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Development of a continuous‐flow anaerobic co‐digestion process of olive mill wastewater and municipal sewage sludge
Author(s) -
Bovina Sara,
Frascari Dario,
Ragini Alessandro,
Avolio Francesco,
Scarcella GianNicola,
Pinelli Davide
Publication year - 2021
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.6570
Subject(s) - anaerobic digestion , hydraulic retention time , wastewater , pulp and paper industry , environmental science , sewage , sewage treatment , waste management , anaerobic exercise , bioreactor , sewage sludge , methane , chemistry , environmental engineering , engineering , biology , organic chemistry , physiology
BACKGROUND Olive mill wastewater (OMW) represents an environmental problem due to its high organic load and relevant concentration of phenolic compounds (PCs). OMW treatment and disposal represents a relevant challenge and cost for olive mills and multi‐utilities in charge of waste management in Mediterranean countries. The goal of this study was to develop an anaerobic co‐digestion (co‐AD) process of OMW and sewage sludge (SwS) from municipal wastewater treatment. RESULTS Different volumetric OMW:SwS ratios up to 100% OMW were fed in continuous 1.7‐L bioreactors. The reactors fed with raw OMW (rOMW) performed better than those fed with OMW dephenolized by adsorption (dOMW). At a 23‐day hydraulic retention time, the best performances were obtained in the reactor fed with 25% rOMW, with a 105% increase in methane yield in comparison to the 100% SwS test. At a 40‐day hydraulic retention time, the reactor fed with 40% rOMW attained a 268 NL CH4 /kg volatile solids methane yield. The conversion of phenolic compoundsreached 70% when the hydraulic retention time was increased from 23 to 40 days. A cost–benefit analysis indicated that both rOMW co‐AD in existing digesters and phenolic compounds recovery from OMW followed by co‐AD of dOMW can lead to relevant additional revenues for the multi‐utilities in charge of wastewater management. CONCLUSION This work proves that, using the existing network of SwS anaerobic digesters, it is feasible to co‐digest the entire OMW production in regions characterized by intense olive oil production, thus attaining a relevant increase in methane production yield (a 144% increase in comparison to 100% SwS). © 2020 Society of Chemical Industry (SCI)