- We currently gather water from wells and reservoirs and distribute it broadly, recollect the wastewater, and deliver it to some third location where it is treated and discharged.
- The sewage collection pipes leak in, collecting potable groundwater from the surrounding soil, in some communities representing 50% of the total volume in the pipes.
In CRWA’s work on Smart Sewers over the past seven years, we’ve learned that with tried and tested technologies, we can gather organics in wastewater to generate energy, and use the by-product to fertilize fields and farms. We’ve learned that energy production can be enhanced by also processing food waste at the same time. We’ve also learned there is significant thermal heat energy in the wastewater, and once treated, the reclaimed water itself is a valuable asset from an economic and environmental standpoint. In other words, there is significant Resource-to-Waste-to-Resource value in wastewater.
By using existing wastewater collection pipes, and building a network of distributed wastewater treatment plants, we can ultimately collect, treat, and discharge the reused and treated water back to the environment. By mimicking natural hydrology, we can begin to replicate the nature we’ve altered. Appropriately configured, we can in this way eliminate the impacts of water leaking into sewer pipes (infiltration) – we can Keep Water Local.
For example, in metropolitan Boston, we collect about 200 million gallons daily from our central Massachusetts reservoirs, distributed as drinking water to 42 (or 48 if including the central MA and backup supply communities) communities and 2.2 million people. That water once used is collected and transported to the nation’s second largest wastewater treatment plant, Deer Island, on the edge of Massachusetts Bay, treated, and then discharged through a tunnel 9.5 miles out in the Bay. Keep in mind that in addition to the wastewater, the piped system also collects another 120 million gallons a day, on average, from groundwater and stormwater, treats it, and discharges it out into the Bay as well.
If we collect, treat, and reuse that wastewater in a series of small plants designed to generate energy and capture thermal heat and distribute the energy and heat to surrounding municipal districts, and then discharge the treated water once reused back to the ground, we could achieve both Resource-to-Waste-to-Resource and Keeping Water Local. We’d also begin to build great flexibility, adaptability, and interconnectedness into our water system.
“By mimicking natural hydrology, we can begin to replicate the nature we’ve altered… build[ing] great flexibility, adaptability, and interconnectedness into our water system.”
When I introduce the notion of a collection of distributed wastewater treatment plants across the landscape, the first reaction I get is “who wants a wastewater treatment plant in their neighborhood?” Understandable, given what we all know about wastewater treatment plants. These plants aren’t those plants, however. These plants are located inside buildings on one to two acres of land, process one to five million gallons daily, and don’t smell. They would represent, in fact, sizeable community assets by providing electricity, home and business heating and cooling, and clean reuse water, dramatically lowering our overall potable water demand. Each plant, before charging a dime for wastewater treatment, would generate significant income from the sales of electricity, thermal energy, reuse water, and remnant organics for fertilizer, and collect tipping fees for organic food waste disposal.
Imagine the opportunities this way: 10,000 people create about one million gallons of wastewater daily. Run that wastewater through one of our distributed plants and the energy generated would meet two percent of those 10,000 residents’ electric energy demand and 16% of their heating and cooling demand. The reclaimed water could be used to meet industrial and commercial process water needs, cooling water needs, irrigation, and all other non-potable water needs. All this while significantly reducing greenhouse gas emissions.
Critically, a collection of distributed plants would be far more resilient to the vagaries of climate. They would be far more flexible and adaptable, providing local sources of energy and water in times of great need. By reducing potable water demand, they would also begin to build real resilience to extended drought.
And, of course, they would help us Restore Nature.