Effects of thermobarical pretreatment of cattle waste as feedstock for anaerobic digestion

Abstract

Lab-scale experiments were conducted to assess the impact of thermobarical treatment of cattle waste on anaerobic digestion. Treatment was at temperatures of 140-220°C in 20K steps for a 5-min duration. Methane yields could be increased by up to 58% at a treatment temperature of 180°C. At 220°C the abundance of inhibitors and other non-digestible substances led to lower methane yields than those obtained from untreated material. In an extended analysis it could be demonstrated that there is a functional correlation between the methane yields after 30 days and the formation rate and methane yield in the acceleration phase. It could be proved in a regression of these correlation values that the optimum treatment temperature is 164°C and that the minimum treatment temperature should be above 115°C.

Keywords: DM; FM; GC–MS; Hydrolysis; Inhibitors; LCM; LHW; Mathematical analysis; Methane yield; ODM; OM; P1; P2; PT[n]M[n]S; SCM; SCMW; SLCM; TBH; VOA; d; days; dry matter; fresh matter; gas chromatography mass spectrometry; liquid cattle manure; liquid hot water; organic dry matter; organic matter; plant 1; plant 2; solid and liquid cattle manure; solid cattle manure; solid cattle manure and water; thermobarical hydrolysis; time period in minutes and seconds; volatile organic acids.