stage process has been widely studied. However, in Malaysia, treating organic and agricultural wastes using an integrated system of dark fermentation (DF) coupled with anaerobic digestion (AD) is scarce. For instance, in most oil palm mills, palm oil mill effluent (POME) is treated using a conventional open-ponding system or closed-digester tank for biogas capture. This paper reviewed relevant literature studies on treating POME and other organic wastes using integrated bioreactor implementing DF and/or AD process for biohydrogen and/or biomethane production. Although the number of papers that have been published in this area is increasing, a further review is needed to reveal current technology used and its benefits, especially in Malaysia, since Malaysia is the second-largest oil palm producer in the world.

Membrane-based zero-sludge palm oil mill plant

The palm oil industry is one of the most important agro-industries for tropical countries because of the unique properties and wide range of uses of palm oil for various end products. In a palm oil extraction process, a large quantity of water is required, of which half the quantity will end up as effluent. This palm oil mill effluent (POME) has an extremely high content of organic matter, which can cause severe pollution of waterways and other environmental problems. Disposal of this highly polluting effluent has become a major problem for the palm oil mills. Therefore, several methods have been proposed either to treat the POME so it could comply with environmental regulation while discharged or to recover water and other valuable components from the effluent. Membrane technology has emerged as a feasible alternative to conventional treatment in vegetable oil processing because of its attractive features such as low energy consumption, reduction in the number of processing steps, high separation efficiency, and improvement of the final product quality. In the case of POME treatment, an integrated membrane-based process promises efficient water recycling and total solid recovery from the effluent, thus eliminating the environmental problem. Recently, a novel concept combining oil–oil extraction and continuous filtration using a superhydrophobic membrane has been proposed to achieve a zero-sludge palm oil mill. In this concept, the huge wastewater effluent generated from the conventional process can be eliminated and the palm oil milling process simplified. Furthermore, the superhydrophobic membrane enables the production of high-purity palm oil. In this paper, we review the prospect of a zero-sludge palm oil mill concept and strategies to achieve the proposed concept. In addition, we also highlight the development of the superhydrophobic membrane and phytonutrient recovery.

Treatment of Palm Oil Mill Effluent Using Membrane Bioreactor: Novel Processes and Their Major Drawbacks

Over the years, different types of alternative technologies have been developed and used for palm oil mill effluent (POME) treatment. Specifically, membrane bioreactor (MBR) has been employed to relegate pollutants contained in POME under different operating conditions, and the technology was found to be promising. The major challenge impeding the wider application of this technology is membrane fouling, which usually attracts high operating energy and running cost. In this regard, novel methods of mitigating membrane fouling through the treatment processes have been developed. Therefore, this review article specifically focuses on the recent treatment processes of POME using MBR, with particular emphasis on innovative processes conditions such as aerobic, anaerobic, and hybrid processing as well as their performance in relation to fouling minimization. Furthermore, the effects of sonication and thermophilic and mesophilic conditions on membrane blockage were critically reviewed. The types of foulants and fouling mechanism as influenced by different operating conditions were also analyzed censoriously.