Sewage sludge
From SourceWatch
This article is based on "Secret Ingredients" and A Brief History of Slime which were published in PR Watch, Volume 2, No. 3, 3rd Quarter 1995. The original articles were authored by John C. Stauber and Sheldon Rampton and is used here with permission. As with all SourceWatch articles, feel free to edit and revise.
A Brief History of Slime
In traditional, agricultural societies, human waste was prized as a prime ingredient in what the Chinese called "night soil"--artfully composted, high-grade fertilizer. Things changed with the industrial revolution, which brought people together in cities where composting and recycling were no longer practical.
At first, open gutters were dug to carry sewage from city streets into nearby bodies of water. When populations were small and water supplies seemed unlimited, the wisdom of using fresh water as a vehicle and receptacle for human waste was not questioned. By the 1920s and 1930s, large cities were piping large quantities of untreated sewage into rivers and oceans, creating serious pollution problems. Septic systems in thousands of small and medium-sized communities were failing due to overloading. Thousands of industries were also producing chemical wastes and needed to dispose of them.
The environmentally sound approach would have been to develop separate treatment systems for human and industrial waste. Biological wastes should have been recycled through a system that returned their nutrients to the soil, and businesses should have been required to separately treat their chemical wastes on-site so that they could be contained and re-used within the industries from which they came. At the time, however, it seemed easier and cheaper to simply dump everything into a single common sewer system. For businesses, the system provided tax-based aid to help them dispose of their toxic byproducts. For people, indoor plumbing that magically "carried everything away" was a luxury that marked their escape from frontier hardship and their entrance into modernity. The system helped limit the spread of communicable diseases, and for many it symbolized the difference between primitive crudity and the civilized benefits of technological society.
The problem with this system, however, is that it collects, mixes, and concentrates a wide range of noxious and toxic materials which are then very difficult, if not impossible, to separate and detoxify. According to businesswoman Abby Rockefeller, an advocate of waste treatment reform, "conventional wastewater treatment systems . . . are not designed to produce usable end-products. Because this is so, it must be said that failure to solve the overall problem of pollution caused by the waste materials received by these systems is a function of their design."
"Today," observe environmental writers Pat Costner and Joe Thornton, "waterless treatment systems--on-site composting and drying toilets that process human wastes directly into a safe, useful soil additive--are available. These dry systems are more economical than water-flushed toilets and their attendant collection and treatment systems. However, water-flushed toilets are so entrenched in the cultural infrastructure that the transition to alternative waste systems has been blocked. Instead, billions of dollars are spent on perfecting the mistake of waterborne waste systems: wastes are first diluted in water and then, at great expense, partially removed. The products of this treatment are sludge--which requires even further treatment before disposal--and treated effluent, which carries the remaining pollutants into receiving waters."
To cope with the mounting problem of water pollution, the United States launched what has become the largest construction grants program in US history, linking millions of homes and tens of thousands of businesses into central treatment facilities. As the 1970s dawned, front-page headlines across America told stories of polluted drinking water and quarantined beachfronts. Environmentalists pressured Congress to pass the Clean Water Act of 1972, which according to US Senator Max Baucus, "put us on the course to fishable and swimmable rivers at a time when one river was known as a fire hazard and others hadn't seen fish in a generation." The Clean Water Act required communities to make sure that by 1977 their sewage plants could remove at least 85 percent of the pollutants passing through them, and allocated funding to pay for the additional treatment and filtering technologies needed to achieve this goal. By 1976, the federal government was spending $50 billion per year to help cities achieve water purity goals.
In the 1980s, however, politicians responded to pressure for reduced federal spending by cutting funds for water treatment, and by the 1990s the money had been virtually eliminated. In the meantime, the push for clean water had created another problem--tons of pollution-laden sewage sludge generated as a byproduct of the treatment process.
According to Abby Rockefeller, the hundreds of billions of dollars spent purifying water through central sewage processing plants has largely been wasted. "Leaving aside the immense costs of this option, both in energy and in money, there is the critical though inadequately recognized problem of the sludge," Rockefeller states. "The more advanced the treatment of the sewage (the more successful the separation), the more sludge will be produced, and the worse--the more unusable and dangerous--it will be. That is, the 'better' the treatment, the greater the range of incompatible materials that will have been concentrated in this highly entropic gray jelly."
What's in sewage sludge
The HarperCollins Dictionary of Environmental Science defines sludge as a "viscous, semisolid mixture of bacteria- and virus-laden organic matter, toxic metals, synthetic organic chemicals, and settled solids removed from domestic and industrial waste water at a sewage treatment plant."
Over 60,000 toxic substances and chemical compounds can be found in sewage sludge, and scientists are developing 700 to 1,000 new chemicals per year. Stephen Lester of the Citizens Clearinghouse for Hazardous Wastes has compiled information from researchers at Cornell University and the American Society of Civil Engineers showing that sludge typically contains the following toxins:
- Polychlorinated Biphenyls (PCBs);
- Chlorinated pesticides--DDT, dieldrin, aldrin, endrin, chlordane, heptachlor, lindane, mirex, kepone, 2,4,5-T, 2,4-D;
- Chlorinated compounds such as dioxins;
- Polynuclear aromatic hydrocarbons;
- Heavy metals--arsenic, cadmium, chromium, lead, mercury;
- Bacteria, viruses, protozoa, parasitic worms, fungi;
- Miscellaneous--asbestos, petroleum products, industrial solvents.
In addition, a 1994 investigation by by the US General Accounting Office found that "the full extent of the radioactive contamination of sewage sludge, ash and related by-products nationwide is unknown." Most of the radioactive material is flushed down the drain by hospitals, businesses and decontamination laundries, a practice which has contaminated at least nine sewage treatment plants in the past decade.
In 1977, EPA Administrator Douglas Costle estimated that by 1990 treatment plants would be generating 10 million tons of sludge per year, a thought that "gives us all a massive environmental headache." Today there are about 15,000 publicly-owned wastewater treatment works in the United States, discharging approximately 26 billion gallons per day of treated wastewater into lakes, streams and waterways. Before treatment, this wastewater contains over a million pounds of hazardous components. Sewage plants use heat, chemicals and bacterial treatments to detoxify 42 percent of these components through biodegradation. Another 25 percent escapes into the atmosphere, and 19 percent is discharged into lakes and streams. The remaining 14 percent--approximately 28 million pounds per year--winds up in sewage sludge.
Once created, this sludge must be disposed of somehow. Available methods include: incineration (which pollutes the air), dumping into landfills (which is expensive, and often leaches contaminants into groundwater), and ocean dumping (where it has created vast underwater dead seas). A fourth method --gasification, using sludge to generate methanol or energy--is favored by EPA's Hugh Kaufman as the "most environmentally sound approach, but also the most expensive." A fifth approach --using sludge as plant fertilizer--was considered hazardous to health and the environment until the 1970s, but it has the advantage of being inexpensive. As budget concerns mounted in the late 1970s, the EPA began to pressure sewage plants to adopt the cheapest method available--spreading sludge on farm fields.
