Studies On Domestic Sewage Treatment Effect And The Solutions Of Substrate Clogging Of The Subsurface Flow Constructed Wetland

The treatmental effects of domestic sewage and the solutions of substrate clogging of the indoor simulation subsurface flow constructed wetland were studied from the system first operating to system substrate clogging, function recovering by the physical and biological methods in this paper. The results are as follows:1.The analysis of the effects of domestic sewage by the indoor simulation of subsurface flow constructed wetland are as follows.1) During normal operationof the system, the domestic sewage flowed into the Horizontal subsurface flow constructed wetlands and the Vertical-flow constructed wetlands at the same time. Choose different hydraulic retention time as three days,two days,one day,half day, the concentration of COD, TN, TP and SS of inlet and outlet sewage is monitored. The results showed that the average removal rates of COD, TN, TP and SS were the highest when the hydraulic retention time was two days, the average removal rates were75.9%,74.97%、77.35%,87.81%respectively in the H#, and the rates were63.05%,81.12,77.65%,76.97%in the V#.2) When the system was clogging, the average removal rates of COD, TN, TP and SS were39.12%,35.37%,37.34%,41.31%respectively in the H#, and the rates were31.41%,37.46%,40.06%,30.41%in the V#;3) When the system recovered, the average removal rates of COD, TN, TP and SS were78.02,82.24%、83.31%、93.37%respectively in the H#, and the rates were67.02%,90.16%,84.16%,91.52%in the V#.2.When the experimental system operated for144days, the wetland system has relatively unfavorable quality of outlet water and almost loses the purification function, with frequent backwater phenomenon. According to statistics of porosity change and measurement&calculation of critical permeability coefficient K, K is equal to0.0128cm/s, close to critical coefficient of the system Kcritical=0.013cm/s. Therefore, it is judged that matrix blocking appears in the system.3.When the substrate of artificial wetland was clogging, the V1#and H1adopted by the single recovery method, while the V2#and H2#adopted by the composite recovery method, When the system operated for7days, the ruction of V2#and H2#were recovered,the porosities were20.78%,21.11%respectively; When the system operated for40days, the VI#and H1were recovered, the porosities werel9.81%、20.76respectively.As a result, the composite solutions has higher recovery speed and degree of recovery than the single type in the study of artificial wetland substrate clogging.