Effects of hydrothermal pre-treatment on methane potential of anaerobic digestion sludge cake of cattle manure containing sawdust as bedding materials.

Abstract

The purpose of this study was to analyze the effect of the hydrothermal pretreatment of anaerobic digestion sludge cake of cattle manure on the solubilization of organic matter and the methane yield in order to improve the anaerobic digestion efficiency of cattle manure collected from the sawdust pens of cattle. Anaerobic digestion sludge cake (ADSC) of cattle manure was thermally pre-treated at 160, 180, 200, and 220°C by the hydrothermal pressure reactor, and the biochemical methane potential of ADSC hydrolysate was analyzed. Methane yield recovered by the hydrothermal pre-treatment of ADCS was estimated based on mass balance. The COD solubilization degree (CODs) of the hydrothermal hydrolysate increased to 63.56, 67.13, 70.07, and 66.14% at the hydrothermal reaction temperatures of 160, 180, 200, and 220 °C, respectively. Considering the VS content obtained after the hydrothermal pretreatment, the methane of 10.2 Nm3/ton-ADSC was recovered from ADSC of 1.0ton, and methane yields of ADSC hydrolysate increased to 15.6, 18.0, 17.4, and 17.2 Nm3/ton-ADSC. Therefore, the optimal hydrothermal reaction temperature that yielded the maximum methane yield was 180 °C based on mass balance, and the methane yield from cattle manure containing sawdust was improved by the hydrothermal pre-treatment of ADSC.