Civilization & Sludge: Notes on the History of the Management of Human Excreta

Abby A. Rockefeller

Originally published in Current World Leaders, Volume 39, No. 6.

The next stage, called "secondary treatment," includes some biological stabilization through forced aeration of the sewage, and chemical flocculation and precipitation of some of the phosphates deriving from laundry detergents. But in spite of the great energy and financial cost of this form of treatment, the effluent reaching the recipient bodies of water continues to be rich in nitrates and phosphates. (These nutrients, as noted above, are called limiting factors. When they are present in water, they cause an explosive growth of algae, which in turn causes lakes to die of eutrophication as the decaying algae robs the water of its oxygen.) Industrial pollutants, such as toxic chemicals and heavy metals, are not addressed by this level of treatment.

So engineering ingenuity developed another, yet more complex, yet more energy intensive and expensive form called "tertiary" or "advanced wastewater treatment." Because of its enormous cost it has been difficult to get American taxpayers to fund this level to any great extent. But even where funded, treatment remains incomplete: some nitrates, some heavy metals, and many toxic chemicals continue to evade tertiary treatment and remain in the water.

Central collection and treatment of sewage cannot be said to have succeeded in solving the underlying problem of water pollution caused by using water to transport wastes. The problem is deeper and systemic. The trouble with the treatment approach to managing the pollution caused by water carriage of excreta and the by-products of industry lies only partly in the inadequacy of even the most advanced processes. Though the trouble may seem to have been ameliorated because this bay or that river is less polluted than it was without wastewater treatment, the pollutants that were in the water have simply been reorganized and concentrated in a new form: sludge.

Sludge is the dewatered, sticky black "cake" consisting of every waste material capable of being sent down the drains of homes and industries and into the sewers, and which the treatment process is able to get back out again. If sewage can be said perfectly to exemplify a high entropy process of matter lost through irretrievable dissipation, sludge is the quintessential example of disparate matter lost to use through unresolvable homogenization.

In the United States Federal Register (Vol. 55, No. 218/November 9, 1990), the United States Environmental Protection Agency (EPA) says of sludge:
The chemical composition and biological constituents of the sludge depend upon the composition of the wastewater entering the treatment facilities and the subsequent treatment processes. Typically, these constituents may include volatiles, organic solids, nutrients, disease-causing pathogenic organisms (e.g., bacteria, viruses, etc.), heavy metals and inorganic ions, and toxic organic chemicals from industrial wastes, household chemicals, and pesticides.

This short list of what sludge "may include" is shorthand for the enormous list of constituents that can actually be present in it. For instance, of the 100,000 or so organic and inorganic chemicals produced and used in industrialized nations, a huge number will end up in the sewers. One thousand new ones are produced every year and are added to the cocktail of synthetic substances affecting life processes. Those pollutants that are put in the sewers--and that are removed from the wastewater by the treatment process--will end up in the sludge. There are the heavy metals which, though they are micro-nutrients crucially needed in tiny amounts for growth of life, are toxic to life when they cross the threshold firmly established in the cells of life. There are organochlorine estrogen mimickers, the best known of which are DDT, chlordane, alpha-hexachlorocyclohexane, 2,4,D, PCBs, and dioxin. There are halogenated aliphatic (chain) hydrocarbons, aromatic (ring) hydrocarbons, chloro- and nitro-aromatic hydrocarbons, phthalates, halogenated ethers, and phenols. There is radioactive matter from hospitals. All of these are destructive of life processes (Reutergårdh 1966).

Attitudes toward sludge--this heterogeneous product of wastewater treatment processes--and toward the disposition of it have a convoluted history of their own. Clearly, sludge contains constituents that are hazardous to life. If we persist in producing sludge, something must be done with it. What to do with it is the subject of intense debate. To understand this debate, one must know something of the interplay between the following forces: the environmental movement that began in the early 1970s; the organic food movement that began decades earlier; the traditional sanitary engineering/regulatory posture; and the exigencies of the prevailing economic/industrial arrangement. The character of the debate taking place in the United States is illustrative of the way these forces interact regarding the technical and management patterns in all the sewered, and about-to-be-sewered, parts of the world.

To begin, it may be clarifying to focus this history on the question why decentralized solutions to water pollution were not developed and promoted over sewering, since, environmental considerations aside for the moment, they would have saved taxpayers immense amounts of money. The answer is in part the engineering/regulatory bias in favor of top-down, centrally controlled solutions. Health authorities are traditionally skeptical of the people's ability to manage problems themselves. The regulatory and sanitary engineering community (very much one body, in general) also feels that troubles are safer in its hands. Moreover, it is the case that there has been a widespread conviction on the part of environmental groups that treatment at the "end of the pipe" is the surest way of cleaning up polluted water. The environmental movement in the United States played a large part in creating the pressure that resulted in the Clean Water Act of 1977. This Act was effectively a sewering act. Enormous sums of money were allocated exclusively for the laying of sewer pipes and the construction of treatment plants. The Clean Water Act funded virtually no on-site, site specific, decentralized systems--either for remediation or for new construction.

But the greatest force behind the drive to sewer has been the interests of industry: first, because public sewers are the cheapest place for industries to put their wastes, and second, because it is the enormously expensive system of central collection that generates the highest profits for engineering and construction firms. For example, 80% of the total cost of sewering and treatment is in the laying of pipes, and engineering and construction firms get a flat 20% of the total project cost. Fixing the 5-10% of septic systems that are failing (i.e., polluting or overflowing) would never generate the profits associated with sewering 100% of these communities' central collection and treatment works.

This powerful coincidence of seemingly disparate interests--regulatory, environmental, and industrial--overwhelmed any popular opposition to the tax burden required to fund this massive public project, which in cost is second only to that of the U.S. highway construction program. When environmentalists are for it, and the governments are for it, corporate interests can just lay low, for who but a philistine would object to tax increases for so good a cause? Thus, town after town, each, as noted above, with typically 5-10% of on-site wastewater systems (mostly old cesspools and "modern" septic tank/leach fields) deemed to be failing, has been herded down the sewer path, and so has come to have 100% of its sewage centrally collected and treated. Since it is treatment of sewage that creates sludge--and since, therefore, the more extensive the treatment, the more and the worse the sludge--the issue of how to dispose of it became for municipalities a major and growing problem.

What was being done with it? In some places sludge was dumped in "sanitary" landfills, where it caused serious groundwater pollution. In other places it was incinerated, causing serious air pollution. And, remarkable as it may seem (given the stated objective of removing pollutants from the water), during the first phase of the sewage treatment era, cities built on ocean shores saw fit to dump the sludge into the ocean--that is, back into the water. As early as 1924, New York City, whose new treatment plant was a striking case in point, began dumping its sludge 12 miles outside New York Harbor. Sixty years later, the U.S. EPA determined that the coastal waters had been unacceptably damaged and ordered that the sludge be barged farther out--to a site 106 miles offshore. Although this strategy seems to suggest a failure of imagination, it remained an acceptable solution in the eyes of the federal authorities until the 1980s, when hypodermic needles and other medical debris from hospitals started washing up on the beaches. (These needles actually came from "solid waste," or trash, which was also routinely dumped into the ocean.) The barren moonscape on the ocean floor created by the unwonted concentrations of heavy metals and other toxins present in the sludge had been of little concern to the public (who couldn't see it and for the most part didn't know about it), but the AIDS epidemic and its attendant focus on hypodermic needles caused a public and media commotion sufficient to cause Congress to ban ocean dumping altogether in 1988.

This was a triumph for many environmental groups who had fought ocean dumping because of its toxic effects on marine ecosystems. But the ban on ocean dumping only moved the sludge problem to other grounds: what to do with it now? And, although not a conflict known to many--not even to many environmentalists--there was a disagreement within and between the groups in the environmental movement over what should be done with the sludge. It seemed that the old debate had reappeared, only this time about sludge: is it a nuisance--or worse, a hazard--that must be "disposed of"; or is it, like the old "night soil," a valuable fertilizer?

Some of the major environmental organizations--including the Environmental Defense Fund (EDF) and the National Resources Defense Council (NRDC)--struck a deal with the EPA, which agreed to shut down ocean dumping if they would join in promoting land application as the long-term solution to the disposition of sludge. Both EDF and NRDC were among the signers of the "consent decree," the legal document mandating land application in place of ocean dumping. To many in these organizations, this must have seemed a very good arrangement: in one fell swoop it ended a poisonous process (ocean dumping) and, it seemed, began a very good one. Wasn't this a promise to "recycle"? Wasn't it "sewage farming" at last?

Continue to the conclusion of the article or return to the beginning.

179 Boylston Street
Jamaica Plain, MA 02130 USA
© 1997 The ReSource Institute for Low Entropy Systems