The Prediction And Risk Assesment Of Wastewater During Qinling Water-conveyance Tunnel Construction Period

Yinhanjiwei was the inter-basin water diversion project of Shaanxi province.Thewater diversion project is from hanjiang river to weihe in sounthern Shaanxi.which canachieve optimal allocation of water resources in Shaanxi province,improve theecological environment of weihe,promote the economic development of guanzhongregion.Qinling water conveyance tunnel length of98.299km, is made up of yellowsection and the mountains.Due to the huge amount of the wastewater during Qinlingwater conveyance tunnel construction, wastewater has to be nearby discharged. As theYueling construction wastewater was discharged to the Black River and its tributarieswhich flow concentration area is Jinpen reservoir,it constitutes potential problems toJinpen reservoir water safety. Therefore, it is important to make a comprehensiveanalysis and evaluation of the Qinling water conveyance tunnel and the composition ofthe construction wastewater pollutants. It is of great significance to the protection andsafety of drinking water sources in Xi’an and maintenance of Qinling local ecologicalenvironment during the construction.Based on the analysis of typical mountain tunnel construction wastewater qualityand different type of construction, predicted the wastewater quality.The result showedthat the Qinling tunnel construction wastewater was inorganic polluted characterized byhigh suspended solids, low COD, less nutrients such as nitrogen and phosphorus.Wherein the suspended solids concentration of80mg/L~300mg/L, COD concentrationof30mg/L~150mg/L, ammonia concentration of2mg/L~7mg/L, the nitrate nitrogenconcentration of2mg/L~10mg/L, petroleum concentration6mg/L~16mg/L.The heavy metals and harmful chemicals may be introduced into the construction wastewaterduring the Qinling tunnel construction process. Health risk assessment was made for thearsenic, ammonia, phenol, fluoride, petroleum pollutants in the wastewater. The resultshowed that all kinds of pollutants in the body did not produce unacceptable health risk.According to the composition of wastewater contaminants, the treatment combinedwith coagulation, precipitation, manganese filtration and adsorption was proposed, andthe static experiments of wastewater collected from construction site and manualsimulated wastewater were conducted. The result indicated that the removal efficiencyof SS can reach90%, the removal efficiency of COD was85%and the removalefficiency for ammonia nitrogen was about60%. And the phenol, fluoride, heavy metalsand harmful chemicals removal efficiency was60%to80%.