Anaerobic Co-digestion of Cattle Manure and Sewage Sludge: Influence of Composition

García K.; Pérez M.
This paper presents the study of co-digestion of two types of organic wastes: cattle manure and sewage sludge from waste water treatment stations. Co-digestion of sewage sludge and cattle manure has the advantage of sharing processing facilities, unifying management methodologies, reducing operating costs and dampening investment and temporal variations in composition and production of each waste separately. The aim of this work was to select suitable operating conditions (both composition and temperature) of anaerobic co-digestion process of cattle manure and sewage sludge to optimize the process in the biogas generation. The batch tests have been developed at mesophilic and thermophilic conditions to determine the anaerobic biodegradability of three different mixtures of cattle manure and sewage sludge, both in static or stirring conditions. The obtained experimental results indicate that the anaerobic biodegradability of raw sludge and cattle manure mixtures is more efficient at thermophilic conditions since a greater elimination of organic matter with a greater methane yield is obtained. The most efficient process corresponds to the mixture with 25% v/v of cattle manure and 75% v/v of raw sludge with values of 62% and 75.7% of COD and DOC removals, respectively and methane yields of 2200 mL CH4/g CODr and 306 ml CH4/gVSr, presenting a period of starting of 12 days. Also, it is verified that a higher amount of cattle manure in the mixture means a higher alkalinity and a greater percentage of methane in biogas. The biodegradability validation tests at stirring conditions confirm the kindness of the thermophilic process.
Co-Digestion; Biodegradability; Cattle Manure; Sewage Sludge; Mesophilic; Thermophilic
Download | Back to Issue| Archive