Analysis of the quality of effluent discharged from petrol stations-the case of National Oil Service Stations-Kenya
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Fuel retail trade is a fast growing sector in the country. However, even with this rapid expansion, few studies have been conducted to examine the environmental impact of effluent emanating from the stations. The ultimate goal of this project is hence to determine if service station in Kenya with particular reference to the National Oil service stations pollute adjacent natural waterways and if so identify the key pollutants. Reference is made to the National Oil service stations as the company is arguably the fastest growing petroleum retail outlet having grown its retail network from only six service stations in the year 2006 to more than 6S service stations today. Simple random sampling was employed and seven stations were identified in Nairobi, Kisumu, Eldoret, Mombasa and Kikuyu. 'Water samll\es were co\\ec\ed from \ne ou\\e\ ex\\ of interce'Qtors at the identif\ed service stations. These water samples were then tested for the key pollutants that are outlined in the Environmental Management and Co-ordination (Water Quality) Regulations, 2006 as the regulations apply to effluent from service stations. Further calibration of the results was conducted by comparing the inlet and outlet water quality in the Muchatha (Kikuyu) and Nairobi West (Nairobi) service stations. Results from these tests show that the Biochemical Oxygen Demand and Total Suspended Solids measurements surpass the set statutory limit of 30mg/l in all service stations. The Total Dissolved Solids and pH parameters as well as the oil and grease measurements in the collected samples fall within the set limits. Faecal coliforms in the Mombasa, Kisumu and Nairobi service stations surpass the nil standards put forth in the water regulations. It was consequently found that the infrequent and unprofessional cleaning practice at the service stations are a cause of the incomplete distillation of waste water at the service stations interceptors. The complete lack of residual chlorine in the waste water is suggestive that operators of the studied service stations do not use chlorine or any other cleaning detergent while cleaning the interceptors. Faecal coliforms in the waste water suggest a compromised piping system within the Nairobi, Kisumu and Mombasa stations. Nonetheless, National Oil service stations demonstrate good environmental monitoring as all other pollutants that are ideally incident from service stations fall below the Water Regulations set limits. However, there is need to improve on the parameters which are above the standard limits.