Utilizing Infrared Electromagnetic Fields to Increase Anammox Activity and Growth Rates

Achieving a rapid start-up of the anammox process is still full of challenges and obstacles due to the slow growth of anammox bacteria. In this study, a new physical energy, infrared electromagnetic fields (EMFs) generated from a widely used traditional Chinese medicine apparatus by accelerating charged particles through thermal excitation, proved to be a “bioactivity enhancer” for the anammox process. Short-term batch tests indicated that the specific anammox activity [26.6 mg of N (g of MLSS)−1 h–1] was increased by 76% after the treatment with infrared EMFs. The long-term effect of the EMFs on anammox was studied in upflow column reactors, and a 36.8% start-up time saving, a 17.7% total nitrogen removal increase, and a 22.5% acceleration of the anammox bacteria growth rate were achieved. The reactor that included EMFs also had better resistance to performance deterioration and shock loading. The high-throughput sequencing results showed that the existence of the EMFs increased the relative abundance of Candidatus Kuenenia and Candidatus Jettenia. Furthermore, the evaluation of the community functions based on the Kyoto Encyclopedia of Genes and Genomes indicated infrared EMFs stimulated anammox bacteria by controlling the metabolism of c-di-GMP. Taken together, infrared EMFs are, therefore, considered to be an efficient “bioactivity enhancer” for promoting the anammox process.