Improved Bioproduction of Short-Chain Fatty Acids (SCFAs) from Excess Sludge under Alkaline Conditions

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• 作者：Hongying Yuan ; Yinguang Chen ; Huaxing Zhang ; Su Jiang ; Qi Zhou ; and Guowei Gu
• 刊名：Environmental Science & Technology
• 出版年：2006
• 出版时间：March 15, 2006
• 年：2006
• 卷：40
• 期：6
• 页码：2025 - 2029
• 全文大小：159K
• 年卷期：v.40,no.6(March 15, 2006)
• ISSN：1520-5851

文摘

The production of short-chain fatty acids (SCFAs) fromexcess sludge was conducted in batch fermentation testsat different pH values ranging from 4.0 to 11.0. Experimentalresults of the impacts of different pHs on SCFAs productionshowed that during the first 8-day fermentation time thetotal SCFAs production at either pH 9.0 or pH 10.0 was muchgreater than that at acidic or neutral pH, and the maximalyield of 256.2 mg SCFAs-COD per gram of volatilesuspended solids (VSS) was at pH 10.0, which was,respectively, over 3 and 4 times that at pH 5.0 and uncontrolledpH. Clearly, SCFAs production from excess sludge couldbe significantly improved and maintained stable by controllingthe fermentation pH at 10.0. The composition of SCFAsand the percent distribution of individual SCFAs accountingfor total SCFAs at pH 10.0 were analyzed. The SCFAsconsisted of acetic, propionic, iso-butyric, n-butyric, iso-valeric, and n-valeric acids, and acetic acid was the mostprevalent product with a fraction of 40-55%. Becausethe results of this study were different from those of previousstudies of SCFAs production, the mechanism of increasedSCFAs production under alkaline conditions was investigated. Results showed that as soluble COD increased, moresoluble protein was provided as the substrate for producingSCFAs. In addition, less or even no SCFAs were consumedby methanogens at alkaline pH, so the SCFAs production wastherefore remarkably improved. Further investigationrevealed that the formation of SCFA at pH 10.0 was dominatedby biological effects rather than by chemical hydrolysis.