| The main component of pickle waste-water is organic matter such as fermentation products,grain residues and so on,which has high salinity.Once mishandled,it can cause great harm to the environment.Multi-stage contact oxidation process is characterized by multiple purification,good treatment effect,strong impact resistance and short treatment time.It is regarded as an effective method to treat waste-water with high organics,high ammonia nitrogen and high salinity.In this project,industrial sauerkraut waste-water was taken as the research object.Multi-stage contact oxidation method was used for experimental study.Operation rules in the start-up and operation process of the 3-stage reactor were investigated.Under the fixed Chemical Oxygen Demand(COD)concentration(2000mglL),the proportion of glucose COD and pickle waste-water COD in the water was gradually changed(10:0,7:3,5:5,3:7,0:10),and the taming start-up reactor was conducted.In the start-up stage,the reactor ran for 50 days,and the COD treatment rate in each stage was above 80%,NH4+-N processing rate is above 90%,and the start-up is successful.The concentration of NO3--N increased obviously and the concentration of NO2--N changed slightly..After successful start-up,the diluted pickle waste-water was used as the water intake,and the COD concentration(2000,4000,6000,8000,11000mg/L)was gradually increased to investigate the system operation characteristics under different COD loads.The results showed that the COD of the effluent increased slowly and the removal rate increased gradually with the increase of the concentration of pickle waste-water.From 83%to 95%,the reactor has a high removal capacity.The first four stages of the running process,the removal rate of NH4+-N remained above 90%,and fell sharply to about 57%in stage 5,indicating that under sufficient COD,the reactor for NH4+-N has normal processing power.The concentration of NO3--N increased dramatically to 148.7 mg/L,and the concentration of NO2--N increased to 62.3 mg/L.Under the normal operating conditions of the system,the effects of single factors such as HRT(Hydraulic Retention Time),salinity and pH on the operation of the combined system were discussed.Within the range of the reactor,the reduction of HRT will increase COD and NH4+-N to a certain extent.If the load exceeds the reactor limit,the removal rate will be reduced.In the range of microbial tolerance,the increase of salt concentration will have a positive stimulation effect on biological activity,but when the salt concentration is higher than 25g/L,the inhibition of biological activity begins.The removal effect of the reactor is affected by pH.The pH value is between 6 and 8,and the microbial activity of the reactor system is the best,and the system treatment effect is the highest.The optimal operation parameters of HRT=3.7d,pH=7.56 and salinity=21.1g/L were finally obtained through experimental simulation.Expected results are achieved through experimental verification.Advanced oxidation treatment of effluent can remove COD and meet the international level discharge standards.Because of nitrification,resulting in an increase in the concentration of NO2--N and NO3--N,and the water was flushed in order to remove TN(Total Nitrogen).The reactor efficiency was analyzed by using different reflux ratios(50%,100%,150%,200%).The results show that the overall removal efficiency of multi-stage contact oxidation reactor is not affected by the change of reflux,but the increase of reflux ratio will improve the removal efficiency of TN,and the removal rate will increase by about 10%. |
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