Ageing treatment plants, tighter nutrient limits, uneven population growth and staffing shortages are increasing interest in decentralized wastewater-treatment systems, according to Fluence.

The company says modular systems can help utilities add treatment capacity near growth areas or upgrade existing lagoon systems without building large centralized plants and long conveyance pipelines.

Fluence cites Dow City, Iowa, where a modular membrane aerated biofilm reactor (MABR) system was added to an existing lagoon to improve nitrogen removal within a regulatory timeline.

Its Aspiral Flex platform is a containerized, modular treatment system intended for constrained sites, satellite developments and lagoon upgrades. Fluence says the system can be expanded in phases and may be offered through a service model in which the company retains responsibility for ownership, maintenance and lifecycle performance.

The article argues that decentralized systems can help utilities align treatment investment with actual growth, regulatory deadlines and available operating staff. Their suitability, however, depends on local wastewater flows, treatment requirements, land, power, operator capacity, lifecycle cost and discharge or reuse standards.