Bioresource Technology, Vol.190, 274-280, 2015
Effect of pH and retention time on volatile fatty acids production during mixed culture fermentation
Mixed culture fermentation consists of stable microbial population hence waste could be potentially used as a substrates. The aim of the work was to investigate the impact of pH and retention time on the anaerobic mixed culture fermentation. Trials at different pH (4-12) in unbuffered systems were conducted for 5, 10 and 15 days. The highest VFAs concentration was achieved after 15 days at pH 10 (0.62 g/g VSadded), promising results were also achieved for pH 11 (0.54 g/g VSadded). For pH 4 and short retention time propionic acid was the major product instead of acetic acid. For batches run at 15 days (besides pH 6) caproic acid presence was noticed whereas at pH 11 occurrence of succinic was quantified. Significant correlation between operational factors and fermentation's effluents was proved. Throughout changing simple operating parameters one could design process to produce desirable concentration and composition of VFAs. (C) 2015 Elsevier Ltd. All rights reserved.