Comprehensive assessment of sludge wet air oxidation and its combination with anaerobic digestion

Jiayi Liu, Debin Li, Lin Wang, Huan Li and Zhou Deng

Renewable Energy, 2024, vol. 237, issue PB

Abstract: Wet air oxidation (WAO) is a promising sludge treatment technology but has yet to be used widely. This study evaluates a new integrated pathway of AD plus WAO, juxtaposing against the standalone AD and WAO, from the aspects of carbon emissions, energy efficiency, and cost-benefits. The assessment unit is 1 t dewatered sludge with a water content of 80 %, and the greenhouse gases are converted to equivalent CO2. WAO can recover the thermal heat released from organic oxidation, resulting in the lowest carbon emissions, 10.92 to −36.86 kg CO2-eq/t. AD plus WAO also performs well with 32.21 to −48.16 kg CO2-eq/t. All three ways can produce renewable energy through biogas utilization or thermal recovery. WAO has the highest energy efficiency of 35%–42 % due to efficient thermal energy recovery, and AD plus WAO has a second-ranked efficiency of 15%–30 %. However, WAO needs expensive facilities and external electricity, resulting in a higher expenditure than AD. The integrated systems also require a high investment, but can simplify digested sludge treatment. According to the normalized scores in the three aspects, WAO is recommended chiefly, especially for treating low-organic-content sludge. AD plus WAO ranked second and can be used for high-organic-content sludge.

Keywords: Sludge; Wet air oxidation; Anaerobic digestion; Carbon emission; Energy efficiency (search for similar items in EconPapers)
Date: 2024
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Persistent link: https://EconPapers.repec.org/RePEc:eee:renene:v:237:y:2024:i:pb:s0960148124018536

DOI: 10.1016/j.renene.2024.121785

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