The performance of nitrogen and phosphorus removal was investigated in pilot-scale A2/O, A2/O-MBR and mA2/O-MBR processes for treating municipal wastewater. The results show that these processes had a similar COD and ammonia removal efficiency, but A2/O process had better denitrification efficiency than MBR processes. In order to explain the difference of nitrogen and phosphorus removal performance in the investigated processes, specific oxygen uptake rate (SOUR), specific denitrification rate (SDNR), anaerobic release rate and anoxic and aerobic uptake rate of the activated sludge taken from A2/O and mA2/O-MBR processes were compared. The results show that the activated sludge of mA2/O-MBR process had a higher nitrifying activity in aerobic tank than A2/O process, the denitrifying activity in anoxic tanks were roughly equal and A2/O process had a higher denitrifying phosphorus removal activity in anoxic tank than mA2/O-MBR process.
Nitrogen and phosphorus are the nutrients induced eutrophication, therefore the removal of nitrogen and phosphorus is the main target of domestic wastewater treatment. In order to achieve better nutrient removal effect with lower construction and operation cost, a new nitrogen and phosphorus removal process was developed based on simulation. New process named MUST was developed by mixing UCT and step-feed BNR technology together, and possessed the advantages of two processes. The results of simulation show that MUST can achieve similar treating effect with 20% shorter hydraulic retention time (HRT) compared with UCT process. The influent splitting ratio of 4:3:3 was recommended for MUST operation. A pilot experiment of MUST was also carried out according to simulation results, and achieved very good pollutant remove effect, the average COD, NH4+-N, TN, TP removal efficiency were 85.4%, 94.0%, 65.1%, 62.3% respectively under the condition of low influent COD/TN ratio. Considering the excellent pollutant removal capacity of MUST, an upgrade project chose it as wastewater treatment process. This paper just starts the research of MUST, further study is necessary and valuable.
Interactive reactor is a powerful and complicated wastewater treatment, it can fulfill various operation modes by changing inlet site, inner recycle site, return sludge site and DO concentration, therefore interactive reactor can adjust to different conditions and achieve steady and efficient wastewater treatment effect. This paper intended to establish integrated optimizing control strategy for better use of interactive reactor. In order to confirm the application boundary of typical operation mode, pilot-scale experiment and simulation were carried out. JHB and ALO modes were experimented for capacity evaluation and simulation calibration. A2/O, inverted A2/O and ALO modes were selected as representatives for the strategy establishment with simulation. According to the study results, inverted A2/O mode was suitable for the influent BCOD/TN value more than 5, A2/O mode was better choice for the influent BCOD/TN value between 4 and 5, and ALO can achieve high nitrogen removal efficiency treating wastewater with influent BCOD/TN between 3 and 4 by short-cut nitrification and denitrification. Contributed to the excellent treating effect of interactive reactor, several projects have been built and run well under the optimizing control strategy.
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