Advances in decentralized treatment: A look forward on expanding technology and design to tackle municipal water and wastewater challenges

As water and wastewater challenges grow in scale and complexity, so does the need for smarter, more adaptable infrastructure. While centralized treatment systems have long been the standard for municipal wastewater management, advances in decentralized wastewater treatment are expanding possibilities for communities of all sizes. These systems are not just an alternative, they are increasingly becoming a strategic solution for addressing critical environmental, economic and regulatory pressures.

This article explores the current landscape of decentralized wastewater treatment, the mounting challenges faced by stakeholders, the practical solutions being implemented across the country, and where the industry is headed next.

A smarter, more customized approach: Decentralized wastewater treatment today

One of the most powerful aspects of today’s decentralized wastewater treatment systems is flexibility. With an array of treatment technologies and design strategies now available, engineers and designers can select the “best fit” solution for a specific application.

Whether it is a conventional septic design for a rural residential project or a complex, nutrient-reducing system with advanced online monitoring, decentralized systems can be tailored to serve specific needs. These systems can also produce high-quality effluent, suitable for non-potable reuse such as irrigation, industrial processes, or aquifer recharge. Further, their smaller carbon footprint compared to centralized infrastructure means significantly reduced capital and operational costs.

Decentralized systems often require less physical infrastructure, less piping, pumping, and excavation making them ideal for rural communities, suburban developments, commercial operations and areas where large-scale utilities are not viable, are at capacity, or need an upgrade. When partnered with decentralized solutions, centralized systems and the communities they serve can gain relief from critical water and wastewater issues and the cost of replacement.

Six key challenges in the modern water/wastewater landscape

The water sector is facing growing pressure, and engineers, system designers, technology developers, municipalities, contractors, and regulators are grappling with a range of challenges:

1. Cost of centralized infrastructure: Both initial capital investments and long-term operations and maintenance (O&M) costs are rising.
2. Aging infrastructure: Much of the nation’s existing centralized infrastructure is outdated and in need of replacement or rehabilitation.
3. Performance and reliability: Systems must maintain optimal performance over decades, even as demand fluctuates and regulations change.
4. Environmental concerns: Saltwater intrusion, combined sewer overflows (CSOs), groundwater contamination, and nutrient loading are just a few of the issues threatening ecosystems and water supplies.
5. Utility staffing: Many smaller municipalities or utility districts have limited staff, often without the resources to manage complex treatment systems.
6. Growth and development: Communities must expand their treatment capacity as they grow, ideally without overhauling entire systems or incurring massive expenses.

Decentralized strategies: A scalable tool for the future

Decentralized wastewater treatment offers a variety of benefits that help address these challenges head-on. For many communities, particularly rural and semi-urban areas, decentralized systems are not just a stopgap solution, they are an integral part of long-term sustainability.

This is due to:

• Scalability: Systems can be sized and phased based on current and future demand, supporting growth without upfront overbuilding.
• Cost-efficiency: Lower capital requirements and the potential for locally sourced materials and labor make these systems more affordable.
• Low O&M burden: Many decentralized systems can operate with minimal oversight, and remote monitoring options are increasingly available to improve efficiency and reduce service visits.
• Environmental stewardship: High-quality effluent enables beneficial reuse and reduces the risk of contamination. The smaller footprint also minimizes land disturbance.
• Tailored design: Each system is engineered from collection through treatment and disposal based on site-specific conditions and performance goals.

These characteristics make decentralized wastewater treatment a viable strategy to help manage some of the most critical water issues facing municipalities and utilities.

Real-world applications: Issues and solutions

To better understand the power and flexibility of decentralized wastewater treatment, explore the following three project examples that address specific infrastructure or environmental challenges.

Highway convenience store high-strength wastewater (Pilot gas station)

The challenge: A busy convenience store located off a major interstate in a rural area requires wastewater treatment. Too remote to connect to a centralized municipal system, the store presented additional challenges due to its 24/7 operation, high-volume traffic from oil and gas workers, and the presence of hot food and beverage service resulting in high-strength wastewater and inconsistent flows.

The solution: A decentralized system was designed to manage both hydraulic and organic loading effectively. The system included an oversized primary tank to improve solids settling after the grinder pump station and flow equalization to address peak periods and stabilize treatment. The design tailored biological treatment based on organic load rather than flow alone. This approach ensured long-term performance, resilience, and reduced maintenance even with the store’s challenging wastewater profile.

Modern replacement for a municipal lagoon system (Section, AL)

The challenge: A small city with limited infrastructure funding needed to replace an aging lagoon system that no longer met regulatory discharge standards. The city required a cost-effective, scalable system with low O&M needs and the potential for future capacity expansion.

The solution: Engineers proposed a fixed film treatment system designed to meet stringent effluent criteria suitable for subsurface drip disposal that could be installed in locally sourced concrete tanks to lower construction costs. The system operates in modular trains providing O&M flexibility and sized with ample sludge storage capacity, minimizing maintenance activities. The design allows for easy expandability, enabling the city to go from 30,000 GPD capacity, to 45,000 GPD capacity to 90,000 GPD capacity in a matter of 10 years. This approach helped the city meet regulatory requirements, manage growth affordably, and minimize staff burden.

Modern sewer solution for development – South Alabama Utilities (SAU)

The challenge: South Alabama Utilities (SAU) needed capacity to for community growth to handle the build out of nearly 4,000 new homes — as well as schools, apartments and business parks.

The solution: SAU worked with developers to install more than 60 miles of Orenco effluent sewer lines, which now serve 47 subdivisions and commercial properties. Filtered wastewater is sent to approximately 150 AdvanTex textile treatment units at 14 different treatment facilities.

Looking ahead: Challenges and opportunities 

The road ahead for the water and wastewater industry is paved with both promise and complexity. Emerging contaminants such as PFAS, pharmaceuticals, and microplastics are raising the bar for treatment technologies. Simultaneously, climate change is intensifying weather patterns, stressing infrastructure with both drought and flood events.

Decentralized wastewater treatment systems will continue to remain effective in protecting public health and the environment through advancements in five key areas:

1. Technology: As regulations evolve, so must treatment technologies. Innovations in treatment technologies as well as monitoring devices will be essential.
2. Data-driven operations: Integrating real-time data, predictive maintenance, and AI-based control systems can drive performance and reduce operating costs.
3. Public-private partnerships: Collaboration between municipalities, engineers, manufacturers, and regulators is key to funding and deploying effective systems.
4. Flexible, modular designs: Solutions that can grow with a community or scale back in times of need will provide long-term value.
5. Focus on resilience and sustainability: Systems must withstand changing climate conditions, protect source water, and operate with minimal environmental footprint.

Conclusion: Our responsibility is water

Decentralized wastewater treatment is not just a technical approach, it is a mindset. It is about building a smarter, more responsive infrastructure that supports communities, preserves the environment, and prepares us for future challenges. Whether it is serving a rural school, a booming suburb, or a critical piece of industry, these systems are already proving their worth. As an industry, our mission is to continue evolving, adapting, and delivering the solutions needed to ensure safe, reliable, and sustainable water systems for all.