Everything Down the Drain - Why?

Bill Nuttle ·
17 April 2013
Applying Science | 

Is it time to rethink our 19th century approach to dealing with human waste?

The discovery of the cause of a cholera epidemic in London, in the mid 19th century, unleashed an international movement that improved sanitation in cities, and also altered the relationship between people and the environment. The result has been an increase in living standards. But at the same time, the technological approach adopted in Europe and North America contributes to one of our most vexing environmental problems - nutrient pollution in estuaries and coastal waters.

Prior to the 19th century, sanitation consisted of discharging waste into the environment as directly as convenient, usually not far from people's homes. This caused problems as people began to aggregate in increasing densities in urban centers during the industrial revolution, and the opportunity for direct disposal of human waste changed. Cholera was one of these problems. Outbreaks of cholera reached pandemic proportions during the 19th century, causing hundreds of thousands of deaths in London and Paris and millions of deaths worldwide.

At the time, no one knew where cholera came from, and this hampered efforts to contain the disease. One popular theory was that cholera was caused by poor air, miasmas, resulting from decaying organic matter. In 1854, Dr. John Snow provided clear evidence that the disease of cholera is transmitted through contact with infected human waste. By plotting the time and location of cholera cases on a map, Snow was able to pinpoint a public well contaminated by leakage from a nearby cesspit as the epicenter of infection in the Broad Street neighborhood of London. Snow's results provided direction to the sanitation movement, waging a political campaign to install modern water supply and sewer infrastructure in cities in Europe and North America.

John Snow monument in London, United Kingdom
This monument is close by the location of the public pump Snow identified as an epicenter in the 1854 cholera outbreak in London.

In the last decades of the 19th century in Paris, the sanitation movement campaigned to dispose of human waste using a brand new system of storm drains. The common practice, left over from the 18th century, was to collect human waste in cesspits located in the basements of buildings. Periodically, sanitation workers used wagons to collect the accumulated waste for transport and disposal outside the city (a practice that is still used in many cities). The beautifully constructed and efficient storm drains, which were installed as part of a massive urban redevelopment project, were intended primarily to remove runoff from rainfall and street washing. To the dismay of the engineers who had built the sewers, the slogan of the sanitation movement, "Tout a l'egout!" - everything down the drain! - became a popular catch phrase for modern comfort.

Opposition to the "tout a l'egout" campaign extended beyond the ranks of the dismayed engineers. Victor Hugo, author and vociferous social reformer, also opposed the move. Hugo used his novel "Les Miserables" to make his case, interrupting the story of Jean Valjean and Cosette to do so. Human waste collected from Paris' cesspits provided the raw material for an industry that extracted valuable chemicals and produced fertilizer. Hugo warned that flushing human waste through the sewers and into the Seine River meant the loss of revenue from this industry and, ultimately, the loss of soil fertility on the farms in the surrounding region. If Victor Hugo were writing today, he would have added eutrophication of the Seine River estuary to his warning.

Reducing the input of nutrients in wastewater flushed into rivers from cities and towns is a major challenge in the restoration of Chesapeake Bay. Even after treatment, water from municipal wastewater treatment plants contributes nearly 20 percent of the nitrogen that enters the bay. Efforts to reduce this source focus on replacing the 19th century sewers that mix human waste and storm drainage, risking overflows during large storms, and upgrading technology at treatment plants to remove a larger portion of the nutrients but at higher and higher cost.

Maybe it's time to consider other options. "Tout a l'egout" was an easy and effective solution to the public health problems encountered in 19th century London and Paris, but Victor Hugo was right when he described it as flushing wealth down the drain. And, there are alternatives. Last year, Bill Gates' charitable foundation funded a competition to design an economical toilet for use in undeveloped countries. Two of the winning designs recover nutrients and other valuable substances directly from human waste without the need to connect to an expensive treatment plant.

High-tech toilet closes the loop by recovering nutrients and other chemicals from human waste rather than dumping them into the environment.

Doesn't it make sense to avoid wasting valuable materials, as an operational goal, especially when doing so risks harming the environment? Closing the loop between nutrient outputs in human waste and nutrient inputs to grow food is an ecosystem management milestone worth working toward. Some progress is being made in recovering nutrients for fertilizer at treatment plants where this can reduce the overall cost of running a treatment plant. More is possible if we are willing to rethink the entire technological approach to sanitation. How can we encourage innovations like these within the larger, regional effort to restore the Chesapeake Bay?

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