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HISTORY OF WASTEWATER TREATMENT IN THE US
1800’s
US population grew from 5 million to 75 million
PRIMARY DEVELOPMENT: COLLECTION SYSTEMS
PRIMARY PURPOSE: DISEASE PREVENTION
Pit privies and open ditches replaced by buried sewers: sewered population
increased from 1 million in 1860 to 25 million by 1900.
“Treatment” was mostly dilution into receiving waters
EARLY MANAGEMENT PRACTICES
TRENDS: awareness and control of impacts of sewage discharge on
receiving waters through standards, regulation, and simple treatment
(probably now called “primary”)
1887, first biological treatment, an intermittent sand filter, was installed in
Medford, Mass.
1886, Standards for discharge loading and treatment developed at
Lawrence, Mass experiment station and for Chicago, IL (Rudolph Hering)
1899, first federal regulation of sewage, Rivers and Harbors Appropriations
(“Refuse Act”) prohibited discharge of solids to navigational waters without
permit from US Army Corps of Engineers
1900’s
Early 1900s, 1 million people served by 60 sewage treatment plants for
removal of settling and floating solids.
TREND: population growth and sewer construction
1900-1930s, sewered population increased at ~ same rate as total
population
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TREND: 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, San Marcos, TX
TREND: PROTECTION OF RECEIVING WATER QUALITY
1920 – 1940’s:
Wastewater treatment linked with importance of dissolved oxygen to
aquatic life, aesthetic properties of surface waters (odor, color, solids),
measurement of organic matter in sewage as biological oxygen demand
(BOD)
1944 Steeter Phelps DO sag curve model for streams to predict BOD
assimilation capacity
Secondary treatment processes to remove BOD
Increased wastewater treatment meant increased residuals (sludge).
Heated sludge digesters and use of gas. 1921: mechanical dewatering of
sludge in vacuum filters and centrifuges, Milwaukee, WI. Early 1930’s:
sludge drying and incineration in Chicago.
TREND: NEW REGULATION AND GOVERNMENT GRANTS
1948: Federal Water Pollution Control Act. Primarily for provision of federal
funds for water quality surveys and construction of collection and treatment
plants.
1952: extension of FWPCA funding. 1966 (Clean Water Restoration Act)
extended federal grants for plant construction.
1960 MILESTONE: 50% of US population had access to some form of
wastewater treatment.
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1960 - present:
TREND: TREATMENT PROCESS ADVANCES to improve receiving water
quality
Nutrient (nitrogen and phosphorus) removal (eutrophication control)
Use of chemical conditioners (polymers, polyelectrolytes), dissolved air
flotation for enhanced solids separation and thickening
New process configurations: high rate activated sludge processes, high
purity oxygen, sequencing batch reactors, high rate trickling filters and
hybrid trickling filter-activated sludge processes, membrane bioreactors
Improved sludge digesters: high temperature processes
Effluent disinfection
TREND: REGULATION
1972 Federal Water Pollution Control Act Amendments (PL 92-500)
amended 1977 (Clean Water Act) and subsequent until 2002. (to be
discussed in detail)
CWA summary
Water Quality Standards for receiving waters (based on designated
uses and related human health and aquatic life criteria)
Antidegradation policy with ambient monitoring
If WQS not met: plan (strategies and controls) to improve impaired
waters using Total Maximum Daily Load (TMDL) approach.
Implementation:
POINT SOURCES. National Pollutant Discharge Elimination System
(NPDES) PERMIT PROGRAM
o Control of toxics, Industrial pretreatment
o Sludge (Biosolids)disposal
Non-point sources (section 319)
Section 404 (Wetlands protection)
State Revolving Funds
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EMERGING TRENDS:
WASTEWATER REUSE
Non-potable, separate distribution
Indirect potable
Direct potable
Local regulation
ENERGY
Recovery of energy (biofuels, co-generation, fertilizer)
Conservation of energy (aeration, pumping, mechanical solids
processing, heating, embedded materials)
CO2 caps?
TRACE CONTAMINANTS
Receiving water
Biosolids
Recycled water