The effect of pH control and 'hydraulic flush' on hydrolysis and Volatile Fatty Acids (VFA) production and profile in anaerobic leach bed reactors digesting a high solids content substrate

► pH control and hydraulic flush improved anaerobic leach bed reactors' performance. ► pH control improved hydrolysis and VFA production. ► Neutral pH produced butyric and Acetic acid; Acetic acid was inhibited at low pH. ► Hydraulic flush enhanced solids degradation and VFA production. ► Hydraulic flush caused cellulolytic microbes wash out; pH control counteracted this.