Human excreta and the environment - Articles and Views

Human excreta and the environment

Recently we came upon a history of the management of human excreta -- urine and feces -- starting back in the mists of time and working forward to the present day.[1] It turns out that this unlikely topic can tell us something important about the way humans make environmental decisions.

For that reason, we're going to recap the story here. The original author, Abby A. Rockefeller, deserves credit for all the original work, though not, of course, blame for any of our lapses or misinterpretations in the retelling. Where we have supplemented Ms. Rockefeller's history with additional facts, they appear inside square brackets.

Humans began to lead a settled life, growing crops to supplement hunting and gathering, only about 10,000 years ago. For all time before that, humans "deposited their excreta -- urine and feces -- on the ground, here and there, in the manner of all other land creatures." The soil and its communities (including plants, small animals and microorganisms) captured almost all of the nutrients in animal excrement and recycled them into new components for soil. In this way, the nutrients were endlessly recycled within the soil ecosystem and largely kept out of surface water.

As a result, what we call "pure water" is low in nutrients, particularly the major nutrients nitrogen and phosphorus. Because these conditions have existed for a very long time, life in lakes, rivers, and oceans is accustomed to the relative absence of these nutrients. Over the past couple of billion years, life has flourished in this low-nutrient environment, growing complex and interdependent in the process -- an aquatic condition we call "clean" and "healthy." When a body of water is suddenly inundated with nutrients -- especially nitrogen and phosphorus -- things change drastically. One or a few organisms flourish and begin to crowd out the others. We can all recall seeing a body of water that is pea-soup green from overgrowth of algae. Such a water body is clearly sick, choked, its diversity vastly diminished.

Today, much of the surface water of the planet is in a state of ill health because of misplaced nutrients. And a main contributing culprit is misplaced human excreta.

Long ago, human civilizations split into two camps regarding the management of excreta. Many Asian societies recognized the nutrient value of "night soil" (as it became known). For several thousand years, and up until very recently, Asian agriculture flourished by recycling human wastes into crop land.

The opposing camp, particularly in Europe, had ambiguous feelings about human waste -- was it valuable fertilizer or was it a nasty and embarrassing problem to get rid of?

most euIn Europe [sorry, but that's how this para starts - EW], a pattern evolved: The first stage was urinating and defecating on the ground near dwellings. As population density increased, this became intolerable and the community pit evolved. For privacy, this evolved into the pit privy or "outhouse" -- a privacy structure atop a hole in the ground. Despite what many people may think, the pit privy is not environmentally sound -- it deprives the soil of the nutrients in excrement, and by concentrating wastes it promotes pollution of groundwater by those same nutrients.

Before the advent of piped water in the late 18th century, European towns stored excreta in cesspools (lined pits with some drainage of liquids) or in vault privies (tight tanks without any drainage). The "night soil" was removed by "scavengers" and was either taken to farms, or dumped into pits in the ground or into rivers. In general, Europeans never developed a clear and consistent perception of the nutrient value of excrement, as Asians had done.

In ancient Rome, the wealthy elite had indoor toilets and running water to remove excrement via sewers. Later, European cities developed crude sewer systems -- usually open gutters but sometimes covered trenches along the center or sides of streets -- though they had no running water until the 18th or even 19th centuries. The putrefying matter in these stagnant ditches did not move until it rained -- thus the name "storm sewers" -- and many cities prohibited the dumping of human wastes into such sewers.

With the advent of piped water, things changed dramatically. In this country, the first waterworks was installed in Philadelphia in 1802 and by 1860 136 cities were enjoying piped water systems. By 1880, the number was up to 598. With piped water, per-capita water use increased at least 10-fold, from 3-5 gallons per person per day to 30-50 gallons per person per day or even more.

Water piped into homes had to be piped out again. This caused cesspools to overflow, thus increasing the problems of odors and of water-borne diseases. To solve these problems, cesspools were connected to the city's crude sewer systems which ran along the streets. The result was epidemics of cholera. In Paris in 1832, 20,000 people died of cholera. Around the world, the combination of piped water and open sewers has consistently led to outbreaks of cholera.

To solve this problem, engineers designed closed sewer systems, pipes using water as the vehicle for carrying away excrement. This solution engendered a debate among engineers: some wanted to return sewage to agricultural land, others argued that "water purifies itself" and wanted to pipe sewage straight into lakes, rivers, and oceans. By 1910, the debate was over and sewage was being dumped into water bodies on a grand scale.

In the cities, cholera epidemics abated. However, cities drawing their drinking water downstream from sewage discharges began having outbreaks of typhoid. This engendered another debate: whether to treat sewage before dumping it into water bodies used for drinking, or whether to filter drinking water. Public health officials favored treating sewage before dumping it; sanitary engineers favored dumping sewage raw and filtering water before drinking. The engineers prevailed. As cities began to filter and disinfect their drinking water, typhoid abated.

Throughout the 20th century, the U.S. and Europe industrialized rapidly. Industry developed a huge demand for low-cost waste disposal, and sewers were the cheapest place to dump because the public was paying. As the pressure for greater waste disposal capacity increased, industrialized nations allocated vast sums of money to construct centralized sewer systems to serve the combined needs of homes and factories.

As a result, the nutrients in excrement became mixed with industrial wastes, many of them toxic. So by the 1950s, essentially every body of water receiving piped wastes was badly polluted with a combination of excessive nutrients and toxicants. This led to a demand to treat wastes before dumping them into water. Thus began the "treatment" phase of the "get rid of it" approach to human waste.

As centralized sewer systems evolved, first came "primary treatment." This consists of mechanically screening out the dead cats and other "floatables." All other nutrients and toxic chemicals remain in the waste water that is discharged to a river or ocean.

Next came "secondary treatment" which speeds up the biological decomposition of wastes by forcing oxygen into them, by promoting bacterial growth, and by other means. This is an energy-intensive process and therefore expensive. Unfortunately, it, too, leaves many of the nutrients and toxic chemicals in the discharge water.

[The Congressional Research Service recently estimated that the federal government spent $69.5 billion on centralized sewage treatment plants, 1973-1999.

Despite this huge expenditure, the Congressional Research Service said in 1999, "States report that municipal discharges are the second leading source of water quality impairment in all of the nation's waters (rivers and streams, lakes, and estuaries and coastal waters). Pollutants associated with municipal discharges include nutrients..., bacteria and other pathogens, as well as metals and toxic chemicals from industrial and commercial activities and households."[2]]

To the extent that primary and secondary treatment are successful, they move nutrients and toxicants (combined) into a new form: sludge. Sludge is the de-watered, sticky black "cake" created in large quantities by modern sewage treatment plants. Sludge contains everything that can go down the drains in homes and industries and which a treatment plant is able to get back out.

In the FEDERAL REGISTER November 9, 1990, U.S. Environmental Protection Agency describes sludge this way:

"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."

Industry is currently using 70,000 different chemicals in commercial quantities; any of these may appear in sludge. About 1000 new chemicals come into commercial use each year, so any of these, too, may appear in sludge. A description of the toxicants that may be found in sludge would fill several books. The U.S. General Accounting Office has reported -- not surprisingly -- that municipal sludge contains radioactive wastes (from both medical and military sources).[3]

With hundreds of sewage treatment plants producing toxic sludge in mountainous quantities, the next question was, what in the world to do with it?

For many years, coastal cities dumped sewage sludge into the oceans, where it created large "dead zones" that could not support marine life. Other communities dumped their sludge into landfills, where it could pollute their groundwater. Still others incinerated their sludge, thus creating serious air pollution problems, then landfilled the remaining ash or simply heaped the ash on the ground for the wind to disperse.

In 1988 Congress outlawed the ocean dumping of sewage sludge. At this point, many communities faced a real waste crisis. There was no safe (or even sensible) place to put the mountains of toxic sludge that are generated every day by centralized sewage treatment systems.

It was at this point in history that U.S. Environmental Protection Agency (EPA) -- feeling tremendous pressure to "solve" the sludge disposal problem -- discovered that sewage sludge is really "night soil" -- the nutrient-rich product that has fertilized crops in Asia for several thousand years. EPA decided that the expedient thing to do with sewage sludge was to plow it into the land.

Shortly after 1992, when the ban on ocean dumping went into effect, EPA renamed toxic sludge "beneficial biosolids," and began aggressively campaigning to sell it to the American people as fertilizer. (See REHW 561.)

Continuing from last week, we are retelling the history of the management of human excrement as originally narrated by Abby A. Rockefeller.[1] Where we have added new facts to Ms. Rockefeller's original history, they appear inside square brackets.

To recap where we are: Cities began to provide running water into homes in the early 19th century. Water piped into homes had to be piped out again, often into open sewer ditches running in the streets. Outbreaks of cholera followed. A debate ensued: should sewage be transported back to farms, where the nutrients had originated, or should it be disposed of by dumping it into bodies of water? Although many cities for a time transported sewage to farms, by 1920 most sewage was being piped directly into bodies of water. This was a crucial choice.

Once the network of sewer pipes began to grow, industry saw these public pipes as a cheap place to dump industrial wastes. As a result, corporations began to dump all manner of toxicants into the nutrient-rich sewage stream. This was another crucial choice. Once they were mixed together, nutrients and industrial poisons could not be separated at any reasonable price. Therefore the whole mess became a toxic waste disposal problem and excrement lost its value as a fertilizer. Dumping it into water bodies accelerated.

By the 1950s, most of the nation's waterways were badly contaminated with a combination of nutrients and toxicants. This gave rise to a demand for treatment of waste prior to disposal. Pipes that used to carry toxic sewage into streams and oceans now began to carry it into centralized "wastewater treatment plants" or "publicly owned treatment works" (POTWs).

Wastewater treatment plants remove the solids and some of the chemicals, creating a black, mud-like "sludge" in the process. It's a trade-off: improved wastewater treatment means cleaner discharge water but it also means more sludge and worse sludge (more toxic). Now a new, and truly intractable, problem appears: what to do with mountains of toxic sludge?

Communities with access to the ocean began dumping sludge there. New York dumped its sewage sludge 12 miles offshore; when that place developed obvious contamination problems, the dumping was moved to a spot 106 miles offshore, where, to no one's surprise, contamination soon developed.

The use of water to carry sewage, and the use of centralized wastewater treatment plants, had great political appeal for several reasons. Most political authorities tend to favor centralized solutions because they basically don't trust people to handle their own problems. Secondly, as we have noted, industry needed a cheap place to dispose of its wastes. [In 1997, according to the Congressional Research Service, industry "dumped 240 million pounds of wastes with hazardous components" into municipal sewers.[2]] Third, and perhaps most important, laying sewer pipes and building centralized sewage treatment plants is extremely costly and engineering firms receive 20% of the initial cost. [Between 1970 and 1993, the federal government appropriated $69.5 billion for sewage construction projects. The Congressional Research Service recently estimated that between now and the year 2016 (17 years), the federal government will spend another $126 billion on sewage projects.[2] These are serious amounts of money.] Only the Federal Highway Administration [and the military] spend more public money on construction. [If even a small fraction of this sewer money is kicked back at election time by consultants, lawyers, investment bankers and engineering firms, it can go a long way toward keeping the present crop of politicians in office.]

In the 1970s, many environmentalists and public health officials favored centralized sewage treatment because it seemed to offer an improvement over dumping raw wastes into waterways. The Clean Water Act of 1977 was essentially a sewering act. Everyone was then locked into centralized wastewater treatment systems.

In 1988, Congress discovered that sludge dumping in the oceans was harming marine life, and the practice was banned as of 1992. This created a massive problem for American cities: [11.6 billion pounds of sludge (that's the dry weight, not counting the water it contains[3]) has to go somewhere, year after year.]

At that moment, EPA decided that the U.S. now needs to mimic 100 generations of successful farmers in Asia, returning human excrement to farmland.

However, EPA has overlooked two important differences between modern sewage sludge and traditional "night soil" (unadulterated human waste):

1) Most of the nitrogen in human waste is in the urine and is water-soluble, so it is not captured in the sludge. Therefore, if sludge is going to substitute for commercial fertilizer, you have to use a lot of it to get enough nitrogen.

And (2) when you add a lot of sludge to soil, you are also adding a lot of toxic metals and a rich (though very poorly understood) mixture of organic chemicals and, very likely, radioactive wastes as well.

EPA has addressed the toxic metals by telling farmers to add lime to their soil along with the sewage sludge, to prevent the soil from becoming acidic. If soil turns acidic, then toxic metals begin to move around, either leaching down into groundwater or moving upward into the crops (which, by definition, are part of some food chain). If soils are alkaline (the opposite of acidic), the metals move more slowly.

[What EPA has overlooked is the fact that ordinary rain is slightly acidic, not counting the excess acidity provided by "acid rain." Normal rain drops falling through the atmosphere dissolve small amount of carbon dioxide, forming carbonic acid. Normal rain has a pH of 5.6 whereas 7 is neutral. Therefore, if soils are not kept alkaline by the regular addition of lime, sooner or later normal rain will begin to leach excess metals out of many soils. The only way to prevent this is to keep the excess metals out of soils in the first place.]

In sum, plowing sewage sludge into soils is essentially guaranteed to harm many of those soils as time passes. [See REHW 561.] [As we know from the ancients who poisoned their soils with irrigation salts, a nation that poisons its farmland is a nation that doesn't have a long-term future.]

A series of bad decisions made during this century has brought us to an impasse: sewage sludge is unmanageable because you can't know from day to day what is going to be in it, and so you cannot monitor its contents.[4] (Even if you could manage the scientific problems inherent in monitoring an unknown mixture of unknown substances, as a practical matter there isn't any government agency with enough staff to monitor the nation's sludge.)

Therefore -- as heroic a task as this may seem -- it is time to re-think centralized water-carriage sewage treatment systems. The present systems were not designed to produce useable products and therefore the DESIGN of present systems is the root of the problem.

Three policy goals are needed: (1) Sewer avoidance (stay off or get off water-carriage, centralized sewer systems). (2) Promote low-cost, on-site resource recycling technologies, such as composting toilets, that avoid polluting water and preclude wasting resources. (3) Price water right so that the market works to keep it clean, not contaminate it with excreta.[4]

[For individual households, real solutions are already available: zero discharge household waste systems. An excellent new book by David del Porto and Carol Steinfeld, THE COMPOSTING TOILET SYSTEM, will dispel any fears you may have that composting toilets are a step backward.[5] With microflush toilets and vacuum-flush toilets now readily available, you can have the bathroom of your dreams, yet compost your household wastes into an odor-free product that is entirely satisfactory as agricultural fertilizer. These days, there are companies that will manage the system for you, including removing the compost. Your household waste system can be installed, maintained, and managed by professionals, just like your electrical and heating systems.

But what about apartment buildings and office buildings in cities? Although we know of no one who has applied it, the technology certainly exists for manufacturing building-scale waste systems based on anaerobic digesters, which would produce methane gas and fertilizer. As Abby A. Rockefeller said recently in an interview, "Surely, human ingenuity can do this." Such systems would be cheaper than current sewage systems because they wouldn't require miles of underground pipes to connect to a centralized sewage treatment plant, and they would conserve hundreds of billions of gallons of water each year.

[Every time we flush the toilet, 3.3 gallons of drinking water are degraded. At 5.2 flushes per day (average), each of us presently degrades 6260 gallons of drinking water each year to flush away our 1300 pounds of excrement -- 1.6 trillion gallons of water per year in the U.S.]

Naturally, we would need to keep toxicants out of these composting systems, but that has always been true (even though we have ignored this fact) and we might as well face up to it now. Toxic household products will have to be phased out as part of any plan for sustainable living.

Toxic industrial wastes should be managed by the industries that make them, not dumped into the environment that sustains all life. Unusable wastes are a sure sign of inefficiency.

Lastly, what to do with today's mountains of toxic sludge? Obviously they must be handled as hazardous wastes because that's what they are. [Probably above-ground storage in concrete buildings is the only satisfactory solution at the present time. (See REHW 260.)]

[You say we can't do any of this because we've been doing it another way for 100 years? Ask yourself, what kind of people would dump their excreta into their drinking water in the first place? And what kind of people, faced with workable, cheaper, more environmentally sound alternatives would continue to insist that dumping their excreta into their drinking water is the only way to live?]

[1] Abby A. Rockefeller, "Civilization and Sludge: Notes on the History of the Management of Human Excreta," CURRENT WORLD LEADERS Vol. 39, No. 6 (December 1996), pgs. 99-113. Ms. Rockefeller is president of the ReSource Institute for Low Entropy Systems, 179 Boylston St., Boston, MA 02130; telephone (617) 524-7258.

[2] Claudia Copeland, WASTEWATER TREATMENT: OVERVIEW AND BACKGROUND [98-323 ENR] (Washington, D.C.: Congressional Research Service, January 20, 1999). Available at: http://www.cnie.org/nle/h2o-29.html

[3] Gary D. Krauss and Albert L. Page, "Wastewater, Sludge and Food Crops," BIOCYCLE (February 1997), pgs. 74-82. Krauss was staff director for the National Research Council study, USE OF RECLAIMED WATER AND SLUDGE IN FOOD CROP PRODUCTION (Washington, D.C.: National Academy Press, 1996).

[4] Robert Goodland and Abby Rockefeller, "What is Environmental Sustainability in Sanitation?" IETC'S INSIGHT [newsletter of the United Nations Environment Programme, International Environmental Technology Centre] Summer, 1996), pgs. 5-8.

The International Environmental Technology Centre can be reached at: UNEP-IETC, 2-1110 Ryokuchikoen, Tsurumi-ku, Osaka 538, Japan. Telephone: (81-6) 915-4580; fax: (81-6) 915-0304; E-mail: cstrohma@unep.or.jp URL: http://www.unep.or.jp/.

See also Abby A. Rockefeller, "Sewage Treatment Plants vs. the Environment," an unpublished paper dated September, 1997.

And: Abby A. Rockefeller, "Sludge is Sludge; The Illusion of Safety," an unpublished paper dated June 26, 1996. Ms. Rockefeller is president of the ReSource Institute for Low Entropy Systems, 179 Boylston St., Boston, MA 02130; telephone (617) 524-7258.

[5] David Del Porto and Carol Steinfeld, THE COMPOSTING TOILET SYSTEM BOOK (Concord, Mass.: Center for Ecological Pollution Prevention, 1999). ISBN 0-9666783-0-3.

See http://www.ecological-engineering.com/ctbook.html;
$29.95 plus $3.30 shipping ($12 overseas shipping)
from: Center for Ecological Pollution Prevention,
50 Beharrell St., P.O. Box 1330, Concord, Mass. USA 01742.
Phone (978) 369-9440. Fax: (978) 368-2484.
E-mail: ecop2@hotmail.com.

See also: Carol Steinfeld, "Composting Toilets Come to the Rescue in Massachusetts," BIOCYCLE (April 1996), pgs. unknown.
See http://www.ecological-engineering.com/rescue.html

And see: Carol Steinfeld, "Composting Toilets Emerge as Viable Alternatives," Environmental Design & Construction (July/August 1998), pgs. unknown.

See http://www.edcmag.com/archives/798-14.htm.
Descriptor terms: sewage; human waste; sludge; agriculture; hazardous waste; compost; sewage treatment systems;

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