Study On Anammox Denitrification For Livestock And Poultry Wastewater

The livestock husbandry has become the most active growth point and the main pillar industry of rural economy in China. The environment was polluted gravely by a large amount of waste discharged by livestock and poultry, and the contamination of livestock wastewater has aggravated the shortage of water resource, The strategy of sustainable development was seriously restricted. The technology of eliminating hydrocarbon in livestock wastewater is already relatively mature, but still lack an ideal method to nitrogen and phosphorus. Based on the newly discovered mechanism of wastewater denitrification, seeking for a reliable ,stable and economical craft for denitrification of livestock wastewater not only has important theoretical significance for innovative wastewater treatment methods, but also has important applications value to solve the water pollution. Based on the ammonia oxidation mechanism, anaerobic - Nitrosation - ANAMMOX combination to treat .with waste water was researched in this text. Through construction of a suit of experimental treatment plant for Livestock Wastewater , ANAMMOX sludge was cultivated successfully by simulated wastewater and The plant was run by ANAMMOX sludge which domesticated by actual wastewater; the anaerobic-nitrosation-ANAMMOX combined processess for treating livestock wastewater has been researched, and the influencing factors, treatment efficacy and reaction mechanism of nitrosation and ANAMMOX processess were studied respectively, and the microbial community in nitrosation and ANAMMOX processess were analyzed.The main results were as follows:1,Situation and developmental requirements of Livestock wastewater treatment was analyzed and four sets of livestock and poultry wastewater treatment process was summarized. A Hydrolysis-UASB anaerobic reactor-SBR Nitrosation reaction-UASB ANAMMOX anti-experimental process was determined.2,Selecting the appropriate reactor and the reaction conditions can cultivate ANAMMOX microorganisms as the main sludge in a short period of time. ANAMMOX reactor showed high NO₂^--N and NH₄⁺-N removal rate in a successful state. when artificial livestock wastewater was simulated, The mature ANAMMOX sludge which seeded with anaerobic sludge treat of livestock wastewater was cultivated successfully in 150 days. When the influent concentration of NO₂^-N and NH₄⁺-N was 490mg/L, the both of removal rate was above 85% at HRT of 24 h.3,Low concentrations of organism and dissolved oxygen has little impact to ANAMMOX reactor, but the existence of organism and dissolved oxygen in the reaction could increase types of reaction in the reactor. Aerobic ammonia-oxidizing bacteria mainly to eliminate the harm caused by dissolved oxygen, Denitrification mainly to eliminate the harm caused by organism.Because sereval reaction exist in the same reactor,the ratio of NO₂^--N/ NH₄⁺-N must be adjusted as the amount of organism and DO in influent wastewater. Keeping the ratio of NO₂^--N/ NH₄⁺-N 1.45 is good for maintaining optimum TN removal rate of ANAMMOX with the concentration of organism 180mg/L, DO 0.5 mg/L and TN 980 mg/L in synthetic wastewater.4,Dissolved oxygen, pH, temperature are the major factors to affect Nitrosation reaction , whereas dissolved oxygen concentration is the crucial factor to control of the degree of denitrification.Data suggested that: The reactor cause to ideal nitrosation condition under the conditions of value of pH 8,aeration rat was from 0.036 m³/h to 0.04m³/h(DO was 0.3mg/L by repeated determine), temperature was 34-36℃. When the influent concentration of NO₂^--N and NH₄⁺-N was 490mg/L, the concentration of NH₄⁺-N in effluent was 35.7mg/L and removal rate was 92.6% at HRT of 24 h, While the concentration of NO₂^--N in effluent was 18.7mg/L, the removal rate was 96.2%.5,Maintaining suitable reaction conditions of Nitrosation , it can controlling of the degree of denitrification by controlling the reaction time, so that the effluent reached requirements NO₂^--N/NH₄⁺-N ratio of anammox microbial.In the studies, nitrosation process with time of 34h, concentration of organism 180mg/L and DO of 0.03 mg/L in influent, ratio of NO₂^--N / NH₄⁺-N 1.45 are good for ANAMMOX reaction.6,ANAMMOX reactor has a outstanding treatment for TN. in the Livestock Wastewater. In the process,the removal rate of NO₂^--N is superior to NH₄⁺-N.During 61 clays domestication, the mature ANAMMOX bacteria treated with synthetic livestock wastewater could treat with actual livestock wastewater,and work stably. the removal rate of NH₄⁺-N , NO₂^--N and TN was 45.5%, 95.1% and 62.6%, respectively after stably working.7,ANAMMOX bacteria have inferior capacity to adapt to environmental conditions,so the harmful materials in actual livestock wastewater influenced the growth and activity considerably. The revomal rate of TN,ammonia and nitrite has descended significantly. Compared with the synthetic livestock wastewater , revomal rate of NH₄⁺-N declined 47%, NO₂^--N didn't decline obviously,and TN declined 31.8%.8,The HRT in the Nitrosation- ANAMMOX combined processess have remarkably influence for the removal rate of TN when they were used to treat with nitrification in the Livestock Wastewate. HRT in the Nitrosation reaction decided whether ANAMMOX was completely progressed.Nitrosation- ANAMMOX combined processes have great effect on nitrogen removal of livestock wastewater,the nitrosation optimal water power standing time of the process was 34h, ANAMMOX reactor optimal water power standing time of the process was 19-20h.9,choosing reactor for the denitrification treatment in the Livestock Wastewater which exist a certain of dissolved oxygen must keep influent in push flow state.Then different growth conditions of microbial are reached and reaction zone is formed in the reactor.It is benefit for enrichment of slowly development microbial. The installation in the reactor is good for enrichment of slowly development microbial and it can form a certain reaction dominating the main reaction zone.In this studies, aerobic ammonia oxidation reaction occurred mainly in ammonia oxidation zone where aerobic microbial community enriched at the bottom of the in let zone of UASB reactor . denitrification reacted during the top of inlet zone and ANAMMOX reacted in the top of the reactor that lack oxygen and filled with inorganisms.10,There are varieties of microorganisms for denitrification treatment of Livestock wastewater, and there is a outstanding difference between microbial community which play a major role in different reactions.The scanning electronmicrograph showed that microorganism species in different parts of nitrosation and ANAMMOX reactors were different .the predominantly microorganism species was Filamentous bacteria,accompanied with Methanobacterium and Sarcina-type bacteria in nitrosation reactor, but Methanobacterium and Sarcina-type bacteria were predominantly in ANAMMOX reactor.