| Non-point source pollution has become one of the main sources of water pollution in China.Especially,the agricultural non-point source pollution caused by large application of chemical fertilizers and pesticides is becoming more and more serious.The ecological ditch plays an important role in intercepting the agricultural non-point source pollutants.However,it is vulnerable to the lack of oxygen supply capacity,the season,the influent water quality and the pollution load.Therefore,this study improve the properties of the ecological ditch technology through the combination of technology,low energy consumption aeration,plants strengthen.In the experiment,the pond-ecological ditch system was combined with the pre-ecological pond and no-powered aeration device to enhance the interception and purification of the organic pollutants and nitrogen and phosphorus.The loofah sponge fiber was introduced into the system to intensify the effect of waste water treatment.The results can be summarized as follows:(1)The pond/ecological ditch coupling system in initial phase had a removal rate of 40.67%,33.61%and 56.86%for CODCr,TN and NH4+-N,respectively.But the removal efficiency of TP was not unsatisfied,which could probably be attributed to a short time,the release of phosphorus in the sediment caused by the disturbance of planting,and the water retention time is not taken into account at the time of sampling.Hence,all sampling processes were based on the hydraulic retention time.The system was conducted at low temperature and revealed removal rates of CODCr,TN,NH4+-N and TP with 54.50%,36.35%,53.00%and 44.20%respectively.Although the system showed fluctuating,it is preferential comparing to the traditional ecological ditch system.(2)The effects of pH,DO and temperature on the efficiency of the coupling system were studied.It was found that the pH had no significant impact on the removal rate of CODcr and TP,while had positive correlation with NH4+-N(R2=0.7059).DO had less impact on CODcr,TP and TN than that of NH4+-N(R2=0.7716).Temperature was positively correlated to removal rate of CODCr,TP,TN and NH4+-N.The correlation temperature was less than that of pH and DO.The results showed that pH has a great effect on the nitrification and denitrification of the coupling system.DO has a great effect on the denitrification of the system,and the low temperature is not conducive to the operation effect of the coupling system.The analysis of DO showed that non-powered aeration device technology effectively enhanced the DO condition of ecological ditch.(3)The coupling pond/ecological ditch was constructed in pilot scale.The experimental results showed that the coupling system has a certain removal of CODcr,TP,TN and NH4+-N.The removal efficiency of CODcr and TP in the system is higher than that of TN and NH4+-N.The pond/ecological ditch coupling system with loofah sponge performed higher removal of organic pollutants and nitrogen and phosphorus than that without loofah sponge.It indicated that the loofah sponge intensified the waste water treatment of the pond/ecological ditch coupling system... |
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