| Recently, the novel nitrogen reomoval technologies based on anammox reaction have been the research focus in wastewater treatment due to that the tranditional nitrification-denitrification process does not meet the demand of low C/N ratio municipal sewage treatment. However, anammox activity is easlily inhibited by the environmental factors of organics, temperature, DO and etc., and the doulbe time of anammox bacteria is long (11d). Hence, the development of combined process based on anammox reaction is a key problem in the industrial application of anammox reaction. At present, some combined processes based on anammox reaction, such as SHARON-ANAMMOX process and CANON process, have been utilized to treat sludge digestion liquid, aquaculture wastewater and landfill leachate. In this study, a low-energy anaerobic wastewater treatment technology was designed to treat low C/N municipal sewage. We mainly studied the feasibility of the intergated anaerobic hydrolysis (A)-nitrification (O)-Den-Anammox (A) bioreactor. The operation condition, carbon-nitrogen removal performance and microbial community of the A/O/A bioreactor were in detail studied. The main research achievements of this study have been obtained as follows:(1) Anerobic hydrolysis reaction could be utilized as the carbon-removal pretreatment process of low-energy anaerobic sewage treatment combination process, which could remove the most organics of wastewater and produce VFA as the organic carbon source of heterotrophic denitrification. The anaerobic reaction serie was2. The maximum COD removal rate of anaerobic hydrolysis reaction arrived to75%, and the substrate removal was achieved in the initial3hours of reaction. The maximum accumulation of VFA appeared in the2nd h. In this study, the produced VFA mainly included acetic acid, propionic acid and butyric acid. The content of acetic acid and propionic acid in VFA arrived to above95%. FISH (fluorescence in situ hybridization) results showed that the ratios of acid-forming bacteria and methanogens in the reactor were39.7%and46.5%, respectively.(2) The nitrogen removal could be achieved by the synergistic effect of heterotrophic denitrifying bacteria and anammox bacteria. The optimum nitrogen substrate of Den-Anammox system was ammonia and nitrate. FISH results showed that the preponderant bacteria of Den-Anammox system based on nitrite was anammox bacteria and the ratio of anammox bacteria was84%; The preponderant bacteria of Den-Anammox system based on nitrate were heterotrophic denitrifying bacteria and anammox bacteria, and the ratio of anammox bacteria was65%. Compared with Den-Anammox system based on nitrite, the Den-Anammox system based on nitrate had better carbon-nitrogen removal performance and better resistance ability for organics and low temperature. The main nitrogen removal approach of Den-Anammox system based on nitrite was anammox reaction and the optimum influent COD:NO2--N:NH4+-N ratios were0.6:1.26:1and0.8:1.33:1. The main nitrogen removal approach of Den-Anammox based on nitrate was heterotrophic partial denitrification1-anammox reaction and the optimum influent COD:NO3--N:NH4+-N ratio was10:7:6.(3) In this study, an integated anaerobic hydrolysis (A)/nitrification (O)/Den-Anammox (A) bioreactor was successfully started up under room temperature (25℃). The TN (total nitrogen) and COD removal rates of bioreactor were89.9%and91.5%, respectively. Compared with the tranditional nitrification-denitrification process, the integrated A/O/A bioreactor could save energy source consumption and reduce greenhouse gas emission. Under the COD/NO3-N of0.94-1.69, the synergistic effect of heterotrophic denitrifying bacteria and anammox bacteria was achieved in the A/O/A bioreactor. The maximum ammonimum and TN removal rates of Den-Anammox reaction were97.6%and93.8%, respectively. According to biological reaction metrology theory, the nitrogen removal contribution percentage of Den-Anammox reaction was above70%. DGGE (denaturing gradient gel electrophoresis) and gene sequencing results showed that the optimum microbial community of Den-Anammox pool changed from single anammox bacterium to heterotrophic denitrifying bacterium and anammox bacterium through175-day running. And FISH results showed that the ratio of anammox bacteria declined from89%down to58%.(4) In order to explore new application ways of anammox, three different anammox granules including blank-anammox granule, Fe-anammox granule and Fe3O4-anammox granule were successfully obtained by anaerobic continuously stirred tank reactor (CSTR). The maximum SAAs of there anammox granlues were0.205kgN·kgVSS-d-1,0.24kgN·kgVSS-d-1and0.239kgN·kgVSS-1d-1, respectively. The maximum granlue rizes [d(0.5)] of three anammox granules were602.8μm (the72nd day),417.3μm (the39th day) and988.5μm (the72nd day), respectively. The forming models of blank-anammox granule, Fe-anammox granule and Fe304-anammox granule were ECP-bonding model, ions-bonding model and ions-bonding model, respectively. The experimental results showed that the optimum ORP of anammox bacteria was205-209mV and QS matter that was produced by anammox bacteria was N-dodecanoyl homoserine lactone. The experimental results showed that Fe3O4-anammox granule was steadier than blank-anammox granule and Fe-anammox granule. The addition of Fe3O4in the reactor was helpful to achieve the quick and steady granulation of anammox bacteria. |
PDF Full Text Request