Quality assessment of vegetable oil industry effluents in Port Harcourt, Rivers State, Nigeria

Five composite samples of waste water were collected from waste water tank of a vegetable oil refining company and were analyzed for physiochemical characteristics, heavy metal and organic pollutants. Physicochemical determinations were done according to standard methods; heavy metals were determined by use of Atomic Absorption Spectrophotometer method while organic pollutants were determined by Gas chromatography system HP 6890 series. Sulphate was determined by vanadomolybdophosphoric acid method while phosphates and chlorides were determined by argentometric method. Results reveal that effluent pH (4.67 ±0.015), salinity (125 ±4.50 %) and BOD5 (17.83 ±1.70 mg/l) were bellow WHO standard whereas TDS (127.7 ±5.77 mg/l), TSS (563.6 ±3.15 mg/l) and COD (3959 ±3.8 mg/l) were above WHO standards. Heavy metal pollution index (0.31) showed no multi-element contamination arising from effluent. The degree of contamination (1.84) showed that the effluent has a moderate polluting potential. Lower molecular weight PAHs showed a significant difference even though most of the organic compounds in vegetable oil refinery wastewater showed good biodegradability that varied weekly. Therefore there is either no treatment or an in effective treatment of the effluents. This could result to serious environmental problems in the near future.