Source and Composition of Organic components in treated wastewater

尽管生物处理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有微量的乐果类物质存在。如果水体的来源主要是经过处理的废水，那么微量的有机物质会影响水环境，那里的流域人口稠密。虽然处理后废水中有机物的来源部分归因于进水中难生物降解的物质，但用于废水处理的微生物可能是处理后废水中有机物的来源。因此，在本研究中，我们研究了活性污泥中的微生物对处理后废水中有机物的贡献。采用有机组成简单的人工合成废水进行活性污泥法处理，对处理后废水中的有机物进行了详细的分析，并对出水进行了微量有机物分析。处理后废水中的有机物用二氯甲烷萃取、浓缩后直接用气相色谱/质谱仪进行分析。共鉴定出4种有机物质。虽然大部分化合物被鉴定为脂肪脂肪酸，但也发现了芳香族化合物。对于同一反应器，如果采样日期不同，检测到的有机物也会发生显著变化。在研究的后期，考察了处理后废水中蛋白质和碳水化合物的行为。蛋白质和碳水化合物解释了处理后废水中近70%的有机物质。据估计，实际污水处理厂处理后的废水中，约有一半的有机物来自活性污泥。出水溶解有机碳的波动与碳水化合物有较高的相关性，与蛋白质的相关性不大。

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.