Study On Kitchen Waste Fermentation Wastewater Nitrogen Removal Treatment Based On Heterotrophic Nitrification-Aerobic Denitrification

To solve the problems of existing kitchen waste fermentation wastewater treatment,such as difficult to establish,low efficiency and complex management,a novel biological nitrogen removal（BNR）treatment based on heterotrophic nitrification-aerobic denitrification（HN-AD）was proposed.In this study,the establishment strategies of high ammonia nitrogen concentration wastewater treatment systems were explored.The impacts of temperature,dissolved oxygen（DO）,p H on the efficiency of HN-AD system for high ammonia nitrogen wastewater treatment were investigated.The optimal working condition parameters for efficient operation were obtained.The microbial community structure and functional microorganism of the systems were revealed by molecular biology technology.And the treatment performance and nitrogen removal mechanism for kitchen waste fermentation wastewater treatment systems under the optimal conditions were explored.The main conclusions were as follows:The microbial growth state and the inoculation had obvious effects on nitrogen removal efficiency and microbial community structures for high temperature,high ammonia nitrogen wastewater treatment system in the establishment period.Results showed that the nitrogen removal performance was better when the biofilm and the dewatered sludge from a Wastewater Treatment Plant（WWTP）were used.And the higher enrichment of HN-AD functional bacteria（Halomonas and Paracoccus）was achieved.Meanwhile,aerobic denitrifying bacteria（Tepidimonas）and anoxic denitrifying bacteria（Natronincola＿Anaerovirgula and Caldilinea）participated in the denitrification process.The kind of filling materials and the increasing mode of ammonia-nitrogen load had significant effects on nitrogen removal efficiency and microbial community for high ammonia nitrogen wastewater treatment in the establishment period.The optimal nitrogen removal efficiency was obtained when natural fiber filler was used.16S r RNA amplicon high-throughput sequencing showed that natural fiber filler was beneficial to the enrichment of HN-AD functional bacteria（Acinetobacter,Paracoccus and Halomonas）,with the relative abundance of 20.41%.And results showed that the system with ammonia-nitrogen-load gradually increasing strategy improved the nitrogen removal efficiency,with NH₄⁺-N and TN degradation rates of 21.64 mg/（L·h）and 21.94 mg/（L·h）,respectively.The ammonia-nitrogen-load gradually increasing mode was beneficial to the enrichment of HN-AD functional（Halomonas and Acinetobacter）,with the relative abundance of 12.11%.And aerobic denitrifying bacteria（Tepidimonas）and anoxic denitrifying bacteria（Natronincola＿Anaerovirgula）participated in the denitrification process.Temperature had an obvious effect on the nitrogen removal efficiency,microbial community and pathways for high ammonia nitrogen wastewater treatment.The optimal nitrogen removal efficiency was obtained with temperature of 50℃.And the COD,NH₄⁺-N and TN removal efficiencies were 99.60%,99.46%and 98.80%,respectively.16S r RNA amplicon high-throughput sequencing showed that the main nitrifying bacteria in the system were HN-AD functional bacteria in all systems.The main nitrogen removal functional bacteria in the system were HN-AD functional bacteria（Rhodobacter and Halomonas）and aerobic denitrifying bacteria（Tepidamorphus and Nesterenkonia）.The main nitrification pathways with of temperature 30℃,40℃and 50℃were heterotrophic nitrification,and the proportion decreased significantly with the increase of temperature.Ammonia stripping process appeared in the system with the temperature of 50℃.The aerobic denitrification process and anoxic denitrification process co-existed in different temperature systems,and the aerobic denitrification process accounted for 66.77%,20.76%and 49.00%respectively.The C/N ratio had an obvious impact on nitrogen removal efficiency,microbial community structure and pathways for high temperature and high ammonia nitrogen wastewater treatment.The optimal nitrogen removal performance was obtained when the C/N ratio was 30,with the average COD,NH₄⁺-N and TN removal efficiencies were99.60%,99.46%and 98.80%,respectively.Meanwhile,the highest enrichment of HN-AD functional bacteria was achieved,and the heterotrophic nitrification rate reached6.59mg/（L·h）.The ammonia oxidation archaea（Candidatus＿Nitrosocosmicus and Candidatus＿Nitrosopumilus）participated in the ammonia oxidation process.And aerobic denitrifying bacteria（Tepidamorphus、Nesterenkonia and Bacillus）participated in the denitrification process.Heterotrophic nitrification was the main nitrification pathway in systems with different C/N ratios,and the proportion of autotrophic nitrification decreased significantly with the increase of C/N ratios.Aerobic denitrification process and anoxic denitrification process co-existed in systems with different C/N ratios.And the aerobic denitrification process accounts for 42.45%,38.35%,46.72%,46.28%,54.47%and 57.17%when the C/N ratios were 5,10,15,20,15 and 30,respectively.DO concentration had a great effect on removal efficiency and nitrogen removal pathway for high temperature and high ammonia nitrogen wastewater treatment.The optimal nitrogen removal performance and the highest heterotrophic nitrification rate were obtained when DO concentration was 6.0 mg/L,with average NH₄⁺-N,TN and COD removal efficiencies were 99.61%,99.46%and 98.80%,respectively.Meanwhile,the system realized the highest enrichment of HN-AD functional bacteria.The main nitrification pathway was heterotrophic nitrification process in different DO systems,and the proportion of that increased significantly with the increase of DO concentration.Aerobic denitrification process and anoxic denitrification process co-existed in different DO concentrations systems.When the DO concentrations were 2.0 mg/L and 4.0 mg/L,the main denitrification pathway was anoxic denitrification.However,it was transformed into aerobic denitrification process when DO concentration was 6.0 mg/L.And the main aerobic denitrifying bacteria were Bacillus,Corynebacterium,Tepidamorphus and Nesterenkonia,with the relative abundance of 5.11%.pH had a great effect on nitrogen removal efficiency and pathways for high temperature and high ammonia nitrogen wastewater treatment.The optimal nitrogen removal performance was obtained with p H of 7.0.And the average COD,NH₄⁺-N and TN removal efficiencies were 99.61%,99.46%and 98.80%,respectively.The heterotrophic nitrification process was the main nitrification pathway in different Ph systems.With the increase of p H,the proportion of ammonia stripping process increased while the autotrophic nitrification process almost disappeared.The highest heterotrophic nitrification rate and the highest aerobic denitrification rate were achieved when the p H was 7.0,which were 6.59 mg/（L·h）and 3.92 mg/（L·h）,respectively.Under the optimal working conditions,the efficient nitrogen removal system for kitchen waste fermentation wastewater was realized.The NH₄⁺-N,TN and COD degradation rates were 27.69 mg/（L·h）,32.65 mg/（L·h）and 830.78 mg/（L·h）;the average concentrations in the effluent were 4.54 mg/L,7.66 mg/L and 293 mg/L,with the average removal rates were 99.53%,99.24%and 99.04%,respectively.The main nitrogen removal pathways were heterotrophic nitrification process（the rate was 3.79 mg/（L·h））.Meanwhile,aerobic denitrification process and anoxic denitrification process co-existed in the system,with the rates of 4.22 mg/（L·h）and 3.62 mg/（L·h）,respectively.