Purification and reduction of pond aquaculture effluents using constructed wetlands in winter

Treatment of aquaculture effluents by the constructed wetlands in winter was studied according to the characteristics of wastewater discharging from aquaculture ponds.The results showed that the effluents from the aquaculture ponds can be purified by the constructed wetlands with the reduction rate of 35.0 %,38.2%,34.7% and 91.6% for TN,TP,COD and TSS respectively under the hydraulic loads of 0.22 m/d.When the hydraulic load increased to 0.36m/d,the reduction rate of TN and COD were 20.0% and 27.9%,which decreased significantly(P0.05);while the reduction rate of TP and TSS were 35.7% and 93.2%,which had no significant difference(P0.05).The concentrations of TN,TP,COD and TSS in the effluent of the constructed wetlands were lower than 1.5 mg/L,0.2 mg/L,8 mg/L and 5 mg/L respectively,which satisfied the discharge requirement for aquaculture wastewater.The low temperature in winter decreased the TN and COD reduction rate of the constructed wetlands(P0.05) while aeration improved the TN and COD reduction rate(P0.05).The application of constructed wetlands can effectively reduce the effluents from aquaculture pond.