Study On The Efficiency Of Enhanced Anaerobic Degradation Of Coal Chemical Wastewater By Using Sludge Crabon-loaded With Nano-Fe₃O₄

Based on the energy characteristics of rich coal and poor oil in China,the coal chemical industry has been developing rapidly.However,the coal chemical process consumes huge amount of water,and it will also produce a large amount of coal chemical wastewater,whose composition is complex and contains heavy toxic and refractory organic pollutants.It will cause serious harm to the environment unless properly disposed.In recent years,anaerobic biological treatment technology has been widely used in the field of environmental protection.It has high organic load,and low energy consumption.In addition,methane and other clean energy will be produced in the process of coal chemical wastewater treatment,which has no pollution to the environment.However,a great quantity of refractory organic pollutants in coal chemical wastewater,which will cause the loss of stability and high efficiency of biological process.With the increasing number of urban wastewater treatment plants in China,surplus sludge containing a large number of pollutants and organic matter is produced in the process of biological treatment of wastewater,causing serious secondary pollution if it is random discharged,but it has the potential to be used as a resource.Aiming at the above problems,this study proposed to prepare sludge carbon loaded with nano-Fe₃O₄ on the basis of surplus sludge,optimizing the parameters of preparation,and characterized the carbon materials,analyzing the effectiveness of sludge carbon loaded with nano-Fe₃O₄to enhance the anaerobic degradation of coal chemical wastewater,and studied the mechanism of its strengthening.The results were as follows:(1)The sludge carbon was prepared by wet impregnation and high temperature carbonization with the surplus sludge produced in the process of wastewater treatment,and the specific surface area of the sludge carbon was taken as the evaluation standard.It showed that the optimal experimental conditions for preparation were carbonization time of 120 min and carbonization temperature of500?,under which the sludge carbon had a higher specific surface area.Sludge carbon loaded with nano-Fe₃O₄ were prepared by chemical precipitation method,using SEM,BET,XRF,XPS,XRD and FITR,the preparation of carbon materials were characterized and SEM showed that the preparation of carbon sludge generated a lot of channel structure.BET data showed that the sludge carbon loaded with nano-Fe₃O₄ than a slight reduction in surface area.XRF results showed that element content increased after the sludge carbon was loaded with nano-Fe₃O₄.XPS data and XRD data showed that the loaded metal was nano-Fe₃O₄,and FITR results showed that sludge carbon loaded with nano-Fe₃O₄ generated basic groups with-OH on the surface.(2)Sludge carbon loaded with nano-Fe₃O₄ strengthening coal chemical industry wastewater anaerobic degradation,the results showed that coal chemical wastewater COD removal rate and total phenol removal rate of coal chemical wastewater were increased by 49.1%and 40.4%,the methane production was increased by 55.8%,and the volatile fatty acid production was decreased,indicating that the nano-Fe₃O₄ has a significant enhancing effect on the anaerobic degradation of organic pollutants in the coal chemical wastewater.(3)The BOD₅ concentration of the effluent increased and the BOD₅/COD increased,indicating that the biodegradability of the coal chemical wastewater was improved by the addition of sludge carbon loaded with nano-Fe₃O₄.Total phenol load was added to the anaerobic process,compared with the control group,sludge carbon loaded with nano-Fe₃O₄alleviated the inhibition of the anaerobic degradation process.When the inlet water was restored to the raw water concentration,the biological activity of the anaerobic process was quickly recovered,indicating that the addition of nano Fe₃O₄ loaded with sludge carbon made the anaerobic process have a higher toxic load and significantly improve the stability of the anaerobic degradation process.(4)With the addition of sludge carbon loaded with nano Fe₃O₄,The conductivity of anaerobic activated sludge was increased by 55.8%and the coenzyme concentration was increased by 42.9%,the concentration of EPS and the average particle size increased significantly,which indicated that the addition of sludge carbon loaded with nano Fe₃O₄could promote the granulation of anaerobic sludge.The electrical conductivity and activity of sludge were significantly improved.The microbial community results showed that the addition of sludge carbon loaded with nano-Fe₃O₄was beneficial to the enrichment of Geobacter and Methanothrix,which indirectly confirmed that Geobacter and Methanothrix through the prepared carbon materials carried out direct interspecific electron transfer(DIET),and improved the performance of anaerobic degradation.In summary,the final results were obtained:sludge carbon loaded with nano-Fe₃O₄ had a significant strengthening effect on the anaerobic degradation of coal chemical wastewater,improving the efficiency of removing organic matter by anaerobic degradation.It improved the biodegradability of coal chemical wastewater and the stability of the anaerobic degradation process,improving the activity and conductivity of the sludge,promoting the DIET process between Geobacter and Methanothrix indirectly,thereby improving the performance of anaerobic degradation.