Filtration Flashcards
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
What 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?
Absorption 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?
Non-ionic 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
Mud balls are caused by which of the following?
Improper backwash
During a plant walkthrough, and operator discovers a filter is air bound. What action should they 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 fourth step in the backwash process?
Start the surface scours
How should an air bound filter be Backwash?
Slowly
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?
Operating the filter at high head loss too long or the release of O2 in saturated cold water due to a decrease in pressure
During a plant tour, an operator noticed the filter 16 has a sudden increase in head loss. What action should they 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 substances 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 will 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 upstart of the new filter and after backwashing a filter
What is the backwash rise rate in inches/minute if the backwash flow rate is 35 GPM/SQ FT?
56 IN/ min
***What is the backwash pumping rate in GPM for a filter 20 ft long and 30 ft wide with a desired backwash rate of 25 GPM/ square foot?
15,000 GPM
During a filter run, flow through the filter was 12.8 million gallons. 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 (water treatment plant)?
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
