Assessment of Agro-Industrial Wastewater Management in Palm Oil Processing in Edo State

This study assesses the management of agro-industrial wastewater from palm oil processing mills in Edo State, South South Nigeria. Palm oil mill effluent is one of the most polluting agro-industrial wastewater streams, characterised by high biochemical oxygen demand, chemical oxygen demand, suspended solids, and oil content that can severely damage waterways and aquatic ecosystems if discharged untreated. Edo State hosts numerous small and medium-scale palm oil processing mills whose effluent management practices have received limited regulatory scrutiny. This study uses an engineering assessment methodology, characterising wastewater quality parameters from 15 processing mills in Ovia North-East, Orhionmwon, and Akoko-Edo local government areas. Effluent samples are collected at mill discharge points and analysed for BOD, COD, total suspended solids, pH, oil and grease, and heavy metals. Current treatment infrastructure is inventoried and performance-tested where present. Regulatory compliance against Federal Ministry of Environment effluent standards is assessed. Treatment improvement cost estimates are developed. Findings reveal that 87 percent of sampled mills discharge wastewater with BOD values 15 to 40 times above the Federal Environment Agency permissible limit. Treatment infrastructure is absent in 73 percent of mills. Constructed wetland and anaerobic pond treatment systems are identified as the most cost-effective treatment options for the typical mill scale in the study area. The study recommends a state-supported mill effluent treatment assistance programme and phased enforcement timeline.

Keywords: palm oil effluent, wastewater management, Edo State, environmental engineering, agro-industrial pollution.