Experimental Studies On Constructed Compound Wetlands Treating Village And Small Town Domestic Wastewater

As a new type of ecological wastewater treatment technology, constructed wetland has been developed at a great speed in its application. It can dispose country family wastewater with simple technique, convenient operation and management, and remarkable eco-environment efficiency. So it is a practical engineering technique for the control of non-point source pollution.Liked with fact condition, reasonable design methods and parameters apply a practical technique methods of treating village and small town domestic wastewater. They are obtained by studying technique and foundation of constructed compound wetlands.The continuous operation of different hydraulic loads were based on three wetlands . By compare, the removal effects of these wetlands were all better on hydraulic load 4cm/d than the others. Among these wetlands, the eighth subsurface flow wetland which use mixture of the same proportion slag, soil and humus soil had the best removal effect. The mean reduction of CODcr, TP, NH/-N and TN were 96.16%, 97.42%, 78.34% and 77.57% respectively. The content of NOs~N and NO2~N were very few in discharge water.In order to study the mechanism of wetlands stuffing, the nitrifying capacity and denitrifying capacity were monitored. The results showed that the nitrifying capacities in depth 5cm were better than that in depth 30cm on the whole. In depth 20cm, the denitrifying capacities were far better than nitrifying capacities and reached to 10.734, 9.375 and 7.646mg/kg ?h.A tracer, sodium chloride was used to study the retention time distribution of wetlands for analyzing the flow pattern in the experimental wetlands. Results indicatedthat the flow pattern were similar to the continuous stirred tank reactor model. The mean retention times based on experiment were shorter than designed times. The experimental wetlands had circulatory and parallel flow, in the same time had different extent short-circuiting.