Enhancement of Methanogenic Activity in Volumetrically Undersized Reactor by Mesophilic Co-Digestion of Sewage Sludge and Aqueous Residue

Vincenzo Torretta, Athanasia K. Tolkou, Ioannis A. Katsoyiannis, Francesca Maria Caccamo, Marco Carnevale Miino, Marco Baldi and Maria Cristina Collivignarelli
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Vincenzo Torretta: Department of Theoretical and Applied Sciences, Insubria University of Varese, Via G.B. Vico, 46, 21100 Varese, Italy
Athanasia K. Tolkou: Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
Ioannis A. Katsoyiannis: Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
Francesca Maria Caccamo: Department of Civil Engineering and Architecture, University of Pavia, Via Ferrata 3, 27100 Pavia, Italy
Marco Carnevale Miino: Department of Civil Engineering and Architecture, University of Pavia, Via Ferrata 3, 27100 Pavia, Italy
Marco Baldi: Department of Chemistry, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy
Maria Cristina Collivignarelli: Department of Civil Engineering and Architecture, University of Pavia, Via Ferrata 3, 27100 Pavia, Italy

Sustainability, 2021, vol. 13, issue 14, 1-11

Abstract: To date, energy recovery from biological sewage sludge (BSS) by anaerobic digestion has been very popular. However, it can often happen that anaerobic reactors are volumetrically undersized, thus reducing performance in terms of biogas production. A continuous-flow pilot-scale plant was used to investigate, for the first time, the effects of mesophilic anaerobic co-digestion (MACoD) of sewage sludge and aqueous residue (AR) from a biosolids treatment plant (BTP) on methanogenic activity under low hydraulic retention time (HRT) conditions (to simulate the undersizing of the reactor). The results showed that the digestate is always more rapidly biodegradable than the matrices fed, while particulate COD hydrolyzed (12 ± 1.3%) is independent of the quantity of AR dosed. Feeding over 35% of soluble OLR, the total VFAs in the system strongly decreased, despite the low HRT. In correspondence with higher dosages of AR, the percentage of CH 4 increased up to 77–78% and the CO 2 CH 4 ?1 ratio decreased to 0.25 ± 0.2. Specific methane production increased from 0.09 ± 0.01 m 3 CH4 kgCOD removed ?1 with BSS alone to 0.28 ± 0.01 m 3 CH4CH4 kgCOD removed ?1 in the case of BSS co-digested with AR. Moreover, co-digestion with AR from a BTP allowed continuous specific methanogenic activity to be enhanced from 1.76 ± 0.02 m 3 CH4 t VSS ?1 d ?1 to 6.48 ± 0.88 m 3 CH4 t VSS ?1 d ?1 . Therefore, the MACoD of BSS and AR from a BTP could be a good solution to enhance methanogenic activity in a volumetrically undersized anaerobic digester with reduced HRT.

Keywords: biosolids; circular economy; biogas; energy recovery; methanogenic activity (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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