A fun fact about sewage: Raw sewage is typically more than 99.9% freshwater.
Honing in on South Florida, the area’s treated wastewater meets, on average, 87 of the 93 drinking water requirements—without any further treatment.
“When this stable, non-seasonal, freshwater source is disposed to the ocean or to deep saltwater aquifers, impurities are increased by a factor of almost 100. Most of this material is salt, which requires extremely high energy to remove, by either reverse osmosis or distillation, if the water is then withdrawn for water supply. Why not save that energy and reuse the treated water, which has approximately the required volume and quality needed to supply urban demand? In addition, 3-4% of total electricity consumption in the US is used for conveyance of water and wastewater, and this energy can be saved through low-energy, on-site water reuse.”
Low-energy re-use of this kind would eliminate the need to treat the billions of pounds of pesticides and toxic substances that are released into the environment every year in the US. It would also remove pharmaceuticals and cleaning chemicals that go down our drains and permeate the environment, causing endocrine disruption in humans and animals around the globe. It would also save a vast amount of energy that is currently going toward water conveyance and desalination, and obviate the need for water rationing and low-flow devices.
With this need to rethink the way we handle wastewater in mind, The University of Miami is developing a “net-zero water” dorm house on campus. The concept of “net zero” describes the goal of re-using a system’s wastewater using an on-site water treatment setup. All of the dorm’s wastewater—from sinks, laundry, toilets, shower and dishwasher—will be routed through a treatment system that brings the water back to drinking-quality standards. The treated water can then be re-used by students, and in this setup the recycled water will be used for everything except drinking and cooking.
Dr. James Englehardt, the project’s principal investigator, describes the project as a preliminary proof-of-concept as part of the “Design for Autonomous Net-Zero Water Buildings” project funded by a $2-million, multi-year NSF Emerging Frontiers in Research and Innovation grant.
“We’re developing design principles for future buildings that are off the water and wastewater grids, and the basic research includes many aspects of system design. Project investigators are studying what net-zero water buildings could include and what they would look like, and designing treatment and risk-detection systems that could be commercialized,” Englehardt says.
One of PWGC’s Environmental Scientists, Dan Furman, who graduated from U-Miami in 2014 and is now one of our Field Hydrogeologists, worked on the net-zero water dorm project while still a student there. Dan had this to say about the project:
“Dr. Englehardt, whom I had as a professor during my sophomore year, did an excellent job of recruiting a team of students comprising a diversified skill set. Each student contributed in whichever way that they could add value; whether participating in design, performing cost analysis, or fabricating components. The decisions made involving design, regulatory requirements, and cost constraints added a complexity to the project that made it engaging, and very real in a professional sense.”