The release of dissolved air in saturated cold water due to a
decrease in pressure
causes which of the following?
Air Binding
The color in filtered water is called?
True Color
What is the final step for removal of suspended solids?
Filtration
Which FAC Chapter addresses drinking water standards, monitoring, and reporting?
FAC 62-550
Inaccurate test results are generally due to?
Poor sampling techniques
What is the highest possible turbidity reduction expected when operating a filtration process under optimum conditions?
99.5%
How is pin point floc removed?
Filtration
Direct filtration omits which process?
Sedimentation
What are the main removal mechanisms in a filter?
Adsorption and sedimentation
Sand drying beds are similar to what type of filters?
Gravity Sand Filters
Which of the following coagulants is generally used as a filter aid?
Nonionic Polymer
What parameters are used to determine when to backwash a filter?
Head Loss, Turbidity, and Time
Where is the application point for a filter aid?
Filter Influent
Before starting the backwash process, what must you check first?
Water supply
Mudballs are caused by which of the following?
Improper backwash
How is the problem in question 15 corrected?
Properly backwash the filter
During a plant walk through, an operator discovers a filter is air bound. What action should she take?
Backwash the filter immediately
Media boils are caused by?
High backwash rates
What is the main goal of filtration?
Removal of turbidity
What is the 4 step in the backwash process?
Start the surface scours
How should an air bound filter be backwashed?
How should an air bound filter be backwashed?
The color in unfiltered water is called?
Apparent Color
After backwashing a filter, there is a high initial head loss. What is most likely cause?
Insufficient Backwash
What causes air binding?
Ans. Operating the filter at high head loss too long
Ans. The
release of O2 in saturated cold water due to a decrease in pressure
During a plant tour, an operator noticed that Filter 16 has a sudden increase in head loss. What action should she take?
Do a jar test
What do you call the process of reversing the flow of water through filter media to remove trapped particles?
Filter Backwash
The common boundary layer between two substyances such as water and a solid is called?
Interface
The difference between the water surface and the media surface is called?
Submergence (Head)
What is the filter rate in GPM/sq ft of slow sand filters?
0.015-0.15 GPM/sq ft
High water temperatures require what type of backwash rates?
Higher Backwash rates
The Filter Backwash Rule requires the backwash water to be sent where after dewatering the sludge?
Upstream of all conventional or direct filtration systems
(includes
coagulation, filtration, and sedimentation)
What is the ripening period of a filter?
This occurs at startup of a new filter or after backwash of a filter
A filter 12" long and 8" wide drops 3" in 90 seconds. What is the filtration rate in GPM/sq ft?
What is the backwash rise rate in inches/minute if the backwash flow rate is 35 GPM/sq ft?
What is the backwash pumping rate in GPM for a filter 20' long x 30' wide with a desired backwash rate of 25 GPM/sq ft?
How much water is needed to back wash the filter in question 35 for 8 minutes?
Question 35:
What is the backwash pumping rate in GPM for a filter 20' long x 30' wide with a desired backwash rate of 25 GPM/sq ft?
120,000 Gallons (15,000 GPM x 8 min)
During a filter run, flow through the filter was 12.8 MG. It took 120,000 gallons to backwash the filter. What percent of the filter's water production was used for backwashing?
1%
What is the minimum treatment required for drinking water by the Surface Water Treatment Rule (SWTR)?
Filtration and Disinfection
Where should you install a particle counter at a WTP?
As close as possible to the point of measurement
The length of a sample line of a particle counter should be how long?
As short as possible
Pumping sample water to the particle counter may cause what problem?
Air bubbles, which may be erroneously counted as particles
What material is recommended for the sample line of a particle counter?
Black Nylon with Hytril Liner
What is the final step for removal of suspended solids?
Filtration