Optimized Selection And Application Of Advanced Treatment Of Chemical Wastewater

《Pollutants Emission Standard of Petrochemical Industry》(GB31571-2015)have been promulgated in 2015.Since the standard had been issued,enterprises are required to complete the transformation of environmental protection facilities and implement the new emission standard before July 1,2017.A petrochemical enterprise’s wastewater workshop contains a first chemical wastewater treatment plants and a second chemical wastewater treatment plants.According to secondary discharge standard of integrated wastewater discharge standard(GB8978-1996),the COD index is less than 100mg/L from first and second chemical wastewater treatment plants complies.Thus,the COD emission index of each sewage treatment plant of the enterprise should reduce from 100 mg / L to 50 mg / L to meet pollutants emission standard of petrochemical industry(GB31571-2015).The first wastewater treatment plant and the second wastewater treatment plant in the wastewater workshop need to meet the discharge standards,so as to ensure that the total discharged waste water index of the enterprise is qualified.In view of the fact that the COD index of the first and second wastewater treatment plant are relatively high,which cannot meet the emission reduction requirements,it is necessary to conduct advanced treatment on the effluent from the two wastewater treatment plants to meet the requirements of the emission standards.By comparing the specific research on advanced treatment technology of industrial wastewater at home and abroad,a number of advanced treatment facilities for wastewater have been built in domestic chemical enterprises on the basis of small-scale test,pilot test and productive system test research.The biological aerated filter,ozone advanced oxidation,Fenton advanced oxidation and other process technologies are widely used.However,due to the production characteristics of petrochemical plant,quantity and quality of water are quite different.Some processes have defects and deficiencies,so the advanced treatment scheme of sewage needs comprehensive consideration.Based on the investigation of the drainage indexes of the first and second wastewater treatment plant,the design basis of water quality and quantity was determined.Through the experimental production and operation,the process plan of "biological contact oxidation tank + radial flow sedimentation tank + flow sand filter+ ozone contact oxidation + activated carbon adsorption" was finally determined.The project began in 2016,and the continuous and stable operation of the device realized before July 1,2017.The device calibration was completed in April 2018,the final effluent index reached the target,such as CODcr is 29 mg / L,NH3-N is 0.05 mg/L,SS is 4mg/L,oil is0.16mg/L.Accroding to the long term operation effect,the CODcr of the influent water is between 50-70mg/L,and the CODcr of the effluent water is 30-45mg/L,besids the other pollutant indexes are all reached the target...