comparative studies of some industrial wastewater treatment techniques”. proceeding of the 4th international environmental conference, faculty of science at damietta, egypt.

Generation of wastewaters in industrial processes is sometimes unavoidable and in most cases, a process to reduce the organic load and other contaminants must be employed before wastewater discharge.

Two industrial effluents from two plants (oil food and a car washing station) at New Damietta industrial Zone were chosen to the pretreatment processes. Among these processes were plain sedimentation, coagulation-flocculation, sedimentation and filtration to minimize the hazardous impacts of contaminated wastewater effluents on the environment. Physicochemical characteristics and heavy metals concentration (Cd, Cu, Fe, Mn, Pb and Zn) were conducted for wastewater samples.

The results showed that a dose of 20 mg/L alum was more effective in reducing several contaminants for car washing station wastewater than that for food oil effluent after gravity settling.

Furthermore, it was found that 5g/L alum (added as solid) is more effective than 100 mg/ L (added as a solution). Therefore, it is recommended to be used for the pretreatment of the food oil effluent. It was also concluded that, the coagulation of the two effluents with dose of 5g/L alum is more effective without addition of lime.

The suggested series of pretreatment techniques for the two effluents is highly effective in reducing several parameters. It is worth to mention that the treated effluents are complying with the regularity standard that regulate the discharge of wastewater into sewerage network (Decree No. 44/2000).