GrokSurf's San Diego

Local observations on water, environment, technology, law & politics

Purified recycled water…it’s perfectly clear

Posted by George J Janczyn on May 29, 2012

Here’s a nicely done educational/promotional video (just over 5 minutes) from the San Diego County Water Authority with the collaboration of the Escondido Water District, Helix Water District, Padre Dam Municipal Water District, and the City of San Diego.

These agencies are working hard to take advantage of purified recycled water to reduce our dependence on imported water, create the potential to improve the quality of the raw supplies now imported, reduce the amount of wastewater discarded into the ocean, and ultimately reduce the cost of water relative to imported water.

(if you’re a GrokSurf email subscriber, the video may not run in your mail program. In that case, just click on the title of the post to go to the web version)


6 Responses to “Purified recycled water…it’s perfectly clear”

  1. merle Moshiri said

    Items like this must send a shudder down the spine of Poseidon. Uh oh! a viable alternative to desal? cheaper, reliable, provides more jobs? Well, maybe some of the fat cats might not make as much money but…..we all have to sacrifice.

    Merle Moshiri, President
    Residents for Responsible Desalination
    Huntington Beach, CA

  2. Burton Freeman said

    Yes, a well-produced video on some of the issues re IPR. The arguments for potable reuse of water point to several different local sources of San Diego County (and city) water. The goals are safety, reliability and cost-effectiveness. No doubt, these also imply diversification of supply, as well as reduction in demand. It is remarkable that conservation, aquifers, purple pipes and seawater desalination don’t get some face-time; they are all part of a menu that is on the competitive water market!

    As for IPR, questions remain regarding sequestration in a surface water body, amount of available advance water supply and cost. Le’s restrain our enthusiasm for IPR until all of the facts are available.

  3. Brad Gore said

    Hey Groksurf, you might want to climb down off of the ‘sustainability’ orthodoxy bandwagon to read the following article, which is based on actual science, not feelings or passion or political pressure:

    And how much do you want to bet that serotonin reuptake inhibitor molecules absolutely sail through the membranes? Especially if the maintenance and operation of said membranes is performed by unaccountable unionized city employees?

    Purple pipe distribution of recycled water for turf irrigation makes SO much sense-it obviously was doomed in San Diego..

    • Thanks for the link Mr. Gore.

      I think you’re directing your concern about contaminants of emerging concern (CECs) against the wrong target (San Diego’s purified recycled water project). Your target should be drinking water standards in general–regardless of the source water.

      San Diego imports about 80% of its water from Northern California and the Colorado River. Imported water from these sources contains treated wastewater (probably mostly only to secondary standards) from over 345 municipal wastewater facilities by the time it reaches us. Therefore, a percentage of our imported (or raw) water has always contained treated wastewater.

      San Diego’s raw water then goes only to a standard potable water treatment facility (Miramar, Alvarado, or Otay) before it comes to our taps. So those CECs you’re worried about are in our entire water supply system, they’re not simply a potential contaminant in our recycled water.

      San Diego’s purified recycled water project, on the other hand, would begin with recycled water (wastewater treated to tertiary, or purple pipe standards) and then add not only membrane filtration (which you mention) but reverse osmosis followed by disinfection with ultraviolet light and peroxide before it is then would be blended with raw imported water and detained for a predetermined time in San Vicente Reservoir where more UV from sunlight and other natural processes would take place. Finally it would be sent one more time through the standard potable water treatment plant.

      Depending on how you look at it, purified recycled water improves the quality of the raw imported water, or the imported water contaminates the purified recycled water.

      I would encourage you to direct specific concerns (such as the antidepressant you mention) to the relevant agencies that regulate drinking water quality…EPA on the federal side and California Department of Public Health on the state side.

      • Brad Gore said

        Thanks for your very measured and thorough response, attempting to debunk any concerns I might have about the safety of recycled wastewater delivered via the San Diego IPR project.

        I understand the political dynamics of this experiment in long term epidemiology, and I also understand why the principle forces behind this initiative, radical environmental activists and public employee unions, tend to dismiss any and all safety concerns.

        Your argument that we are already consuming treated wastewater is indeed a heavily relied-upon red herring. First, the San Diego IPR as it is currently configured will constitute a positive feedback loop for potential contaminants such as serotonin re-uptake inhibitors that manage to get through the treatment cycle. Many of these emerging contaminants, such as endocrine disruptors, are thought to be biologically active in the parts per trillion range. Secondly, the portion of San Diego’s water that is imported from the Sierra Nevada is essentially free of treated wastewater discharges. That which comes from the Colorado River contains highly diluted treated wastewater discharges from towns and cities which, unlike the City of San Diego, cannot obtain annual waivers to the Clean Water Act and must therefore treat their wastewater discharges to a tertiary standard. These discharges then must travel hundreds of miles in a natural riverine hydrological cycle. The IPR discharges will simply be dumped into San Vicente Reservoir. These discharges will not mix very well due to seasonal lake stratification. Contaminants will be concentrated over time.

        In my humble opinion, the San Diego Public Utilities Department has not obtained anything like informed consent from the rate-payers for this experiment. All I see is spin and white wash.

  4. Mr. Gore,

    On the first point, San Diego’s water reuse project is no more a “positive feedback loop” for potential contaminants that may or may not make it through the advanced purification process than is seawater desalination, the ocean being the ultimate destination for the world’s wastewater, treated and untreated.

    On the second point, it is incorrect to suggest that water imported from Northern California is “essentially free” of treated wastewater. On the contrary, a large number of California municipalities discharge wastewater into rivers and streams with their eventual confluence in the Sacramento-San Juaquin Delta from which our northern water is drawn — the most obvious and far from the only example being wastewater from the City of Sacramento. Surely you know know that the pumps for the California Aqueduct draw our water from the Delta, not from the heights of the Sierra Nevada.

    As for water from the Colorado River, Las Vegas (unlike Sacramento) has for years already been treating all, not just a portion, of its wastewater to the advanced purification standards that San Diego contemplates before they dispose of it via outfall into the Colorado River at Lake Mead. Since Las Vegas draws its drinking water from Lake Mead, some of that purified recycled water gets reused by Las Vegans (a feedback loop?) and some of it continues down the river.

    You’re also incorrect about the other cities and towns along the Colorado River complying with the Clean Water Act by performing tertiary treatment to their wastewater before outfall into the river. The Act mandates secondary treatment and that’s what those cities are doing.

    Further, the Colorado River is naturally high in total disolved solids from the eroded land it carries (if that’s what you mean by “natural riverine hydrological cycle”). The river’s high salinity is lowered to more acceptable levels when it blends with Northern California water (which is lower in TDSs) inside the Metropolitan’s reservoir and pumping infrastructure before it flows to San Diego.

    Lastly, it is wrong to blame the Public Utilities Department for spin and white wash and not obtaining informed ratepayer consent.

    The decisions made to proceed with the advanced purification project were made by the City Council and Mayor who determine policy for the Public Utilities Department. Our City government has been encouraged to set this policy by an educated, informed coalition of environmental, consumer, business, labor and technical organizations — and informed individual citizens.

    The spin and white wash comes from the political process and the news media.

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