Water-energy nexus: Anaerobic co-digestion with elephant grass hydrolyzate

• Published in: Journal of environmental management 2016-10, Vol.181, p.48-53
• Main Authors: Carvalho, A.R., Fragoso, R., Gominho, J., Saraiva, A., Costa, R., Duarte, E.
• Format: Article
• Language: English
• Subjects: Anaerobic co-digestion; Anaerobiosis; Bacteria, Anaerobic - metabolism; Biodegradation, Environmental; Bioreactors; Chemical oxygen demand; Energy; Grasses; Humans; Hydraulics; Methane yield; Pennisetum purpureum; Poaceae - enzymology; Protein Hydrolysates - metabolism; Reactors; Sewage sludge; Treatment performance; Waste Water; Water; Water Microbiology; Water Pollutants - metabolism
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2016.06.012

The anaerobic co-digestion process in a continuous stirred-tank reactor (CSTR) was carried out under mesophilic conditions (37 ± 0.2 °C). All the trials were performed at a hydraulic retention time (HRT) of 15 days and the AD reactor was daily fed with a mixture of sewage sludge (SS) and elephant grass hydrolyzate (EGH). In this study, three different trials were assessed, with different mixture proportions of SSSS and EGH: F0 (100:0,v/v), F1 (75:25, v/v) and F2 (50:50, v/v), during 90 days each trial, keeping the organic loading rate (OLR) in a range of 0.94–1.16 g VS L−1 day−1. The experimental results obtained showed that the soluble chemical oxygen demand (SCOD) removal efficiency was around 77% and 86% for trials F1 and F2, respectively. SS co-digestion with EGH enhanced methane yield, leading to an increment between 23% and 38%, in comparison with the reference scenario (F0). [Display omitted] •Mesophilic anaerobic digester performance linked with WTPS and EGH.•A 12 L bench-scale reactor operated at mesophilic conditions and 15 days of HRT.•A combination of a pretreatment and anaerobic digestion was assessed.•The effectiveness of adding easily biodegradable organic matter was confirmed.