Study On Enhancement For Anaerobic Digestion And Denitrification Of Coal Chemical Industry Wastewater

Coal chemical industry consumed a lot of water and the wastewater was not easy to be treated because it contained a lot of toxic and refractory organic matter.In order to reduced the environmental burden and basically achieved "near zero discharge" in the coal chemical industry,it was very necessary to sought an economic and efficient treatment method.In this paper,the operation of wastewater treatment in a coal chemical enterprise was investigated and the existing problems were analyzed and summarized.The enhanced treatment strategies for coal-to-gas wastewater and butyl alcohol wastewater were put forward,and the feasibility and enhancement mechanism were explored,which provided a new idea for the quality-classification and resource treatment of coal chemical wastewater.In this paper,the sources and treatment methods of wastewater in a coal chemical enterprise were investigated,and the process parameters and operation conditions of wastewater treatment were analyzed.The results showed that there was a large amount of ammonia nitrogen in the coal-to-gas wastewater,and the treatment effect of methanol carbon source was not good,and toxic and refractory substances such as quinoline affected the biological nitrogen removal and organic matter removal effect of the treatment process.Food fermentation liquid could be introduced to constructed co-metabolism to strengthen the treatment effect.The investigation founded that the butyl alcohol production wastewater contained a large number of toxic and refractory substances,which was difficult to be directly treated by traditional biological treatment technology.Therefore,granular activated carbon could be introduced to constructed DIET function and enhanced the methane production efficiency of anaerobic digestion,so as to achieve the purpose of low cost and effective wastewater treatment.In this study,the food fermentation liquid was used in the quinoline degradation and denitrification system.Two groups of reactor were set:sodium acetate(A)and kitchen fermentation liquid(B).Under the condition that the concentration of quinoline was 200 mg/L the ratio of chemical oxygen demand to nitrate nitrogen content(COD/NO3--N,)was 7,no quinoline was detected in the effluent of group A and B,and the COD removal rate were 83.2±0.4%and 87.6±1.1%,respectively.The total nitrogen(TN)removal rates were 90.9±3.5%and 95.8±1.5%,respectively.The food fermentation liquid could promote the abundance of Trichococcus in the sludge,accelerated the degradation of quinoline,and improved the denitrification efficiency of the system.At the same time,the food fermentation liquid would increase the sludge particle size,improved the sludge settlement,increased the diversity of microorganisms,and improved the stability of the process operation.In this study,granular activated carbon was used to enhance anaerobic digestion of actual butyl alcohol wastewater.The control group and granular active carbon(GAC)dosing reactor were set.When the reactor temperature was 30? and the influent COD concentration was 4000 mg/L,the effluent COD concentration of the GAC group was reduced by about 22.0%compared with the control group,and the daily methane production volume of the GAC dosing group was increased by about 34.9%.When the temperature of the reactor was reduced to 22? and the influent COD concentration was increased to 8000 mg/L,the COD removal and methane production of the two reactors remained stable.The results showed that the addition of GAC reduced the start-up time of the reactor,and increased the electron transport activity,extracellular protein content and electrical conductivity of the sludge.At the same time,GAC could enrich Methanobacterium,which had a potential direct interspecies electron transfer(DIET)effect between Syntrophomonas and Geobacter,etc.,thus promoting efficient methane production of wastewater.