In Situ Remediation Of Black And Odorous Water By Composite Medicament Combined With Biofilm

The improvement of black and smelly water bodies is the focus of current and future work about environmental protection and sponge city construction.Numerous pollutants are discharged into the water through various ways such as surface runoff generated by the atmospheric sedimentation wastewater.Plenty of pollutants,including heavy metal nitrogen and phosphorus and refractory organic pollutants,can adhere to the bottom sediment through adsorption,precipitation,complexation,and other chemical or physical effects and cause the sediment pollution.There is a dynamic balance of material exchange between bottom sediment and water body.The bottom deposited pollutant can be released to the overlying water body through desorption,dissolution,biological decomposition and other actions under certain circumstances,which is an important source of secondary water pollution.Therefore,it is of particular importance to repair the contaminated sediment.In order to explore the in situ repair technology of black and smelly water body sediment,the case study of a black smelly lake in Jinzhai County was conducted in this paper.In view of the serious pollution of black smelly organic matter in the bottom mud,a self-made composite agent combined with the biological rope method was adopted to carry out the laboratory simulation repair,and the repair effect and mechanism of combined process on black smelly bottom mud were explored.The characteristics of the combined process and its treatment effect on the polluted lake water,and also the maintenance and management of the chemical compound agent/biological rope system are discussed.The following conclusions can be drawn from the pilot test in the last eighteen months:?1?By changing the temperature,p H and dosage of the compound,the effects of the compound agents on the removal of COD,TN,NH₄⁺-N and TP pollutants in the polluted water were studied.According to the experimental results,the order of the influence of temperature,p H and dosage on pollutant removal rate is:dosage>temperature>p H.The optimal treatment condition is determined based on the practicability and economy of the engineering treatment,in which the temperature is 30?,the p H value is 8,and the dosage of composite agent is 5%?accounting for the mass ratio of sediment?,while the removal rates of COD,TN,NH₄⁺-N and TP are the highest,reaching 56.49%,69.89%,42.71%and 68.42%respectively.?2?The removal efficiency of four treatment systems,blank group,biofilm group,medicament group and composite medicament/biofilm,was evaluated.Evaluations revealed that the treatment of polluted water by the combination of composite agents and biological rope was better than that of single treatment group.Among them,the removal rate of COD,TN,NH₄⁺-N,TP and AVS are67.18%,81.81%,52.54%,74.56%and 89.47%,respectively.?3?At the end of pilot project,the effluent quality of each system can attain the standard of surface water III?GB18918-2002?and bring significant treatment effect,in which the transparency of overlying water is increased and the obvious odor is eliminated,indicating that the combined process of composite agent and biological rope can be applied to the treatment of black odor lake.The research results provide a good theoretical guidance for the further application of the technology.