California drought: How wastewater recycled for consumption could help fight dwindling supplies

SAN JOSE, Calif. (KGO) — We recycle cans, bottles, paper and some plastics. Yet most of our sewage flows into sewers where it is discharged into the bay or ocean. California has yet to develop regulations allowing the use of recycled water for drinking, but the South Bay water wholesaler and several cities see it as a critical step due to ongoing drought and declining l ‘water supply.

“As long as people are flushing, we continue to create more water. That’s very important. We’re hoping, we’re planning to make sure that’s about 10% of our water supply over the next few years. next few years,” says Valley Water. Board Director Tony Estremera.

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Valley Water and the City of San Jose invested $72 million to open an advanced water purification center in 2014. It takes treated wastewater and puts it through additional processes so it can be used by residents. industrial and agricultural customers.

“We send it to microfiltration, which has a pore size 300 times smaller than the diameter of a human hair, and that small pore can remove bacteria, protozoa and large viruses and all the other large particles that are in that water,” says Valley Water Associate Engineer Zach Helsley.

Two additional steps, reverse osmosis and ultraviolet light, turn cloudy wastewater into clear water.

The facility is remarkably quiet, yet operates 24 hours a day, seven days a week, and produces eight million gallons of purified water per day. By law, state regulators by next year must pave the way for indirect potable reuse of purified water. The goal is to pump it into underground reservoirs where it is mixed with groundwater and imported water for eventual use as drinking water. The city of Palo Alto is working with Valley Water for its own treatment plant.

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“We want to pump purified water to our groundwater recharge ponds located in the town of Campbell along Los Gatos Creek,” says Kirsten Struve of Valley Water.

The final step will be to close the loop and introduce recycled water directly into our drinking water. To help people overcome the so-called yuck factor, Valley Water runs tours of its treatment plant to familiarize the public with the process. The effort seems to help.

A poll from last year showed that up to 58% approve of using purified water, while 31% oppose it and 11% are undecided.

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“We’re blessed in Silicon Valley. People believe in science, and so we find that as long as people understand the process, they understand,” Estremera says.

This will require a shift in thinking about wastewater as a resource to be recycled.

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