الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The Middle East region has become on the verge of water poverty. It has
become imperative to reconsider the policy of water spending and
rationalization of consumption and to consider recycling all types of water,
thus in this study, two identical stages of the RBCs system were used to
treat wastewater after its primary treatment at Zenin wastewater treatment
plant in Giza, Egypt. Different materials were used in the treatment process
such as geotextile, in form of circular discs and gear shaped, with 15 discs
per RBC’s stage, then those disks were replaced with a steel cylinder
having 25cm diameter along the tank per RBC’s tank. In addition, a plastic
bottle with holes with sugarcane straw inside, one per each RBC’s tank.
Moreover, another plastic bottle with banana leaves inside, one per each
RBC’s tank. The rotation speeds were varied between 5, 8 and 10 RPM,
with 40% submergence for the geotextile discs of the normal circular shape
and for the rest of the materials a rotation speed of 5 RPM were used, where
it was found later that it gave the best results. The hydraulic retention time
ranged from one to seven days. It was found that the best results obtained
at HRT of 3 days. Results showed that the removal rates of BOD, COD
and TSS were almost 82%, 86.7% and 81.5% at 5RPM for normal circular
discs shape respectively, while for gear shaped discs removal rates were
almost 83.7%, 91% and 81.3% respectively. For sugarcane straw plastic bottle, BOD, COD and TSS removal rates were almost 64.86%, 69.49 and
68.18% at 5RPM respectively, noting that sugarcane straws removal rates
were the lowest among the rest of materials. Removal rates were almost
86.9%, 94.4 and 82.14% for BOD, COD and TSS respectively at 5RPM
for steel cylinder. Steel cylinder showed the highest removal rates among
all other materials and the resulted water matches the Egyptian
specifications for water intended for irrigation purposes.