Relationship between the synergistic/antagonistic effect of anaerobic co-digestion and organic loading

Abstract

Results from this study reveal a notable relationship between the synergistic/antagonistic performance of sewage sludgefood waste anaerobic co-digestion (AcoD) and organic loading. At the same sewage sludge content, biomethane potential (BMP) assays show an increasing specific methane yield as the content of food waste increased to the optimum organic loading of 15 kg VS/m 3. Under these conditions, the specific methane yields experimentally measured in this study were considerably higher than those calculated by adding the specific methane individual co-substrates during mono-digestion. On the other hand, at above the optimum organic loading value, the antagonistic effect (i.e. lower specific methane yield compared to mono-digestion) was observed. The relationship between synergistic performance of AcoD and organic loading was also evidenced in the removal of volatile solids as well as chemical oxygen demand. Further analysis of the intermediate products show that methanogenesis was the rate limiting step during AcoD at a high organic loading value. As the organic loading increased, the digestion lag phase increased and the hydrolysis rate decreased.

A pilot scale study on synergistic effects of co-digestion of pig manure and grass silage

“…Synergistic effects can be quantified using a combined kinetics modelling and COD balance approach during batch anaerobic co-digestion of sewage sludge and organic wastes (Xie et al, 2017a). In this study, a universal equation was adopted to qualitatively illustrate the synergism as follows (Xie et al, 2017b):…”

Treatment of Cattle Manure by Anaerobic Co-Digestion with Food Waste and Pig Manure: Methane Yield and Synergistic Effect

“…Co-digestion is a simple and effective strategy to improve the properties of the mixed substrate for efficient AD by adjusting the carbon/nutrient balance, increasing the buffering capacity, and diluting the concentration of inhibitors [ 14 ]. However, co-digestion can sometimes result in an antagonistic effect, depending on the characteristics of the co-substrates [ 15 ], and, therefore, the proper selection of co-substrates and their mixing ratio is critical for successful co-digestion [ 16 ]. A previous study on the co-digestion of FW and PM reported an antagonistic effect attributable to the inhibition of methanogenesis by excessive nutrients [ 17 ].…”

Current status and perspectives on anaerobic co-digestion and associated downstream processes

“…The extent of the synergistic effects can be notable during AcoD [47][48][49][50][51] . In contrast, antagonistic effects have also been observed during AcoD of sewage sludge and organic waste 52 . Antagonistic effects have negative impact on overall downstream processes.…”

“…long chain fatty acids) can suppress methanogenic microbial population, and lead to VFA accumulation, system instability and negative downstream impact. Thus, it is important to avoid co-substrate organic overloading during AcoD 52 .…”