The Physicochemical-biochemical Coupling Deep Purification Technology Of Sewage In High-salt And Refractory Industrial Parks

During the development of industry,the types of organic pollutants in the discharged sewage are changing with each passing day.Traditional biochemical treatment technologies have been difficult to completely remove new organic pollutants.Especially when the industrial sewage contains biologically toxic organic pollutants,this will not only affect the metabolic activity of microorganisms in the biochemical treatment process,but even lead to the collapse of the entire biochemical reactor.Therefore,the exploration and development of the treatment technology of refractory industrial wastewater is an environmental engineering problem of water treatment that needs to be solved urgently.Pyridine carboxylic acid substances,due to their stable structure,are difficult to biochemically degrade and have strong biological toxicity,currently there are few studies on such wastewater treatment methods,especially under high chlorine conditions.In this paper,the effluent（raw water）of the biochemical regulation pond of a sewage treatment plant in an industrial park in Linxiang,Hunan was used as experimental water to treat high-salt and refractory industrial wastewater containing pyridine carboxylic acids.First of all,the raw water in the park was directly biochemically treated.The experiment used a two-stage AO biochemical reactor.It was found that the removal ability of COD、TN and NH₄⁺-N was very poor.After 35 days of continuous operation,the effluent still could not meet the level A discharge standard.After the raw water was tested for biological toxicity,it was found that the effluent contained tetraclopicolinic acid,an organic substance with high biological toxicity.Then a pretreatment is added before the biochemical treatment to reduce the concentration of tetraclopicolinic acid in the raw water.This article compares the traditional Fenton treatment technology and the catalyst heterogeneous Fenton treatment technology on the removal of tetraclopicolinic acid under high salt conditions.It is found that under the condition of 3000 mg/L chloride ion concentration,the catalyst heterogeneous Fenton treatment technology is better than the traditional Fenton treatment technology in removing tetrachloropicolinic acid.The removal rate of tetrachloropicolinic acid by the heterogeneous catalyst Fenton can reach more than 70%.In the process of catalyst heterogeneous Fenton treatment of raw water,its mineralization rate can reach 69.15%,and the removal rate of tetrachloropicolinic acid can reach 97.75%.In addition,the characterization and analysis of the catalyst used in the experiment revealed that the catalyst is mainly composed of ferrous sulfide（Pyrite）and other trace metal elements,and the surface of the catalyst has a large number of small pores for adsorption.Pass the pretreated raw water into the biochemical reactor,using a two-stage AO biochemical process,the sludge concentration is 8 g/L,HRT=48 h,after 47 days of continuous operation,the COD、TN、NH₄⁺-N、NO₃–N、NO₂-N and TP can reach Class 1 A emission standards.And in the biological community analysis of the activated sludge in the biochemical reactor,the existence of Corynebacterium sp.which obligately degrades pyridine and its derivatives was found.This technology has in-depth exploration significance for the treatment of sewage in high-salt industrial parks.This article mainly discusses the failure of traditional Fenton technology under high Cl^-conditions,and gives an effective treatment method.