Effects of thermal and thermal-alkaline pretreatments on continuous anaerobic sludge digestion: Performance, energy balance and, enhancement mechanism

Hong Chen, Hao Yi, Hechao Li, Xuesong Guo and Benyi Xiao

Renewable Energy, 2020, vol. 147, issue P1, 2409-2416

Abstract: The effects of thermal pretreatment (TP) and thermal-alkaline pretreatment (TAP) on a continuous mesophilic anaerobic digestion (AD) of sewage sludge were investigated. Both TP (134 ± 1 °C and 30 min) and TAP (pH 12, 134 ± 1 °C and 30 min) released, hydrolyzed, and mineralized the organic matter of sludge, but TAP provided superior results. The methane yields of thermal pretreated sludge (TPS) and thermal-alkaline pretreated sludge (TAPS) were 1.88 times and 2.20 times that of raw sludge (RS), respectively. Moreover, the average methane content of biogas produced from TAPS (73.4 ± 3.4%) was higher than that from TPS (69.1 ± 3.1%) and from RS (67.2 ± 2.9%). The energy balance of the total process with TAP was the highest (4.326 kJ/g VS) and that of the RS AD was the lowest (2.045 kJ/g VS). Both pretreatments enhanced the sludge hydrolysis with TAP presenting higher efficiency, and shifted the rate-limiting step of the anaerobic sludge digestion from hydrolysis to methanogenesis.

Keywords: Continuous anaerobic sludge digestion; Energy balance; Enhancement mechanism; Thermal pretreatment; Thermal-alkaline pretreatment (search for similar items in EconPapers)
Date: 2020
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Citations: View citations in EconPapers (4)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:renene:v:147:y:2020:i:p1:p:2409-2416

DOI: 10.1016/j.renene.2019.10.051

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