| According to the existing circumstance of low concentration and low rate of C/N of the influent water quality in many municipal sewage plants, traditional biological denitrification efficiency was low and difficult to achieve emission stardards. Based on the returns about the ANAMMOX process treating wastewater with Ammonia, an SBR reactor seeded with anaerobic granular sludge was started-up to enrich ANAMMOX bacteria and investigate its nitrogen removal characteristics. Through the experimental investigation of ANAMMOX process, the ANAMMOX reactor was rapidly started up; Based on the successful startup of reactor, the effect of environmental factors on ANAMMOX process was studied. Several conclusions were summarized as follows:(1) The ANAMMOX reactor was started up successfully with anaerobic granular sludge under the low concentration of ammonia nitrogen. It took 90 days for the ANAMMOX reactor startup, which was departed into initial phase of startup, transition period and steadily operative period. Research results showed that hydraulic retention time (HRT) was the most important factor to enrich ANAMMOX bacteria. When the HRT was controlled at 30 d during the initial cultivation, the SBR reactor presented ANAMMOX activity at t=58 days. Simultaneously, the anaerobic granular sludge changed gradually from dust black to brownish color and its diameter became smaller. At t=90 days, the ANAMMOX was obvious, and ANAMMOX granules was cultivated successfully. NH4+-N and NO2―-N were removed simultaneously with higher speed and maximum removal rate reached 14.6g/(m3·d) and 6.67g/(m3·d) respectively.(2) Between t=110 days and t=161days, the nitrogen load was increased gradually to a hydraulic retention time of 5 days. The removal rate of ammonium and nitrite were 60.6% and 62.5% respectively. The ratio of nitrite/ammonium was 1.12. The sludge changed to henna and formed ANAMMOX granulation with high nitrogen removal activity. The total nitrogen load was 34.3g/(m3·d).(3) Through the influence study of factor like inorganic carbon on the ANAMMOX reaction, the results indicated: when the NaHCO3 concentration increased from 0.5g/L to 1.5g/L, total inorganic nitrogen daily removal rate reached most highly, reaching 66.4mgN/(L·d), and total inorganic nitrogen removal rate reached 87.8%, meanwhile inorganic carbon was plentiful of source, and ANAMMOX bacteria activity reached the strongest. When the NaHCO3 concentration increased from 1.5g/L to 2.0g/L, inorganic carbon excessive, total inorganic nitrogen removal rate decreased dramatically to 65.1%.(4) Through the influence study of factor like the ratio of NH4+-N and NO2―-N on the ANAMMOX reaction, the results indicated: in this experiment, the appropriate ratio of NH4+-N and NO2―-N was 1:1.13. The experiments showed that in anaerobic conditions in SBR, granular sludge, not only the existence of a large number of anammox bacteria. Moreover, the presence of small amounts of nitrite bacteria, which coexisted in the system as a whole, into a common matrix of ammonia, all contributed to ANAMMOX.(5) Through the influence study of factor like the organic matter on the ANAMMOX reaction, the results indicated: After adding COD=200mg/L, removal of ammonia was inhibited obviously by COD in the early reaction. After 12 days, due to the existence of a small amount of dissolved oxygen, the aerobic nitrification occurred anammox reaction to the lifting of oxygen poisoning. Next, the pilot found that the removal of ammonia achieved mainly through ANAMMOX process, the ANAMMOX bacteria of the granular sludge produced N2 with the formation of nitrite as electron acceptor and ammonia as electron donor. As the reaction, denitrifying bacteria activity has been increasing and traditional denitrification process played a role. ANAMMOX bacteria and denitrifying bacteria so that the joint action to remove ammonia and nitrite nitrogen.
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