Toward Sustainable Lagoon Wastewater Treatment: A Review of Nutrient Management Technologies and Their Suitability for Small Communities

Lagoon wastewater systems are popular in small communities (<10,000 people) due to their cost-effectiveness and energy efficiency. However, these systems struggle to meet regulatory discharge limits for ammonia, total nitrogen, and total phosphorus, emphasizing the need for improved nutrient management. Most existing reviews focus on large-scale mechanical systems, leaving a gap for stand-alone lagoon systems in resource-limited settings. This systematic review analyzed 1003 peer-reviewed articles spanning five decades, evaluating nutrient management technologies for municipal lagoons. Technologies were categorized by nutrient target, process type, installation location, and development phase. Biological processes dominate (79%) due to their adaptability and cost-effectiveness, while advanced and hybrid systems are gaining traction. Performance varied widely based on design, climate, and operational conditions, highlighting the importance of site-specific considerations. To support context-sensitive selection, this study developed the Suitability Index (SIDX), a multicriteria framework incorporating complexity, automation, availability, and operational feasibility. SIDX identified several applicable and promising technologies for small-community lagoons. The review also highlighted an evolving focus toward circularity, resource recovery, and emissions reduction, moving beyond traditional pollutant removal. These insights provide practical guidance to support adaptive, context-appropriate nutrient management strategies aligned with current regulatory standards and future environmental goals.