Study On Integrated Anaerobic Ammonium Oxidation Treatment Of Coal Glycol Wastewater

With the transformation of the traditional coal chemical industry into coal-to-glycol industry,the environmental problems caused by it have also received much attention.In order to deal with the wastewater in the production process of coal-to-glycol and make the effluent meet the national emission standards,this paper utilizes IFAS-CANON(Integrated Fixed-film Activated Sludge process-Completely autotrophic nitrogen removal over Nitite)to treat the coal-to-glycol wastewater through lab-,pilot-and practical-scale studies.During pilot-and practical-scale studies,the nitrogen removal efficiency and microbial community structure characteristics were analysised.Besides,the reliability and stability of CANON process for treating coal-to-glycol wastewater was investigated,to demonstated the feasibility of using CANON process in coal-to-glycol wastewater.(1)It was found the nitrogen removal rate in IFAS-CANON process kept stable,around 0.25 kg/m3/d in the pilot test and could be further improved,which proved the feasibility of IFAS-CANON process treating coal-to-glycol wastewater.However,the granules disaggrated obviously and the nitrogen removal efficiency decreased rapidly when only single-stage ANAMMOX process was used,indicating that single-stage ANAMMOX process couldn't be directly used to treat coal-to-glycol wastewater.(2)The pilot-scale experiment about 150 days was set up to verify the stability and reliability of the system.After 14 days of operation,the IFAS-CANON process was successfully started up and the nitrogen removal rate was above 0.1 kg N/m3/d.And the highest nitrogen removal rate achieved at 0.58 kg N/m3/d at day 77.AT 88th day,the bacteria was inhibited by high concentration of nitrite in influent.After that,the system recoverd on 92th day by adjusting operation parameters and NRR returned to 0.21 kg/m3/d.In high nitrite loading rate stage(123-145 days),the NRR finally settled around 0.4 kg/m3/d mainly due to denitrication process.Then,the practical-scale studies about 148 days was established.After 51 days of operation,the IFAS-CANON demonstration project successfully achieved the IFAS-CANON process with a nitrogen removal rate over 0.1 kg N/m3/d.after 111 days,the system entered a stable period and the nitrogen removal rate was maintained at 0.15-0.24 kg N/m3/d.(3)The high-throughput sequencing was used to analyze the abundance of the main functional bacteria in the pilot-scale and practicle-scale experiment at the level of gate,class and genus.It was both found that the main functional bacteria of IFAS-CANON process werewas distributed in different forms of sludge.Anaerobic ammonium oxidizing bacteria tend to be enriched in biofilm fillers,while denitrifying bacteria and nitrosating bacteria tend to be enriched in suspended sludge.In pilot test the mainly ANAMMOX bacteria was Ca.Brocadia,but with the difference in the practicle test is that the anammox oxidizing bacteria Ca.Kuenenia becomes the dominant genus,which may be related to the nitrite concentration.