| The laboratory waste gas has the characteristics of complex composition,extremely unstable emission concentration and volume.Combustion,biofiltration,low temperature plasma,single adsorption and other methods are suitable for the treatment of laboratory waste gas.Because of its mature technology,strong adaptability,easy operation,safety and stability,and convenient maintenance and management,liquid absorption method has gradually become the preferred technology for waste gas treatment in university laboratories.The absorption tailing produced by the absorption method has the characteristics of high content of organic pollutants,complex composition and difficult biodegradation.If it is discharged directly without treatment or improper treatment,it will cause serious damage to the environment and ecosystem.In this paper,based on the investigation of the basic situation of the waste gas absorption tail liquid in a university laboratory,aiming at the characteristics of the water quality of the absorption tail liquid,the quality of the process water in and out and the operation parameters are explored through the experimental comparison and evaluation of the treatment process.On this basis,the process design of the waste gas absorption tail liquid treatment in a university laboratory is carried out to provide technical support for the absorption tail liquid treatment project.The research contents and results of this paper are as follows:(1)UV Fenton and micro electrolysis Fenton pretreatment processes were selected.The effluent effect,dosage and power consumption of the two processes were compared.Micro electrolysis Fenton was selected as the pretreatment process of this design and the optimal operation conditions were determined.The experimental results show that when the initial pH value is 3.0,the dosage of iron and carbon is 100mg/L,the reaction time of micro electrolysis is 30min,the dosage of H2O2 is 20ml/L,the reaction time of Fenton is 40min,the removal efficiency of COD is up to 48%,the concentration of cod is 3120mg/L,the concentration of NH3-N is 76mg/L,and the B/C is increased from 0.13 to 0.35.(2).UASB-MBBR biochemical combination experiment was used to treat the tail liquor after pretreatment.After 64 days of gradient start-up and acclimation,the reactor can operate stably,and then 160 days of optimization experiments are carried out to study the optimal operation condition and effluent quality of the reactor.The results show that the best treatment is when the HRT of UASB and MBBR is 16h and 19h,the reflux ratio of nitration liquid is 200%,the organic volume load of UASB and MBBR is 4.5kg/(m3·d)and 4.0KG/(m3·d)respectively,and the influent pH is 7.5.Under the optimal operation parameters,the COD of effluent of biochemical system is 210mg/L,the total removal rate is 96.5%;the NH3-N content of effluent is 20mg/L,the total removal rate is 79.6%.The main water quality meets the effluent requirements in the water quality Standard for sewage discharged into urban sewers(GB-T31962-2015).(3).According to the water quality and process parameters determined by the experiment,the process flow is defined as regulating tank-micro electrolysis-Fenton-vertical flow sedimentation-UASB-MBBR-biochemical sedimentation,and the designed treatment scale is 30m3/d.Design calculation,process drawing,equipment selection,operation cost analysis,project investment estimation and project benefit analysis are carried out for the main structure of the process.The total project investment of the treatment system is 1.36 million yuan,the operation cost is 9.98 yuan/m3,and the floor area is 70m2.The process design has the characteristics of high efficiency,advanced technology,high degree of automation,convenient operation and management,low investment and operation cost,and has practical significance and promotion value. |
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