Abstract
In this study, co-digestion of mixed sewage sludge from a wastewater treatment plant (WWTP) and partially dephenolised two-phase olive pomace (DOP) as a co-substrate was addressed with the aim of improving the biodigestibility of both substrates. The introduction of DOP into WWTP anaerobic digester facilities could significantly increase biomethane production and enhance the sustainability of both activities. An improvement in the system's performance was supported by stability parameters: total alkalinity increased and stabilised with the addition of 5% v/v DOP, and the specific energy loading rate was maintained at 0.177 ± 0.03 d-1, which indicated better buffer capacity and stability in the bioreactor, and the possibility of enhancing the organic loading rate. In terms of average daily biogas production rate, an increase of 39% was achieved, up to 0.39 ± 0.11 L L-1d-1. Moreover, there was a 40% and 37% improvement in specific methane production and methane production rate, respectively, up to 0.28 ± 0.02 L CH4 g TVS-1 and 0.26 ± 0.08 L L-1d-1. In addition, the proposed strategy leads to an energy saving of 20,328.6 kWh year-1 at the WWTP as a result of the electric energy production surplus, corresponding to an annual saving of €3293.23.
Highlights
At wastewater treatment plants (WWTPs), which are typically located in urban areas and operated and designed on the basis of bio-oxidation processes, a substantial portion of the potential chemical energy in wastewater streams in the form of carbon dioxide is unrecoverable
The organic loading rate (OLR) was set at 0.90 ± 0.02 gTVS L−1reactor day−1 during anaerobic mono-digestion experiments with mixed sewage sludge (MSS), whereas it was increased to 0.94 ± 0.06 gTVS L−1reactor day−1 during AcoD runs when dephenolised twophase olive pomace (DOP) was added
The impact on anaerobic digestion performance when DOP is added to MSS is considered
Summary
At wastewater treatment plants (WWTPs), which are typically located in urban areas and operated and designed on the basis of bio-oxidation processes, a substantial portion of the potential chemical energy in wastewater streams in the form of carbon dioxide is unrecoverable. A huge amount of waste-activated sludge (WAS) is generated (Yang et al, 2019) Under this framework WWTPs face a new paradigm that will have serious environmental and economic impacts, and anaerobic co-digestion of sewage sludge with other nutrient-rich substrates such as agrofood waste is a potential strategy that could be further explored to enhance energy recovery and nutrient balance (Pellera and Gidarakos, 2017). Such a strategy could improve the management of WWTPs and promote energy self-sufficiency (Zhang et al, 2014, 2017). At least 25% of all bioenergy in the future is expected to come from anaerobic digestion/anaerobic co-digestion (AD/AcoD) of wet organic materials such as sewage sludge, whole crop silage and agrofood waste, among others (Kathijotes, 2016)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Waste Management & Research: The Journal for a Sustainable Circular Economy
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
