The Poop on Biosolids
L.A.’s Sewage Recycling Program Garners Awards and Fierce Criticism
People flush the toilet maybe five to 10 times a day. Ever wonder where it all goes and, once it gets there, what they do with it?
On a per capita basis, Los Angeles area homes, businesses and industry together generate roughly 90 gallons per day of raw sewage from toilet flushing, bathing, housekeeping and discharging industrial waste into drains. Most of us care not to think about sewage once it’s out of sight.
However, thinking about sewage, and what best do with it, is exactly what wastewater treatment facilities do. The Hyperion treatment plant in Playa Del Ray is state-of-the-art and by far the largest of L.A.’s four plants, managing the wastewater produced by over four million people in L.A. and 29 surrounding cities. There, the goal is to separate the water from the solid components – aka sewage sludge – in a sustainable fashion for recycling.
To give a feeling for the enormity of this task, Hyperion handles a daily sewage inflow averaging 330 million gallons, enough to fill 500 Olympic-sized pools.
For three decades through the 1980s, the routine disposal of sewage from L.A. and surrounding cities into the Santa Monica Bay created a dead zone in the area of sewage outfall, prompting the city to launch a program to keep all sewage sludge out of the bay and find environmentally sound reuses for it. Since 1994, the Hyperion plant has achieved its goal of 100% “beneficial reuse” of sewage sludge by converting it into “biosolids” which can be utilized as soil amendment or compost or as an energy source and a means to sequester greenhouse gases.
L.A.’s Biosolids Environmental Management System (EMS) has won awards for innovation and environmental stewardship but has also elicited opposition from parties claiming it is unsafe for both people and the environment because of the contaminants still present. A closer look into how L.A. is recycling its biosolids exemplifies the struggle American communities face in finding solutions to a major waste problem we’d rather not face.
What Are Biosolids?
At Hyperion, the Biosolids EMS starts with separating much of the liquid from the solids and incubating the liquid in oxygen-rich and later anaerobic conditions so bacteria can digest the disease-causing pathogens before the water is discharged five miles offshore and 190 feet deep into Santa Monica Bay.
The sewage sludge left behind is a black slurry with the consistency of mud or toothpaste.
Biosolids are sewage sludge which has been “stabilized” to reduce odors and pathogens and turned into marketable products. At Hyperion, stabilization takes 13 days during which the sludge is incubated in enclosed vessels at 128°F where anaerobic bacteria do the work of breaking it down. The 7.5 million cubic feet of methane gas produced as a byproduct each day is converted to electricity and suffices to cover all Hyperion’s operating needs.
The resulting biosolids are what the U.S. Environmental Protection Agency (EPA) defines as “Class A,” an organic product which can be applied, as is, to agricultural land to improve crop yields or processed further into an earth-like composting material for fertilizing home and commercial gardens. Because Class A biosolids are supposedly near pathogen-free, the EPA deems them safe for human contact, and agricultural uses do not require a waiting period between land application and harvesting of crops.
Class B biosolids, produced in other biosolids programs like the one in Orange County, do require a waiting period because of greater residual pathogens.
Hyperion produced 650 wet tons of biosolids per day in 2010. L.A. has invested in huge centrifuges to remove most of the water, thereby reducing the cost of transporting biosolids to one of three destinations.
In 2010, 78% of L.A.’s biosolids were spread on a 4,688-acre farm in Kern County called Green Acres where, because of a local ordinance, only animal feed crops are grown—mostly wheat and corn—and sold to local dairies. L.A. generated $100,000 from such sales in fiscal year 2008-2009.
The City of L.A. purchased Green Acres in 2000 to insure a reliable location for recycling its biosolids and also touts the use of recycled wastewater from nearby Bakersfield for irrigation.
Another 9% of L.A.’s biosolids in 2010 were routed to a Griffith Park facility for composting together with “zoo poo” and green park trimmings, yielding a registered trademark product, TOPGRO®, owned by the City of L.A. Half is utilized in Griffith Park, and the rest is sold in bulk to landscapers and nurseries or else used for landscaping at LA City facilities.
TOPGRO® is marketed as “natural” and “organic” and is not subject to any hazardous waste regulations because the EPA considers it nontoxic.
Since 2008, a portion of the biosolids is being diverted to a first-in-the-nation, five-year pilot project overseen by the EPA wherein petroleum industry technology is used to inject biosolids into permeable sandstone a mile underground within depleted, abandoned oil and gas reservoirs at Terminal Island.
This so-named Terminal Island Renewable Energy Project, or TIRE, capitalizes on the high temperatures at such depths which enable anaerobic bacteria to biodegrade the biosolids, producing methane gas and carbon dioxide. The carbon dioxide remains dissolved and permanently sequestered underground in a brine solution, whereas the methane travels to the surface for capture as a renewable energy source.
In the last year, 13% of L.A.’s biosolids were processed at TIRE, and the success of this project is prompting the City to ask the EPA for a five-year extension for further testing.
In 2006, L.A. was awarded Platinum Level Certification (the highest level) for it biosolids EMS by the National Biosolids Partnership, a nonprofit alliance of water quality organizations that recognizes biosolids programs for sustainable management practices that go beyond regulatory compliance.
The prestige of L.A.’s biosolids EMS has been especially enhanced by awards to the TIRE project for innovation and community improvement granted by the National Association of Clean Water Agencies in 2008 and both the National League of Cities and the California Association of Sanitation Agencies in 2010.
Are Biosolids Safe?
Despite such accolades, to say that not everyone is thrilled about what L.A. is doing with its sewage waste would be an understatement.
In 2006, a whopping 83% of Kern County voters passed an “anti-sludge ordinance” (Measure E) to prevent L.A. and other Southland jurisdictions from dumping their biosolids in Kern County. This gesture reflected concerns about threats to human health and groundwater (Green Acres sits atop an aquifer), plus local resentment that the practice had been going on for a decade. Some residents have complained of dust, flies and odor, according to a representative of the County Counsel of Kern County, and there is local suspicion that the amount of animal feed actually being grown on Green Acres is limited.
Implementation of Measure E has been delayed by court battles led by the City of LA. A federal case against Measure E was dismissed in late 2010, but L.A. and others are suing Kern County again, now in Tulare County Superior Court, to block the ordinance which is scheduled to be implemented on Oct. 19.
Should Kern County ultimately prevail, L.A. still plans to find beneficial reuses for all its biosolids by calling upon contingency contracts for land application in Arizona and composting in California and Arizona, though at increased cost to the City.
Another stink over biosolids erupted in 2009 in San Francisco when “organic compost,” given away for free to the public by the Public Utilities Commission, tested positive for several endocrine-disrupting chemicals including flame retardants and triclosan, an anti-bacterial agent. The giveaway is now on temporary hold, and Food Rights Network, a nonprofit research group that oversaw the testing, has called for a permanent end to the program which it accuses of using home gardens as a dumping ground for the sewage waste industry.
In general, controversy over the wisdom of recycling biosolids on farmland and gardens has heated up following release in 2009 of results of an EPA survey in which biosolids from water treatment agencies in 35 states were tested for 145 chemical residues. Every sample contained, at minimum, a host of different flame retardants, heavy metals and pharmaceuticals.
The EPA report did not comment on what the implications might be for the safety of applying biosolids to home gardens or lands used for crops or grazing. However, the Organic Consumers Association OCA), a nonprofit group which advocates for organic standards, has launched a campaign against all such practices, emphasizing that biosolids are regulated by the EPA only for levels of certain pathogens and 10 heavy metals. The regulations do not cover the wide spectrum of other chemical pollutants found in biosolids.
Furthermore, OCA claims that the levels of toxic heavy metals allowed by the EPA are the least restrictive among industrialized nations and do not take into account the unknown effects of long-term exposure to even low levels.
Hyperion’s biosolids undergo monthly testing that exceeds EPA requirements because it covers more pathogens and more high priority pollutants like dioxins, cyanide, pesticides and herbicides. Furthermore, Diane Gilbert Jones, an environmental engineer representing L.A.’s biosolids EMS, points out that there is no evidence that anyone has ever been harmed by L.A.’s biosolids and that the level of contaminants is lower than what people are exposed to through interaction with everyday consumer products.
Nevertheless, both the OCA and Food Rights Network take issue with the fact that no laws require any labeling to inform consumers when compost is derived from sewage sludge and might contain contaminants. They want the public to know that the term biosolids was coined in a 1991 contest orchestrated by the Water Environment Federation—an association of water quality professionals—to find a marketable euphemism for sewage sludge.
Adding to the controversy about biosolids, very little is yet known about the extent to which contaminants from biosolids might build up in soil over time or enter the food chain. However, red flags have been raised by studies published in recent months by researchers at the Colorado School of Mines.
In one, higher levels of PFCs or perfluorochemicals were measured in soils amended with the most biosolids, raising concerns because PFCs are known to persist in the environment and bioaccumulate. Another study found evidence for bioaccumulation of antimicrobial chemicals in earthworms living in biosolid-amended soil, suggesting biosolids might alter soil ecosystems.
Furthermore, articles recently appearing in the New York Times outlined concerns raised by federal regulators that radioactive waste from drilling for natural gas is turning up in wastewater and could end up on farmlands treated with biosolids.
The OCA suggests that consumers concerned about the impact of biosolids on food safety should seek out foods labeled “USDA Organic” because, since 1998, organic standards have prohibited use of sewage sludge as fertilizer in food production.
The OCA and the Food Rights Network are among the more strident opponents of biosolids recycling programs who want all sewage sludge handled as toxic waste and contained for disposal, which could mean landfilling or even incineration. Others have called for more nuanced approaches.
Congressman Jose Serrano of New York has recently introduced federal legislation that would prohibit grazing or growing crops and animal feed for a full year on land spread with biosolids and would require any foods grown on such land be labeled as such (HR 254).
The Sierra Club’s recommendations include tightening restrictions on allowable contaminants and creating buffer zones around treated fields to protect nearby residents from airborne contaminants.
Whatever future tacks L.A. might take to improve on the sustainability and public acceptance of its program for managing sewage waste, homeowners, businesses and industry also must move beyond “out of sight out, out of mind” and give due attention to the toxicity of what is being flushed down drains and in whose backyard that waste ends up. LA’s ongoing “No Drugs Down the Drain” public education campaign is meant to foster such awareness.
Perhaps a debate over the safety of recycling sewage waste is just the wakeup call America needs to compel us to rethink the reckless approach to chemical regulation which has allowed some 80,000 chemicals into commerce, most without any health or environmental safety testing, let alone plans for how to best handle the tainted sewage that inevitably results.