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首页> 外文期刊>Environmental Science & Technology >Improved bioproduction of short-chain fatty acids (SCFAs) from excess sludge under alkaline conditions
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Improved bioproduction of short-chain fatty acids (SCFAs) from excess sludge under alkaline conditions

机译：碱性条件下过量污泥可提高短链脂肪酸（SCFA）的生物产量

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The production of short-chain fatty acids (SCFAs) from excess sludge was conducted in batch fermentation tests at different pH values ranging from 4.0 to 11.0. Experimental results of the impacts of different pHs on SCFAs production showed that during the first 8-day fermentation time the total SCFAs production at either pH 9.0 or pH 10.0 was much greater than that at acidic or neutral pH, and the maximal yield of 256.2 mg SCFAs-COD per gram of volatile suspended solids (VSS) was at pH 10.0, which was, respectively, over 3 and 4 times that at pH 5.0 and uncontrolled pH. Clearly, SCFAs production from excess sludge could be significantly improved and maintained stable by controlling the fermentation pH at 10.0. The composition of SCFAs and the percent distribution of individual SCFAs accounting for total SCFAs at pH 10.0 were analyzed. The SCFAs consisted of acetic, propionic, iso-butyric, n-butyric, isovaleric, and n-valeric acids, and acetic acid was the most prevalent product with a fraction of 40-55%. Because the results of this study were different from those of previous studies of SCFAs production, the mechanism of increased SCFAs production under alkaline conditions was investigated. Results showed that as soluble COD increased, more soluble protein was provided as the substrate for producing SCFAs. In addition, less or even no SCFAs were consumed by methanogens at alkaline pH, so the SCFAs production was therefore remarkably improved. Further investigation revealed that the formation of SCFA at pH 10.0 was dominated by biological effects rather than by chemical hydrolysis.
机译：在4.0至11.0的不同pH值下，通过分批发酵测试从过量污泥中生产短链脂肪酸（SCFA）。不同pH值对SCFAs产生影响的实验结果表明，在发酵的前8天中，pH 9.0或pH 10.0时的SCFA总量比酸性或中性pH值大得多，最大产量为256.2 mg每克挥发性悬浮固体（VSS）的SCFAs-COD的pH值为10.0，分别是pH 5.0和不受控制的pH值的3倍和4倍。显然，通过将发酵液的pH值控制在10.0，可以显着改善过量污泥产生的SCFA，并保持稳定。分析了SCFA的组成和单个SCFA的百分比分布（占pH 10.0时的总SCFA）。 SCFA由乙酸，丙酸，异丁酸，正丁酸，异戊酸和正戊酸组成，而乙酸是最常见的产物，其比例为40-55％。由于本研究的结果与以前的SCFAs生产研究不同，因此研究了碱性条件下SCFAs产量增加的机理。结果表明，随着可溶性COD的增加，提供了更多的可溶性蛋白作为产生SCFA的底物。另外，在碱性pH下，产甲烷菌消耗的SCFA很少甚至没有，因此，SCFA的产量得到了显着提高。进一步的研究表明，pH 10.0时SCFA的形成主要是由于生物学作用而不是化学水解。

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