Study of the Effect of Temperature to Optimize the Anaerobic Digestion of Slaughterhouse Sludge by Co-Digestion with Slaughterhouse Wastewater

Abstract

The anaerobic co-digestion (ACoD) of sludge (S) and slaughterhouse wastewater (SW) can improve biomethane production and removal efficiency in terms of organic matter. The aim of this study was to determine the impact of temperature on co-digestion, considering different hydraulic retention times (HRTs). The substrates were selected at a 50:50 weight ratio and two single-stage digesters of 2 L capacity were used, operating under ideal thermophilic (55 °C) and mesophilic (35 °C) conditions. The HRTs studied were 30, 25, 20 and 15 days. The biomethane production reached 588 mL CH4/d at 55 °C and 477 mL CH4/d at 35 °C for an HRT of 15 days, indicating a significantly higher yield under the thermophilic process. The volatile solids removal efficiency ranged from 41% to 66% for the thermophilic digester and between 32% and 42% for the mesophilic digester. This further highlights the superior performance at higher temperatures.