The Studies On Domestic Wastewater Treated By Three-Phases Inner Loop Bio-fluidized Bed Process

Three-Phases Inner Loop Bio-fluidized Bed is new kind of wastewater biological treatment process, which integrates traditional activated sludge wastewater treatment process with biofilm technology. It is a promising wastewater treatment process because of its high loading and efficiency. Hydraulics, the formation of biofilms, effect of wastewater treatment and the model of organic degradation were presented firstly in this paper. Then a pilot scale reactor was designed according to the results in the lab to treat domestic wastewater.The experimental results showed that the distance between inner tube and bottom of the reactor(Ah)was an important parameter, which affected the model of reactor, inner circle velocity and oxygen transfer efficiency. Volumetric gas rate was another parameter except the factors of reactor's structure, which impacted on the oxygen concentration in the bulk water and inner circle velocity. The effect of Hydraulic Retention Time(HRT) on the formation of biofilms was obvious, low HRT benefited the formation of biofilms. Autotrophic nitrifying organisms were developed on the surface of the carriers, while heterotrophic microorganisms were suspended in the reactor when HRT was equal to 4h; whereas both microorganisms grew on the carriers when HRT was equal to 1h. COD and NH/-N removal rate changed from 75% to 93% and 85% to 93% respectively when HRT increased from 20mins to60mins. The pilot scale experiment showed that it was acceptable for Three-Phases Inner Loop Bio-fluidized Bed Process as the following treatment step of anaerobic biogas digester.