Enhanced Production of Methane from Waste Activated Sludge by Pretreatment Using a Gas Diffusion Cathode

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• 作者：Yufeng Jia ; Huajun FengDongsheng Shen ; Yuyang Zhou ; Yanfeng Wang ; Wei Chen ; Bin Huang
• 刊名：Energy & Fuels
• 出版年：2016
• 出版时间：December 15, 2016
• 年：2016
• 卷：30
• 期：12
• 页码：10511-10515
• 全文大小：324K
• ISSN：1520-5029

文摘

Anaerobic digestion is an alternative technology for the pretreatment of waste activated sludge (WAS) before final disposal. Hydrolysis is the rate-limiting step in this process; therefore, pretreatment of WAS to allow for high-efficiency anaerobic digestion is beneficial. In the present work, an electrochemical system characterized by a gas diffusion cathode (GDC) was established to facilitate WAS pretreatment. This GDC was composed of a carbon black diffusion layer and a Ni/NiO_x catalytic layer. H₂O₂, an essential component of the pretreatment, was evolved on the electrode surface at a rate of 27.3 mg cm^–2 day^–1. Upon varying the potential of the GDC from 0 to −1.0 V (versus Ag/AgCl), the soluble chemical oxygen demand (SCOD) and the protein and carbohydrate concentrations increased from 134 ± 6, 38 ± 6, and 20 ± 3 mg/L to 3617 ± 65, 1436 ± 121, and 470 ± 64 mg/L, respectively, over 8 h. The ratio of SCOD to the total chemical oxygen demand (TCOD) was 48 ± 1.3%. The total methane output of the GDC pretreated sludge at the end of 10 days was close to 234 mL/g TCOD, which was 33.8% greater than that of the control sludge. The Ni/NiO_x-modified GDC also exhibited excellent stability performance. The results of this work demonstrate the pivotal role of the combination of H₂O₂ and alkali generated by the GDC in the enhanced pretreatment of WAS.