Facilitating Digester Recovery from Acid Inhibition at High Organic Load Rates by Limited Calcium Peroxide Addition

Abstract

This study evaluated the performance of limited calcium peroxide (CaO2) addition in maintaining the system stability of anaerobic digestion using lignocellulose biomass as a substrate at high organic load rates. Results showed that an overloaded digester, which had been on the verge of system collapse, regained its stability after 20 mg/L CaO2 was periodically added. Especially, limited CaO2 addition significantly reduced the volatile fatty acid (VFA) concentration and restored pH levels, thus enhancing methane production from 24.6 ± 0.4 to 80.9 ± 0.7 mL/g·VS. By combining the reactor performance, carbon mass balance, cell vitality of the microbial community, and metagenomic analyses, this study found that limited CaO2 addition stimulated the aerobic conversion of the VFA precursor to CO2 for VFA level control by facultative bacteria, which triggered their higher energy metabolism. Additionally, after limited CaO2 addition, acetotrophic and hydrogenotrophic methanogeneses were both promoted.

The Effects of Using Evogen Biogas Additive on the Microbiome and Performance of Full-Scale Biogas Plant

“…Other operational problems that can be resolved through the use of biogas additives include VFA accumulation, acetate inhibition, H2 partial pressure, H2S accumulation, NH3 accumulation, temperature, and heavy metal toxicity [10]. For example, the addition of acidic buffer solutions or alkaline agents can help to maintain the pH balance within the digester, reducing the accumulation of VFAs and preventing acetate inhibition [15,16]. Similarly, the use of bioaugmentation agents can help to optimize the microbial community, reducing the accumulation of H2S and other problematic compounds [17].…”

The Effects of Using Evogen Biogas Additive on the Microbiome and Performance of Full-Scale Biogas Plant

“…Other operational problems that can be resolved through the use of biogas additives include VFA accumulation, acetate inhibition, H 2 partial pressure, H 2 S accumulation, NH 3 accumulation, temperature and heavy metal toxicity [11,18]. For example, the addition of acidic buffer solutions or alkaline agents can help to maintain the pH balance within the digester, reducing the accumulation of VFAs and preventing acetate inhibition [19,20]. Similarly, the use of bioaugmentation agents can help to optimize the microbial community, reducing the accumulation of H 2 S and other problematic compounds [21].…”