초록
<P><B>Abstract</B></P> <P>The study investigated the influence of the target pH-values 4.5, 5, 5.5 and 6 in the acidification reactor on process parameters, such as substrate-specific methane yield and the intermediates, in the two-stage anaerobic digestion of sugar beet silage. The total specific methane yield (Nlkg<SUP>−1</SUP> CODd<SUP>−1</SUP>) increased with an increase in the pH (pH 4.5: 140.58±70.08, pH 5: 181.21±55.71, pH 5.5: 218.32±51.01, pH 6: 256.47±28.78). The pH-value also had an effect on the dominant intermediate in hydrolysate. At the pH-value of 4.5, almost no acidification and microbial activity was observed. At pH 5 and 5.5, butyric acid production dominated, guided by H<SUB>2</SUB> production. At pH 6 acetic acid was the main product. The absence of H<SUB>2</SUB> and the highest SMY makes it favorable under practical aspects.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Effect of acidification pH on two-stage AD of sugar beet silage was investigated. </LI> <LI> Instead of a buffer, effluent refeeding was used for pH control. </LI> <LI> The highest specific methane yield was achieved at pH 6. </LI> </UL> </P>