OPTIMISATION OF PHYSICAL CHEMICAL TREATMENT FOR OILY WASTEWATER AT A PIPE MANUFACTURING COMPANY

Within the European Union (EU) increased legislation means that manufacturing companies are being asked to improve upon the quality of effluent discharged to either sewer or controlled water bodies. In order to meet these requirements, onsite treatment is regularly practised. This paper discusses work carried out to optimise the performance of a Dissolved Air Flotation (DAF) treatment plant at a pipe mill in the UK. The laboratory studies showed that the most effective treatment for the mill wastewater was a combined treatment of FL4440 (polydiallyldimethylammonium chloride, PDADMAC, used as a primary coagulant), ferric chlroride or alum (used as a secondary coagulant) with final pH control and Flopam AN934 (a polyacrylamide based flocculant). This treatment was able to breakdown a wide range of emulsions produced from the mill and the results obtained were totally independent of initial pH, COD and oil & grease. However, larger flocs were only seen when pH was increased to 7.08.5. This paper reports the results of a pilot study onsite to evaluate the effectiveness of these chemicals derived from the laboratory studies.