ELC mid-term Flashcards
To study for ELC drinking water examination, in preparation for required certification as an Entry-level Drinking Water Operator
This regulation describes which water systems need certified operators to conduct certain regulatory tasks
O. Reg 170/03
A certified operator receives training and certification under what regulation?
O. Reg 128/04
What are the responsibilities required by certified operators under the SDWA?
Sampling and testing of water
Make adjustments
Examine within 72 hours the test results
Take appropriate action in response to alarms
Perform combined chlorine residual, free chlorine residual, turbidity and fluoride testing
Perform regular checks on water treatment to confirm functioning
True or false
Except for large municipal residential systems, checks for turbidity and chlorine residual for the other 4 types of systems above can be conducted by persons other than certified operator water quality analyst if certain conditions are met
True
Failure to comply with regulations can lead to what consequences?
Provincially issued orders
A charge with an offence to failure to comply
Financial penalties up to 7 million for an individual, or 10 million for a corporation
Interim operation authorities can be appointed
Threats to source water
4 vulnerable areas in the CWA
Surface water intake protection zone
Wellhead protection area
Highly vulnerable aquifer
Significant groundwater recharge area
The minimum alarm standard for free chlorine residual
0.1 mg/L less than the free chlorine residual that is required to achieve primary disinfection
The minimum alarm standard for free chlorine residual and total chlorine residual (for the purpose of determining combined chlorine residual) in a distribution sample
0.25 mg/L
The minimum and maximum free chlorine residual in a distribution sample
Maximum alarm standard is N/A
Minimum is 0.05 mg/L
A drinking water system not using chlorination or chloramination as their primary disinfection,
must have one of the two following features installed in the system
A feature that ensures no water is directed to users
A feature that causes an alarm to sound in the building where disinfection occurs/ at location where person is present
What is the Purpose of the coagulation process?
the rapid dispersion of coagulation to destabilize particles
Adverse results of drinking water tests
- Presence of bacteria
- A result exceeding standards outlined in 169/03
- Presence of pesticide not listed in 169/03
- Chlorine residuals below minimum values
- Filter effluent turbidity >1.0 NTU
- Sodium >20mg/L
- Exceeding an MAC for any health-related parameter
- Fluoride >1.5 mg/L
- Any observation indicating improper disinfection
- Test results from continuous monitoring equipment
Components of a free chlorine residual
Hypochlorous acid
Hypochlorite ion
The minimum treatment required for a groundwater source
2-log removal/inactivation of viruses
The electrical treatment of 02 or dry air can generate what onsite?
03
ozone
What disinfectants can be used for secondary disinfection?
Chlorine Gas sodium hypochlorite calcium hypochlorite chlorine dioxide chloramination
Define Turbidity
The cloudy appearance of water that is caused by colloids and suspended particles. Turbity is the interaction of light upon these particles.
True Colour vs Apparent Colour
True colour is the colour of water after turbidity has been removed, while apparent colour is measured in an unfiltered sample.
factors affecting disinfection process
Dosage temperature mixing pH contact time concentration of microorganisms type of chemical
Some common sources for taste/odour
algae
dissolved gases
dichloramines
minerals/other compounds
drawbacks encountered when flushing
low water pressure
discoloured water
no water
define alkalinity
the buffers against sudden changes in pH.
Necessary during coagulation process
4 types of backflow prevention devices used to prevent backflow of non-drinking water into system
Vacuum breaker
Double check Detector Assembly
Pressure zone valve
2x diameter Air gap
Shoring must be used in a trench if it is more than _______m/ft deep
4 feet
1.2 m
What is chloramination? what type of residual is monitored during this disinfection process?
the addition of ammonia to chlorinated water to form monochloramines, which are a persistent residual.
the breakpoint in chlorination is what exactly?
The point in disinfection at which chlororganices and chloramines are partly destroyed and a free available residual is formed
O. Reg 169/03 (1,2,3)
The limits on health based parameters that can be present in drinking water.
The difference between clearwells, standpipes and elevated tanks?
Clearwells store treated water for continuous operation
Standpipes and elevated tanks are used for both storage, and pressure
the MAX, MIN and NORMAL pressures in the distribution system
NORMAL 40-80 psi
MIN 20 psi
MAX 100 psi
3 Factors that reduce shelf life of Sodium Hypochlorite
Concentration
light
heat
Pressure is defined as
Force per unit area
What is head loss?
pressure loss due to friction
Water hammer is:
a) caused by opening/closing valves slowly
b) the formation of bubbles
c) The force of water when it changes to a direction
d) the force caused by sudden change in water velocity
d)
True or False
The hydraulic grade line is the line which connects a booster pump to the storage tank
False
The Hydraulic Grade Line represents the residual pressure in the water main after taking into account the pressure loss due to friction
Thrust is:
The force of water when it changes to a direction
The products created due to the reaction of chlorine or other disinfectants with organic materials present in raw water during treatment
Disinfection Bi-Products (DBP)
True or False
Colloids usually have a negative electrical charge
True
Why they do not attract and settle out without coagulant
Name one significant impact on the disinfection process when raw water has increased temperature
Higher temperature increases potential formation of DBPs
Affects rate of chlorine decay
makes it more different to maintain a chlorine residual
what are the operational guidelines for pH in drinking water?
6.5-8.5
The regulations/guidelines that define GUDI
O.Reg 170/03
contains a checklist to identify groundwater sources
Multi-Barrier Approach
What are the 5 barriers?
Source water protection Drinking water treatment Distribution system security Automatic control and early warning monitoring Responses to adverse conditions
The CT Concept
CT = Concentration (mg/L) x Time (minutes)
What is the minimum Treatment for Surface Water according to O.Reg 170/03
Chemically assisted filtration, followed by disinfection (or equivalent)
99 % (2-Log) inactivation of Cryptosporidium
- 9 % (3-log) inactivation of Giardia
- 99 % (4 log) inactivation of viruses
3 Reasons for Secondary Disinfection
1) to maintain a persistent disinfection residual
2) reduce re-growth of bacteria
3) Contol Biofilm formation
4) Serve as an indicator of system integrity
What chemicals can be used for secondary disinfection?
Chlorine
Chlorine Dioxide
monochloramine
(only)
True or False
Disinfection efficiency increases with the pH
False
Lower ph is more efficiently treated
When is Uv Disinfection acceptable as a primary source of treatment?
Non-GUDI
GUDI, only with chemically assisted filtration
The Maximum Chlorine Residual at any time and in any location within the distribution system
4.0 mg/L (when measured as free chlorine)
3.0 mg/L (when measured as combined chlorine)
.8 mg/L when measured as Chlorine Dioxide
Major Steps in Conventional Surface Water Treatment Process
intake/screening pre-disinfection coagulation chemical addition coagulation flocculation clarification (ie. sedimentation) Filtration Post disinfection clearwell storage (contact time) High lift pumping
Single level Intake vs. Multi level intake
single level: inexpensive, but subject to seasonal water quality variations (from temperature and nutrient fluctuations)
multi-level: expensive, but water can be taken from depth of best water quality at any time
The purpose of Tube Settlers
increase settling efficiency by providing a higher ratio of effective surface area per volume
Purpose of storage facilities
Pressure Reduce size of transmission mains Firefighting Industrial requirements Balance fluctuating demands
Purpose of elevated tanks
Maintain pressure
Eliminate need for continuous pumping
Standpipes are storage tanks located where?
On ground level
Providing low pressure
Taller than diameter
What is a surge tank?
Controls water hammer
Absorbs sudden a pressure to provide air brakes
Preventing ice damage in water storage tanks can be done how
Varying water level 50% every 24 hrs for above ground tanks
25% every 24 hrs for underground reservoirs
Pressurizing distribution system or steam generator will aid in ice removal/prevention
Types of piping
Cast iron Asbestos-cement Plastic-PVC Steel Concrete Others-
How often are storage tanks cleaned and drained?
Inspected annually and cleaned every 3 years
Larger diameter pipes are usually made of
Concrete
3 types of plastic pipes
PVC
Hdpe
PB
Tapping machines
Used to drill or thread holes into a pipe surface
“Wet tapping”
Ensure cutter bit is fully withdrawn
The most accurate way to detect leaks in distribution system
Sound rods
Unidirectional flushing
Flow of water in a single direction
Frozen lines are thawed how?
Electrical thawing
Hot water
Thawing using a steam generator
“Steam Jennie”
Types of corrosion
Internal pipe corrosion- tuberculation
External pipe corrosion- electrical chemical reactions and pinhole leaks or rust on outside of pipe
Chlorine Demand =
Dosage-residual
3 parameters that determine the length of a filter run. Any one of these parameters can determine when a backwash is required in the system.
Head loss
increase in turbidity
the filter run time
4 different zones of a sedimentation tank
inlet zone
settling zone
sludge zone
outlet zone
What is the recommended concentration of flouride in drinking water?
0.5-0.8 mg/L
3 chemicals typically used for fluoridation
sodium flouride
hydrofluosilicid acid
sodium silicofluoride
Common Chemical used as a coagulant in water treatment
Alum
Aluminum Sulphate
Al2(SO4)3
psi x ____ = kPa
kPa / ____ = pis
6.895
1m head = how much kPa?
9.804 kPa
Friction loss depends upon what factors
velocity pipe diameter length degree of roughness fittings/valves
Pressure lost due to friction
headloss
Occurs when absolute pressure at the pump drops below the vapour pressure of the liquid
forms vapour bubbles
Cavitation
2 types of shoring
Timber shoring
Hydraulic aluminum shoring
True or false
Odwqs for cyanobacterial toxin microcystin-LR is 0.0015 mg/L
True
Indicator organisms are used for what
To determine whether or not pathogens are present in raw water
True or false
E. coli is always an indication of fecal contamination
True
True or false
Sodium hypochlorite lowers pH
False… It increases ph
Addition of chlorine to an intake system ( sirface water) is usually down to control what?
Zebra mussels
Direct filtration is basically conventional treatment with no ____________
Clarification
Non gudi
The destabilization of particles so they can clump together and for floc
Coagulation
Alkalinity and coagulant for a precipitate that captures particles, therefore…
Adjusting alkalinity can be done by adding soda and may mean less coagulant is needed (cheaper)
Water is densest at what temperature?
4 degrees
Filtration removes up to __ percent of turbidity in water
95 percent
Back washing methods
Surface wash
Air scour
During filter ripening period, you perform what practice
Filter-waste
Examine filter media condition includes checking for
Algae, mud balls, proper gradation
What is gac?
Adsorption
Granulated activated carbon
Chemical oxidation using compounds like potassium permanganate assist with what?
Destruction of organica and the oxidation of inorganic compounds that cause taste and odour
NTU
Nephelometric turbidity units
Regulated turbidity limits
1 NTU
Secondary disinfection must create a residual and therefore must be done with….
Chlorination
Alum is used in winter months
True or false
True
Reg 170 talks about when and how,
169 lists chemical standards
True
128/04
Training and certification
Well legislation
908
Drinking water systems are regulated under
170/03
True or false
Any indication water isn’t properly disinfected according to opddwo is considered an adverse effect
True
Chlorine to ammonia ratio
4.5:1
Monochloramine is a weak primary disinfectant, but provides the best residual
T of F
True
The most effective for no chorine residual
Hypochlourous acid
True or false
Sodium hypochlorite increases the pH of water as is corrosive
True
The most important dbps
Thms
Pump curves and values require what information to determine values?
Capacity
Total head
Power
Efficiency
