Anaerobic biotransformation of acrylic acid was investigated in UASB reactors with three different cultures, namely granular, homogenized (crushed) granular and acrylate-acclimated acetate-enriched Methanosarcina. The microbial acclimation, operational parameters such as F/M ratio, influent concentration and loading rate of acrylic acid as well as process staging and significance of physical homogenization (crushing) of microorganisms were emphasized in the experiments. Results indicated that a single-stage UASB with granular biomass biotransformed acrylic acid (influent concentration of 3000 mg l−1) to acetic and propionic acids efficiently, but these intermediate products could not be metabolized efficiently (<45% COD removal). A two-stage UASB with the same culture, on the other hand, metabolized acetic and propionic acids efficiently and provided more than 97% COD removal for the same influent acrylic acid concentration. Furthermore, the significance of homogenizing granules and acclimating the cultures on process performance were clearly observed.
- Acrylic acid
- Physical homogenization