Bioaugmentation with a proprietary facultative bioculture in a two-phase anaerobic digestion process of cobia fish wastes from indoor aquaculture system

For this study, we investigated a BioAugmentation Process (bioagumentation) system for the degradation of indoor aquaculture fish wastes using a specially designed acid producing bioculture in the facultative (FAC) phase of a two-phase anaerobic digestion reactor at mesophilic temperature (40°C ±2°C). This bioagumentation-FAC system was expected to increase the rate of the anaerobic digestion through addition of the proprietary FAC bioculture containing microorganisms that are responsible for one or more rate limiting steps in the digestion process. Additionally, the bioagumentation-FAC was also expected to elevate the end point of digestion by suppressing undesirable metabolic pathways. With undesirable byproducts (e.g. hydrogen sulfide) being largely avoided at the FAC phase and more acid-producing microorganisms present, more fatty acids would be produced and available for methane producing organisms, thereby increasing the rate of methane production. In this study we demonstrated improved performance of a bioagumentation-FAC compared to non bioagumentation-FAC anaerobic digestion system used to treat an aquaculture waste from the bottom of fish tanks, which primarily consists of fish feces, excess fish food and other excretory wastes. Fishwaste exhibited high digestibility. In a semi-batch test for 50 days, 95% of theoretical methane production was produced as total biomethane potential for the bioagumentation-FAC reactor. The bioagumentation-FAC anaerobic system produced 21% to 36% more total methane (ml/g VSadded) in the semi-continuous experiment. bioagumentation hydrogen sulfide concentrations were 13% to 22% lower. Finally, applying plastic media in our bioreactors has increased methane production by 83% and 48% for 8 days and 16 days HRT, respectively.