Two-stage anaerobic process coupled with single-stage aerobic process for raw palm oil mill effluent treatment

Abstract

Malaysia is the second large contributor in the palm oil industry after Indonesia. Yearly, approximately 13 million tonnes of crude palm oil are produced. During the crude palm oil extraction process, huge amount of brownish-oily liquid sludge, known as palm oil mill effluent (POME), are generated. The acidic and high organic loadings characteristics of POME can cause severe water pollution if being discharged to the water bodies without proper treatment. In most oil palm production mills, ponding treatment system is adopted. The treatment paradigm, however, has shifted from ponding system to integrated high rate bioreactors by coupling anaerobic and aerobic processes. Despite the outstanding treatment performance exhibited by this bioreactor, diluted POME was used in almost all previous studies instead of fresh raw POME. Thus, treatment performance by the researched bioreactors for fresh raw POME real application may not be as efficient. Therefore, this study aimed to employ the principle of two-stage anaerobic process followed by a single stage aerobic process for the treatment of fresh raw POME. The treatment efficiency of this system was examined by evaluating the removal of several important parameters, namely chemical oxygen demand (COD) and sludge reduction reported in terms of total suspended solids. Throughout the 150 days of operation, approximately 93% and 55% of reduction were observed for COD and TSS, respectively, suggesting this integrated system was competent in treating high strength wastewater. Nonetheless, further research need to be made to ensure the stability consistency and feasibility of this integrated system.