Resource recovery strategies to transform wastewater into revenue
As the world grows more focused on sustainability and resource management, wastewater systems are in a unique position to make a substantial impact. Traditionally viewed as waste, wastewater contains a bounty of valuable resources — nutrients, energy, and other resources that can be recovered, reused, or sold to help offset operating costs and provide a meaningful return on investment in our communities.
For years, water and sewer utilities have focused primarily on treating wastewater to meet regulatory requirements standards and release the treated effluent back into receiving water bodies. However, with advancements in nutrient removal technologies and a growing recognition of the value in wastewater, the industry is now recovering these nutrients for reuse — thereby creating a sustainable green solution while potentially significant revenue in the process.
One of the key frameworks guiding this shift is the "Utility of the Future" initiative, developed by the National Association of Clean Water Agencies (NACWA), the Water Environment Federation (WEF) and the American Water Works Association (AWWA) in 2013. This comprehensive blueprint envisions utilities as entities that go beyond day-to-day wastewater treatment. Wastewater treatment plants have evolved and are often referred to as water resource recovery facilities (WWRFs).
By capturing nutrients, heat, and other resources, utilities can transform their facilities into hubs of sustainability while creating meaningful cost recovery and even revenue from the offtake agreements by the end users. Many wastewater utilities have transformed their operations by leveraging this critical element of our circular economy—with nutrient recovery as a backbone for future-forward resource planning.
Nutrient recovery: The low-hanging fruit
Among the most valuable resources in wastewater are nutrients like nitrogen and phosphorus. While these nutrients are essential for agricultural fertilizer production to support the U.S. food supplies, these nutrient loads, particularly phosphorous loads, are detrimental to water resources if not properly treated. The U.S. and the world are facing a diminishing supply of naturally occurring phosphorus, making wastewater-based phosphorus recovery a sustainable solution with long-term benefits.
Nutrient recovery technologies such as Ostara's Pearl are helping utilities extract valuable nutrients from wastewater and convert them into high-quality fertilizer. This process precipitates struvite formation, turning a typically wasted resource into a marketable resource for agriculture. By reducing waste and promoting reuse, these innovations support a circular economy, reintegrating essential nutrients into the agricultural fertilizer market to support our food supply system.
Examples of successful nutrient recovery installations in Georgia include the F. Wayne Hill Water Resources Center, which has been using the Ostara Pearl(TM) and WASTRIP(TM) technologies to recover nutrients from the wastewater treatment process. The system has not only improved nutrient management but also created a new revenue stream for the utility, producing over a ton of fertilizer per day. Similarly, the RM Clayton Water Reclamation Center (WRC) in Atlanta, Georgia, has benefitted from this nutrient recovery technology as part of the Mayor’s Sustainability and Resiliency program to aid with permit compliance, and reduce chemical and operating costs.
As nutrient recovery systems improve, the financial benefits from the sale of fertilizer products can be substantial to help offset the annual operating costs within a facility especially after the payback period ends.
Energy and heat recovery: A multi-resource approach
In addition to providing nutrients, WRRFs also offer latent heat and energy that is converted to biogas during the treatment process. Methane gas, a by-product of anaerobic digestion, can be captured and used to generate combined heat and power (CHP) or even returned to the local gas system. This biogas is considered a renewable energy source and when used in a CHP system, can generate substantial power and heat which reduces the purchased power from the local power utility. By combining nutrient recovery with energy and heat management, utilities can significantly reduce operational costs and improve their bottom line. Both of the WRRFs mentioned in Georgia have utilized CHP programs for over a decade.
Compliance considerations: meeting regulations while maximizing recovery
Utility executives need to balance revenue potential with compliance to avoid penalties and maintain the integrity of local ecosystems. Compliance requirements for nutrient removal and discharge vary significantly depending on the location of the treatment plant and the specific receiving water body and discharge location.
To address these regulatory requirements, utilities need stronger nutrient management strategies. These strategies include advanced biological nutrient removal processes as well as nutrient recovery technologies to meet increasingly more stringent discharge limits while harnessing the value of nutrient recovery. By integrating nutrient recovery into their treatment process, utilities not only improve their compliance performance but also add a valuable revenue stream.
Another important consideration is the increasing regulatory scrutiny on biosolids management. With the growing concerns over the presence of PFAS in wastewater and biosolids, land application of treated solids is becoming more challenging. Side-stream treatment processes provide another pathway for valuable resources to potentially leave the plant, offering an alternative to landfilling or land application of biosolids.
By recovering the nutrients before they become part of the biosolid waste stream, utilities can better manage some of the compliance challenges posed by the evolving regulations around biosolid disposal.
How to Find Buyers for Recovered Resources
For utilities looking to monetize recovered nutrients, identifying buyers is key to success. Ostara typically offers a turnkey solution with multi-year offtake agreements with haulers and buyers that alleviate the burden on the utility.
Agricultural markets are the most obvious target for fertilizer products made from wastewater and biosolids, but finding the right buyers requires a strong market assessment and outreach. Establishing partnerships with fertilizer producers, local agricultural cooperatives, and large-scale farms is one way to secure a reliable customer base for recovered nutrients and biosolids.
In addition to fertilizers, or biosolids products, wastewater effluent treated to advanced treatment or water reuse standards, can also be used for industrial cooling, irrigation, or even aquifer storage and recovery systems (ASR) that replenish groundwater supplies while offsetting potable water (drinking water) usage.
Utility leaders looking to integrate or expand existing water reuse solutions as an immediate or future resource recovery strategy should have a strong understanding of the local market drivers of high population growth and industrial water demands for new industries or that have a high demand for water reuse due to ongoing water scarcity issues or fertilizer. By diversifying the market opportunities for recovered resources, utilities can improve the revenue potential of their nutrient recovery programs.
The revenue potential of nutrient recovery
The revenue generated from nutrient recovery depends on several factors, including the volume of wastewater treated, the technology used, and the local demand for the recovered products. However, early adopters of nutrient recovery systems are already seeing financial benefits.
In some cases, nutrient recovery can reduce operational costs by lessening the need for chemical treatments or reducing the volume of biosolids needing disposal. As more utilities implement these technologies, the overall revenue of wastewater-based nutrient recovery is expected to grow.
Leveraging wastewater as a resource for a circular water economy
The wastewater treatment industry is undergoing a transformation. As utilities move toward becoming utilities of the future, they are discovering the value of wastewater as a resource rather than just waste. By embracing technologies that recover nutrients, energy, and heat from wastewater, utilities can not only meet compliance requirements but also create new revenue streams.
The key to success lies in integrating these technologies, understanding the regulatory landscape, and seeking out buyers for the recovered resources. The move to a circular economy for wastewater has the potential to benefit both the environment and the utility’s bottom line.
About the Author
Chris Haney
President of the Water operating group at STV
Chris Haney, P.E., is the president of the Water operating group at STV. With nearly 30 years of experience in the U.S water sector specializing in wastewater treatment, biosolids, and resource recovery applications including energy management, water reuse, and nutrient recovery, his experience includes facility evaluations, planning, design, permitting, construction, and start-up commissioning. He has worked at over 60 treatment facilities ranging in size from 4 MGD to 1.2 BGD and with a combined project value over $1B. As a technical leader and subject matter expert, he has led major facility process evaluations, technology evaluations, plant optimization and operational assessments, business case evaluations, and pilot demonstrations through full-scale implementation for new wastewater treatment, biosolids, and resource recovery technologies and innovations. Chris has served on global standards committees for energy management and innovation and is an active member of the National Association of Clean Water Agencies and Water Environment Federation.