Improving anaerobic sewage sludge digestion by implementation of a hyper-thermophilic prehydrolysis step

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• 作者：Jingquan Lu ; Hariklia N. Gavala ; Ioannis V. Skiadas ; Zuzana Mladenovska ; Birgitte K. Ahring
• 关键词：Anaerobic digestion ; Microbial activity ; Pre-treatment ; Primary ; Sludge ; Thermal ; Thermophilic ; Two-step process
• 刊名：Journal of Environmental Management
• 出版年：2008
• 出版时间：September 2008
• 年：2008
• 卷：88
• 期：4
• 页码：881-889
• 全文大小：281 K

文摘

The present study focuses on a two-step process for treatment and stabilisation of primary sludge. The process consists of a hyper-thermophilic hydrolysis step operated at 70 °C and a hydraulic retention time (HRT) of 2 days followed by a thermophilic (55 °C) anaerobic digestion step at a HRT of 13 days. A one-step anaerobic digester operated at 55 °C and 15 days HRT was used as a reference process. The two-step process was characterized by a 12 % higher organic suspended solids removal efficiency and better pathogen reduction effect than the conventional one-step digestion. The microbial community of the digester fed with pre-treated sludge was characterised by a higher activity compared to that of the digester treating raw sludge. Moreover, the pre-treatment of the primary sludge resulted up to 48 % increase of the methane potential (20.09 and 13.56 mmol CH₄ g⁻ VS⁻¹ with and without pre-treatment, respectively) and up to 115 % increase of the methane production rate. Finally it was shown that the extra energy requirements for the operation of a pre-treatment step would be covered by the energy produced from the extra methane production and in addition there would be a significant energy surplus of 2.17 kJ d⁻¹ for the system tested.