Performance and stability of sewage sludge digestion under CO2 enrichment: A pilot study

• DOI: 10.1016/j.biortech.2017.08.071
• Publication Date: 2017-08-16T17:15:26Z
• Authors: Luca Alibardi; Kevin Green; Lorenzo Favaro; Peter Vale; Ana Soares; Elise Cartmell; Yadira Bajón Fern...
• Keywords: Anaerobic digestion; Carbon dioxide utilisation; Pilot scale; Process stability; Sewage sludge; Bioengineering; Environmental Engineering; Renewable Energy, Sustainability and the Environment; Waste Management and Disposal; 660; Carbon dioxide utilisation; Sewage; Pilot scale; Pilot Projects; Carbon Dioxide; Process stability; 7. Clean energy; 01 natural sciences; 6. Clean water; 12. Responsible consumption; Bioreactors; 13. Climate action; Anaerobic digestion; Anaerobiosis; Sewage sludge; Methane; 0105 earth and related environmental sciences

Carbon dioxide (CO2) injection in anaerobic digestion has recently been proposed as an interesting possibility to boost methane (CH4) recovery from sludge and organic waste by converting a greenhouse gas into a renewable resource. This research assessed the effects of exogenous CO2 injection on performance and process stability of single-phase continuous anaerobic digesters. Two pilot scale reactors treating sewage sludge were operated for 130days. One reactor was periodically injected with CO2 while the other acted as control. Two injection frequencies and injection devices were tested. The results indicated that CO2 enrichment allowed an increase in CH4 production of ca. 12%, with a CH4 production rate of 371±100L/(kgVSfed·d) and a CH4 concentration of ca. 60% when dissolved CO2 levels inside the test reactor were increased up to 1.9-fold. Results also indicated an improvement in process resilience to temporary overloads and no impacts on stability parameters.