Recent advances in sustainable biological nutrient removal from municipal wastewater

Microalgae-based systems offer an eco-friendly solution for municipal wastewater treatment by sequestering nutrients and carbon dioxide. However, high ammonium levels in municipal wastewater create competition between microalgae and ammonium-oxidizing bacteria. The synergy in microalgae-bacteria consortia enhances nitrogen and phosphorus removal, utilizing solar energy and facilitating beneficial gas exchange, which reduces traditional aeration costs. Despite this, the complexity of these systems complicates the understanding of their metabolic processes. This review examines the competition for ammonium uptake between microalgae and bacteria, factors influencing this competition, methods to measure their activities, and strategies to control nitrification for improved treatment efficacy. Integrating microalgae-bacteria consortia in municipal wastewater treatment faces challenges in maintaining microbial community control and process stability. The paper explores biological processes, bioreactor technologies, limitations, and large-scale applicability. Addressing global water demand, the collaboration between microalgae and bacteria presents a sustainable, carbon-neutral solution for nutrient removal.