Anammox bacteria growth: bioaugmentation and biostimulation strategies from activated sludge biomass

Abstract

The application of anaerobic ammonia oxidation (anammox) processes has gained prominence in wastewater treatment due to its high efficiency in biological nitrogen removal, with low energy consumption and reduced greenhouse gas emissions. However, the slow growth rate of anammox bacteria and the reliance on mature sludge limit the large-scale adoption of this technology. This study explores bioaugmentation and biostimulation strategies as promising alternatives to accelerate the startup of anammox and deammonification reactors, thereby minimizing the dependency on enriched cultures. Biostimulation of activated sludge (AS), commonly available in wastewater treatment plants, successfully established anammox activity in 129 days. This approach eliminates the need for transporting mature anammox sludge between regions, significantly reducing logistical challenges and costs. Additionally, by employing bioaugmentation with varying concentrations of anammox sludge (0.02 to 0.40 gVSS L-1) and 2.0 g VSS L-1 of AS, the startup time was reduced to as few as 10 days. This allows for using smaller quantities of anammox sludge without compromising process efficiency, which is particularly advantageous in scenarios where mature sludge is scarce. Moreover, in these same reactors, it was possible to establish a single-stage deammonification process without adding pre-acclimated ammonia-oxidizing bacteria (AOB), enabling the process to be established in 3 days. The results of this study introduce a new strategy for implementing the anammox process in countries where plants are not yet operational, suggesting effective methods for rapid and sustained reactor startup. Developing these strategies is crucial for the global expansion of anammox processes, promoting more efficient and sustainable wastewater treatment.