Study On Strengthening Coal Chemical Wastewater Treatment By Activated Carbon Coupling Activated Sludge Process In Micro-oxygen Environment

The most basic feature of China’s energy is "rich coal,lean oil,less gas",and the coal chemical industry to use coal to produce oil,natural gas,olefins,will greatly improve the plight of China’s poor oil and less gas.The coal chemical industry has the characteristics of large amount of water and wastewater,complicated water quality and difficult to handle,and the environmental hazard is large.The state has also raised high requirements for the “zero emission” of wastewater in the coal chemical industry.However,the “zero emission” of coal chemical wastewater still has many problems in technology and economy.This paper introduces the water quality characteristics and treatment technology status of coal chemical wastewater.In view of some difficulties faced by coal chemical wastewater treatment technology,the paper points out the technical superiority of using activated carbon for biochemical treatment of coal chemical wastewater.The technology is to add activated carbon to the anoxic unit of coal chemical wastewater treatment,control certain hydraulic conditions,and the activated carbon and activated sludge form a coupling system of activated carbon-activated sludge.The activated carbon first adsorbs the pollutants,and then the microorganisms degrade the pollution adsorbed by the activated carbon.The activated carbon is regenerated to form a cycle of adsorptiondegradation,which improves the performance of the system to degrade pollutants while improving the properties of the activated sludge.In this study,the adsorption properties of activated carbon on phenolic substances and the regeneration of activated carbon on activated carbon were first discussed.The results show that under the condition of powder carbon concentration of 1.25g/L and phenol 300mg/L,the removal of phenol can reach more than 70%,and the adsorption capacity of powdered carbon is 2~3 times that of granular carbon.Powdered carbon and granular carbon respectively meet the requirements.Freundlich and Langmuir models,both of which are second-order kinetic models.Under the conditions of sludge concentration of 6000mg/L,phenol 3000mg/L,HRT of 48 h,powdered coal charcoal and pellet carbon concentration of 1.25g/L and 3.0g/L,the activated sludge has different regeneration rates for the two carbons.It is about 70% and 60%.When the new cycle is started,the coupling system will adsorb about 70% of phenols within 3 hours.At the same time,the effects of regeneration cycle,activated carbon concentration,sludge concentration,phenol concentration and regeneration time on regeneration rate were studied by single factor variable method.The degradation of phenolic substances in activated carbon and sludge coupling system is divided into two stages: system adsorption and biodegradation.Activated carbon addition enhances the removal of phenolic substances.In the pilot test,the powdered carbon and granular carbon were separately coupled with sludge to enhance the efficiency of coal chemical wastewater treatment.In the stable operation stage of the reactor,the first group of powdered charcoal and the second group of pelletized carbon were added.The removal rates of COD were 81.92% and 81.59%,the total phenols were 95.16% and 94.77%,the ammonia nitrogen was 38.63% and 37.50%,and the total nitrogen was 31.56% and 30.29%.The degradation performance of the first set of reactors was slightly better than the second set.The inoculation sludge concentration of the two sets of reactors was 4000mg/L,and the operation was about 50 d.The sludge concentrations of the two reactors were 6010mg/L and 5460mg/L,respectively.The EPS,particle size and high-throughput analysis of the sludge were carried out.It was found that powdered carbon has a more obvious optimization effect on sludge traits and microbial population.In the pilot test,the strengthening of coal chemical wastewater treatment by powdered carbon was studied.In the stable operation stage,the COD,total phenol,and ammonia nitrogen effluent concentrations were 15 mg/L,12.07 mg/L,and 4.45 mg/L,respectively.The removal rates were 86.84%,93.5%,and 90.87%,respectively.Highthroughput analysis showed that the microbial population that degraded the coal chemical wastewater in the sludge was strengthened compared to the inoculated sludge.