Research And Practice On Treatment Of Chemical Industry Park Wastewater By Physicochemical And Biological Combination Prosess

China's chemical industry park is in a stage of rapid development,which produces a large amount of comprehensive chemical wastewater,and the excessive discharge of wastewater in the park will destroy the environment.The characteristics of wastewater in chemical parks are complex composition,toxic,harmful and difficult to degrade.It is difficult to complete the degradation by a single process and need to use a combination process to raise the effluent standard.Aiming at the characteristics of actual chemical industry wastewater,this paper uses biochemical-physicochemical combination process as the main treatment method,domesticates the sludge through bench-scale experiments,determines the optimal biochemical and physicochemical reaction conditions and investigates the treatment effect on water quality indicators such as Chemical Oxygen Demand,ammonia nitrogen and total nitrogen.Moreover,we apply the combination process to actual production,optimize operation to achieve qualified treatment effect and stable operation state.The water quality of chemical wastewater in an industry park is analysed,and the methods of accelerating the load and increasing the proportion of wastewater are used to domesticate the activated sludge.After domestication,the sludge can remove the COD,ammonia nitrogen and total nitrogen in the wastewater effectively.With the cycle operation increasing,the pollutants in wastewater will be further removed.The optimal biochemical cycle was determined as aerobic 24 h,anoxic 4 h,re-aerobic 1 h,precipitation 1 h and drainage 20 min.Domestication can change the aerobic breath rate of activated sludge,promote the growth of denitrifying bacteria and alkane-degrading bacteria,and the salinity of water increases the settleability of sludge.Co-metabolism can reduce the COD effluent value by about 34.5 mg/L with sodium acetate as the co-metabolism substrate,with no obvious effect on the removal of ammonia nitrogen and total nitrogen.Through static experiments,the experimental results confirmed that the best powdered activated carbon,the best dosage and the best reaction time were WP-AO Plus,0.75 g/L and 120 min respectively.The investigation found that p H and temperature had little effect on the adsorption.The static experiment and actual situation show the best reaction conditions of Fenton that the optimal ratio of n(H2O2):n(Fe2+)is 3:1,the initial p H is 4?4.5,m(H2O2):m(COD)is 1.5?2,the best reaction time is 45 min.Optimize the dosage of PAC and PAM after adsorption and oxidation to reduce the coagulation precipitation time.It is determined that the combination sequence of physical and chemical process is Fenton oxidation + powder activated carbon adsorption,which has a good removal effect on COD and color,and all indicators of biochemical effluent meet the emission standards.The sequence of actual production combination process is SBR biochemical tank,Fenton oxidation tank,activated carbon adsorption tank,sedimentation tank and clear water tank through bench-scale experiment,which was used to production commissioning.In the stable operation stage,the average effluent COD,ammonia nitrogen,total nitrogen and total phosphorus are 47.7 mg/L,4.96 mg/L,13.71 mg/L and 0.48 mg/L.The effluent is colorless and transparent,which show that the process has good removal of chroma and SS.The role of the biochemical section in the combination process is to remove pollutants in the water,while the role of the physicochemical stage is to remove refractory organic matter,total nitrogen and color in the water.The biochemical-physicochemical combination process has a significant effect on the chemical wastewater treatment in the industry chemical park and can provide experience and technical support for the transformation of other chemical wastewater plants.