Modules
Objective:
SOURCES :
The earth contains about 326,000 cubic miles of water. Most of it is in the oceans (about 97%). However, water goes through phase changes (solid, liquid, gas), and its movement is ultimately driven by the sun. For example, the oceans ultimately supply the following 3 sources:
USES :
The U.S. supplies billions of gallons/day in water, but most of it is lost to:
Average U.S. water use has been steadily increasing, although not all of it has been for drinking. Typical uses include:
Average home uses include:
Various fittings can save about 6-12 % in the average home (from toilets, showers, and laundry).
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Modules
2: The Safe Drinking Water Act (SDWA)
PRE-SDWA:
The U.S. Public Health Service originally issued standards for drinking water. They developed the primary and secondary standards that were covered in our last lecture.
SDWA:
1974 saw the passage of the Safe Drinking Water Act (SDWA). Several things were fundamentally different about this law:
The primary federal agency that oversees water quality is the Environmental Protection Agency. However, a number of federal agencies are involved with various aspects of water quantity and quality, including:
Progress in adding standards was slow, however, as scientists in 1974 were just beginning to detect many of the synthetic organics that find there way into water.
1986 AMENDMENTS:
Congress gradually became disenchanted with the EPA's progress, which led to the 1986 SDWA Amendments. This law required addition of 83 contaminants by 1989, and required adding 25 contaminants to the list every 3 years thereafter. Examples of new standards from this law include various VOCs in water, and inorganics such as aluminum, nickel, and beryllium. At the same time, the new law designated "best available technologies" for water treatment.
1996 AMENDMENTS:
The 1996 SDWA amendments canceled the schedule of 25 new standards every three years, and in its place set up a mechanism to set standards based on the occurrence and assessed risks of contaminants. The law also authorized $1 billion in federal grants to individual states for upgrading water treatment systems. Research programs were set up for a consortium of American and Mexican Universities (especially for states on the Mexican border), for estrogen screening programs, and for general research.
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Objective: The purpose of this assignment is:
Hard water is water that contains hardness minerals (e.g., calcium, manganese and magnesium) above 1 GPG (grain per gallon). 1 GPG is equal to 17.1 PPM of water hardness as defined by Standard Methods. Hard water is not as efficient or convenient as "soft water" for bathing, washing (dishes, clothes or cars), shaving, and many other uses. For example:
If the hardness is over 3 GPG, softening can usually save enough to pay for the cost and maintenance of a water softener. Water softeners can also remove copper, iron, and other minerals. De-ionization is a more extensive form of water softening that removes anions as well as cations.
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4: Alternatives to Chlorination
Objective: The purpose of this section is to analyze the alternatives to chlorination for their advantages and disadvantages (relative to traditional chlorination). A "+" means the alternative has a relative advantage over chlorination, and a "-" has a relative disadvantage relative to chlorination.
A. General considerations:
+: All the alternatives will reduce microbes and THM's
-: All the alternatives tend to cost more than chlorination
B. The alternatives:
1. Chloramines:
+: chloramine residual is more stable
-: chloramines need longer contact times
chloramines may add taste and odor
dialysis patients are susceptible
2. Chlorine dioxide (ClO2):
+: ClO2 more effective in disinfection
ClO2 destroys many taste and odor compounds
-: ClO2 must be generated on site
no reliable test for the residual
3. Iodine:
+: Iodine more effective in disinfection
Iodine has little reaction with organics
Iodine safe to transport
Iodine leaves a traceable residual
-: expensive
taste and odor
4. Ozone (O3):
+: Ozone more effective in disinfection
Ozone destroys many taste and odor compounds
-: Ozone must be generated on site
Ozone has no residual protection
5. U.V.:
+: no added taste or odor
-: interference by turbidity
viruses are especially resistant
no residual protection
6. Heat:
+: good for emergencies, no taste or odor added
-: impractical for large scale
no residual protection
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5: California Swimming Pools Standards
Objective: The purpose of this assignment is understand some of the minimum legal requirements for public pools in California for:
Disinfection
1. Free chlorine residual: at least 1 ppm is required. This is to be achieved by automatic hypochlorinators (units which provide for continuous chlorination) that are listed by NSF (the National Sanitation Foundation).
2. pH: must be between 7.2 to 8.0. If necessary, soda ash can be added to raise the pH. More typically, the pH naturally rises from the use of hypochlorites.
3. Other disinfectants: others may be used, provided that they are registered with the EPA for disinfectant use, and that they provide a protective residual.
Clarification
4. Turbidity: the drain must be visible (this is, of course, the deepest point)
5. Filters: filtration units are similar in concept to units discussed for water treatment (e.g., diatomaceous earth filters)
6. Turnover time: this is the time it takes for a unit to filter the complete volume of a pool. The minimum legal standard in California is once every 6 hours for pools, and once every 1/2 hour for spas.
Safety
7. Lifesaving equipment: life rings must be at least 17 inches in diameter, with a line (rope) that is long enough to span the maximum width of the pool. Rescue poles (long poles with body hooks) must be at least 12 feet long.
8. Posted signs: if there is no lifeguard, a sign must be posted stating "Warning -- No Lifeguard On Duty."
9. Access: access to the pool must be limited by fencing (at least 4 ft. high) with gates that must be self closing and self latching.
Other
10. Records: there must be daily records of maintainence (including chlorine levels, pH, etc.).
11. Spas, hottubs: high temperatures can be especially risky to the elderly; the powerful suction at the bottom of spas can also, in some cases be, risky. Numerous agents can be a risk in spas, including Pseudomonas aeruginosa (causing rashes), and Naegleria fowleri (causing PAM, or primary amoebic meningoencephalitis).
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Modules
Objective: The purpose of this assignment is to analyze soils in terms of the content (elements), horizons, profiles, soil types, and biological components. This section also analysis types of wells.
1. The earth's crust is composed of the following elements (given in the order of average % of soil content):
O2: 46%, Si: 28% (mostly
SiO2),
Al: 8%, Fe: 5%;
Ca, Mg, Na,
and K:
11%;
all
others: about
1.5%
2. Horizons are horizontal layers of different soils. Examples of the different layers include:
Horizon
A: top soil:
zone of maximum bioactivity
Horizon
B: sub soil:
zone of eluviation (washing in)
Horizon
C: parent
material:
Horizon
R:
consolidated bedrock:
3. Profiles refer to different patterns of soil horizons. For example, the topsoil may be very thin or even missing in some soil profiles.
4. Soil types: soils are made of combinations of three different grains:
sand: coarse grained (> .05 mm)
silt: medium grained (.05 - .002 mm)
clay: fine grained (< .002 mm)
Finally, loam is a combination of all the above: 40% silt, 40% sand, 20% clay.
5. Humus refers to the organic material in soil
6. Biological components include such diverse components as:
nematodes, fungi (molds), protozoans, algae, actinomycetes, and various bacteria.
7. Wells fall into at least three basic categories:
dug wells: relatively shallow, hand excavated wells that are easily contaminated (diameter of 3-30 ft.).
driven wells: constructed by driving a steel point into the ground (diameter of 1 to 4 inches).
drilled wells: constructed by using various types of drills. This is generally the safest and most efficient of wells (diameter between 2-48 inches)
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