Wet 111 Combined

How many ________ million americans use private wells for drinking water?

42

Taste and Odor Problems: monochloaramine

5 mg/L

Name the (5) Water treatment processes that can be used to control THMs.

*Aeration *Feed oxidation chemicals instead of pre chlorination *Coagulation, flocculation, sedimentation, and filtration *Water softening processes (Ion exchange) *Powdered activated carbon.

What are the (3) basic Chlorine compounds and describe them?

*Chlorine Demand: how much chlorine reacts with clay, silt, iron, manganese, bacteria. *Combined Chlorine Residuals *Chloramines: chlorine reacted with Inorganic ammonia compounds (NH3) Organic nitrogen proteins (amino acids) Used to produce less DBP But, weak against virus's and protozoa

Step 2a: Calculate Ctcalc = C * T

*Ctcalc: concentration time (calculated value (min * mg/L) *C: residual disinfectant concentration measured during peak flow (mg/L) *T: Actual detention time (min)

Free Chlorine Residual

*point past breakpoint where *HOCl (hypochlorous acid) and OCL- (hypochlorite ion) form. *25 times more powerful than combined chlorine for disinfection

C•T (concentration and contact time):

Effectiveness of chlorination is dependant on chlorine concentration and contact time.

For most private wells the priamry source of contamination is the owners septic system?

t

Oftentimes before disinfection water at a conventional treatment plant undergoes coagulation, flocculation, sedimentation, and filtration.

t

Ozone requires a shorter contact time and dosage then chlorine.

t

Sodium hypochlorite can be generated onsite by electrolysis of sodium chloride solution.

t

Sodium hypochlorite has a solution concetration from 5 to 15% chlorine. It is more expensive then chlorine gas but easier to handle.

t

Filter Type: Sand What is is Log removal of Giardia cysts?

2.5

Taste and Odor Problems: Free (HOCL)

20 mg/L

Chlorine- Ammonia reactions are governed by (5) reactions, name them:

*Rates of formation of mono and dichloramine. *pH *Temperature *Time *Cl:NH3 ratio Fact: High Cl:NH3 ratio, low temp & pH favor dichloramine

What log removal do we want for removal of viruses?

4

Taste and Odor Problems: Trichloramine

0.02 mg/L

Baffle factor: unbaffled tank

0.1 "How well the chlorine is in contact with the water"

Baffle factor: poor baffling

0.3 "How well the chlorine is in contact with the water"

Baffle factor: average baffling

0.5 "How well the chlorine is in contact with the water"

Baffle factor: superior baffling

0.7 "How well the chlorine is in contact with the water"

Taste and Odor Problems: Dichloramine

0.8 mg/L

Cl:NH3 and pH Impact in Water

1. If ammonia (NH3) is present in water, the hypochlorus acid (HOCL) will react to form one kind of chloramine depending on the pH, temperature, and reaction time. 2. Monochloramine and dichloramine are formed at pH 4.5 - 8.5 3. Monochloramine is most common @pH>7.5; Cl2:NH3 <5:1 4. pH 4-5-7.5, Cl:NH3 > 5:1 -Monochloramine converts to dichloramines 5. pH < 4.5, Cl2:NH3 ~15:1 -Trichloramine which produces a very foul odor.

Chlorine Effectiveness Part 1:

1. pH (low pH =better disinfection) want pH < 7.5=more hypochlorus acid 2. Temperature (warm temp=better disinfect) chlorine disinfection power doubles every 10 degrees. 3. Chlorine Demand (Low Chlorine demand=better disinfect) Fe+3, Mn+4, HS and turbidity cause chlorine demand 4. Suspended solids/nitrite/organics/ reduced chemicals

Baffle factor: pipe flow

1.0 "How well the chlorine is in contact with the water"

All chlorine cylinders are required to contain at least one fusible metal safety device designed to melt at between ___ to___ degrees F.

158-165

Filter Type: Slow Sand What is is Log removal of Giardia cysts?

2.0

Filter Type: Diatomaceous Earth What is is Log removal of Giardia cysts?

2.00

Filter Type: Direct Filtration What is is Log removal of Giardia cysts?

2.00

Chlorine gas is _____ times heavier than air.

2.5

Chlorine Effectiveness Part 2:

5. Contact time (longer contact = better disinfection) *Varies depending on tank dimensions 6. Concentration (higher concentration=better disinfection) *OPTIMIZE THE DISINFECTION PROCESS 7. Mixing Intensity (Rapid Mixing=better disinfection) *Rapidly disperse chlorine better kill rate 8. Disinfection CT (higher actual CT=better disinfection) *As disinfection CT increases by 50, effective kill increases 10 times (EPA set guidelines)

4 mg/l of chlorine is added continuously to a water flow that averages 5 MGD. How many lbs. chlorine will be used in 30 days?

5000lbs

Chlorine will destroy bacteria most rapidly at what pH?

7.5

What percent of communties rely on groundwater as their primary drinking water source?

80

Step 3B: Calculate ratio Ctcalc/Ctrequired to see if you are in compliance

= 65 (min mg/L) / 145 (min mg/L) = 0.45 Are we in compliance for disinfecting Giardia? How about for Viruses?

Breakpoint chlorination

A. Amount of chlorine required Theory: 7.6 to 15 times the ammonia nitrogen content of the water Practice: up to 25 times the ammonia nitrogen content B. Beyond breakpoint 90% free residual chlorine (HOCL and OCL-) 10% combined chlorine C. Why must breakpoint chlorination be reached? Necessary for the production of free residual chlorine (HOCL and OCL-) Reduces taste and odors Reduces chloramines

A chlorine leak can be detected by

All the below a. smell b. green or reddish depostis on metal c. waving an ammonia soaked rag that will react with the chlorine and create a white cloud

Where should sodium hypochlorite (liquid bleach) be stored?

Away from equipment that is susceptible to corrosion.

If your 1 ton chlorine cylinder is leaking, what type of Chlorine Institute repair kit should be used?

B

Breakpoint chlorination: Zone 4

Breakpoint. Beyond this point, free available residual is formed. Some chloroorganics still remain as combined residual.

THM (TRIHALOMETHANES)

Carcinogenic byproduct of a reaction with chlorine. Form when free chlorine comes into contact with organic compounds. ID by EPA in 1974.

Breakpoint chlorination: Zone 2

Chlorine comes into contact with organics and ammonia. Chloroorganics and chloramines are formed.

Chlorine applied minus ____ equals chlorine residual

Chlorine demand

Which is the correct set of characteristics for chlorine as used in disinfection?

Chlorine gas is toxic, corrosive, and heavier than air

Breakpoint chlorination: Zone 1

Chlorine is destroyed by reducing agents such as iron, manganese, clay and silt. Chlorine reduced to chloride

Breakpoint chlorination: Zone 3

Chloroorganics and chloramines are partially destroyed. Chloramines are broken down and converted to nitrogen gas which leaves the system

A chlorine injecter works by:

Creating a vacuum that draws the chlorine out of the cylinder.

Chlorine residual may be determined using the reagent:

Diethyl-p-phenylene diamine

Chlorine Residual

Measurable chlorine remaining after the demand is satisfied.

Name several Substitute Oxidants for Pre-chlorinations

Ozone O3 Potassium permangante KMnO4 Hydrogen peroxide H2O2 hypochlorous acid HOCl Hypobromous Acid HOBr Bromine Br Hypoiodous acid HOI Chlorine Dioxide ClO2 Iodine I2 Oxygen O2

Step 1: Calculate Theoretical Detention Times

Parameters measured at Peak Flow: *Peak Flow, Q = 347 gpm *Free chlorine residual, C = 0.8 mg/L *pH = 6.0 *Temperature = 0.5 oC Cylindrical Basin Information *Diameter = 40 ft *Minimum tank water lvl = 30 ft *No baffling, BF = 0.1 Calculate TDT = V/Q Calculate Actual Detention Time = TDT * BF

Step 2b: Calculate CTcalc

Parameters measured at Peak Flow: Peak Flow, Q = 347 gpm Free chlorine residual, C = 0.8 mg/L pH = 6.0 Temperature = 0.5 oC Cylindrical Basin Information Diameter = 40 ft Minimum tank water lvl = 30 ft No baffling, BF = 0.1 Ctcalc = C * T

Name the (4) most common THM's and their MCLS

THM MCL MCLS Chloroform 0.08 mg/L 0 mg/L Bromodichloromethane 0.08 mg/L 0 mg/L Dibromochloromethane 0.06 mg/L Bromoform 0.08 mg/L 0 mg/L

Step 3: Calculate Ctrequired

Take conditions (pH = 6.0, Temperature = 0.5oC and chlorine concentration = 0.8 mg/L) and find CT99.9 for Giardia in table.

Chlorine Demand

The amount of chlorine destroyed by reaction with Fe, Mn, turbidity, organics, and microorganisms in the water.

The diamater of the well casing must be large enough such that a submersible pump can be installed.

t

Breakpoint chlorination

The point at which near complete oxidation of nitrogen compounds are reached . Any point beyond breakpoint is mostly free chlorine (HOCL and OCL-)

Breakpoint chlorination:

The point at which near complete oxidation of nitrogen compounds are reached . Any point beyond breakpoint is mostly free chlorine (HOCL and OCL-)

*Chloramines: chlorine reacted with Inorganic ammonia compounds (NH3) Organic nitrogen proteins (amino acids) Used to produce less DBP But, weak against virus's and protozoa? T or F?

True

Add more chlorine to the wastewater to prevent the formation of chloramines and form stronger disinfectants?

True

Chloramines are an effective disinfectant against bacteria but not against viruses?

True

Chlorine demand is difference between applied chlorine and the free chlorine residual at any two points on the breakpoint curve?

True

The total Giardia inactivation required for surface water treatment CT is log 3?

True

Tracer studies can be done on reservoirs and contact basins to determine the actual disinfectant contact time for various flow conditions?

True

Which of the following are EPA approved disinfection methods? a. chlorine b. chloramine c. ozone d. ultraviolet radiation

all

Which of the following impact the formation of disinfectant byproducts? a. type and kinds of organic matter present b. the dosage amount of chlorine and contact time c. pH and temperature of the source water d. all the above

all the above

Combined residual chlorine

chlorine combined with organics or ammonia *NH2Cl (monochloramine) and *NH(Cl)2 (dichloramine) *N(Cl)3 (nitrogen trichloride)

Combined Available Chlorine

chlorine existing in the water in chemical combination with ammonia-nitrogen or organic nitrogen

The least potent, but longest lasting form of chlorine residual is the _________ residual.

combined

Chlorine Residual Analysis: Starch Iodide Titration

common in wastewater

Chlorine Residual Analysis: Amperometric Titration

common in wastewater with cloudy or turbidity problems

Chlorine Residual Analysis: DPD colorometric

common in water and wastewater. Measures free residual or combined residual.

High dosages of chlorine with short contact time are equivalent to small dosages of chlorine with long contact time. In fact, destruction of pathogenic organisms by chlorine is directly related to _____ time and the _______ of the chlorine.

contact & concentration

Chloramine is the most powerful type of chlorine available for disinfection?

f

Its okay to mix calcium hypochlorite and petroleum.

f

There are two types of disinfection with chlorine primary that inactivates or kills pathogens and secondary disinfection that maintains a disinfectant residual in the finished water to prevent regrwoth of bacteria.

t

There is an MCL for total trihalomethanes a disinfecantant byproduct.

t

Add the Extra Free Chlorine (HOCL)

l free chlorine (HOCL or OCL-) reacts with chloramine to produce hydrogen ion, water , and nitrogen gas which will come out of solution. In the case of the monochloramine, the following reaction occurs: 2NH2Cl + HOCl ---)N2 + 6HCl + H2O Added free chlorine reduces the concentration of chloramines in the disinfection process. Instead the chlorine that is added is allowed to form the stronger disinfectant, hypochlorus acid.

To make chloramines you first inject chlorine and then add ammonia.

t

Ultraviolet radiation detroys bacteria and viruses. It still requires chlorine as a secondary disinfectant

t

In water disinfection, hypochlorination refers to the use of _________ hypochlorite

sodium

A basic liquid chlorination system or hypochlorinator includes two metering pumps, a solution tank, and a diffuser to inject the solution into the water

t

A total coliform is an indicator organisms.

t

A well screen can be a perforated or slotted pipe that is placed in the water bearing section of the aquifer.

t

According to the SWTR public water supplies using surface water or groundwater under the direct influence of surface water must be disinfected.

t

At normal pressures, elemental chlorine is a toxic, yellow-green gas, and is liquid at high pressures. It can be lethal at 0.1 percent air by volume.

t

Better chlorine disinfection occurrs at lower pH.

t

Calcium hypochlorite is a white solid that contains 65% available chlorine

t

Chloramine are formed when water containing ammonia is chlorinated or when ammonia is added to the water containing chlorine. Its a weak disinfectant but works well as a secondary disinfectant to prevent bacterial regrowth in a distribution system.

t

Chlorine gas is supplied as liquid in high pressure cylinders.

t

Disinfectants destroy pathogens or disease causing organisms.

t

Filter packs are made of sand and gravel that is smooth, uniform, clean and well rounded. Its placed between the well screen and bored wall of the well. It can improve permeability around the well head.

t

A properly constructed well helps prevent groundwater contamination?

t "One of the most important things to consider in providing a good location for your well is to find high ground, thus, making sure surface water drains away from the well and all possible surface contamination sources are at a lower elevation than your well. A well must be no closer than 10 feet to sewers with water tight joints (e.g., schedule 40 PVC pipe or heavier with solvent welded water tight joints); 50 feet to septic tanks and barnyard or animal confinement lots; and 75 feet to septic fields and manure piles.

Chloramines are formed when water containing ammonia is added to water containing chlorine (DO NOT TRY THIS AT HOME)! They produce fewer disinfection byproducts and can be generated onsite. The negatives are that chloramines are weak disinfectants.

true

Chlorine reactions with "natural organic humus" can produce many by-product chemicals?

true

If ammonia (NH3) is present in water, the hypochlorus acid (HOCL) will react to form one kind of chloramine depending on the pH, temperature, and reaction time. t or f?

true

UV works by destroying a cells genetic material. It is highly effective against bacteria and viruses. Nevertheless, a secondary disinfectant is still needed. Turbidity, organic matter, and suspended solids can impact UV light. With UV disinfection there are no chemical byproducts.

true

When treatment by filtration precedes disinfection, the 3 log removal is accomplished by a combination of the filtration treatment and the disinfection process?

true

You can disinfect using chlorine, chlorine dioxide, ozone, ultraviolet radition, and/or chloramines in the US.

true

Does High Cl:NH3 ratio, low temp & pH favor dichloramine ?

yes