Treatment Of Petrochemical Wastewater Through Pulse Hydrolysis Acidification A/O Process

Petrochemical wastewater contains petroleum,benzene and benzene derivatives and other refractory organic compounds,its composition is complex,which contains a large amount of toxic and hazardous substances.The concentration of pollutants is high,and the biodegradability of the pollutants is low.So,it is difficult to deal with the wastewater.In addition,the environmental surface water is contaminated seriously,however the simple treatment of wastewater is hardly to meet the requirements.This paper dealt with the petrochemical wastewater by combining the pulsed hydrolysis acidification process and the A/O process,then further obtained the effective design and operation parameters of the process through analyzing the removal effect and change rule of COD,ammonia nitrogen,total phosphorus,sulfate radical,sulfurion,VFA.The composition of the bacteria in the hydrolytic acidification pool and A/O pool were further studied and analyzed.The dynamics analysis in order to analyze the pulsed hydrolysis acidification process better.In this study,we dealt with the actual petrochemical wastewater by using pulse distributor designed by ourselves and built the pilot plant of pulsed hydrolysis acidification and-A/O process.The volume of the hydrolytic acidification pool and A/O were 2.6m3 and 3.9 m3 respectively.The frequency of the pulse distributor was 10 times /h;the age of sludge in the A / O pool was 25 days,and the reflux ratio of the sludge was 100%,the concentration of dissolved oxygen in the O pool was controlled in the range of 2mg/L-3mg/L.The operation temperature of reactor which changes with the seasons was controlled in the range of 15℃-32 ℃.The reactor was continuously operating stably for seven months,and the results showed that even though the concentration of the ammonia nitrogen and COD in the entering water had large variation,the removal rate of COD and ammonia nitrogen in the outing water was stable.When the concentration of the COD in the entering water was 500mg/L-1350 mg/L,the removal rate of the outing water was 86.2%,and the removal rate of COD in the hydrolytic acidification pool was 59.3%,the concentration of ammonia nitrogen in the entering water was 10mg/L-50 mg/L,the removal rate of ammonia nitrogen in the outing water was 85.8%;the average removal rates of UV254,TN and TP were 57.7%,57.5% and 85.8% respectively.The condition of mixing between the water and sludge was good,the VFA concentration of outing water was doubled compared to entering water,the value of the BOD5/COD in the outing water was increased by 35% than that in the entering water,which showed the good effect of hydrolytic acidification,and improved the biodegradability of the entering water.In the analysis of the bacteria in the pulse hydrolysis acidification pool and A/O pool,the result of Ilumina Miseq sequencing showed that Proteobacteria and Bacteroidetes were the dominant bacteria,accounting for more than 50% of the total bacteria.At the level of the genus,the abundance of Anaerolineaceae and Clostridiales in the hydrolytic acidification pool is higher;the abundance of the Flexibacter,Thiobacillus,Nitrosomonadaceae and Nitrospira was higher in the A/O pool.The organic pollutants in the petrochemical wastewater can be effectively degraded by collective effect of the microbial community in the hydrolytic acidification pool and A/O pool in the reactor.In summary,the results showed that the reactor of pulsed hydrolysis acidification pool and A/O pool is a promising petrochemical wastewater treatment technology,which can be applied to the treatment of other industrial wastewater.In order to explore the hydrolytic acidification effect of the hydrolysis acidification pool and optimize the process,The optimum reaction conditions were obtained by dynamics research on the change of the value of VFA in the outing water in the hydrolysis acidification pool: the reaction time was 15 h,the value of pH was 7,the temperature was 27 ℃,the concentration of sludge was 20g/L.The conversion rate of VFA was 80%.The dynamics research showed that when the activation energy of the reacting is 854.6792kJ/mol,the pre-exponential factor was 1.5212,the concentration,the value of pH and the exponential of the residence time were 0.1513,0.9492 and 0.1340 respectively,the best experiments results were obtained,the calculated values were in good agreement with the experimental values,and the deviation did not exceed ± 10%.The results of the above studies showed that effect of pulsed hydrolysis and acidification combining with A/O process was better than the previous process,which result to a better rate,and can reach the requirement of the national emission standards.