Study On Technologies Of Coagulation-sedimentation Treating Wastewater During Bridge Construction

In recent years,transport construction in China has been going through a rapid development.As one significant part of transport construction,the highway bridge construction is also undergoing this important period.This means that at about 2020 the total number of highway bridge will reach 800,000.This great boost in highway bridge construction will result in increasing sewage pollution produced in highway construction to the surrounding aquatic environment.This sewage is mainly in form of slurry or mortar which contains much suspended solids(SS)and some gelatinoid.In sewage produced in the bridge construction,the suspended solids(SS)and viscosity is too high,which leads to the absence of sedimentation phenomenon in the static settlement process.This kind of sewage would cause critical damage once discharged into the environment.In this research,a basic study of sewage treatment in the bridge construction process,a study of the effect of single flocculant,a study of the production and field application of complex flocculant were conducted.Based on these studies,the researcher tried to find out the new method of sewage treatment in the bridge construction and invented new complex flocculant for this specific situation that is the treatment of sewage in bridge construction.The whole research showed that in the experiment of solid-liquid separation of slurry,anion polyacrylamide(APAM)turns to be most efficient.When the concentration of APAM reaches 0.15g/L,the effect of flocculant becomes stable and the flocculation rate(the ratio of sediment volume to original solution volume)reaches 89.86%.In the flocculation experiment of slurry,the best flocculation is proved to be the poly chloride,by which the COD becomes 85.71mg/l and pH in the water becomes 6.88.The optimum concentration of poly chloride is 0.001g/l;the removal rate is 99.6%;SS in the reaches only 0.91g/l.These statistics all conform to the GB8978-1996.Based on the preliminary theoretical research,the key technique of sewage treatment was applied in the sewage treatment during the construction of Yueyang Dongting Lake Bridge.In this research,key techniques along with new methods and equipment of sewage treatment was invented which means the purpose of the research is successfully achieved.It means to combine the two ways of chemical flocculation and mechanical treatment.With the combined first flocculant and second flocculantand new central-fugal equipment,the treatment of sewage will achieve a better flocculation effect and reduce the water content in sediment.This research can be of significant instruction for contemporary sewage treatment in bridge construction and contribution for sewage treatment techniques.The sewage treatment in the bridge construction is promising in the traffic construction,which implies that the extended application of research result will be of great economic value.