Study On Ammonium-rich Wastewater Treatment With Partial Nitrification-ANAMMOX Process

The partial nitrification-anaerobic ammonia oxidation(ANAMMOX)is a sort of new nitrogen removal process based on the biological reaction of partial nitrification and ANAMMOX,and has advantages of no organic carbon addition,low operating cost,low oxygen consumption and energy consumption.Plenty of experiments, theoretical analysis and application research on this object have been performed,and have bought about a lot of results by many investigators.On the bassis of summarizing the results,partial nitrification reactor and Anammox reactor were started up by synthetic wastewater,respectively,and the influence factors such as ammonia loading rate,temperment,pH,organic substrate,DO and SRT were studied. Then the performance of the system for partial nitrification-ANAMMOX was studied with synthetic wastrwater and sludge dewatering effluent,respectively.The main results were as follows:1)When temperature at 30±0.5℃,influent pH at 7.8-8.2,DO concentration at 1.0-1.5 mg/L and HRT at 1.25 d,partial nitrification reactor was successfully started up in 80 d with influent NH₄⁺-N concentration at 210 mg/L and COD concentration at 300 mg/L.The results showed,NO₂^--N accumulation rate was above 95%.2)Low DO condition is beneficial to nitrosobacteria to gain advantages in competition.If DO is too low or two high,it could not favorable to partial nitrification. The NHa₄⁺-N removal rate and NO₂^--N accumulation rate was kept in a high level when DO controlled at the range of 1.0-1.5 mg/L.On this test,SRT at 2-3 d and pH value at high level(pH=8-9)was beneficial for the formation of partial nitrification. The partial nitrification reactor can perform well when concentration of NH₄⁺-N increase to 420 mg/L,the tests indicated that ammonia loading rate has little effect on nitrosobacteria,but it has great effect on the activity of nitrobacteria.3)When the DO concentration controlled at 0.5-1.0 mg/L,sewage sludge return flow rate properly reduced and HRT controlled at ld,the partial nitrification matching with ANAMMOX was successfully achieved in about 20 d.The results showed that the average concentration of effluent NH₄⁺-N,NO₂^--N were 71.29 mg/L and 89.01 mg/L,respectively.And the ratio of effluent NH₄^--N and NO₂^--N were still maintained in about 1.25.4)When influent pH kept at 8.0 and the temperature kept at 30±0.5℃,the ANAMMOX bioreactor was successfully started up in 120d with the nitrification biofilm as inoculum.The results showed,the volumetric total nitrogen loading rate was 0.109 kg/(m³Â·d),the removal rate of NH₄⁺-N,NO₂^--N and total nitrogen were 86.68%,96.04%and 81.05%,individually.The ratio of NH₄^--N removal,NO₂^--N removal and NO₃^--N production was 1:1.16:0.30.5)The ANAMMOX reactor have high ability in wastewater treatment of high concentration nitrogen.The average removal rate of NH₄⁺-N,NO₂^--N and total nitrogen were 74.84%,86.33%and 69.74%when influent NH₄^--N concentration and NO₂^--N concentration at 250 mg/L,and total nitrogen concentration at 500 mg/L. When influent NH₄^--N concentration and NO₂^--N concentration increased to 300 mg/L,and total nitrogen concentration increased to 600 mg/L,the average removal rate of total nitrogen was reduced to 62.10%.The reason is that the ANAMMOX reaction was inhibited by the high NO₂^--N concentration in the ANAMMOX reactor induced by high nitrogen load.6)In order to keep the effluent ammonia meet the national discharge standard I, the HRT should not be kept lower than 10 h.The removal rate of total nitrogen was above 80%,and the removal rate of other substrates were above 90%while HRT at the range of 20-25h.7)The performance of the system for partial nitrification-ANAMMOX was studied with synthetic wastrwater.When influent COD concentration at 300 mg/and NH₄^--N concentration at 210 mg/L,COD average removal rate of the whole nitrogen removal system was 84.25%,average removal rate of NH₄⁺-N and total nitrogen were 93.23%and 87.06%,respectively.Then the performance of the system for partial nitrification-ANAMMOX was studied with sludge dewatering effluent.The whole nitrogen removal system reach stable in 29 d.The average total nitrogen removal rate was 87.16%.The average concentration of effluent NH₄^--N,NO₂^--N,NO₃^--N were 13.86 mg/L,8.95 mg/L,2.55 mg/L,respectively.The effluent ammonia can meet the discharge standard of nation,and it showed that this nitrogen removal technology is feasible in technology.