The Theory and Study for Filamentous Bacteria Caused Sludge Bulking Problems

Wang Kaijun，Xu Xiaoming

Beijing Research Center of Water Environmental Technology & Equipment

　　Abstract:In this paper, the analysis and summarize of filamentous bacteria caused sludge bulking phenomena have been conducted. Based on generalized Monod model, an unified theory for sludge bulking has been proposed. It has been found that generalized Monod model can well explain the substrate limiting, dissolved oxygen limiting, nutrients and trace elements deficiency, high and low pH and high sulfide concentration caused sludge bulking problems. These are included most kinds of sludge bulking phenomena. Based on the Monod model for carbon and dissolved oxygen limiting, system kinetic equations are formulated, the computer simulation has conducted according to above models. The effects of loading rate, dissolved oxygen, variation of flow rate and concentration etc. factors on the competition relationship floc-forming bacteria and filamentous bacteria have been studied intensively. According to the results of computer simulation, the different strategies for sludge bulking have proposed.
　　Key Word：Sludge bulking，filamentous bacteria，floc-forming bacteria, Monod model

一、污泥膨胀控制方法的演化过程

　　早期控制丝状菌引起的污泥膨胀(简称污泥膨胀)的主要手段是利用丝状菌具有较大的比表面积值，采用药剂杀死丝状菌，或是投加无机或有机混凝剂或助凝剂以增加污泥絮体的比重^<1>。这些方法往往无法彻底解决污泥膨胀问题，并且相反地会带来出水水质恶化的不良后果。人们逐渐认识到活性污泥中的菌胶团细菌和丝状菌形成一个共生的微生物生态体系。在这种共生关系中，丝状微生物是不可缺少的重要微生物，其在活性污泥工艺中对于高效、稳定地净化污水起重要作用。人们逐渐的从简单地杀死丝状菌过渡到利用曝气池中的生长环境，调整丝状菌的比例，控制污泥膨胀的发生--即环境调控阶段。环境调控概念的使用是人们在污泥膨胀控制技术和实践上的一大进步。其主要出发点是使曝气池中的生态环境，有利于选择性地发展菌胶团细菌，应用生物竞争的机制抑制丝状菌的过度生长和繁殖，将丝状菌控制在一个合理的范围之内，从而控制污泥膨胀的发生和发展。同时利用丝状菌特性净化污水，稳定处理工艺。近年选择器理论得到充分发展和应用就是这一概念具体体现^<2><3>。