Pollutants Removal Characteristics And Operating Performance Of The Carrier Media Of Biological Aerated Filter

In this experiment, two different carrier media, ceramsite and porcelain, were used to treat domestic wastewater in Biological Filtration Oxidization Reactor (BIOFOR). By comparing the removal effect with the two different carrier media, analyzing the removal effect at different bed material height and explaining the phenomenon of simultaneous nitrification-denitrification in the reactor, the main results were conducted as below:1,By using ceramsite as carrier media to treat domestic wastewater in the BIOFOR, the experimental results showed that ceramsite could be used as carrier media to remove CODcr, NH3-N and SS in the wastewater effectively. The removal efficiency of CODcr, NH3-N and SS was 80%,90% and 80%, respectively, and the effluent concentration of CODcr, NH3-N and SS was 28.9mg/L,0.94mg/L and 31.5mg/L, respectively, which was comparable to the removal effect when using porcelain as carrier media.2,Domestic wastewater was adopted to start the BIOFOR. The process of forming biofilm was completed in 2~3 weeks, when CODCr and NH3-N removal efficiency in effluent reached 70% and the reactor run stablely.3,When CODCr in influent was 75.39~184.8mg/L, the ratio of gas to liquid was 3:1 and HRT was 5~12h at the bed material height of 20cm, the CODCr in effluent was always under 40mg/L and further increase of bed material height has almost no effect on the removal of CODCr. At the exit of the reactor, CODCr removal efficiency was stable. So it was concluded that appropriately increasing hydraulic loading was beneficial to the BIOFOR for nitrification or denitrification without limiting the factors such as aeration demand,temperature and backwashing.4,BIOFOR had good function of nitrification. When the average NH3-N concentration in influent was about 25mg/L, the NH3-N removal efficiency with porcelain or ceramsite as carrier media was both above 90%. The best bed height for nitrification was 20cm. With the increasing of the bed height, NH3-N removal efficiency also raised slightly. When the bed height was more than 80cm, NH3-N removal efficiency almost unchanged.5,When the bed material height was within 0~120cm, the removal efficiency of SS was enhanced with the increase of bed material height. The best removal efficiency of SS occurred when the bed material height was 40cm initially, when the SS removal efficiency was 75.7% and SS in effluent was 23.67mg/L with the carrier media of porcelain. If the carrier media was ceramsite, the SS removal rate arrived at 55.7% and SS in effluent was 52.94mg/L correspondingly. In contrast, porcelain was better than ceramsite for SS removal. The SS removal efficiency rises slowly with the further increase of bed material height.6,When the influent was 1.5L/h and aeration demand was 4.5L/h, the highest dissolved oxygen concentration occurred at the bed material height of 60cm with the carrier media of porcelain and 80cm with the carrier media of ceramsite. Before the highest point, dissolved oxygen concentration goes up with the increase of bed height.