By Peter Chawaga
It is apparent that the future of wastewater treatment is in the recovery and reuse of its byproducts. While some ambitious plants have already made this future a reality, a bulk majority of the country’s wastewater treatment systems have a hard enough time doing the bare minimum within their current budgets, let alone investing in new technology necessary to revolutionize the way they process influent.
But a new type of facility promoted by the Charles River Watershed Association (CRWA), an agency advocating for better water and wastewater management in Massachusetts, is designed to help small, decentralized wastewater treatment facilities turn byproducts into sellable commodities. The facility concept is called a “Community Wastewater and Energy Resource Center” (CWERC), a potential headquarters for a variety of technologies where locally-generated waste can be transformed.
“CWERCs mine wastewater from existing sewer pipes and food waste from nearby restaurants, schools, hospitals, and other institutions, and transform the waste into renewable energy, reclaimed water, nutrients, and compost,” said Julie Wood, the director of projects for CRWA.
There are currently no CWERCs in operation. CRWA has developed conceptual designs for two such centers, but the technology and approaches would be customized based on the specific needs and settings of operation. The goal, however, stays the same.
“They combine a variety of waste to resource techniques into a single facility to maximize resource recovery and create efficiencies by combining multiple types of capital-intensive infrastructure into a single facility,” Wood said. “This combination of resource recovery technologies make CWERCs financially viable in initial modeling, making them attractive investment options.”
Another key component of the CWERCs would be their ability to connect decentralized wastewater treatment plants with one another so that sewer overflows can be avoided.
“Flow can be routed to different plants and storage facilities to even out flow inputs,” said Wood. “If one plant goes down, there is backup to absorb the flow so it does not have to get discharged untreated into local waterways… The ability to route flows and take advantage of storage within the collection system also helps reduce plants being overwhelmed and should reduce the need for plants to be designed for a rare peak-capacity event.”
By focusing wastewater treatment in smaller community locations, instead of transporting the wastewater to large, centralized plants, CWERCs would also increase recovery efficiency.
“Wastewater is captured close to the generating source, so thermal energy loss in the collection system is considerably reduced compared to what it would be in a centralized system where water is traveling over far distances,” said Wood. “Similarly, energy and reclaimed water are produced close to users, so transmission losses are reduced and less energy may also be required for water delivery.”
Though the program is still conceptual, CRWA is actively discussing the CWERC model with communities around the country. One such community, the town of Littleton, MA, has allocated $450,000 to planning and designing the country’s first such plant. There is reason for confidence that the investment will pay off.
“We conducted extensive financial modeling to determine how communities and operators could recoup their initial investment through CWERC operations,” Wood said. “For example, a 2-MGD CWERC will essentially pay for itself and a full replacement over 20 years of operation without charging for wastewater treatment if it’s built with a 0 percent loan, there is no cost associated with the land it’s constructed on, and reclaimed water is sold at only $1.66 per 1,000 gallons.”
But the benefits of CWERCs are not primarily financial. They are critical to CRWA’s objective of resorting and sustaining local water resources. In addition to turning wastewater into reusable water to reduce the demand on surface waters and aquifers, they are strategically placed to benefit the local area.
“CWERCs are … surrounded by green districts where CWERC effluent is used to restore natural water features and enhance aquatic habitats,” Wood said. “CRWA also develops extensive green infrastructure designs for the district surrounding a CWERC to filter and infiltrate stormwater runoff and restore the natural water cycle.”
With a combination of attributes that could save costs, increase efficiency, and better serve the environment, it seems that CWERCs are poised to become part of wastewater’s future.