You can make a difference to the hurt being caused by climate chaos and the great extinction event, in your town or your city! How? Reuse, repurpose, and recycle this information.
This is the letter for week 28 of a weekly climate strike that went on for 4 years in front of San Francisco City Hall, beginning early March 2019. For more context, see this story. For an annotated table of contents to see topics for all the strike letters, see this story.
STRIKE FOR THE PLANET
because we can’t waste anything, especially water,
and we only have 65 weeks left in which to act.1
This week’s topic is WATER RECYCLING.
TO RECAP
The ability of the planet to support life is gravely and immediately in danger. San Francisco must respond. All long-term responses must begin now in order to have any impact. There are three long-term projects vital to SF’s survival. These projects are: urban forestation, water recycling, and transportation. Last week’s letter (week 27) was on forestation of SF. Next week’s letter (week 29) will cover transportation. This week’s strike, though, is all about municipal water recycling.
WHY WATER RECYCLING
SF water use per capita is roughly 154 L per person per day (40.6 gal).2 While this amount is low in comparison to other areas in CA, it is still too high to meet coming water challenges such as:
- Population increase
- Drought
- Ecosystem needs, especially in newly higher temperature environments.
Additionally, SF faces an entirely new set of water problems, including:
- Controlling for increasing and increasingly diverse pollutants (plastics, pesticides, pharmaceuticals, fracking injection fluids, endocrine disruptors, PFAS, etc.)
- Increased water stress3
- And decreasing snow pack storage for the 85% of our water imported from Hetch Hetchy.
That is why we must recycle our wastewater into potable water.
HOW TO RECYCLE WASTEWATER
Black water recycling involves removal of solids, aeration, clarification, filtration, disinfection, and then final treatments before the water is sent back to the tap. The start of the process, with large flotation ponds and aeration tanks, is identical to conventional sewage treatment. But at the point where the cleaned wastewater would be discharged into the bay or ocean, another set of processes instead begin. At this point, either bacteria or chemicals (aluminum sulfate, chlorine, and sulfur dioxide) are used to eliminate organics, denitrify the water, and kill pathogens. The water is then purified with ozone and activated carbon, or disinfected with micro-filters and reverse osmosis and UV, and then sent back into the tap water supplies.4, 5
COSTS
Recycling sewage into potable water requires additions to SF’s treatment procedures. The Big Spring water recycling facility in Texas cost $12 million to build6 and treats 16 million gallons per day.7 Orange County Water District has stated that the cost of blackwater purification is 30% cheaper than the cost of imported water.8 SF’s sewage treatment facilities are all at current sea levels and will soon be inundated by sea level rise. SF needs to build water recycling plants above probable flooding levels with added elevation to deal with unforeseen circumstances. Assuming both a 100-year operational lifespan and the need for low energy operation, with SF’s water recycling plants built to utilize gravity as much as possible, we should be looking to build at mid-elevation spaces in the hills.
SAVINGS
A life-cycle assessment looking at energy, GHG (greenhouse gases), NOx (all nitrogen oxides), PM (particle pollution), and SOx (all sulfur oxides) produced by differing water supply alternatives found reclaimed water used less energy and produced less GHG, NOx, and PM than even imported water (and much less than any method of desalination), while it was equal to imported water in SOx production (both sources substantially lower than SOx production by any of the desalination methods).9, 10 This is significant as Hetch Hetchy water is imported water.
Black water reclamation also will force us, and allow us, to test for and figure out how to screen out the multiple contaminants that currently get into our water and into us. Since we know that many of these contaminants cause a host of medical issues from cancer to autoimmune diseases to developmental disabilities, learning how to filter them out will be a boon to SF’s population, and will decrease medical costs for SF residents.
TIMELINE
Wichita Falls, Texas, during the multi-year drought of 2010 to 2013, was able to move to a 50/50 blend of recycled to lake water in 6 months.11 However, they had already started on the black water reclamation project prior to this. Orange County has been building up their percent recycled water since 2008.12
RESOURCES
Who else is doing water recycling? The Padre Dam Municipal Water District in the San Diego area, and the City of San Diego (accessing Title XVI Water Reclamation and Reuse Projects monies13 to help pay for it), Singapore14, Israel15, and Namibia16 among others. Namibia has over 50 years of experience, and San Diego is only a day’s train ride away.
Additionally see the Strike letters from weeks 1 and 20 for more details on the water issues involved. See weeks 13 and 19 on why it’s absolutely got to happen immediately (hint: it’s all about municipal bonds). See week 11 on the issues with our current sewage treatment facilities.
We only have 65 weeks left. The time to act is right now.
FOOTNOTES
1. Based on the 2018 IPCC report that world emissions need to peak by 2020 in order to change our path from 3°C (or more) increase to 1.5°C. There are only 420 gigatons of CO2 remaining to be used in total before we pass that goal. And this goal only give us a chance of not shooting beyond 1.5°C. We need to act now.
2. Is California water use increasing? KPCC Southern California Public Radio. Aaron Mendelson & Chris Keller. 07-09-2016. http://projects.scpr.org/applications/monthly-water-use/san-francisco-public-utilities-commission/.
3.
4. Wastewater Recycling. Beachapedia. 22-10-2018. http://www.beachapedia.org/Wastewater_Recycling.
5. Recycling sewage into drinking water is no big deal. They’ve been doing it in Namibia for 50 years. PRI. Daniel A. Gross. 15-12-2016. https://www.pri.org/stories/2016-12-15/recycling-sewage-drinking-water-no-big-deal-theyve-been-doing-it-namibia-50-years
6. Texas Gets Creative With Plans for Recycling Water. The Texas Tribune. Kate Galbraith. 11-06-2012. https://www.texastribune.org/2012/06/11/texas-gets-creative-recycled-water/.
7. Water Treatment Plant. Big Spring Texas. http://www.mybigspring.com/298/Water-Treatment-Plant.