Barrios JA, Duran U, Cano A, Cisneros-Ortiz M, Hernández S. Sludge electrooxidation as pre-treatment for anaerobic digestion.
Water Sci Technol 2017;
75:775-781. [PMID:
28234278 DOI:
10.2166/wst.2016.555]
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Abstract
Anaerobic digestion of wastewater sludge is the preferred method for sludge treatment as it produces energy in the form of biogas as well as a stabilised product that may be land applied. Different pre-treatments have been proposed to solubilise organic matter and increase biogas production. Sludge electrooxidation with boron-doped diamond electrodes was used as pre-treatment for waste activated sludge (WAS) and its effect on physicochemical properties and biomethane potential (BMP) was evaluated. WAS with 2 and 3% total solids (TS) achieved 2.1 and 2.8% solubilisation, respectively, with higher solids requiring more energy. After pre-treatment, biodegradable chemical oxygen demand values were close to the maximum theoretical BMP, which makes sludge suitable for energy production. Anaerobic digestion reduced volatile solids (VS) by more than 30% in pre-treated sludge with a food to microorganism ratio of 0.15 g VSfed g-1 VSbiomass. Volatile fatty acids were lower than those for sludge without pre-treatment. Best pre-treatment conditions were 3% TS and 28.6 mA cm-2.
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