Polluted River Water Treatment Using Multi-Soil-Layering System

Dianchi Lake is in the downstream of Kunming city, the rivers flowed into Dianchi Lakecarry and transmitte large of pollutants, and this make dianchi seriously polluted，lost thefunction of being drinking water source, it also destory the aquatic ecosystem seriously，hampering the region’s social and economic development. The reality that Dianchi Lake haveno environmental capacity decide the further treatment of the river into the lake, effectivelyreduce the pollutants into the lake have become a serious problem.Recent years, Kunming government has taken many measures such as interception,riverbank remediation, but the river water quality improvement still of the overall poor results,so rivers treatment still is important and difficult to the Dianchi Lake. The development of newriver training techniques is imperative. MSL system with the advantages of less investment,lower operation cost, higher efficient for different kinds of wastewater treatment, because ofits special ‘brick pattern’structure, MSL can overcome clogge which is common phenomenonto the traditional soil percolation systems. MSL has been widely used In Japan, Thailand,Indonesia, and the United States to treat domestic wastewater,river water and dairy water,butthere is few research about MSL in our country. This experiment using MSL system technologyto study the removel efficiency and removel mechanism of the organic matter, TN, ammonianitrogen, total phosphorus, choose the best surface load and load reduction adajust thisapplication. Further, experiment will be acted to enhance its nitrogen removal efficiency byadding PBS carbon resource and space optimization.The final purpose of this study is providetheoretical support and guidance to further demonstrate engineering and promote the applicationused for city’s polluted river treatment in our country.The results indicated that:MSL system start-up quickly when using natural method to formbiofilm, its start-up priod is25days. When the surface load is1000L/m2d, the averageremoval rate of BOD5, COD, TN, NH3-N and TP are80.2%,74.8%,28.9%,88.5%and87.0%respectively; when the surface load is1500L/m2d, the average removing rate of BOD5, COD,TN, NH3-N and TP are77.0%,72.4%,20.2%,83.9%and84.1%respectively.The removalefficiency of the pollutants decrease with the increasing of surface load, The degrees of thesefactors affecting the removel efficiency is：NH3-N>TP> COD> BOD5>TN, With a view to considering the removal capability for pollutants, load reduction and economic factors, the mostappropriate surface load of the MSL in this study was suggested as1000~1500L/m~2d.Further experiment carried out to strength the removel efficiency of TN by adding PBScarbon resource and improve system’s structure, When adding PBS carbon resource, theremoval efficiency of total nitrogen from43.7%increase to64.3%, average effluentconcentration from5.83mg/l down to3.60mg/L; When improve the space structure of thesystem, the removal efficiency of total nitrogen from43.7%increase to71.7%, average effluentconcentration from5.83mg/l down to2.85mg/l. The three system have few difference on theremove of COD, ammonia nitrogen, Tp.Above all，experiments show that, MSL system have a relatively good results when usingto treat polluted river water, with the advantages of high surface load, high load reduction,against the shock polluted load. It also has good performance on TN removel-which is themost important factor in eutrophicate. The experiment provides a new ideas for the dianchi laketreatment, but also provides the control of China’s non-point source pollution river a newmethod. This technology has a bright prospects in our country.