Influence of Stepwise Increased Organic Loading on Anaerobic Mono-digestion of Dead Fish in Sequencing Batch Reactor Process

Abstract

© 2022, The Author(s), under exclusive licence to Springer Nature B.V.Highly nutrient content dead fish (DF) waste can be considered a potentially valuable substrate for the anaerobic digestion (AD) to produce biogas. The effects of stepwise increased organic loading rate (OLR) on the process performance were investigated during mono-digestion of DF waste in anaerobic sequencing batch reactor mode. Two different sets of experiments have been conducted using whole dead fish (RDF) and boneless dead fish (RBDF) and OLR increased in five steps (1.95, 2.39, 2.73, 3.19, and 3.64 g VS/L/days) during the operational period. With the increasing of OLR, the biogas production rate increased by 79.07% and 58.20% at the end of the operation of RDF and RBDF, respectively. Higher alkalinity values throughout the experiment maintained stable pH values in between 7.87 to 8.01 for both RDF and RBDF. Total volatile fatty acids kept accumulating with the increasing OLR and the final concentrations were 7.69 ± 0.16 and 8.33 ± 0.19 g/L in RDF and RBDF, respectively. Overall, decreasing COD and VS removal efficiencies resulted in decreasing methane yields. The energy recovery rate was maintained at > 60% with the maximum OLR of 3.64 g VS/L/d of DF waste demonstrating its feasibility in the AD process as the only carbon source. Graphical Abstract: [Figure not available: see fulltext.].