Vermifiltration of untreated raw palm oil mill effluent (POME)

Abstract

Palm oil industry is one of the leading agricultural industries in Malaysia and has been contributing significantly towards the country's economy to increase the standard of living among Malaysians. The raw palm oil mill effluent (POME) is acidic, with a pH level 4.6 and it may cause environmental problems. Hence, treatment of POME is necessary. In Malaysia, high generation of POME from crude palm oil production is currently treated using a conventional method known as ponding system, which is space inefficient. As an attempt to resolve the long-standing dilemma, recent and alternative methods such as vermifiltration is being studied and introduced to wastewater treatment. Vermifiltration is a filtration process where solids are separated from liquid, aided by earthworms. In this research, the performance of a vermifilter (VF) containing the earthworms, African Night Crawler and a control filter (CF), without earthworms were compared using the mixture of sand and garden soil as vermibed. Worm density of 8 g/L with flow rate 100 mL/min was used in the vermifilter for a 150 day period. The research was conducted at laboratory scale. Both filters, vermifilter and control filter were set as triplicates. The POME pH increased from acidic to neutral. It was observed that vermifilter reactor showed the highest reduction rate of BOD5, COD, TSS and turbidity by 92%, 90%, 95% and 86%, respectively compared to control filter by 55%, 45%, 65% and 52%, respectively. Vermifiltration technology can therefore be applied as an environmentally friendly technique and has potential to treat POME.