Wastewater Treatment in the USA

A Brief History

Despite large supplies of fresh water and the natural ability of water to cleanse itself over time, U.S. populations had become so concentrated by 1850 that outbreaks of life-threatening diseases were traced to bacteria in the polluted water. Since that time, the practice of wastewater collection and treatment has been developed and perfected, using some of the most technically-sound biological, physical, chemical, and mechanical techniques available. 

Homes, businesses, industries, and institutions throughout the modern world are connected to a network of below-ground pipes which transport wastewater to treatment plants before it is released to the environment. At a typical wastewater plant, several million gallons of wastewater flow through each day— 50 to 100 gallons for every person using the system.

What happens in a wastewater treatment plant is essentially the same as what occurs naturally in a lake or stream. The function of a wastewater treatment plant is to speed the process by which water purifies itself. A treatment plant uses a series of treatment stages (primary and secondary) to clean the water so that it may be safely released into a lake, river, or stream.

1800s – Awareness & Response

  • U.S. population grew from 5 million to 75 million
  • Collection systems for disease prevention were developed
  • Pit privies and open ditches were replaced by buried sewers, increasing the sewered population from 1 million in 1860 to 25 million by 1900
  • Treatment was mostly dilution into receiving waters
  • Awareness of the negative impacts of sewage discharge on receiving waters increase the need for standards and regulation. Simple treatment begins (now called “primary” treatment)
  • 1886 – Standards for discharge loading and treatment were developed at a Lawrence, MA experiment station and for Chicago, IL (Rudolph Hering)
  • 1887 – First biological treatment, an intermittent sand filter, was installed in Medford, MA
  • 1899 – First federal regulation of sewage; Rivers and Harbors Appropriations (“Refuse Act”) prohibited discharge of solids to navigational waters without permit from U.S. Army Corps of Engineers

1900s – Technology & Regulation

  • Early 1900s, 1 million people served by 60 sewage treatment plants for removal of settling and floating solids
  • Development of secondary (biological) treatment

1901 – First trickling filter operated in Madison, WI
1909 – First Imhoff tank (solids settling)
1914 – First liquid chlorination process for effluent disinfection
1916 – First activated sludge plant was built in San Marcos, TX

  • 1944 – Steeter Phelps created the DO (dissolved oxygen) sag curve model for streams to predict BOD assimilation capacity. Secondary treatment processes to remove BOD were developed
  • 1948 – Federal Water Pollution Control Act was passed primarily for the provision of federal funds for water quality surveys and construction of collection and treatment plants
  • 1960 – 50% of US population had access to some form of wastewater treatment
  • 1966 – Clean Water Restoration Act extended federal grants for plant construction
  • 1972 – Federal Water Pollution Control Act Amendments
  • 1977 – Clean Water Act (subsequent until 2002)
  • Emerging trend of wastewater reuse (Non-potable, separate distribution, indirect potable, direct potable)

21st Century – Challenges & Opportunities

Global Trends that Impact Wastewater Treatment

  • Population increase and urbanization
    • By 2030, 60% of the world’s population will be near a coastal region
    • Withdrawing water from inland areas, transporting it to urban population centers, treating it, using it once, and discharging to coastal waters is unsustainable
  • Climate Change
    • Rise of sea level
    • Impact of storm events
  • Aging Infrastructure
  • Opportunities
    • Paradigm shift in view of water
    • Alternative collection systems
    • Food waste management
    • Energy and nutrient recovery
    • Recycling through direct potable reuse
    • Integrated wastewater management 
Additional Information