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Drinking Water and Wastewater Treatment

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Presentation on theme: "Drinking Water and Wastewater Treatment"— Presentation transcript:

1 Drinking Water and Wastewater Treatment
Historical Perspective Federal Protection of Drinking Water Treatment Process Wastewater

2 Drinking Water: Historical Perspective
The Greeks and Romans recognized that poor water quality caused disease and death Bathing once or twice a year was “healthy” Sand filters became common in 1700s Urban water was poorer than water from forested watersheds Chlorination was introduced in 1907.

3 Potable Water Water used for drinking, cooking, and washing
Requires filtering, disinfection, desalinization Groundwater has natural filtration, may need disinfection New York City does not filter suface water because it is from forested areas. Reverse osmosis is needed to remove salts.

4 Calcutta, India, during rainy season

5 London Water Works (Thames River)

6 China

7 Water Quality Concerns
Pathogens Bacteria (E. coli, fecal strep, cholera) Viruses (polio, hepatitus) Protozoa (Giardia) Dysentary (Amoeba and Shigella) Emerging Contaminants Endocrine disruptors (contraceptives) Antibiotic resistant pathogens, pharmaceuticals Metals (lead, arsenic), Organics (gasoline, herbicides)

8 Federal Protection 1914: U.S. Treasury established a limit of 2 coliforms per 100 mL for drinking water 1942: U.S. Public Health Service standardized drinking water standards 1948: Federal Pollution Control Act 1974: Safe Drinking Water Act 1986: Wellhead Protection Program 1996: Source Water Assessment and Protection

9 This intake structure for the Mount Werner Water Filtration Plant is located near the mouth of Fish Creek Canyon above Steamboat Springs, Colorado.

10 Drinking Water Standards, 2004
Copper (liver and kidney damage) 1.3 mg/L Fluoride (bone disease) 4.0 mg/L Nitrate (Blue Baby syndrome) 10 mg/L Nitrite (same) 1 mg/L Dioxin (cancer) No detectible Xylenes (nervous system damage) 10 mg/L Atrazine (Cardiovascular damage) mg/L

11 Raw water from the Mississippi River is pumped to the Carrollton Water Purification Plant, one of two such plants that serve the city of New Orleans.

12 Drinking Water Treatment
Watershed and wellhead protection: prevents contamination Diversion, storage, and intake Flocculation/coagulation => settling Filtration Fluoridation Disinfection: Cl2, O3, UV, chloramines BOD - biochemical oxygen demand; biological oxygen demand Distribution: storage and pressure

13 The water treatment process at larger facilities includes numerous steps such as bar screen, grit removal, primary and secondary settling tanks, aeration, flocculation and coagulation, sand filters, and chlorination.

14 BOD The amount of oxygen used by microorganisms in the process of breaking down organic matter in water. The more organic matter there is (e.g., in sewage), the greater the number of microbes. The more microbes there are, the greater the need of oxygen to support them; consequently, less oxygen is available for higher animals such as fishes. The BOD is therefore a reliable gauge of the organic pollution of a body of water. One of the main reasons for treating sewage or waste water prior to its return to a water resource is to lower its BOD-i.e., reduce its need of oxygen and thereby lessen its demand from the streams or rivers into which it is released.


16 The water tower at Clarkson, Nebraska, is located on a hill in the farming community of 700 residents in eastern Nebraska.

17 Water intake clogged with Zebra Mussels.

18 Flouride and Tooth Decay
Flouride is added to strengthen teeth and bones Many communities add F to improve teeth Dentists can tell whether you grew up on city water or not Adding too much causes brittle bones

19 Lead in Drinking Water Sources: lead solder and pipes
Problem: behavior problems and learning disabilities

20 Drinking Water from Wells
City wells are routinely tested Private water wells are seldom tested Sources of contamination include wastewater, landfills, junkyards

21 Leaking Underground Storage Tanks

22 NAPL: Non-Aqueous Phase Liquids
DNAPL: Dense NAPL (dry cleaners, industrial) LNAPL: Light NAPL (gasoline, diesel)

23 Wellhead Protection

24 Arsenic Poisoning

25 Wastewater: Historical Perspective
A major problem since the earliest cities Most went down roads to the nearest stream 1370: First underground sewers 1867: First wastewater treatment (London) 1928: First U.S. operation (Fessenden, ND) 1964: First Athens treatment plant

26 Wastewater Disposal Wastewater leaves homes thru property laterals and enters City Sewer System. Sewers increase in size as Collection System moves wastewater into Interceptor Lines.

27 Wastewater Treatment Process
Primary Treatment: Remove large debris (sand, stones, garbage) Secondary Treatment: Break down organic matter by adding oxygen to promote decay Tricking filter: Water cascades down over coarse materials (stones, balls) Activated sludge: Large motors churn air into the water Tertiary Treatment: Nutrient Removal

28 The wastewater treatment process at larger facilities includes numerous steps such as bar screen, grit removal, primary and secondary settling tanks, aeration, flocculation and coagulation, sand filters, and chlorination.




32 First U.S. operation: The Fessenden, North Dakota, sewage lagoon is famous in the realm of wastewater treatment around the world.

33 Septic Tanks and Leach Fields
Septic tank collects biosolids and breaks them down. Aerobic decay requires oxygen, anaerobic decay does not. Facultative decay is when both are present. Leach field takes water that has gone through the septic tank, and is allowed to percolate through the soil


35 Wetlands and Water Treatment
Similar to the original Fessenden plan. Natural biodegradation and nutrient removal. Good environment (mixed aerobic and anaerobic) for facultative bacteria. Provides habitat, increases water storage and prevents overflows during wet weather.


37 CSOs Combined Sewer Overflows
Used to carry sewage to treatment plant during dry weather Also collects stormwater during wet weather System is overloaded during big storms, and is routed directly to the river


39 NPDES Permit National Pollution Discharge Elimination System
Used to regulate wastewater discharges Requires a minimum treatment standard Dissolved Oxygen, pH, BOD, ammonia, toxicity These permits get more strict over time as more users need to add to the river

40 Chapter 13: Quiz 1. Describe how large particles are removed during drinking water treatment. 2. Adding ____________ to drinking water helps to prevent cavities. 3. Name one process for disinfection: 4. Name and describe the three steps in wastewater treatment: a. b. c.

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