摘要:
分段进水缺氧/好氧(A/O)工艺是一种高效的污水生物脱氮工艺。但原水多点投配给该工艺带来诸多好处的同时, 也为其优化运行带来一定困难。其中,可行的流量分配方法的建立是分段进水工艺发挥其优势并高效运行的瓶颈问题。提出3种不同的流量分配方法并进行相应的理论分析: (1) 采用等负荷流量分配法,其遵循的原则是保证各段硝化菌负荷相同, 以利于硝化菌生长,优先满足系统硝化, 最大程度地降低出水氨氮浓度; (2)采用流量分配系数， 原则是各缺氧段进水有机物质恰好可以为上段好氧区产生的硝酸盐氮反硝化提供充足的电子供体。 利用该方法可以充分利用原水中碳源,发挥缺氧区反硝化潜力,并保证最后一段进水量最少, 降低出水硝酸盐氮含量; (3)末端集中进水，用于暴雨等产生洪峰流量时, 将进水点向系统末端移动, 并加大末端进水量, 以减小二沉池固体负荷, 避免污泥冲刷流失。3种流量分配方法的提出,可以应对水厂不同的进水水质和出水要求,增强分段进水A/O生物脱氮工艺的实际可操作性,提高处理效率,为目前采用分段进水A/O工艺的污水厂的优化运行管理提供可靠的理论借鉴。
关键词:
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污水
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生物脱氮
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分段进水
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A/O
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流量分配
Abstract:
Stepfeed anoxic/oxic(A/O) process is an attractive biological nitrogen removal system for wastewater treatment. The feed pattern enhances the nitrogen removal performance; however, the facility of operation of this process could be negatively affected. The establishment of optimal distribution method for influent flow is a bottleneck problem of this process to promise the high performance and put the advantage into play. Three methods proposed in this paper for influent flow distribution include: (1) equilibrium loading to nitrifiers. It is a sensible method that the F/M ratio for nitrifiers is the same in the different aerobic tanks, which can favor the growth of nitrifiers and promise the nitrification； (2) the optimal coefficient of influent flow rate distribution. The main idea has been to let the influent organic in some of the anoxic zone be determined by the nitrate concentration produced by the former stage. The suggested method could fully use the influent carbon source and denitrification potential of anoxic zone and, consequently, reduce the influent flow of last stage and get a lower effluent nitrate concentration; (3) a voluminous influent flow in the end of system. To reduce the solids loading to the settler and prevent sludge from being washed out, the feeding point is moved away from the inlet of the system towards its end and the feeding flow in the last stage is increased accordingly during periods with hydraulic peak flows ( caused e.g. by storm weather). Based on the different influent qualities and effluent standards, the suggested influent distribution methods, could improve the operation feasibility and enhance nitrogen removal, as well as providing the reliable theoretical reference of operation and management in step-feed A/O process.
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