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

The ecacy of the oxidation pond on the outskirts of the 10th of Ramadan, the main industrial city, in Egypt was examined. Samples of wastewater collected from the inlet and the outlet were screened for some priority pollutants. Acenaphthene and ̄uorene were the most frequently detected polycyclic aromatic hydrocarbons, while dimethyl phthalate was the most frequently detected phthalate ester. The spectrum of pollutants, their concentrations and frequencies were similar in the inlet and the outlet, indicating an inferior mineralization capability of the pond. Several degradative bacterial strains were isolated from the pond and grown on M56 minimal media supplemented with di€erent pollutants as the carbon source. The ecacy of pure and mixed cultures to break down ̄uorene, the most frequently detected pollutant was examined. Fluorene degradation was fast in the ®rst 10 days, then followed by a slow phase. Mixed culture had a higher rate of ̄uorene degradation in comparison to pure cultures. High performance liquid chromatography analysis of ̄uorene degradation showed three degradative metabolites. But GC/MS analysis detected one compound, identi®ed as acetamide. The present work has indicated the poor ecacy of the pond. Lack of primary treatment of industrial e‚uent at factory level, coupled with shock loads of toxicants that may damage the microorganisms and their degradative capabilities are presumably main factors behind such inferior performance. Moreover, the type of pollutants discharged into the pond tend to ̄uctuate and change 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 specialized strains of bacteria capable to degrade such persistent pollutants. # 1999 Elsevier Science Ltd. All rights reserved.