Occurrence Of Ammonia-oxidizing Archaea In Wastewater Treatment Plant

The removal of ammonia nitrogen pollution is an important issue of thesewage treatment, the key steps is ammonia oxidation. For a long time, peoplethought that the main microorganisms involved in this process were ammoniaoxidizing bacteria (AOB). Recently a new kind of archaeal which can also achieveammonia oxidation was found, it was called ammonia oxidizing archaea (AOA).But, most studies about it focus on the natural environment, and few focus onsewage treatment system. In order to understand the distribution of population ofAOA in the sewage treatment system, this study give a systematic research onAOA’s distribution of a typical wastewater treatment system, BAF process.With quantitative PCR and clone library technology, this research studied thepopulation and community structure of AOA in BAF sewage treatment system aswell as its physical and chemical factors systematically.The research results are shown as follows:(1) The number of AOA in wastewater varies in different processing unit. Inprimary settling tank and anaerobic tank, AOA was not detected. In aeration tanksit is101.73copies/ngDNA,4.06times thigher than influent. The number of AOA inbiofilm is much higher than AOB, the ratio of them is80.7to2414.4. The numberof AOA in aerobic biofilm is much higher than anaerobic biofilm, the ratio of themis1028. The number of AOA was positively correlated with nitrate andtemperature, negatively correlated with ammonia, pH, nitrite.(2) The community structure of AOA from influent to effluent was notchanged; Its main community is distinct in wastewater and biofilm; Maincommunity in aerobic biofilm and anaerobic biofilm is the same; The diversity ofAOA in aerobic tank was higher than anaerobic tank; The diversity of AOA inwater is higher than biofilm; From influent to effluent of aeration tank its diversitygradually increased. The main factors of the AOA community were COD, DO andpH.(3) In the experimental conditions of this study, the optimal dissolved oxygenconcentration of AOA is2mg/L; Its optimal pH is7; The higher temperature(15-37℃), the more number; At lower ammonia levels(0-50mg/L), its optimalammonia concentration is10mg/L and at higher ammonia levels(50-200mg/L), itsoptimal ammonia concentration is200mg/L; Its optimal COD is50mg/L.