Sample Pages From Various Courses

Beginning Water Math:
Volume Part 2 – Circular Tank

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Circular Tank:  D squared x .785 x H x 7.48 = gallons in tank

You need to fill a 20’ high circular tank that has a 15’ diameter. How many gallons will the tank hold?

15 x 15 x .785 x 20 x 7.48 = 26,423 gallons

Calculate the volume of water, in gallons, in a tank with a 25 foot diameter that has a water depth of 18 ft.

25 x 25 x .785 x 18 x 7.48 = 66,057 gallons

Note:  If given circumference:  D = Circumference / 3.14

If circumference = 1o0, then
D = 100 / 3.14
D= 32

 

Water Quality Problems and Treatment Techniques:  Nitrification – Methemoglobinemia

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Nitrification:
The process by which ammonia present in water is transformed into nitrites and then nitrates, which are bad because they can harm, and even kill, infants at high concentrations.  This increase in nitrite and nitrate concentration can lead to Methemoglobinemia (blue baby disease).

An error people make is in assuming that because nitrate is the end product of nitrification, that it is therefore the only harmful one.  Also, so much talk is spent on Nitrates.  That can also lead to confusion.  Both are bad.  Nitrite is actually worse, pound for pound, hence the much lower MCL, its just less stable and therefore around in much less concentration, and for a much shorter time.  Nitrite actually causes BBD, and so will nitrate, because once ingested the body is able to turn a portion of nitrate into nitrite.

Methemoglobinemia (blue baby disease) and Nitrates:
Nitrates are ingested and converted within the body into Nitrites.  Nitrites then react with hemoglobin, the oxygen carrying blood protein, and turn in into methemoglobin, which cannot carry oxygen.  How it works is by oxidizing the ferrous iron, which can bind with oxygen in hemoglobin, to a ferric form which cannot bind with oxygen.  If a large amount of this is formed, body tissues may be deprived of oxygen, causing a blue coloration and respiratory problems, and leading to internal suffocation.

Methemoglobin is always being produced in humans, but we also have an enzyme in the human body that reduces methemoglobin back to hemoglobin. In most individuals, methemoglobin is rapidly converted back to hemoglobin.

Under normal conditions, less than 2% of our blood circulates as MetHb.
Up to 10% MetHb can occur without any signs
Concentrations above 10%:  bluish skin and lips
Concentrations above 25%:  low blood pressure, rapid pulse, and rapid breathing
Concentrations above 50%:  can be fatal

Why babies?
To cause methemoglobinemia, nitrate must be converted to nitrite. The conversion is performed mainly by bacteria that resides in the mouth and stomach. The depth of the danger of nitrate depends on the extent to which it is converted to nitrite, which depends on the concentration and type of bacteria in the mouth and stomach.

In adults, our stomach acids are strong enough to reduce the danger of this bacteria.  In infants, their stomach acids are not as strong and they are more likely to have nitrate-reducing bacteria.

 Infants, also have a very low concentration of the reducing enzyme which  reverts methemoglobin back to hemoglobin.

Infants take in more fluid as a percentage of body weight than adults.

More common in bottle fed infants.

Treatment:
Stop drinking water high in nitrates.

For acquired methemoglobinemia the typical treatment is with an IV injection of a chemical that reduces methemoglobin back to hemoglobin.  According to medical sites I looked at, it takes about five minutes to administer and results can be seen within 20 minutes.

High methemoglobin levels are often unrecognized until symptoms become extreme. People often think it’s a cold or flu, and so people often just wait for it to go away. Sad because treatment success is high, but the failure or delay in treatment can cause death.

 

Biological Contaminants and Disinfection:
Chlorine – The Good and Bad Sides of Chlorine

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Chlorine: Main chemical used for disinfection

Benefits of Chlorine in water treatment:

Potent Disinfectant
Kills disease causing organisms that could contaminate out drinking water..

Biological Growth Control
Eliminates slime bacteria, molds and algae that could grow in reservoirs, water mains and storage tanks.

Chemical Control:
Helps to remove iron and manganese from raw water through oxidation.

Removes ammonia and other nitrogenous compounds that can cause bad tastes and hinder disinfection.

Taste and Odor Control
Destroys hydrogen sulfide, which has a rotten egg odor.

Benefits in Pre-Treatment:
Control of algae and slime growths
Reduction of tastes and odors
Improved coagulation
Increased chlorine contact time

Negatives:  in Pre-Treatment:
Trihalomethanes:  Organic precursors (leaves, grass, decaying vegetation, ect.) break down into humic and fulvic acids and react with chlorine to create Trihalomethanes (THMs) which have been known to cause cancer.

1 per 1,000,000 at reduced MCL rates

In the early 1970s, EPA scientists first discovered trihalomethanes.
EPA set the first regulatory limits for THMs in 1979.

Ways of dealing with THMs:
No pre-chlorination – Use an alternative
Remove after formed with granular activated carbon
Reduced pre-chlorination dose

Ozone or UV

Pro:
No THMs
Can inactivate cryptosporidium while chlorine cannot

Con:
No chlorine residual, so none of the pros of chlorine