Sewage Treatment

Before sewage treatment, cities were hell-holes of horribly foul smells from rotting human waste, industrial effluent, and garbage.  Few people lived beyond 50 because of the many waterborne diseases.  In fact, sewage and water treatment systems are the main reason lifespans nearly doubled (Garrett).  Here are just a few of the diseases possible from drinking untreated water: Adenovirus infection, Amebiasis, Campylobacteriosis, Cryptosporidiosis, Cholera, E. Coli 0157:H7, Giardiasis, Hepatitis A, Legioellosis, Salmonellosis, Vibrio infection, Viral gastroenteritis, free living amoebae (ADHS).  For the full list of waterborne diseases, see post Water-borne diseases will increase as energy declines.

Pikaar, Ilje, Keshab R. Sharma, Shihu Hu, Wolfgang Gernjak, Jürg Keller, Zhiguo Yuan. August 15, 2014. Reducing sewer corrosion through integrated urban water management. Science  Vol. 345: 812-814  

Abstract: Sewer systems are among the most critical infrastructure assets for modern urban societies and provide essential human health protection. Sulfide-induced concrete sewer corrosion costs billions of dollars annually and has been identified as a main cause of global sewer deterioration. We performed a 2-year sampling campaign in South East Queensland (Australia), an extensive industry survey across Australia, and a comprehensive model-based scenario analysis of the various sources of sulfide. Aluminum sulfate addition during drinking water production contributes substantially to the sulfate load in sewage and indirectly serves as the primary source of sulfide. This unintended consequence of urban water management structures could be avoided by switching to sulfate-free coagulants, with no or only marginal additional expenses compared with the large potential savings in sewer corrosion costs.

Sewer systems are corroding at an alarming rate, costing governments billions of dollars to replace. Differences among water treatment systems make it difficult to track down the source of corrosive sulfide responsible for this damage. Pikaar et al. performed an extensive industry survey and sampling campaign across Australia (see the Perspective by Rauch and Kleidorfer). Aluminum sulfate added as a coagulant during drinking water treatment was the primary culprit in corroding sewer systems. Modifying this common treatment strategy to include sulfate-free coagulants could dramatically reduce sewer corrosion across the globe.

Urban sewer networks collect and transport domestic and industrial wastewaters through underground pipelines to wastewater treatment plants for pollutant removal before environmental discharge. They protect our urban society against sewage-borne diseases, unhygienic conditions, and noxious odors and so allow us to live in ever larger and more densely populated cities. Today’s underground sewer infrastructure is the result of an enormous investment over the last 100+ years with, for example, an estimated asset value of one trillion dollars in the USA (Brongers). This equates to ~7% of its current gross domestic product. However, these assets are under serious threat with an estimated annual asset loss of around $14 billion in the United States alone. Sulfide-induced concrete corrosion is recognized as a main cause of sewer deterioration in most cases.

Many water utilities will need to upgrade both their water supply and wastewater service infrastructure over the next 10 to 15 years, which will require enormous capital investments.


ADHS. Waterborne diseases. Arizona Department of Health Services.

Brongers, M. P. H., P. Y. Virmani, J. H. Payer. 2002. “Drinking water and sewer systems in corrosion costs and preventative strategies in the United States”.  Federal Highway Administration Publication FHWA-RD-01-156, U.S. Department of Transportation, Washington, DC.

Garrett, L. 2001. Betrayal of Trust: The Collapse of Global Public Health. Hatchette Books.

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