Source and Composition of Organic components in treated wastewater

虽然生物法对废水中的有机污染物有很好的去除效果，但在处理后的废水中仍残留有微量的有机物。当水体来源主要为处理后的废水，且流域人口密集时，微量有机物会影响水体的可持续性。虽然处理过的废水中的有机材料的来源部分归因于流入废水中的难以生物降解的材料，但用于废水处理的微生物可能是处理过的废水中有机材料的来源。因此，在本研究中，我们调查了活性污泥中的微生物对处理后废水中有机物的贡献。采用活性污泥法处理简单有机物组成的人工合成废水，对处理后废水中的有机物进行了详细的分析。处理后的废水中的有机物用二氯甲烷萃取，浓缩，并直接通过气相色谱/质谱分析。48种有机物质被鉴定。结果表明，在处理过程中，大部分化合物被鉴定为脂肪族脂肪酸，但也发现了芳香族化合物。同一反应器，不同采样日期的有机物检测结果也有较大差异。蛋白质和碳水化合物解释了近70%的有机物质在处理后的废水。据估计，在实际的污水处理厂中，处理后的污水中约有一半的有机物来自活性污泥。出水溶解性有机碳的波动与碳水化合物的相关性较高，而与蛋白质的相关性较低。

Although biological wastewater treatment is very efficient in removing organic pollutants in wastewater, there still remains trace level of roganic materials in treated wastewater. The trace organic materials can affect water environmtent if the source of a water body is mainly treated wastewater, where the watershed is densely populated. While the origin of the organic materials in treated wastewater is partly attributed to hardly biodegradable materials in influent wastewater, microorganisms used for wastewater treatment might be contributing as a source of organic materials in treated wastewater. Thus in the present study, we investigated the contribution of microorganisms in activated sludge to the organic materials in the treated wastewater. Activated sludge processes were operated with synthetic wastewater with simple orgnaic composition, and the organic materials in the treated wastewater was analyzed in detail.In the former part of the study, trace organic materials in the effluent were analyzed. Organic materials in the treated wastewater was extracted with dichloromethane, concentrated, and directly analyzed by gas chromatography/mass spectrometry. Fourtyeight organic materials were identified. While most part of the compounds were identified as aliphatic fatty acids, aromatic compounds were also found. The organic material detected changed significantly even for the same reactor if the sampling date was different.In the latter part of the study, the behavior of protein and carbohydrates in the treated wastewater was investigated. Protein and carbohydrates explained almost 70% of the organic materials in treated wastewater. It was estimated that about half of organic materials in treated wastewater in actual wastewater treatment plant is coming from activated sludge. The fluctuation of effluent dissolved organic carbon had high correlation with carbohydrates, but not with protein.