Microbial load and biodegradation of palm oil mill effluent (POME) by microorganisms at different stages of discharge

Abstract

The raw palm oil mill (POME) effluent has an extremely high content of degradable organic matters as a result of unrecovered palm oil during production of palm oil. The aim of this study is to evaluate the microbial load and biodegradation of POME by microorganisms at different stages of discharge. Standard dilution methods were used for the isolation of bacteria and fungi. The estimation of colony forming unit per mL (cfu/mL) was assessed using 10-fold serial dilution method. The results showed that the total microbial count (TMC) decreased with time. Statistical analysis using analysis of variance (ANOVA) further revealed a significant variation in microbial load after 28 days of discharge. This was followed by a significant decrease after 36 days when compared with other samples. The physicochemical studies further revealed the presence of relatively low levels of sodium, potassium, calcium, magnesium and iron. The concentration of nitrate was relatively high, 70.13 mg/L. The biological oxygen demand (BOD) and the chemical oxygen demand (COD) were also high 2250mg/L and 3360mg/L respectively. High BOD and COD values are important indicators of high organic and inorganic components of the effluent and possible negative environmental consequences. The presence of the following species Clostridium, Proteus, Pseudomonas, and Micrococcus implied possible degradation of the effluent.