Erdal U G, Erdal Z K, Randall C W
Virginia Polytechnic and State University, Blacksburg, VA 24060, USA.
Water Sci Technol. 2003;47(11):123-8.
Temperature is one of the key parameters that affects the reaction kinetics and performance of enhanced biological phosphorus removal (EBPR) systems. Although studies agree regarding the effect of temperature on kinetic reaction rates, there are contradictory results in the literature regarding the effect of temperature on EBPR system performance. Early investigators (Sell, Ekama et al., Daigger et al.) reported better performance with lower temperatures, but others have reported partial or complete loss of EBPR functions at low temperatures (McClintock et al., Brdjanovic et a., Beatons et al.). One speculation is that deterioration in the EBPR system performance at cold temperatures can be attributed to rigid-like behavior of the cell membranes. Most cells (not all) on the other hand have the ability to alter their membrane fatty acid composition as temperature changes in order to keep their membrane at nearly the same fluidity despite the temperature changes. This unique ability is known as homeoviscous adaptation. In this study, homeoviscous adaptation by EBPR activated sludge was investigated for a series of temperatures ranging from 20 degrees C to 5 degrees C using a lab scale continuous flow EBPR system fed with acetate and supplemental yeast extract. The fatty acid analysis results suggested that the unsaturated to saturated fatty acid ratio increased from 1.40 to 3.61 as temperature dropped from 20 to 5 degrees C. The increased cis-9-hexadecanoic acid (C 16:1) at 5 degrees C strongly indicated the presence of homeoviscous adaptation in the EBPR bacterial community. Thus the cell membranes of the EBPR community were still in a fluid state, and solute transport and proton motive force were operable even at 5 degrees C. It was concluded that loss of EBPR performance at low temperatures is not related to the physical state of the cellular membranes, but is possibly related to the application of unsuitable operational conditions (low SRT, excessive electron acceptors, low anaerobic detention time, non-acclimated sludge, etc.).
温度是影响强化生物除磷（EBPR）系统反应动力学和性能的关键参数之一。尽管关于温度对动力学反应速率的影响已有相关研究达成共识，但文献中关于温度对EBPR系统性能的影响却存在相互矛盾的结果。早期研究人员（塞尔、埃卡马等人、戴格尔等人）报告称，较低温度下性能更佳，但也有其他人报告称在低温下EBPR功能会部分或完全丧失（麦克林托克等人、布尔贾诺维奇等人、比顿斯等人）。一种推测是，低温下EBPR系统性能的恶化可归因于细胞膜类似刚性的行为。另一方面，大多数细胞（并非全部）有能力随着温度变化改变其膜脂肪酸组成，以便尽管温度改变仍能使细胞膜保持几乎相同的流动性。这种独特能力被称为同黏适应。在本研究中，使用一个实验室规模的连续流EBPR系统，以乙酸盐和补充酵母提取物为进水，对一系列温度范围从20℃至5℃的EBPR活性污泥的同黏适应进行了研究。脂肪酸分析结果表明，随着温度从20℃降至5℃，不饱和脂肪酸与饱和脂肪酸的比例从1.40增加到3.61。5℃时顺式-9-十六碳烯酸（C 16:1）增加，有力地表明了EBPR细菌群落中存在同黏适应。因此，即使在5℃时，EBPR群落的细胞膜仍处于流体状态，溶质运输和质子动力仍可运作。得出的结论是，低温下EBPR性能的丧失与细胞膜的物理状态无关，而可能与不合适的运行条件（低污泥龄、过量电子受体、低厌氧停留时间、未驯化污泥等）的应用有关。
