The efficacy of an oxidation pond in mineralizing some industrial waste products with special reference to fluorene degradation: a case study

The efficacy of the oxidation pond on the outskirts of the 10th of Ramadan, the main industrial city, in Egypt was examined. Samples of wastewater col lected from the inlet and the outlet were screened for some priority pollut ants. Acenaphthene and fluorene were the most frequently detected polycycli c aromatic hydrocarbons, while dimethyl phthalate was the most frequently d etected phthalate ester. The spectrum of pollutants, their concentrations a nd frequencies were similar in the inlet and the outlet, indicating an infe rior mineralization capability of the pond. Several degradative bacterial s trains were isolated from the pond and grown on M56 minimal media supplemen ted with different pollutants as the carbon source. The efficacy of pure an d mixed cultures to break down fluorene, the most frequently detected pollu tant was examined. Fluorene degradation was fast in the first 10 days, then followed by a slow phase. Mixed culture had a higher rate of fluorene degr adation in comparison to pure cultures. High performance liquid chromatogra phy analysis of fluorene degradation showed three degradative metabolites. But GC/MS analysis detected one compound, identified as acetamide. The pres ent work has indicated the poor efficacy of the pond. Lack of primary treat ment of industrial effluent at factory level, coupled with shock loads of t oxicants that may damage the microorganisms and their degradative capabilit ies are presumably main factors behind such inferior performance. Moreover, the type of pollutants discharged into the pond tend to fluctuate and chan ge depending on the rate from the factories discharge and work shifts. Such irregular feeding of persistent pollutants may have led to a wash out of s pecialized strains of bacteria capable to degrade such persistent pollutant s. (C) 1999 Elsevier Science Ltd. All rights reserved.