The evaluation on Wastewater Quality and Investigation on Wastewater Treatment During Qin Ling Water-conveyance Tunnel Construction Period

According to the continuous monitoring and investigating results of previous constructional wastewater quality,focused on the large quantity of wastewater and high SS content during Qinling water-conveyance tunnel construction period,based on the water matrix analyzing principal,restricted by the treated wastewater safely emission standard to conduct the weighting analysis on each contaminant,it can be found that the order of each contaminant ranking from high environmental impact to low is SS,COD,Fe,NH3-N,TN,oil type.The result shows that SS is the controlling factor which restricts the safely emission of wastewater during the tunnel construction.According to the composition of wastewater contaminants,the treatment combined with coagulation,precipitation,manganese filtration and adsorption was proposed,and the static experiments of wastewater collected from construction site and manual simulated wastewater were conducted.And the result indicates that the removal rate of SS can reach 90%,the removal rate of COD is 85% and the removal rate for ammonia nitrogen is about 60%.And the treated water quality can meet the demand of Ⅱ water index in accordance with "Environmental Quality Standards for Surface Water"(GB3838-2002).