Study On Anaerobic Ammonium Oxidation Reactor Under Normal Temperayure And Low Substrate Concentration

With the perfection and improvement of the standard of human life, nitrogen content increased sharplyat the industrial wastewater and sewage, and water euthophication often happened, so the new urbansewage treatment plant pollutants standards (GB18918-2002) strictly controlled the nitrogen andphosphorus concentrations of effluent in China. As the new standard implemented, nitrogen andphosphorus need removal both in the establishing and established WWTPs. Traditional biological nitrogenremoval technology has some disadvantages, such as long process and large energy consumption. And anew concept was found for denitrification with the discover of anaerobic ammonium oxidation(Anammox).Anammox is a new high efficient autotrophic bio-nitrogen removal technology, it involves theauthtrophic oxidation of ammonium to dinitrogen gas using nitrite as electron acceptor under anaerobicconditions. Compared with the traditional nitrification/denitrification, Anammox has some advantages,such as less oxygen consumption, without plus carbon sources, low sludge production and free ofsecondary pollution, therefore it has the broad application prospect and a high development value. It is themost economic dentrification technologyNow, it has confirmed that Anammox phenomena exists generally in nature, meanwhile, it plays anirreplaceable role in the process of nitrogen cycle in the ocean. This biological transformation process iswidespread in nature which has a huge advantage in denitrification process, so if the Anammox technologywas intensified artificially, and used in the sewage treatment, it will bring huge economic benefits.Under normal temperature and low substrate concentration, the start-up, operation efficiency andinfluencing factors was researched at the up-flow Anammox reactor at this topic. The main research resultswere as follows:(1) Start-up and operation efficiency. In this study the influent pH for7.50-7.80, NH+4-N for30-40mg/L, NO-2-N for35-50mg/L and temperature for20-25℃were controlled. A lab-scale up-flowbiofilter reactor feeded with the oxidation ditch backflow sludge was used to start-up the anaerobicammonium oxidation (Anammox) process. First, aerobic nitration biofilm was cultivated, and thenAnammox biofilm was cultivated under anaerobic condition, and after224days of operation, the Anammox reactor was started up successfully. In the stable operation stage, the average concentration ofeffluent NO2--N and NH4+-N were1.4mg/L and4.6mg/L, the removal rate of NO2--N and NH4+-N were95.3%and90.1%, removal proportion was (1-1.8):1and focused on (1.4-1.5):1. The NO-2-N andNH4+-N removal volumetric loading rate were104.2mg/(L.d) and146.0mg/(L.d).(2) Influencing factors. After Anammox reactor was started up successfully, the factors of pH value,organic, the ratio of influent nitrite and ammonium, HRT and substrate loading were researched at (20±1)℃. The result showed that Anammox reactor was evidently influenced by this factors. The best pH valuewas6.7～8.5for Anammox reaction, and when pH value was inferior to6.7or overtopped8.5, theconcentration of FA and FNA exceeded8.93mg/L and2.67×10-2mg/L, Anammox reaction was inhibited.When COD concentration was maintained above60mg/L, Anammox reactor was inhibited evidently.Anammox reactor would back to its original state after a period of operation, when COD was wiped off..TN removal rate was the highest and average value was89.0%when the ratio of influent nitrite andammonium was (1.35-1.37):1. The HRT of Anammox reactor was not less than2h at this experimentalconditions. Anammox bacteria would be restrained when nitrite concentration was more than140mg/L, butdid not fully deactivation. And it estimated that Anammox bacteria would gradually adapted to thiscondition after long time, but it also had a limit. The extreme concentration of Anammox bacteria was nottested in this experimental conditions.(3) The SBR influent and SBR effluent of nitritation was mixed according to the ratio of1:1as theAnammox experimental wastewater. Result showed that Anammox reactor was not affected and runningwell. Only effluent ammonium and nitrate were a little high, and removal rate of TN was only70%-80%.