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 organic farming and natural food movement developed in response to the post-World War II period when agriculture was turning to chemical fertilizers and synthetic pesticides. By the 1970s the movement had attracted a diverse, passionate, and international following. Organic gardeners and farmers were "environmentalists" before the emergence of the more encompassing environmental movement in the 1970s. Fundamental to the organic movement's philosophy is the belief that human health depends on food grown on healthy soil--soil alive with humus, the partly decomposed residue of organic matter. Feeding the soil--rather than feeding the plants "intravenously" with soluble synthetic chemical fertilizers, as is the practice in agribusiness--is, according to this view, the way to support the health of the soil. And humus is the "food" for soil. Hence, compost, the managed creation of humus, is the essential ingredient of the organic method. Crucial to this orientation, also, has been the belief that, since all life is related, the pesticides, herbicides, and fungicides routinely employed in chemical agribusiness will damage human health at least as much as they will damage the smaller and rapidly multiplying creatures they were designed to destroy. It is logical to expect that using sludge in agriculture would be abhorrent to the organic movement.

The organic food and agriculture movement gained in strength in spite of the silent but monumental opposing interests of the agro-industry, whose economic health has depended on the petrochemical-based fertilizers and, given vertical integration of the chemical and agriculture industries, on pesticides of every sort. The organic food and agriculture movement also gained strength in spite of the ruling view of the EPA, which to a large extent is composed of engineers who have little respect for ideas associated with anything "organic." Indeed, the U.S. Department of Agriculture and the EPA regarded the practice of composting, the organic farmers' means of achieving soil health and fertility, as being unscientific--until, that is, the late 1980s when, soon after the signing of the consent decree stopping ocean dumping of sludge, "land application" of sewage sludge came into its own.

In 1992, the ocean dumping ban went into effect, and then, with the full fanfare and pomp of a formidable public relations campaign, sewage sludge was rechristened "beneficial biosolids." Thus the EPA's classification of sludge as a hazardous material was evaporated and then reconstituted with the trappings of the recently despised word "compost": sludge would be composted; the word "compost" would achieve official dignity. And environmental groups such as EDF and NRDC blessed this conversion.

At the same time, industry and the big environmental organizations were forging a new kind of relationship. These groups believed they could modify the behavior of industry for the sake of the environment by sitting at the same table in a spirit of negotiation. Industry on its part began to fund these organizations. EDF and NRDC both received funding from the waste handling industries, and subsequently were notably silent when questions were raised about the toxic constituents of sludge and the likely dangers of its application to the land. And within the organic movement,Compost Science, a spinoff of Rodale's very popular Organic Gardening and Farming magazine, became the prime publicist of land application of sludge, not only through its articles, but also through its copious advertisements for sludge hauling and sludge spreading equipment.

This sanction by the most respectable environmental organizations was key to getting public and regulatory acceptance for what would be for the waste industry the most profitable sludge disposal method among all the alternatives. Land filling is expensive for them because of tipping fees. Incineration is expensive because of unabated environmental opposition. Land application, on the other hand, is profitable. Municipalities pay waste haulers to take the sludge away and then dump it--for free (hence no tipping fees)--on farms. But beyond free dumping, through high-powered public relations expropriation of the words "natural" and "organic" and "compost," this same sludge, neatly pelletized and bagged, could be sold retail to gardeners. And, as long as there were environmentalists who condoned it, gardeners would buy it.

For every municipality with a sewer system and some kind of sewage treatment, the growing mounds of sludge are becoming an increasingly serious problem. This problem gives them a compelling interest to support land application: every town and city needs a way--a cheap way, if possible--to dispose of this sludge. The public, already burdened by taxes first for sewering and then for treatment of sewage, will not easily take on the further cost of the treatment of sludge. Land application isn't treatment: it's "beneficial reuse" that costs taxpayers nothing. Waste haulers began offering sludge as a "free fertilizer" to the farmers along with free spreading of lime, which was a bonus of thousands of dollars to small and middle sized farms, in those parts of the country with acid soils in need of liming. This offer has made advocates of many of those farmers.

The claim that "biosolids" are beneficial is based on the presence in the sewage sludge of nutrients deriving from human excreta. But the benefit of this content compared to the dangers of the toxic matter in it is a key point in the debate about land application of sludge. It is the view of this writer that the menace of toxic and otherwise non-life-compatible substances that can be found in sludge so greatly outweigh the potential nutrient benefit as to make that potential benefit an irrelevance. Let me now present the reasoning on which my position is based.

Nitrogen is the main nutrient promoted to farmers as the "free fertilizer" in sludge. The land application wing of EPA (primarily the wastewater division) claims that the total nitrogen fertilizer requirement of agriculture can be met by using sewage sludge. However, most of the nitrogen in excreta derives from the urine, and the forms of nitrogen in urine are highly soluble and, once mixed with water, are not easily removed from it. Therefore, sewage treatment processes allow most of the nitrogen to remain in the wastewater, transferring correspondingly little to the sludge. Since the concentrations of nitrogen are so relatively low, and the concentrations of heavy metals (e.g., lead, cadmium, zinc, copper, mercury, chromium, and arsenic) are, relative to ambient levels in soils, so high, it follows that massive quantities of sludge must be spread on farmland to attain the levels of nitrogen needed to act as fertilizer. This means heavy metals will accumulate in the soil. Or they will move. Where? Into bacteria, into plants, into the chain of life.

The offers of free lime, besides serving as an inducement to farmers to accept sludge on their land, serves another purpose. The regulations governing land application of sludge require the maintenance of a pH above 6.5 in soils on which sludge is spread. This 6.5 pH is needed in order to bind up the heavy metals--precisely to prevent them from moving--either up, causing "bio-accumulation" in life chains, or down, causing pollution of groundwater. There is an active debate between soil scientists and advocates of land application about this effort to "bind up" the heavy metals. This debate has two questions: whether or not liming works on all the metals from a strictly chemical point of view, and whether or not it matters if it works, since the monitoring and enforcement of pH levels on farms is a virtual impossibility.

There are many problems surrounded by intense controversy over the issue of land application of sludge. Its noxious odor is the first to be complained of, if the least threatening to life. Disease--from viability and regrowth of human pathogens in raw sludge, and other diseases caused by the sludge composting processes--is of major concern to many. But, serious as these concerns are, serious as is the danger of heavy metals' toxicity due to land application, sludge has another yet more threatening characteristic. Far more dangerous to all life is the fact that combinations of some chemicals can cause levels of life process disruptions many times in excess of the effects of any chemical alone. For example, recent research has demonstrated dramatic increases in the estrogenic effects of common pesticides when they act in combination. Whereas the endocrine disrupting effect is 1:1 in the case of the doubling of one single compound, where two or more are combined, their destructive effects are not just doubled but, rather, multiplied and magnified to the order of 600 or even 1600 times. Sludge provides perfectly the conditions for combinations of thousands of chemicals to cause a cataclysmic devastation of life (Colborn et al. 1993; Arnold et al. 1996).

What is to be done with sludge, then? This question has two parts. The first is immediate: is there a safe way to deal with the sludge that the world is now producing? The second is a policy question: should we continue to commit resources to a sewering-and-treatment-of-sewage system which creates so unresolvable a problem as is embodied in sludge?

In answer to the immediate question, the sludge that is still being produced by existing treatment plants should be treated as the hazardous waste that it is. It should either be isolated in secure storage, as nuclear waste is, or it should be processed by means of emerging technologies such as gasification which, through high-heat oxidation, avoids the creation of dioxins in the stack gases and reduces the sludge to a mineral ash. Both these strategies have the advantage of making possible the minimizing of the contact of sludge with life, rather than the maximizing of it as is currently the case with land-application.

The answer to the second part--the policy part--is prevention. Prevention rather than inevitably futile attempts at "cure" is the form any positive change must take. Prevention in this case means not creating sludge in the first place. Communities that are not already sewered should practice sewer avoidance. Sewering is the most expensive technology. It degrades the environment more than protects it, and it unceasingly produces sludge in overwhelming quantities. Communities need to take the political initiative to insist that substandard or failing on-site systems (e.g., pit latrines, cesspools, septic tank/leach fields) must be remediated by on-site technologies that solve, instead of merely move the problem. Many options now exist for on-site remediation of failing or polluting septic systems. There are waterless composting toilets, greywater purification-by-use systems, and reed beds and other water-based biological systems for cleaning organically polluted wastewater from industrial processes. The key to preventing the trouble caused by this homogenized mess of mixed matter is separation at the source.


No society in the world today deals well with human excreta. At all levels of technical sophistication, damage is done to water, soil, and human health--whether by the pit latrine, the flush toilet, the septic tank/leach field, or, most insidiously and destructively, by the central sewage collection and treatment plant, which creates an unpredictably toxic, and therefore unrecyclable, sludge. The only principle by which we can simultaneously protect the soil, the water, and human health is through technologies and management systems that systematically segregate human "wastes" and recycle them to agriculture, from which for the past 10,000 years, they have come.

The sheer number of dangers associated with treating sludge as if it were a fertilizer is so great, so various, and so serious that it would be the life work of thousands of professionals to divide up and respond to the categories of problems that will arise from this practice. The real significance of all this--of the names and numbers, of the long list of "anecdotes" about human illness, about cows and horses dying after eating hay grown on sludge and of people who live next to agricultural lands to which sludge has been applied developing strange illnesses--lies in the unknowability of it all: what goes down the drains is unpredictable; what goes into the sewer--from hour to hour, from week to week, from month to month--is unpredictable; what is extracted from the wastewater can neither be predicted nor monitored to an extent even remotely adequate. And no system of regulations can be either designed or enforced in such a way as to protect life chains from the potential of devastation by the constituents of sludge.

Collecting our "wastes" in sewage, then "treating" them so as to disentangle them again, then distributing the residue, the sludge, on agricultural land, can be made to look like "recycling," for some of the sludge did come from food growth and food use processes. But much of it did not come from such processes, and when those materials, foreign to the cycles of life, are insinuated into these cycles through the food chain, the consequences for life can be terrible. Because we cannot find a certain way either to keep all the toxics out of the sludge or to get all the toxics out of the sludge, we must say, I think, that the consequences of dumping sludge on agricultural land will be terrible.

To entertain the view that the benefits of application of sewage sludge to agriculture will outweigh the harm is either sentimental evasion or shortsighted greed. Uncertainty because of unpredictability is the unavoidable character of sewage sludge. And when uncertainty risks damage to all life of the order that industrial society's toxic chemicals certainly involve, gambling on the dangerous route is absurd.

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