Nitrogen Removal Enhancement And Mechanism Of The Up-flow Partially Aerated Biological Filter

The biological aerated filter(BAF) is a novel wastewater treatment based on the traditional biological filter, which has good performance, high loading, less operation cost and less occupied area. Traditional BAF always need complete aeration and a large amount of carbon source, therefore, making the BAF consuming less energy and carbon is with a great value. In this study, an up-flow partially aerated biological filter(UPABF) was designed. The U-PABF could achieve integrated aerobic and anoxic environment separately in one reactor by changing the aeration and inflow position. Two parts of experiments were involved in this study, including the experiments of nitrification/denitrification U-PABF system and the experiments of partial nitrification/anammox U-PABF system.The U-PABF for nitrification and denitrification was built by moving the traditional BAF aeration position from bottom to middle part. The main contents include the absorption property of ceramic and zeolite, comparison of ceramic U-PABF and zeolite U-PABF’s performance, the effect of HRT on nitrogen removal performance of U-PABF, the nitrogen concentration change along the U-PABF, characteristics of microbial community structure. The results showed: zeolite U-PABF and ceramic UPABF both had high performance on nitrogen and COD removal with influent NH4+-N of 40 mg/L; the capacity of nitrogen removal by zeolite U-PABF mainly relied on adsorption, and ceramic U-PABF were used to study the nitrogen removal mechanic; the NH4+-N and COD removal efficiency by ceramic U-PABF were 97.90%±0.37% and 88.41%±2.91% with HRT of 5.2 h, and its NH4+-N removal performance decreased with HRT of 2.6 h and 3.5 h while COD removal less changed; nitrification and denitrification were built successfully in ceramic U-PABF, and anammox was also detected in the reactor; obvious structure of microbial community was observed in ceramic U-PABF, the results were consistent with the experiment phenomenon.The U-PABF for partial nitrification and anammox was built by moving the inflow from bottom to middle part. By changing the carbon source type, C/N and DO, the operation parameters of partial nitrification were studied. The results showed: comparing with no carbon source and organic carbon source, inorganic carbon source promoted the nitrite accumulation; with the ratio 0.1:1 of inorganic carbon to nitrogen, nitrite concentration increased; with the DO of 3.33 mg/L and 2.08 mg/L, the nitrite concentration maintained at 0.76 mg/L and 1.46 mg/L, low DO concentration was beneficial for nitrite accumulation.A novel U-PABF was designed in this study, and two operation systems were built using simulated domestic wastewater. The filling material, operation parameters and microbial structure characteristic were all researched, which provided a reference for BAF study in the future.