Two Stanford University environmental engineers say it’s time to begin rebuilding outdated wastewater treatment plants with new considerations of water scarcity and energy intensity, and they have a pilot project they hope will soon support the validity of their plea by turning an energy-intensive wastewater facility into a green power plant.
Funded by a $2-million grant from the California Energy Commission, the researchers have a demonstration treatment plant under construction in Redwood Shores that by fall 2018 is expected to be online, running without air, or anaerobically, using bacteria that avoid oxygen while producing burnable methane. Wastewater treatment plants have traditionally relied on aerobic bacteria that require oxygen to survive, making them some of the most energy-intensive pieces of municipal infrastructure due to blower technology.
The Stanford researchers, Craig Criddle and Bill Mitch, estimate that a full-scale anaerobic plant capable of operating at 15 million gallons per day might save as much as $3,000 per day in energy demand over a comparable aerobic plant.
Construction is now underway for the project to test the staged anaerobic fluidized-bed membrane bioreactor, or SAF-MBR technology, at a larger scale. Stanford will work closely with environmental engineers from Silicon Valley Clean Water (SVCW), next to a large conventional plant that purifies wastewater for some 250,000 people and businesses from Redwood City to Menlo Park, according to a news publication affiliated with Stanford University.
The new demonstration system is expected to double testing capacity from 10,000 gallons at the Codiga Resource Recovery Center on the Stanford campus, to 20,000 gallons of wastewater per day at the Redwood Shores site.
“If this technology pans out, it will greatly reduce the amount of energy we use. It will also decrease the amount of solids that we have to haul off at the end of the treatment process,” said Teresa Herrera, chief engineering officer with SVCW, in a Stanford video about the technology. “Sustainability, resource recovery, climate change, all of these factors give us the impetus as an industry to look to alternative means of treating the wastewater to a high level. This technology, as well as others, can really help us in this direction,” added Herrera.
The project will run over four years with an overall budget of $3.2 million, with contributions from Stanford University, Silicon Valley Clean Water, GE Water, Santa Clara Valley Water District, and LG NanoH2O.