| Coking wastewater is a typical refractory industrial wastewater,with high content of organic and nitrogen compounds,complex components,and toxic and harmful substances such as phenols,cyanide,polycyclic aromatic compounds,etc.There are a series of problems in the coking wastewater treatment process of Qianlishan wastewater treatment plant,such as high operation cost,complex process,poor biochemical treatment effect and so on.Therefore,it is of great significance to study the influencing factors of enhanced denitrification of coking wastewater and improve the denitrification efficiency.The research object of this paper is the coking wastewater from Qianlishan wastewater treatment plant.Aiming at the problems of difficult nitrogen removal,low utilization rate of organic matter and low microbial activity of coking wastewater,combined with microbial immobilization technology,the research on strengthening the biochemical treatment effect of coking wastewater is carried out.SBBR reactor was set up to carry out small-scale test to study the enhanced treatment effect of different carriers on coking wastewater.After determining the best carrier,the effects of DO,temperature,additional carbon source,operation mode,reaction time,influent load and hydrolysis acidification experiment on the biochemical treatment effect of coking wastewater were investigated,and the degradation rules of organic matter and nitrogen compounds were analyzed The actual operation provides a reference.The main conclusions are as follows.(1)The results showed that the pfmf carrier SBBR reactor had the best treatment effect on coking wastewater.Under the conditions of 26 ? and 48 h,the pfmf carrier SBBR reactor had the best treatment effect.The average removal rates of COD,ammonia nitrogen and total nitrogen were 39.15%,96.40% and 50.40% respectively.After 12 hours of aerobic operation,the concentration of ammonia nitrogen decreased to 5.97 mg/L,and the total nitrogen concentration was 40.02 mg/L.at this time,125 mg/L glucose was added.After 36 hours of anoxic operation,the total nitrogen effluent concentration was 20.73 mg/L.(2)The influencing factors of carrier enhanced biological nitrogen removal of coking wastewater were studied.Through single factor experiment,the optimal conditions of biological nitrogen removal of coking wastewater were determined as follows: cod influent load 450-600 mg / L,total nitrogen concentration below 90 mg/L,reaction time 48 h,DO 2-4mg/L,temperature 25?,C/N value 8-10,operation mode O: A=1:1,ammonia nitrogen concentration below 5 mg/L,total nitrogen concentration below 30 mg/L,All of them meet the discharge standard of discharge standard of pollutants for coking chemical industry;The COD concentration of effluent is stable at about 250 mg / L,which reduces the pressure of subsequent advanced treatment;The biodegradability of coking wastewater was not significantly improved by hydrolysis acidification process.(3)The mechanism of carrier enhanced biological denitrification of coking wastewater was studied.(1)When the reaction time is 48 h,the degradation rate of organic matter in coking wastewater is faster in 6 h,and the organic matter removal is basically completed in 36 h.at the beginning of organic matter degradation,ammonia nitrogen is rapidly degraded,and the concentration tends to be stable after 24 h.nitrite nitrogen accumulates in the process of nitrification and rapidly oxidizes to nitrate nitrogen.Nitrate nitrogen reacts continuously in the process of denitrification,and total nitrogen is further degraded,but the lack of carbon source leads to the degradation The results show that the denitrification efficiency decreases and the biological denitrification reaction is completed in the operation cycle;prolonging the reaction time to 72 h does not improve the denitrification efficiency of coking wastewater.(2)When the temperature is 26 ?,DO is 2-4 mg/L,A/ O operation mode and methanol addition can ensure the simultaneous nitrification and denitrification in the system,and the denitrification effect of coking wastewater is better.(3)When the influent COD concentration is 598.85mg/L and the reaction time is 48 h,the concentration of refractory organics is 206.11mg/L.When the influent COD concentration is between 450-600mg/L and the total nitrogen concentration is below 90mg/L,the microorganism can degrade the most organic matter,and the ammonia nitrogen and total nitrogen can meet the discharge standard of discharge standard of pollutants for coking chemical industry.In this paper,through the small-scale experiment of microbial immobilization,the experimental results show that the use of microbial immobilization technology can improve the biochemical treatment effect of coking wastewater,reduce the waste of additional carbon sources and the use of advanced treatment agents,and provide the relevant basis for the treatment of similar industrial wastewater. |
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