الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Modification of activated sludge process is proposed herein as a means to improve pollutants removal. Mainly BOD5, COD and SS were considered, also nitrogen was detected. The modification process involves applying mixed culture media. This media was applied at different percentage with respect to aeration tank volume. The reactors were employed with plastic media percentage of zero, 25%, 50%, 67%, of reactor volume which represent surface areas, zero, 37.5, 75, 100.5 m2/m3, of reactor volume. The reactors were then subjected to different operational loads at different retention periods varied from, 7, 6, 5, 4, 3, and 2 hrs. In order to investigate and to evaluate the biological system exhibiting a mixed culture process in wastewater treatment and thus by adding media for attachment of culture in the aeration tank to exhibit both suspended and attached growths. A pilot plant employing aeration tank followed by sedimentation tank was used in the experimental study. This study evaluate the performance and design the applied system under various operating conditions. to achieve the suitability of the new system with our condition, the obtaining of the formula and parameter for design, the obtaining the percentage and type of media which give good performance, durability This series of investigation concluded that Hydraulic retention & Media specific surface area was found to have direct effect on substrate removal rates. for gravel media its clear that increasing surface area increase process performance and in opposite inert volume of gravel media reduced the actual volume of reactor and reduces process performance. The reactor readily recovered its ability to remove COD after a the reactors were subjected to step and transient hydraulic shock loads. Reduction in the aeration tank volume A hydraulic retention time of 3 hrs is the most suitable for design. With plastic media specific surface area 100 m2/m3 or higher (that achieve max RR of pollutants). The obtained results indicated that old and over loaded plants can be improved using attached media to carry the extra hydraulic and organic loading rates.