Study On The Efficiency Of PACT Process For Treating Coal Chemical Wastewater

In recent years,China's coal chemical industry has been developing rapidly,and the wastewater treatment technology of coal chemical industry has been making continuous progress,but the standard of "zero discharge" has not been reached yet.Wastewater treatment of coal chemical industry has become an important factor restricting the development of coal chemical industry.Aiming at the problems of low biochemical property and carbon nitrogen ratio of coal chemical wastewater,this paper proposes to use “Powdered activated carbon treatment(PACT)+ Wet Air Regeneration(WAR)” process instead of original “AO+ advanced treatment” process.The effects of PACT process on organic matter removal and nitrification and denitrification in water,the effects of WAR activated carbon regeneration technology on the properties of activated carbon,and the effects of reclaimed liquid phase products on the removal of organic matter and nitrification and denitrification effects of PACT process were investigated.The adsorption kinetics and thermodynamics of activated carbon were studied by static experiment,and one activated carbon with fast adsorption rate,large adsorption capacity and high performance in PACT process was selected as experimental carbon.The optimal dosage of activated carbon was determined to be 1.5g/L.The process of "adsorption-degradation-bioregeneration-readsorption" in PACT is discussed.The results of dynamic experiments show that the removal efficiency of organic matter,ammonia nitrogen and total nitrogen can be improved by PACT technology,the removal rates of COD and total phenol can be increased by 10.03% and 2.76% respectively,and the removal rates of ammonia nitrogen and total nitrogen can be increased by 42.03% and 9.22% respectively.Activated carbon can promote nitrite nitrogen to nitrite nitrogen in nitrification process.Activated carbon can enhance the removal of unsaturated compounds in water that are not easily biodegradable,and can adsorb macromolecules produced by microbial activities.Improve sludge sedimentation performance and enhance microbial reproduction ability.Change the microbial community in the sludge to promote the growth of functional bacteria related to nitrification,denitrification and degradation of aromatic compounds.WAR technology affects the adsorption performance of activated carbon by changing the pore size distribution and surface functional groups of activated carbon.The regeneration rate of activated carbon was 83.33%.The regenerated solution contains volatile fatty acids such as acetic acid and propionic acid,which have better denitrification effect than methanol.Combined experiments of PACT+WAR technology show that regenerated liquid as external carbon source and co-matrix can effectively promote the removal of organic matter and total nitrogen.Microbial mass balance,material mass balance,activated carbon mass balance and microbial and activated carbon mass balance were established.Economic analysis shows that "PACT+WAR" technology has great economic advantages over the original "AO+ advanced treatment" technology,and the operating cost of ton of water can be reduced by 0.85 yuan.