Abstract The need for water is growing with increasing population and the adverse impacts of climate
change especially in the Mediterranean basin. Innovative concepts and technologies are
urgently needed to close the loop for water. Among the options for innovative water resources, segregation
of grey water and reuse is receiving crucial attention for decentralized areas as a sustainable
approach. Grey water represents substantial portion of household water consumption in
volume. Treated grey water to a level complying reuse rules and regulations can be reused for several
purposes including agriculture, landscaping and toilet flush. The mathematical model was used
to investigate the performance and treatment capability of Rotating Biological Contactors (RBC)
to treat the grey water. The GPS-X (version 5.0) simulation program was used in this study to simulate
the proposed RBC plant. The proposed Rotating Biological Contactors (RBC) plant is composed
of three parts, first is the RBC tank unit, second is the settling tank unit and third is the
disinfection tank unit. After the model optimization, three different concentrations of the grey
water were used to run the proposed mathematical model. Low, medium and high concentrations
of the grey water were used to run the model. The proposed model was verified by using data from
RBC experimental pilot plant. The results of this study showed that, the treatment efficiency of the
RBC system based on BOD removal was ranged between about 93.0% and 96.0%, and based on
TSS removal was ranged between about 84.0% and 95.0 % for all concentrations of influent grey
water. Also, the proposed model results indicated that grey water can be properly treated by RBC
system and can be reused for many purposes after disinfection and sand filtration.
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