Innovation in design and optimization can help municipalities and water districts as they face the future

Municipal wastewater treatment is facing challenges: Populations are growing, environmental regulations are tightening, energy costs continue to climb, and the call for improvements is never-ending. At the same time, climate goals are pushing utilities to rethink how they design and operate treatment systems. It is no longer enough to simply meet discharge standards. Modern systems must be efficient, flexible, and sustainable. With limited budgets and mounting environmental mandates, many utilities are discovering that traditional centralized systems no longer make economic or operational sense.

At Fluence, we’re dedicated to these goals, helping plants perform more efficiently with modular design, biofilm-based processes, and intelligent control systems. These concepts are not on the horizon — they’re already being applied in communities that need reliable and sustainable treatment solutions without the long construction timelines or large footprints of traditional plants.

Modular and Decentralized Design

For decades, municipal wastewater systems were built around large centralized facilities that served entire regions. While these plants offered economies of scale, they were often expensive to expand or adapt to changing conditions. The newer approach focuses on modular and decentralized treatment. Fluence’s Aspiral™ Flex units, for example, come as complete containerized systems that can be installed quickly and expanded as needed.

This approach allows municipalities to scale capacity gradually as populations grow or as treatment requirements evolve. In rural or remote areas, decentralized systems also make it possible to provide reliabl treatment where extending sewer networks would be impractical.

Modular design changes how infrastructure planning is approached. Instead of building one large facility and routing miles of expensive sewer and piping systems, utilities can combine multiple smaller systems to achieve the same treatment performance, often at lower overall cost.

Membrane Aerated Biofilm Reactor (MABR)

One of the most significant advances in wastewater treatment is the membrane aerated biofilm reactor, or MABR. In this process, oxygen is delivered through membranes directly into a thin biofilm where microorganisms grow, supporting both nitrification and denitrification within the same reactor, simplifying process design and improving nitrogen removal efficiency. MABR typically cuts energy use by up to 90% compared with conventional aeration.

MABR technology reduces energy use because its passive diffusion transfers oxygen much more efficiently than conventional aeration can. MABR also stabilizes biological performance and reduces the overall footprint of a treatment plant. Fluence packages MABR in its containerized Aspiral™ line as well as in SUBRE systems that upgrade existing or greenfield concrete plants with MABR towers to achieve high treatment levels with low energy consumption. For example, at the Mayan Zvi wastewater treatment plant in Israel, Fluence’s SUBRE system upgraded existing basins with MABR towers, doubling treatment capacity without expanding the footprint. The retrofit cut energy use by about 33% while consistently producing high-quality effluent.

Adaptability

Innovation in wastewater treatment is not limited to new hardware. It also depends on how systems are designed and optimized from the beginning. Fluence’s digital design tools, which are based on experience and calibration information from the more than 300 MABR plants it operates, allow engineers to model treatment options quickly and select the best configuration based on effluent targets, local conditions, and cost. Standardized modules make design faster and ensure that proven performance can be replicated across multiple sites.

Once in operation, smart control systems allow plants to continuously adjust and improve. Real-time monitoring tracks key indicators such as oxygen levels, nutrients, and energy use. Automated controls can optimize aeration, balance flows, and identify maintenance needs before problems occur. This creates a plant that is dynamic and self-optimizing rather than static and reactive.

Upgrading Existing Infrastructure

Many municipalities must modernize aging plants without replacing them entirely due to a lack of space or financial constraints. Retrofitting existing facilities is often the most practical path. Technologies like SUBRE allow operators to add advanced treatment capability without major civil work. By upgrading in this way, utilities can meet stricter regulations, reduce energy costs, and extend the useful life of existing assets.

Scalability is also possible with modular, containerized plants. Communities can start small, then add additional modules as capacity needs increase. This stepwise approach aligns infrastructure investment with real demand rather than a guess as to what the future holds.

The next generation of municipal wastewater treatment will rely on technologies that are flexible, efficient, and digitally connected. Modular systems can be deployed and expanded quickly. Advanced biological processes can achieve more with less energy.

But the larger shift is in perspective. Wastewater is no longer viewed only as something to dispose of, but as a source of recoverable water, nutrients, and energy. Optimized treatment design supports that vision by building systems that are sustainable, resilient, and adaptable to change.

As innovation continues, the boundary between research and practice is becoming less distinct. Municipalities that embrace flexible, data-driven, and modular approaches are proving that the best way to prepare for the future is to design for it from the start. Contact Fluence for expert advice on how to make these innovations work for you.