Material balance and microbial community of activated sludge process with excess sludge minimization stream

为了减少废水处理过程对环境的影响并实现“零排放”技术，拥有能够最大限度地矿化废水中有机物质并最大限度地减少多余污泥产生的废水处理系统非常重要。为此，开发了带有污泥消化流的活性污泥工艺，其中一部分回流污泥在返回曝气池之前被消化和溶解。这是一个很有前途的过程，但为了解决系统中无机成分积累的问题，并确认系统的长期稳定性，这是系统实际使用的必要目的。本研究以某城市污水为原料，在实验室进行了臭氧氧化回用污泥消化的活性污泥工艺，并对不同无机化合物的物质平衡进行了研究。本研究的具体目的是通过ICP分析来监测进入系统的无机物的行为，并阐明其行为机制。实验结果表明：1)Na等部分金属没有在系统中积累，而是以可溶性形式随出水排出。2)铁、铝等金属在污泥中积累，但在一段时间后积累趋于饱和；3)锌、铜等金属在整个实验期间继续在污泥中积累。在这些金属中，铁表现出一个有趣的行为：在铁积累达到饱和后，出水可溶性铁浓度增加，表明存在铁的再溶解机制。需要进一步研究铁再溶解的化学机理。

In order to reduce the environmental impact from wastewater treatment processes and to achieve "zero emission" technology, it is very important to have wastewater treatment systems that can maximize mineralization of organic mattes in the wastewater and to minimize the excess sludge production. For such a purpose, the activated sludge process with a sludge digestion stream has been developed, in which a part of the return sludge is digested and solubilized before returning to the aeration tank. This is a promising process, but it is necessary for the purpose of practical use of the system to solve the problem of the accumulation of inorganic components in the system and to confirm the long-term stability of the system. In the present study, an activated sludge process with a return sludge digestion by ozonation was operated in the laboratory with a municipal wastewater and the material, balance of different inorganic compounds was investigated. The specific objective of the study was to monitor the behavior of inorganic matters entering the system by using ICP analysis and to clarify the mechanism of their behaviors. The experimental results indicated that: 1) Some metals like Na did not accumulate in the system and go out in the effluent in the soluble form. 2) Some metals like Fe and Al accumulated in the sludge, but after some time the accumulation appeared to come to a saturation, and 3) Some metals like Zn and Cu continued to accumulate in the sludge throughout the experimental period. Among these metals, Fe showed an interesting behavior: after the accumulation of Fe came to saturation, the effluent soluble Fe concentration increased, indicating there is a mechanism of Fe re-solubilizatlon. It is needed to further investigate the chemical mechanism of this re solubilization of Fe.