You really have to hand it to San Francisco for taking low-impact living seriously. Whether it’s enacting ironclad recycling laws, banning plastic shopping bags, making it financially less cumbersome for home owners to embark on energy-saving home improvement projects or, as I mentioned yesterday, permitting the non-potable indoor use of captured rainwater, the City by the Bay has long been ahead of the eco-curve.
Home and business owners around San Francisco have also been proactive in installing low-flow toilets (a city-funded rebate program has certainly helped things along) to help conserve water. According to Tyrone Jue, a spokesman for the city Public Utilities Commission, SanFran's low-flow toilet boom has cut the city’s annual water consumption by 20 million gallons.
But as reported by the San Francisco Chronicle, not all is well in low-flow toilet land. The profusion of water-saving potties in Frisco has resulted in a “multimillion-dollar plumbing stink” with sludge backing up inside sewer pipes and emitting a “rotten egg stench” in certain areas of the city. Ahhh … there’s nothing like the delightful smell of human waste on a warm summer day.
Over the past five years, the city has spent a whopping $10 million in sewer system and sewage plant upgrades to tame the stink. And, according to the Chronicle, the city has just spent even more, investing in a $14 million, three-year supply of a certain odor-combating chemical: bleach. The city plans to use highly concentrated sodium hypochlorite to alleviate the stench and disinfect the city’s treated water before it’s pumped into the San Francisco Bay. The Chronicle does the math: “That translates into 8.5 million pounds of bleach either being poured down city drains or into the drinking water supply every year.”
While I applaud San Francisco’s efforts in looking out for health of both Mother Nature and its residents, this is one instance of the city’s somewhat aggressive tactics backfiring in a big way.
Adam Lowry, eco-blogger, chemical engineer, and co-founder/"Chief Greenskeeper" of green cleaning product line Method and Michael Braungart, a chemist and co-author of "Cradle to Cradle/Remaking the Way We Make Things,” suggest an alternative to bleach in an op-ed piece published in the Chronicle:
Hydrogen peroxide, that common chemical used in your home to disinfect cuts and scrapes or put to work when you add ‘oxy’ powder to your laundry to whiten whites, is equally effective and produces none of the downstream issues of chlorine bleach. It is being used cost effectively today to treat sewage odor in many places in the United States, such as Boston and Miami, as well as internationally in Germany and France.
An even better choice would to use a pro-biotic solution, that is, enzymes or bacteria that would simply ‘eat’ the smell then degrade harmlessly. Used correctly, they could even be used to prevent the problem from occurring again by restoring the healthy balance of microbes in our sewer system.
Using sodium hypochlorite, commonly known as bleach, is the equivalent of using a sledgehammer to crack an egg; it's the wrong tool, and it will cause irreversible collateral damage.
Officials claim that the stink has been made worse by the increase in the number of installed low-flow toilets, which reduce the amount of water in the sewage system that otherwise would dilute the smell. It is a tragic irony that the city's plan to address a nuisance created by positive conservation efforts is to pollute our water system with toxic chemicals.
Such a toxic shock to our system would render our sewage eternally dependent on chemicals to treat this problem, not to mention damage our system by corroding our sewage pipes. A redesign of our system is needed.
Why are we using 19th century chemistry to combat a 21st century problem? Is San Francisco not in the cradle of clean tech innovation? Other cities are already using better solutions today, and they are simple and cost effective.
Via [San Francisco Chronicle]
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