Study on two anammox start-up and operation strategies: Low-intensity direct current electric field and negative pressure

Abstract

The bottlenecks of applying the anaerobic ammonia oxidation (Anammox) process are the low growth rate of anaerobic ammonium oxidation bacteria (AnAOB) and the sensitive response to the environment. How to rapidly enrich AnAOB is of great significance for its future application. This study focused on the effects of low-intensity direct current field (DCF) and negative pressure (NP) operating systems on granulation process, extracellular polymeric substance (EPS) secretion, AnAOB activity, and microbial community structure of granules. The results showed that appropriate DCF stimulation could accelerate the growth rate of AnAOB and promote more EPS secretion. Nitrogen removal rate (NRR) and nitrogen removal efficiency (NRE) of total nitrogen (TN) reached the highest under 2 V voltage intensity. NP could accelerate the reaction rate of the system and enhance the sludge retention capacity of the reactor. The two start-up strategies can shorten 30–33% anammox start-up time and maintain 86–88% NRE. These results indicate that the two start-up strategies have feasibility and potential for the rapid start-up and stable operation of the Anammox process.