碳源类型对污泥沉降性能及丝状菌生长的影响

Effects of carbon sources on sludge settling and filamentous bacteria growth

污泥膨胀的发生与进水水质和运行工况密切相关,为弄清碳源类型是否会引发污泥膨胀,以及不同碳源是否会导致不同的优势丝状菌,在3个严格控制运行条件的序批式反应器中,分别采用乙酸钠、葡萄糖、淀粉作为碳源,研究了碳源类型对污泥沉降性能及丝状菌生长的长期影响。当反应器内底物浓度梯度低导致微生物贮存能力下降时,乙酸钠、葡萄糖作碳源的污泥出现了大量丝状菌繁殖,引发了严重污泥膨胀,SVI超过了600ml.g-1。而淀粉作碳源时污泥絮体结构始终松散多孔,SVI值在300ml.g-1以内,污泥沉降性能并未出现严重恶化。乙酸钠和葡萄糖作碳源时第一优势丝状菌分别为Thiothrix nivea和S.natans,淀粉作碳源时第一优势丝状菌为N.limicolaⅡ和M.parvicella。可见,碳源类型的不同将会导致污泥出现不同的底物代谢特性,而污泥膨胀的发生与微生物的动力学和底物贮存特性密切相关。

The filamentous bulking of sludge is directly associated with specific influent characteristics and operational regime. In order to understand whether the types of carbon source can cause filamentous sludge bulking and lead to the formation of dominant filamentous bacteria, their long-term effects on sludge settleability and filaments growth as well as the competition between filaments and floc-formers were investigated. Three lab-scale sequencing batch reactors under controlled conditions were operated by using acetate, glucose and starch as carbon sources, respectively. When the storage capability of microorganisms was limited by decrease of substrate concentration gradient, there appears a great quantity reproduction of filamentous bacteria i. e. filamentous bulking （sludge volume index, SVI〉600 ml· g^-1 ） for acetate- and glucose-fed systems. SVI was kept below 300 ml · g^-1 for starch-fed reactor, although much open, fluffy and porous flocs were formed, and settling performance had no serious deterioration. The results from staining reactions and fluorescent in situ hybridization showed that the first dominant filament was Thiothrix nivea for the acetate-fed reactor, S. natans for the glucose-fed reactor, N. limicola Ⅱ and M. parvicella for the starchfed reactor. So, it was demonstrated that various carbon sources can lead to different metabolic characteristics for various substrates, and the occurrence of filamentous bulking was closely associated with kinetics and storage properties of microorganisms.