Investigation of possibility of treated urban wastewater in aquaculture of the common carp and the silver carp species and their effects on the quality parameters of wastewater

Reuse of unconventional waters, such as wastewater, is very important in point of environmental principles view. The main objectives of the present study was to survey feasibility of the growth and survival performance of two species of silver carp and common carp at different concentrations of wastewater, and also investigation of the effects of presence of these two species on improving the quality parameters of wastewater BOD, COD, TSS, TDS, nitrate and phosphate parameters in the Mahdishahr wastewater treatment plant (active sludge method) in the Semnan province. For this study, five wastewater treatments were considered as control treatment (without wastewater) and treatments of 25, 50, 75 and 100% wastewater with triplicate in 80 liter reservoirs. In each tank, 10 common carp and 10 of silver carp were introduced with average weight 30± 5 gr. In one month, the growth performance and survival rate of fish were compared in different treatments. Also, changes in different wastewater parameters in the 100% wastewater treatment with presence of fish and without of fish (control) were also investigated during the 10-day intervals. According to the results, the highest growth (WG) (18%) and specific growth rate (SGR) (0.23) were related to the 75% and 100% of wastewater treatments. Also, in the treatment of 100% of wastewater in the presence of fish compared to the control (without fish) during the study period, BOD, COD, TSS, nitrate and phosphate parameters decreased significantly (P≤0.05) during the research period, while the trend for the TDS parameter was increasing in the treatment. The results showed that urban wastewater without water mixing also has the potential for reuse in aquaculture of resistant species such as Cyprinidae family species. Also, the presence of aquatic species with regard to diet has a significant effects on the improving the quality parameters of the wastewater.