• 关键词：游离菌  碳源  活性污泥  凝聚  胞外聚合物

• 基金项目：国家自然科学基金（No.50878180）

• 魏萍
• 西安建筑科技大学陕西省环境工程重点实验室, 西北水资源与环境生态教育部重点实验室, 西安 710055

• 袁林江
• 西安建筑科技大学陕西省环境工程重点实验室, 西北水资源与环境生态教育部重点实验室, 西安 710055

• 陈希
• 西安工程大学城市规划与市政工程学院, 西安 710048

• 王骞
• 西安建筑科技大学陕西省环境工程重点实验室, 西北水资源与环境生态教育部重点实验室, 西安 710055

• 袁林杰
• 西安建筑科技大学陕西省环境工程重点实验室, 西北水资源与环境生态教育部重点实验室, 西安 710055

• 摘要：为揭示碳源种类在细菌形成菌胶团中的作用，在好氧批式培养条件下研究了以4种有机物作为人工废水中的碳源，培养污水中细菌从完全游离到凝聚为絮体的过程.结果显示，当以小分子有机物（乙酸钠或葡萄糖）和大分子有机物（蛋白胨或可溶性淀粉）作为碳源时，分别培养大约48 h和24 h即出现直径大于30 μm的絮体.碳源为大分子有机物时，絮体形成过程中絮体的胞外聚合物（EPS）中蛋白与多糖比值达到极值所用时间较以小分子有机物为碳源要短.以蛋白胨为例，这些指标在培养开始24 h时即分别达到了最大接触角（64.91°）、最小Zeta电位（9.21 mV）和最大PN/PS值（6.25），但用乙酸钠培养时，达到最大接触角（53.52°）、最小Zeta电位（12.2 mV）和最大PN/PS值（8.03）所需时间为36 h.研究发现，絮体的PN/PS比值与接触角之间呈显著正相关（r>0.7，p<0.05），但与Zeta电位绝对值之间呈显著负相关（r<-0.89，p<0.05）.大分子有机物作碳源时，细菌EPS中蛋白质的合成相比多糖更快更多，增加了细菌表面EPS的疏水性，从而使细菌个体间静电斥力降低，导致游离细菌易于因搅动和相互碰撞凝聚成团.

• Abstract：Aiming to investigate the effects of different carbon source on the floc formation from completely free bacteria, 4 organic substrates were selected as carbon source in synthetic wastewater, and batch experiment of cultivation fed the wastewater were conducted under aerobic condition applying free bacteria from municipal sewage. Results indicate sludge flocs (bigger than 30 μm in diameter) appeared roughly after cultivation for more than 48 hours when feeding small molecular organics (such as sodium acetate or glucose), while earlier at 24 hour for macro-molecular organics(such as peptone or starch). In the cultivation with feeding the macro-molecular organic substrates, time that the indices of contact angle(in maximum), zeta potential(in minimum) and ratio of amount of protein to polysaccharide (PN/PS)(in maximum)of the culture reached limit values taken, is less than that of the small molecular organics, in which were 64.91°, 9.21 mV and 6.25 respectively in case of peptone at 24 h and 53.52°, 12.2 mV and 8.03 for sodium acetate at 36 h. It was revealed that there was a significant positive correlation regressed between the PN/PS and the contact angle (r>0.7, p<0.05) during the flocs formation, while negative (r<-0.89, p<0.05) between the PN/PS and absolute value of the Zeta potential. It is suggested that free bacteria fed macro-molecular organics, will synthesize more protein and less polysaccharide in their within shorter time than that of small molecular organics, so that hydrophobicity of the EPS of the bacteria increase resulting in decrease in electrostatic repulsion among the bacteria, and facilitate bacteria to coagulate into flocs when colliding with each other due to agitation.

• Key words：free bacteria  carbon sources  activated sludge  aggregation  extracellular polymer substance(EPS)

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