By Alec Mackie
For a century, centralized and on-site wastewater treatment have co-existed although somewhat siloed from one another. They each serve separate geographic regions with cities depending on centralized systems and distant communities using on-site septic systems.
Those two worlds are starting to come together in California as a new movement forms to add on-site water reuse inside buildings, commercial facilities and multifamily housing units within the sewer sheds of centralized treatment systems.
The new combined vision came into focus during the Silicon Valley Water Summit on September 16th in Palo Alto. Brought together by Sustainable Silicon Valley (SSV), elected officials, water technology companies, engineers, regulators and owners of large commercial properties discussed what’s possible and how the Valley can embrace a new way of living – reusing greywater onsite over and over so local water districts can cut back on the amount of water imported into Silicon Valley. Currently the Valley imports two-thirds of its water.
What is greywater? It’s the flow collected from sinks, laundries and bathtubs and once safely treated by an onsite system is reused for toilet flushing or landscape irrigation. Blackwater – which gets flushed down the toilet – must go to a centralized sewage treatment plant according to current state regulations.
“Onsite water reuse is the smart grid for water,” said SSV’s Executive Director Marianna Grossman during opening remarks. According to Ms. Grossman her Association is encouraging action over simply talking about the drought. “Regulations and attitudes must change so all sources of water on a site can be considered for treatment and reuse,” she added.
Sustainable Silicon Valley has spent the last year helping large tech companies, such as Google, Facebook, LinkedIn, VMware and other companies and public agencies, move forward with their on-site reuse systems. “The Summit was a chance to bring everyone together so onsite reuse projects can move forward,” Ms. Grossman said.
Stanford University is also in the process of installing an on-site wastewater reuse system based on an anaerobic treatment design from Dr. Perry L. McCarty, a noted professor emeritus in environmental engineering and a former speaker at CWEA’s Annual Conference.
Centralized and Decentralized
Where does that leave centralized sewage treatment plants? The question was never fully answered, even after an employee from the local water resource recovery facility brought it up. Panelists said the best model going forward is coexistence and collaboration. The onsite decentralized systems still depend on the sewer system as a back-up in case something goes wrong and is the place where water from toilets is sent.
Jonathan Lanciani, CEO of Sustainable Water, said he never gets into a fight with the local water district and if a project turns acrimonious “we’ll walk.” He frequently finds water districts come around to the benefits of onsite reuse and discover there are benefits for everyone involved. His firm, Sustainable Water, is a consulting engineering firm specializing in onsite reuse using natural treatment systems.
For engineer S. Bry Sarte, onsite reuse and storage in California is a must. “The real issue is we are losing the snow pack in the Sierra. We have no choice, we must store more water as the snow pack declines.” Mr. Sarte is founder of Sherwood Design Engineers in San Francisco. He also pointed to the importance of regulations. “Protecting public health is job #1, our biggest challenge is public health,“ he said.
San Francisco architect Russ Drinker pointed out California is losing its cutting-edge leadership in water resources. Israel and Singapore now reuse nearly 100% of their water while California is barely recycling 30%. “The single biggest challenge is having regulations worked out for water reuse standards,” said Mr. Drinker.
Several recurring themes came up as the architects and engineers spoke:
- The State Water Board plays an important role in setting regulations to protect human health and allow water technology innovation. Currently they’re not creating enough room for innovation.
- As decentralized systems grow – how will it impact the centralized sewer systems?
- More installations are needed so the process goes mainstream and gains public support.
Several of the water technology companies presented examples of their installations and the lessons learned along the way.
Michael Conciatore of Australian company AquaCell presented their rain water and greywater treatment systems. They’ve learned everybody wants to use recycled water – for toilet flushing or irrigation – but no one wants to know they’re using it. His company focuses on making sure the treated water is crystal clear so it does not discolor toilet water. His company has a long working relationship with Sydney Water. Aqua Cells are used for new developments outside of the Sydney Water’s sewer shed or inside large buildings. These locations have sewage flow, which Sydney Water is unable to handle at this time. AquaCell works with Sydney Water to decide which buildings and in which neighborhoods the onsite reuse systems can get installed.
Researcher Michael Flynn from the NASA Ames Research Center described the technology they’ve developed to help astronauts survive for long space flights while reusing all water. Their latest technology combines forward and reverse osmosis treatment. The agency installed the water reuse system they designed inside their building in order to conduct long-term testing. They quickly found out double plumbing was one of the large cost factors for onsite reuse. “Don’t do double plumbing,” warned Mr. Flynn. “A system inside our building included the greywater system for $50,000 and dual plumbing cost $300,000.”
The Ames Research Center sells several different reuse systems to federal agencies and the military in the 1-600 gallon per hour range. A key feature of the Ames system is their fail-safe design. Multiple, redundant back-ups ensure the system only produces clean drinking water. If there’s a failure, the system will not produce water. Mr. Flynn felt it was important to produce potable water at all times and if there is a failure ensure the system does not produce water in order to protect human health.
During the discussion about balancing centralized and decentralized systems, panel moderator Laura Shenkar, CEO of the Artemis Project, called on audience members to show leadership on these issues.
“This is where leadership is needed. There will be wins, losses and change. Where can we create something that is going to work for the community?” Ms. Shenkar said. The Artemis Project provides strategic consulting to start-up water technology companies.
Zach F. Gallagher, Vice President of Natural Systems Utilities, said both centralized and decentralized systems can prosper together in the future. “How can we both coexist and both benefit,” Mr Gallagher asked. “The New York Department of Environmental Protection says their old infrastructure has too much flow which leads to sewage overflows, so onsite reuse helps them.” Natural Systems Utilities designs, installs and operates reuse systems for buildings and neighborhoods, including managing the systems inside the Battery Park buildings in New York City.
What do you think? What will the future of centralized and decentralized look like from where you stand? Are there already onsite reuse systems in your community? Let us know in the comments section below…