الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Sewage treatment is a complex process involves primary, secondary and tertiary treatments. Secondary treatment removes dissolved and suspended biodegradable organic matter by indigenous, water-borne micro-organisms in the managed habitat or added previously prepared sludge. A great inefficiency was reported to the biological treatment of the Municipal Wastewater Treatment Plants (MWTP) at the cities of Mansoura and Talkha, Dakahlyia, Egypt. A total of twenty four bacteria were isolated from the two sites. Some of these isolates showed antagonistic activities among themselves which affect their degrading abilities of organic pollutants. In a simulated setup, different combination of six bacterial isolates were tried to treat sewage and their efficiency was judged by final biological oxygen demand (BOD) values. The reduced BOD values are indicative of wastewater purification and higher rate of degradation of organic matter. These six isolates were identified at both biochemical and molecular levels. Four bacterial isolates were identified as members of the Bacillus cereus group, one isolate was identified as Escherichia coli and one as Pseudomonas. In conclusion, the malfunctioning sewage treatment plant operation in the open system, such as those in Mansoura and Talkha, requires continuous monitoring for microbial antagonism followed by microbial augmentation to speed up the biological treatment process.