Anaerobic digestion of sewage sludge with grease trap sludge and municipal solid waste as co-substrates

• Published in: Environmental research Vol. 155; pp. 249 - 260
• Main Authors: Grosser, A., Neczaj, E., Singh, B.R., Almås, Å.R., Brattebø, H., Kacprzak, M.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01-05-2017
• Subjects: Anaerobiosis; Biofuels - analysis; Biological Oxygen Demand Analysis; Bioreactors; Carbon - analysis; Co-digestion; Co-substrate; Lipids; Long chain fatty acids; Methane - analysis; Methane yield; Nitrogen - analysis; Sewage; Sewage sludge; Solid Waste; Waste Management - methods; Water Pollutants - analysis; Long chain fatty acids; Methane yield; Sewage sludge; Co-digestion; Co-substrate
• ISSN: 0013-9351; 1096-0953
• DOI: 10.1016/j.envres.2017.02.007

The feasibility of simultaneous treatment of multiple wastes via co-digestion was studied in semi-continuous mode at mesophilic conditions. The obtained results indicated that sewage sludge, organic fraction of municipal waste (OFMSW) and grease trap sludge (GTS) possess complementary properties that can be combined for successful anaerobic digestion. During the co-digestion period, methane yield and VS removal were significantly higher in comparison to digestion of sewage sludge alone. Addition of GTS to digesters treating sewage sludge resulted in increased VS removal and methane yield up to 13% (from 50 to 56.4) and 52% (from 300 to 456,547m3/Mg VSadd), respectively. While the use of OFMSW as the next co-substrate in the feedstock, can boost methane yield and VS removal up to 82% (300–547m3/Mg VSadd) and approximately 29% (from 50% to 64.7%), respectively. Moreover, the results of the present laboratory study revealed that the addition of co-substrates to the feedstock had a significant influence on biogas composition. During the experiment methane content in biogas ranged from 67% to 69%. While, the concentration of LCFAs was increasing with the gradual increase in the share of co-substrates in the mixtures, wherein only the oleic acid was higher than some inhibition concentrations which have been reported in the literature. However, it did not significantly affect the efficiency of the co-digestion process.
•Addition of two waste into the sewage sludge digester improves process efficiency.•Co-digestion of 3-component mixtures increases VS removal up to 29%.•While, methane yield increased up to and 82% relative to the control digester.•Effectiveness of the process depends on OLR and the content of waste in the feedstock.