Study On Reverse Anaerobic Ammonium Oxidation And Partial Nitrification MBR Coupling Process

The exploitation of new effective and low-cost biological nitrogen removal processes has recently been a research focus in water pollution control field. As a new autotrophic nitrogen removal technology, the combined anaerobic ammonium oxidation (ANAMMOX) reaction with partial nitrification has the advantages of no organic carbon addition, low operating cost, low oxygen and energy consumption, which contribute to its wide application prospects. However, this postpositional ANAMMOX combined process still has deficiencies. For instance, the ratio of NO2--N/NH4+-N in the partial nitrification effluent is the key operation condition for the combined partial nitrification/ANAMMOX process (1.32 as required), which is difficult to achieve, but very important and necessary. Once NO2--N, dissolved oxygen and organics concentrations in the effluent are beyond the preferred value, ANAMMOX bacteria will be inhibited in this process, leading to the decline of nitrogen removal efficiency.To solve these problems, reverse ANAMMOX and partial nitrification with MBR features was combined, the new integrated process was studied in this thesis, and the main conclusions are as follows:(1) Nitrite accumulation could be achieved when the pH value was about 8, the reactor at 32±1℃and dissolved oxygen (DO) concentration was equal to or lower than 1.0 mg/L in partial nitrification reactor. High concentration of free ammonia is a crucial and useful factor, which could inhibit the activities of nitrite oxidizing bacteria. The stable operation of partial nitrification could be realized under COD concentration equal or lower than 100 mg/L (COD/ NH4+-N≤0.25).(2) When the operation was stable, the results showed that the ANAMMOX consortium was found adapted to the wastewater containing dissolved oxygen (DO), with the average removal rates of NH4+-N, NO2--N and TN at 0.68 kg-N/(m3-d),0.73 kg-N/(m3-d) and 1.29 kg-N/(m3·d). After COD was added into the influent, the average removal rates of NH4+-N, NO2--N and TN were 0.67 kg-N/(m3-d),0.74 kg-N/(m3·d) and 1.32 kg-N/(m3-d).(3) The best operation condition for the reverse anammox/partial nitrification process is: the temperature at 32±1℃, pH value at 8, the hydraulic retention time (HRT) at 12 h, and the recycle ratio at 200%. The removal efficiencies of various nitrogen compounds in the effluent were improved obviously after the NH4+-N concentration is 300 mg/L, COD concentration equal or lower than 150 mg/L (COD/NH4+-N≤0.5), and DO equal or lower than1 mg/L. The average removal rates of NH4+-N and TN in reverse process were 0.59 kg-N/(m3·d) and 0.47 kg-N/(m3-d).(4) Utilizing the reverse process to treat real high ammonium wastewater, HRT at 12h, and the recycle ratio at 200%, the average removal rates of NH4+-N and TN were 0.50 kg-N/(m3·d) and 0.40 kg-N/(m3·d), and the concentrations of NH4+-N, NO2--N and COD were 1.38 mg/L,38.92 mg/L and 15.78 mg/L respectively when the operation was stable. The result shows that this reverse ANAMMOX/partial nitrification process can treat special wastewater with high NH4+-N and low C/N rate.