The Feasibility Research Of Treating Direct Runoff By Constructed Wetland In Tang Keng Reservoir

Based on the present situation of water and sediment in Tang Keng reservoir, wepredicted the developing trend and analyzed the measures that can be used in the promotionof water quality, to make out the necessity of the promotion and the conformity of thosemeasures. After carefully analyzed, we found out constructed wetland is the way that cancontrol the pollution import by direct runoff, and improve the water quality effectively. Weselected the applicable site, plants and substrates, and drew up the maintenance scheme andfinished the feasibility analysis. Comparing the cost of constructed wetland and othermeasures generated in the promotion of water quality, to finish the feasibility analysis.Tang Keng reservoir is located in Tang Xia town. According to the 《Surface waterfunctional district allocation in Dong Guan city》, the water quality in Tang Keng reservoirshould satisfying the second grade in《Surface Water Environment Quality Standard》(GB3838-2002).The monitor results of water and sediment in Tang Keng Reservoir shows that someindexes were higher than the second grade, and all concentrations of Chlorophyll a werehigher than19μg/L, with all concentrations of phytoplankton higher than108cells/L. Thevaluation of water quality indicates that all sites in the reservoir were eutrophic. Theself-purification capacity of reservoir was so low that there need to be some measures to dealwith that.Based on the situation of Tang Keng reservoir, we discussed the main problems, andconcluded the measures that could be taken. Finally, we found out that constructed wetland isthe best choice.We selected the right site, plants and substances, et al and arranged them reasonable tocomplete the design. In contrast with other substances and plant, gravel and sand, Acoruscalamus Linn, Vetiveria zizanioides L. and Canna indica are more suitable to be used inconstructed wetland. Based on the reservoir, substances and plants’ characteristics we drew upmaintenance scheme. The area of constructed wetland was9,000m~2, and the treatmentcapacity was2,712m~3/d. According to the design scheme, we estimated the quantities, and evaluated theinvestment. The constructed wetland need about5,910,000RMB, and105,000RMB formaintaining. We discussed if the measures such as ecological floating islands are suit for theimprovement of water, and evaluated the investments, compared them with the investment ofconstructed wetland to finish the cost effectiveness analysis. After comparing, we found outconstructed wetland is the most effective method.Constructed wetland is the best way in which we can get the most benefit with least costin the promotion of water, and it should be adopted in the promotion of the water.