Study On In-situ Chemical Treatment Of Urban Black And Odorous Water By Coupling Of CaO₂,Zeolite And Ascorbic Acid

Since the reform and opening up,China's achievements in urbanization development can be called a miracle of the world,and a large number of outsiders have burst into cities.However,the supporting infrastructures of many cities are far behind the speed of urban expansion and population inflow.A large amount of untreated DO mestic sewage and industrial sewage is directly discharged into the nearby water body.In addition,a large amount of DO mestic garbage flows into the water body,causing the water body to be seriously polluted.Due to the rapid deterioration of the urban water environment,many water bodies have experienced extremely serious black odor,which has caused serious harm to the urban environment and residents' lives.At present,the problem of black and stinky water has become one of the most difficult problems in urban governance.Although government departments have invested a lot of human and financial resources in it,they still have not been able to comprehensively and effectively eliminate the black odor of water bodies.How to effectively control the black and odorous water body is one of the difficult problems to be overcome.As a fast and effective treatment method for black and odorous water,in-situ chemical treatment technology is favored by many researchers.In this paper,the sediment and overlying water of the black and odorous water body collected on the spot were taken as the research object,and the black and odorous environment was simulated under the experimental conditions.Based on calcium peroxide,natural zeolite and ascorbic acid,a new compound chemical agent was invented to investigate the repair effect of the new compound agent on black and odorous water bodies,analyze the repair mechanism,and determine the optimal dosage of the compound agent.On this basis,the experimental conditions were optimized and supplemented with aeration to further explore the repair effect of the compound medicament on black and odorous water bodies under different conditions.Through experiments,the conclusions reached are as follows:(1)Compared with the repair effect of a single agent,the repair effect of the new compound agent on the black and odorous water body has been significantly improved.However,its repairing effect does not always increase with the increase of the dosage of the compound medicament.Considering the reduction rate of various pollution indicators,the optimal dosage of the new compound agent is 6 g/L of calcium peroxide+8 g/L of natural zeolite+1 g/L of ascorbic acid(both based on the amount of sediment).The removal rates of COD,ammonia nitrogen,nitrate nitrogen,total nitrogen,total phosphorus,chromaticity and turbidity were respectively 82%?81%?58%?77%?94%?74%and 66%.The new compound agent releases oxygen for about 4 to 6 days longer than the compound agent composed of calcium peroxide and calcium peroxide and natural zeolite alone.(2)By setting different initial pH of the reaction device,it was found that when the initial pH of the reaction device was adjusted to 5,the reaction rate of the compound agent would be greatly accelerated,and the compound agent had basically completed the oxygen release process in the first 2 days of the experiment.Moreover,the treatment effect on COD is obviously better than without adjusting the initial pH,However,when the initial pH is 5,it is not conducive to the removal of TP by the compound agent.When the initial pH of the reaction device was adjusted to 7,the new compound agent had the best removal effect of ammonia nitrogen,nitrate nitrogen and total nitrogen,which were respectively 88%,67%and 84%?(3)After adding the compound agent,aeration can still improve the removal rate of nitrogen and the content of dissolved oxygen in the overlying water.The dissolved oxygen content of the overlying water in the experimental group aerated for 9 hours a day increased the most,which was 23%higher than that of the experimental group in which only the compound agent was added without aeration.The removal rate of ammonia nitrogen in experiment group with aeration of 9h was 92%,which was 11%higher than that of experiment group without aeration,while the removal rate of total nitrogen was increased by 13%The maximum nitrate nitrogen is 19%.Because the TP removal rate of the overlying water in the experimental group,which only added the compound agent without aeration,was already very high,the effect of aeration on the further improvement of the TP removal rate was not obvious.At 9 hours of aeration,the removal rate of overlying water TP was up to 96%.Compared with the non-aerated experimental group,the removal rate of TP increased by only 3%.