| Wasterwater from large-scale pig farm is a kind of organic wastewater containing high ammonia nitrogen. Although after the treatment of anaerobic digestion, the effluent ammonia concentration is stil higher than the influent ammonia concentration. Simultaneous anaerobic ammonium oxidation, methanogenesis and denitrification is a new type of nitrogen and carbon removal process. So this study investigated the feasibility of anammox bacteria, methanogenic bacteria and denitrifying bacteria were all enriched in a UASBB reactor. The mechanisms and technology of simultaneous anaerobic ammonium oxidation, methanogenesis and denitrification were studied from multi-angles such as the operating performance, influence factors, microbiology and dynamic model. Then the research results were applied to remove nitrogen and carbon in real wastewater from piggery. The aim of our study is to provide a theoretical basis for the further development of treatment process of organic wasterwater with high ammonia nitrogen. And the main contents and conclusions are as follows:1. The implementation of the process integrating anaerobic ammounium oxidation, methanogenesis and denitrification in a UASBB reactor was investigated. The results showed that with the vaccination of some anaerobic sludge and denitrification sludge,the UASBB reactor was started fastly and successfully after 48 days, the volume load reached 0.76kg COD/(m3·d), COD removal rate achieved above 95%. Then NH4Cl and NaNO2 were added in the experimental water and the synchronization process of anammox, methanogenesis and denitrification was achieved gradually. After the operation of the reator about 90 days, the removal rates of COD, TN andNH4+-N were 80～90%,50～60% and 8～24%, respectively. When the influent organic matter concentration was decreased to 100 mg/L, the removal rate of ammonia nitrogen was increased from negative value to 41.2%. The detection of sludge samples in the reactor by the method of molecular biology, indicated that the homology similarity between anammox bacteria and Candidatus Brocadia was 94%, and that between denitrifying bacteria and Pseudomonas Pseudomonas sp. was 100%. 2. The effect of Cu2+, Zn2+ in swine wastewater on the sludge activity was also investigated. When there was only Cu2+ or Zn2+ in the sludge, the activities of anammox, denitrification and methanogenesis were all inhibited. The inhibition of Zn2+ on the activities of denitrification and methanogenesis was greater than that of Cu2+, while the inhibition of Zn2+ on the anammox acitivity was lower than Cu2+ However, when both the two heavy metal ions were in the sludge, there were antagonistic effects on the sludge activities of denitrification and methanogenesis, as well as cooperation effects on the anammox activity.3. Kinetic parameters of anaerobic ammonium oxidation, methanogenesis and denitrification were revealed. According to Haldane model and test data of anaerobic ammonium oxidation, the calculated results fitted through the Matlab software were as fllows:the ammonia half-saturation constant (K S,nh) is 34.03 mg/L, ammonia inhibition constant (K Lnh) is 1274 mg/L, nitrite half-saturation constant (K s.NO2-) is 42.31 mg/L, nitrite inhibition constant (K l.NO2-) is 159.03 mg/L, the maximum substrate reaction rate (qmax) is 1.55 mg/(g h). Baesd on the Monod equation and test data of methanogenic activity, the following data was obtained by linear fitting:the maximum specific degradation rate of methanation Vmax is 122mg/(g h), Ks is 124 mg/L, methane yield coefficient (y) is 0.29 mL/mg. Compared with the theoretical value of 0.35 mL/mg, it was about 82.8% of the theoretical value and further validated that methanogenic bacteria ability was affected by denitrifying bacteria and anaerobic ammonium-oxidizing bacteria. COD concentration and the corresponding denitrification rates were fitted with a straight line and the organic half-saturation constant Ks'COD achieved is 3.03 mg/L. According to the nitrite concentration and corresponding denitrification rate, the maximum denitrification rate qmax is 25.25mg/(gh) and nitrite nitrogen half-saturation constant Ks'NO2- is 1.1 mg/L were obtained.4. The feasibility and process conditions of UASBB combined biological contact oxidation pond were studied. An integration of anaerobic ammonium oxidation, methanation, and the integration of nitrification and denitrification was achieved in the combination of UASBB and biological contact oxidation pond. The best external reflux ratio was determined 300%, then the removal rates of average ammonia, COD and total nitrogen in the system were 81.3%,95.2% and 77.6%, respectively.5. The combination process of UASBB-biological contact oxidation pond was applied in the treatment of real wastewater from piggery. In the test, the composite technology of simultaneous anaerobic ammonia oxidation, denitrification and methanogenesis was ruuning 60 days. During the operation, the secondary and first level biogas slurry had been introduced for 15 days separately while raw water had been for 30 days. The maximum COD load of system was up to 3 kg/(m3·d). The average removal rate of COD in secondary, first level slurry and raw water were 94.4%,94.0% and 97.0%, respecitively. The maximum TN load of system was up to 0.51 kg/(m3·d). The average removal rate of TN in secondary, first level slurry and raw water were 83.8%,82.5% and 84.2%, respecitively. The maximum ammonia nitrogen load of system was up to 0.3 kg/(m3·d). The average removal rate of ammonia nitrogen in secondary, first level slurry and raw water were 91.0%,91.9% and 88.2%, respecitively. The effluent water quality of the technology was better than the requirement of "Emission Standards for Livestock and Poultry Industry" (GB 18596-2001). The simultaneous process compared with conventional activated sludge could save 0.52 kg O2/(m3·d),0.838 kg COD/(m3·d) and recover 40.51L CH4/(m3·d). |
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