低温对寒冷地区活性污泥沉降性能的影响及机理研究

Activated sludge is the most widely used method in municipal wastewater treatment plant now and the municipal wastewater treatment plants built in Xinjiang are almost used it. The project will be aimed at the problem occurred in municipal sewage treatment system by activated sludge method at low temperature in winter in cold region in Xinjiang. The problem is that the settlement of activated sludge is ineffective and the effluent can’t reach the discharge standards stably. In this project, we will combine practical wastewater treatment plant research and laboratory simulation to explore the effect of low temperature on the sedimentation of activated sludge as well as to reveal the composition variation law of extracellular polymeric substances of activated sludge and to distinguish sludge zoogloea structure characteristics. We will also analyze the sludge microflora and will screen out the key factors affecting the settleability of the activated sludge at low temperature. By analyzing the relationship between activated sludge settleability and treatment effect at low temperature, we can present some special measure to improve the activated sludge settleability in cold region in Xinjiang. Combined the local municipal sewage quality and the local climate characteristics in winter in cold region in Xinjiang, a systematic research on the influence to the activated sludge settlebility at low temperature in winter and the its mechanism will be done in this project. We hope this research will lay the foundation for the theory and the practice of activated sludge sewage treatment in cold region and will improve the treatment effect in winter in Xinjiang. The project is beneficial to protect the ecological environment in Xinjiang. It is very important for ensuring the sustainable economic and social development in Xinjiang.

活性污泥法是目前运用最广泛的城市污水处理方法，新疆已建成的城市污水处理厂绝大部分采用活性污泥法。本项目将针对新疆寒冷地区冬季低温时活性污泥法城市污水处理厂出现的活性污泥沉降性能下降、出水不能稳定达标排放的问题，采用污水处理厂实际运行研究和实验室模拟研究相结合的方法，探讨水温变化对活性污泥沉降性能的影响过程;揭示活性污泥胞外聚合物组分随水温变化的规律；辨别低温下活性污泥菌胶团结构特点；分析低温时活性污泥菌群组成；筛选出低温下影响活性污泥沉降性能的关键因子；分析低温下活性污泥沉降性能与污水处理效果关系，提出新疆寒冷地区冬季改善活性污泥沉降性能的具体措施。本项目结合新疆寒冷地区当地污水水质及当地气候特点，系统研究低温对新疆寒冷地区活性污泥沉降性能的影响及机理，有望夯实寒冷地区活性污泥法污水处理的理论和实践，对提高冬季污水处理效果，保护新疆脆弱的生态环境及保障新疆经济社会的可持续发展具有重要意义。

污泥膨胀一直困扰活性污泥工艺高效稳定运行的主要问题，虽然污泥膨胀的研究已经取得大量研究成果，但针对干旱寒冷地区污水处理厂活性污泥沉降性能及其影响机理的研究较少。本项目以新疆北疆寒冷地区氧化沟城市污水处理厂为研究对象，探讨了干旱寒冷地区活性污泥的沉降性能及其影响因素，并采用高通量测序技术，分析了不同沉降性能活性污泥的菌群结构特征；在实验室启动3套SBR反应器，进行了污泥膨胀的影响因素及控制措施实验研究。通过本项目的研究，获得了以下重要成果：(1) 水温对干旱寒冷地区对活性污泥的沉降性能有一定影响。有的污水厂水温越低，污泥沉降性能越差，出现冬、春季季节性污泥丝状膨胀；有的污水厂一年四季均出现污泥丝状膨胀；而有的污水厂冬季水温低至7℃,污泥沉降性能却良好。(2)在好氧段前增设30min厌氧段，可以快速抑制污泥丝状膨胀，主要是对菌群进行了选择，抑制了引起膨胀丝状菌的生长。(3)首次报道了活性污泥中细菌腐螺旋菌属（Saprospiraceae_norank）相对丰度较高时，可引发污泥丝状膨胀。（4）细菌微丝菌属（Microthrix）和黄杆菌属（Flavobacterium）在活性污泥中的相对丰度随水温呈现出季节性变化是干旱寒冷地区出现季节性丝状污泥膨胀的微生物学原因。（5）干旱寒冷地区活性污泥法污水处理厂采取超低污泥负荷、高溶解氧的运行措施，可在冬季低水温时取得良好的水质处理效果和良好的污泥沉降性能。（6）干旱寒冷地区活性污泥中细菌优势门和真菌优势门均与非寒冷地区活性污泥差异不大，但优势细菌属和优势真菌属与非寒冷地区有显著差异。（7）没有化学除磷的活性污泥法污水处理厂，活性污泥的胞外聚合物含量越多，污泥沉降性能越差；而在投加化学除磷的污水处理厂，活性污泥胞外聚合物与污泥沉降性能相关不大。本项目的研究，可为干旱寒冷地区活性污泥法污水厂的高效稳定运行提供理论和技术支撑。