TREEO Drinking Water Treatment C

Iron Secondary MCL (affects aesthetic quality)

0.3 mg/l (red water complaints)

HAA5 MCL

0.060 mg/l

Manganese Secondary MCL (affects aesthetic quality)

0.05 mg/l (red water complaints)

pH Secondary MCL (affects aesthetic quality)

6.5-8.5

Chloride MCL

250 mg/l

TDS (Total Dissolved Solids) Secondary MCL (affects aesthetic quality)

500 mg/l

Odor Secondary MCL (affects aesthetic quality)

3 TON(Threshold Odor Number)

Color Secondary MCL (affects aesthetic quality)

15 units

Copper Secondary MCL (affects aesthetic quality)

1.0 mg/l

Fluoride Primary MCL (direct threat to human health)

4 mg/l

Lead Primary MCL (direct threat to human health)

0.015 mg/l (lead poison/brain issues)

Copper Primary MCL (direct threat to human health)

1.3 mg/l (Organ issues)

Total Nitrate Primary MCL (direct threat to human health)

10 mg/l (Blue Baby Syndrome/lack of oxygen)

Turbidity Primary MCL (direct threat to human health)

5.0 NTU (bacterial growth)

Total Coliform Primary MCL (direct threat to human health)

No more than 1 (40 samples or less) or 5% (more than 40 samples) per month

Fluoride Secondary MCL (affects aesthetic quality)

2 mg/l

Sodium Primary MCL (direct threat to human health)

160 mg/l

Chlorine/Chloramines MRDL

4.0 mg/l

Chlorine Dioxide MRDL

0.8 mg/l

Aluminum, zinc, and magnesium are often used as anodes to prevent corrosion to other metals. Where does aluminum, zinc and magnesium place in the galvanic series?

The most active metals

In the corrosion cell, which pole is the ANODE?

Positive pole

In the corrosion cell, which pole is the CATHODE?

Negative pole

A lump or mound of rust on a pipe surface

Tubercule

The point on metal where electron activity begins and where the tubercule forms

Anode

The point on metal where electrons leave the metal

Cathode

The fluid that allows the flow of electrons (water in pipes)

Electrolyte

Metallic corrosion and potable water is always the result of which type of corrosion?

Electrochemical

Where does stainless steel, bronze and copper place in the galvanic series?

The least active metals

Which is the anode and cathode on a copper pipe with lead solder?

Copper=Cathode , Lead=Anode

A positive Langelier Index indicates that the water is supersaturated with CaCO3(calcium carbonate), will it be scale forming or corrosive?

Scale forming

A negative Langelier Index indicates that the water is undersaturated with CaCO3(calcium carbonate), will it be scale forming or corrosive?

Corrosive

A piece of steel that can determine the rate of corrosion or scale

Coupon

TTHM MCL

0.080 mg/l

Location where metal is lost in a corrosion scale

Cathode

If water leaks and lead & copper results have increased in the water system, which lab test will confirm that corrosion is taking place?

Dissolved Oxygen, pH & Coupon Analysis

The reaction of dissolved oxygen with ferrous ions is reduced during which condition?

Low pH values

An insulator used to prevent corrosion by separating two dissimilar metals

Dielectric

A chemical used to mask red water problems by bonding with iron, but increases corrosion by reducing calcium carbonate scale forming ability.

Sodium hexametaphosphate

The most corrosive component of water chemistry

Dissolved Oxygen

Compound formed with three parts chlorine to one part ammonia

Monochloramine

Data used to calculate CT values

Concentration & Time - chlorine concentration after contact time and total detention time

Minimum distribution pressure

20 psi

Chlorine exposure causing slight throat irritation can be relieved by drinking...

Milk

The effect on pH when sodium hypochlorite or calcium hypochlorite is added

Increases pH

What is the problem if the chlorine residual dropping in the system; chlorine feed is not the problem, one ton chlorine container is full and ejector is working properly

Hydrogen sulfide entering the system from the well

To reach breakpoint, chlorine is fed to overcome...

Chlorine demand and chloramines

Normal pressure of chlorine gas in a 150 lb cylinder or one ton container

20-30 psi

Causes increased formation of TTHMs

High pH

Process effective in removing TTHMs after they have formed

Aeration

Regarding pH and Temperature, disinfection is best....

pH=Low & Temperature=High

Max amount of liquid in chlorine cylinder/container

85% Full

Minimum free chlorine residual

0.2 mg/l

Minimum combined chlorine residual

O.6 mg/l

A CWS serves 34,673 people and has 5 wells, how many samples per month?

45 (40 for population + 5 for each well)

Sample procedure for positive distribution sample

1 at original tap, 1 five connections and 1 five connections downs (within 24 hours of positive again)

Sample procedure for positive well sample

2 repeat samples: first within 24 hours of notification and second the next consecutive day

What causes fast TTHM formation

High water temperature, hIgh pH and high free chlorine/organics in the water

More hydroxide ions than hydrogen ions, the solution is...

Basic

Which ions are being used during the service phase during the ion exchange process?

Calcium and magnesium are exchanged with sodium

The addition of lime during the softening process will cause which reaction to the alkalinity?

Bicarbonate alkalinity converts to carbonate alkalinity

Finished water leaving the ion exchange unit is considered...

Corrosive

Reason for using soda ash during the softening process...

Remove non-carbonate hardness

The ion exchange units has a finished water hardness of one grain, what should be done?

Monitor until over 1 GPG

Main chemical present when pH is at 8.3?

Bicarbonate (HCO3)

Main chemical present when pH is at 10.2?

Carbonate (CO3 -2)

Main chemical present when pH is at 11.3?

Hydroxide (OH)

Main chemical present when pH is at 4.3?

Carbon Dioxide (CO2)

Hardness of finished water at lime softening plant is near the hardness of the raw water, what could be the problem?

Carbon Dioxide dose too high causing pH to lower to quickly which causes Ca and Mg to dissolve back into solution

No phenolphthalein (P) alkalinity present means the alkalinity is in which forms?

Only bicarbonate

Correct operation sequence of ion exchange softener

Service, Backwash, Brine, Rinse

What mg/l is water considered Hard?

150-300 mg/l

Is Carbonate hardness temporary or permanent?

Temporary Hardness

Is Non-carbonate hardness temporary or permanent?

Permanent Hardness

Conversion of grains of Hardness to mg/l

1 gpg = 17.1 mg/l

Calcium Hardness is 3.2 gpg & magnesium harness is 8.5 gpg, what is the total Hardness in mg/l?

200.07 mg/l (3.2+8.5=11.7x17.1)

If total alkalinity is greater than total Hardness, what causes the hardness?

All Hardness is carbonate (temporary) hardness

If total Hardness is greater than total alkalinity, what causes the hardness?

Carbonate and non-carbonate compounds

Amount of permanent and temporary hardness, if total alkalinity is 114 mg/l and total hardness is 115 mg/l?

Permanent hardness: 1 mg/l

Temporary hardness: 114 mg/l

What charge is a cationic coagulant?

Positive charge

What do very tiny alum flocs forming in the flocculation basin indicate?

Chemical/Alum dosage is too low

What does it indicate when about 80% of floc has settled in the jar test within one or two minutes after the mixing is stopped?

Coagulant dose is too high and should be decreased

Fine alum floc particles washing over the effluent wires of the sedimentation basin indicates what?

Chemical/Alum dosage is too high

What is it called when turbulence in flocculation basins are reduced by gradually reducing the speed of mixers in each succeeding basin?

Tapered energy mixing

What condition would require the mixing speeds to be increased?

Low water temperature

For every 1.0 mg/l of alum added, how much bicarbonate alkalinity needs to be available?

0.45 mg/l

How much excess alkalinity should be available in regards to chemical dosages?

20 mg/l

What pH range is best for coagulation?

5 to 7

What are the best floc sizes for floc formation?

0.1 to 0.3 mm

Detention time is not as important and needs to be just long enough for chemical process to take place during which process?

Coagulation

Detention time is extremely important during which process?

Flocculation

Minimum detention time for direct filtration

5 - 20 minutes

Detention time for conventional filtration

30 minutes

What does short circuiting indicate about flocculation?

Mixing speed/intensity to low

What does floc shearing (large Alum flocs) indicate about flocculation?

Mixing speed/intensity to high

Floc should be 80-90 % settle how long after the mixer turns off?

15 minutes

What does a Milky or bluish tiny during flocculation mean?

Too much chemical/Alum

As water becomes colder what happens to settleability?

Slower

How do we evaluate the settleability changes?

Jar test

How do you compensate for changes to settleability?

Increase mixer speed

add chemical/coagulate aid

increase detention time

What should be done if filtration rates on a dual media filter are over 5 GPM/sg ft, finish water turbidity has increased and filter runs have shortened due to shearing of iron floc?

Add a polymer coagulant aid