Effect of ultrasonication on anaerobic degradability of solid waste digestate

• Published in: Waste management (Elmsford) Vol. 48; pp. 209 - 217
• Main Authors: Boni, M.R., D’Amato, E., Polettini, A., Pomi, R., Rossi, A.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 01.02.2016
• Subjects: Anaerobic digestion; Anaerobiosis; Biodegradability; Biodegradation, Environmental; Biofuels; Biological; Biomethane; Degradation; Digestate treatment; Food; Gain; Hydrolysis; Lignin - chemistry; Lignocellulose; Lignocellulosic waste; Methane - biosynthesis; Organic chemistry; Refuse Disposal - methods; Residues; Sewage - chemistry; Solid Waste; Sonication; Ultrasonics - methods; Hydrolysis; Sonication; Biomethane; Digestate treatment; Anaerobic digestion; Lignocellulosic waste
• ISSN: 0956-053X; 1879-2456
• DOI: 10.1016/j.wasman.2015.10.031

•The effect of sonication on digestibility of lignocellulosic residues was studied.•Sonication was applied as a post-treatment of food waste digestate.•Sonication positively affected the residual methanogenic potential of the digestate.•The maximum biogas production exceeded that of the unsonicated substrate by 30%. This paper evaluates the effect of ultrasonication on anaerobic biodegradability of lignocellulosic residues. While ultrasonication has been commonly applied as a pre-treatment of the feed substrate, in the present study a non-conventional process configuration based on recirculation of sonicated digestate to the biological reactor was evaluated at the lab-scale. Sonication tests were carried out at different applied energies ranging between 500 and 50,000kJ/kg TS. Batch anaerobic digestion tests were performed on samples prepared by mixing sonicated and untreated substrate at two different ratios (25:75 and 75:25 w/w). The results showed that when applied as a post-treatment of digestate, ultrasonication can positively affect the yield of anaerobic digestion, mainly due to the dissolution effect of complex organic molecules that have not been hydrolyzed by biological degradation. A good correlation was found between the CH4 production yield and the amount of soluble organic matter at the start of digestion tests. The maximum gain in biogas production was 30% compared to that attained with the unsonicated substrate, which was tentatively related to the type and concentration of the metabolic products.