Recycling of Waste Water Collected from Automobile Service Station

This paper compares the effectiveness of chemical and physical methods in treating the wash water collected from automobile service stations. Wash water was collected from two service stations in the city of Bangalore, and the effluent was characterised for different parameters such as pH, turbidity, conductivity, total solids, oil and grease, COD (chemical oxygen demand), BOD (biological oxygen demand), chlorides, sulphate and total hardness. For chemical treatment, alum was used and locally available natural materials such as saw dust and sugarcane bagasse were used for physical treatment. Alum at different concentrations was agitated with the effluent for a prescribed contact period which led to the formation of flocs. The filtered samples were tested for COD and oil & grease. in the form of filter columns of three different heights. The percentage reduction in COD and oil and grease was correlated with the depth and type of filter media. A comparison of physical and chemical methods of treatment revealed that natural materials are effective in removing oil & grease and COD from the automobile effluent and hence provide a viable solution because of its eco-friendliness. From the experimental studies it is observed that in physical treatment, the sorption capacity of any material is dependent on its porosity, surface area and height of filter bed.