The Treatment Of Low C/N Sewage Based On ABR Partial Denitrification-ANAMMOX Process

This experiment had a deep reseach on the quick start-up of partial nitrification and ANAMMOX reactor and the influencing factors of reactor operating conditions, the main conclusions are as follows:(1) proposed a method of quick start-up of partial nitrification process, investigated the effect of partial nitrification conditions under different operating parameters.Tests showed that with in the CSTR reactor seeded with anaerobic granular sludge, under the condition of 30 oC in temperature, p H of 7.5~8.0, DO of 2~3 mg·L-1,used a continuous flow water, in the intermittent anoxic/aerobic conditions can quick start up partial nitrification process. In this experiment, three groups of anoxic/aerobic time were set up during the start-up process:30min/30 min, 45min/45 min and 15min/45 min, the experimental results showed that the cumulative rate of anoxic / aerobic time had an effect on NO2--N accumulation. The short cut nitrification effect is the best when the anoxic / aerobic time ratio is 30min/30 min, and the average accumulation rate of NO2--N was 89.1%.Gradually shorten HRT can wash out the flocculent sludge from the reactor, in favor of panning out NOB. Too long HRT would lead to extended aeration and nitrite oxidized. When the influent concentration of NH4+-N was 100mg·L-1, the optimum HRT was 4h. The technology is suitable for the short range nitrification of low NH4+-N concentration. When the inlet NH4+-N concentration was 50 mg·L-1,the HRT was 3h, the nitrite rate could reach to 90%.(2) Examined the start-up characteristics of ANAMMOX reactor, inspected the operating conditions of ANAMMOX collaborative denitrification process.In this study, an Anaerobic Baffled Reactor(ABR) was constructed. The reactor was start-up ANAMMOX process successfully in 45 days under the condition of 27 oC in temperature, p H of 8, HRT of 10 h, the influent NO2--N/NH4+-N of 1.32. At stable phase, the average TN removal percentages arrived to 83% and the ΔNH4+-N:ΔNO2--N:ΔNO3--N was 1:1.31:0.27. In the process of treating municipal sewage, inevitably contains a certain amount of organic carbon in the influence. Organic carbon had no obvious effect on Anammox process at C/N of 0.5; Nitrogen removal was improved, and the average total nitrogen(TN, including ammonia, nitrite and nitrate nitrogen) removal efficiency of 93% was obtained at C/N of 1. However, at C/N of 2, TN removal performance reduced due to the suppression of Anammox by organic carbon; the Anammox bacteria could return to activity in a short period of time by reducing the influence COD concentration. Researched the performance of Anammox-denitrification process treated municipal sewage, the effluent TN concentration was 7.5 mg·L-1, the average TN removal percentages arrived to 86%.(3) Proposed the process of integration of partial nitrification- ANAMMOX, investigate the optimum operating conditions of the system.Take advantage of the special construction of ABR, specific microbes could be enriched in different formats, can achieve the purpose of integration parcial nitrification – ANAMMOX process, ABR carbon removal system is suitable for the treatment of low concentration organic wastewater, and could resiste to organic load impact. when influent COD was at range of 200mg/L to 600 mg / L, can maintain the effluent COD stable at about 80 mg·L-1, made the C/N ratio remains stable for the subsequent paitial nitrificationANAMMOX system. By shortened the HRT to improve the volume load of paitial nitrification- ANAMMOX system. The expriment proved that the optimal HRT of the integrated reactor was 10.5h, and the volume load of TN could reach to 0.36kg(D--1) m3. The effect of DO concentration on the removal of TN was investigated,The partial nitrification reactor could achieve good nitrification effect when the DO was 1~2 mg·L-1, nitrification rate can be maintained at 90% for a long time.At the temperature of 30 oC, PH was 7.5~8, the system’s HRT was 10 h, aerobic zone DO controlled at 1~2 mg·L-1, the integration of partial nitrification- ANAMMOX reactor can be a stable and efficient treatment of domestic sewage, the effluent TN concentration reduced from 47.9 mg·L-1 to 7.5 mg·L-1, the effluent COD concentration reduced to 40 mg·L-1.