Central Biosolids Flashcards
(24 cards)
What is the purpose of the Dissolved Air Floation Thickener?
To release saturated air into the sludge, causing it to float to the surface and thicken the sludge.
The clarified water remains at the bottom, while the thickened sludge is skimmed off for further treatment.
What is the input and output of the thickening process in biosolids treatment?
Input: Waste Activated Sludge, Dissolved Air, Polymer
Output: thickened sludge (4-5% solids), Subnatant, Settled solids.
What does the Rise Raise Test measure in sludge treatment?
The time it takes for sludge to rise to the top of the surface, which should be within 25 seconds.
What is the purpose of strainpresses in biosolids treatment?
To remove coarse solids and fibrous material from the sludge.
What occurs during the digestion process in biosolids treatment?
Microorganisms break down organic matter, producing biogas (50-60% methane, 30-35% carbon dioxide).
What is the output of the digestion process?
Output: Supernatant (contains fatty acids and nutrients), Digested Sludge (50% solids), Biogas (65-70% methane, 30-35% carbon dioxide).
Define Acid Fermentation in the context of biosolids.
Microorganisms attack soluble solids, creating organic acids, high gas production, odor, and a pH of 6.8-5.1 or lower.
What is the pH range during Acid Digestion?
6.6 to 6.8.
What is Intensive Digestion focused on?
Attacking more resistant materials such as proteins and amino acids.
What is the solids retention time in the central biosolids facility?
22 days.
What is the function of a centrifuge in biosolids treatment?
To separate solids from liquids using centrifugal force.
What is Stokes Law?
It expresses the drag force resisting the fall of small spherical particles through a fluid medium.
What is the input and output of the centrifuge process?
Input: Thickened Sludge (2-6% solids), Polymer
Output: Cake (20-30% solids), Centrate (liquid component).
What does the dryer do in biosolids treatment?
Utilizes hot air to evaporate water from the wet cake, producing biosolids pellets.
What is the formula for water evaporation rate in the dryer?
Ev = Fc(1-Xc/Xp).
What components are included in the Wet Feed Group?
- Recycle material bin
- Recycle material dowing screw
- Wet sludge material
- Wet sludge material bin live bottom screws
- Wet sludge material pump
- Plowshare Mixer.
What is the role of the Pre-separator and Polyclone units?
To separate dried biosolids pellets from humid process air.
What does the Regenerative Thermal Oxidizer do?
Reduces volatile organic compounds using heat and combustion.
What is the purpose of the Drum quench system?
To add water to the furnace outlet to prevent an explosion or over-temperature.
What is the function of the Induced Draft Fan?
Moves or circulates process air through the dryer system.
True or False: The polymer is used in the centrifuge process to increase dryness.
True.
What is the purpose of the Roll Crusher in biosolids treatment?
To crush the sludge into very fine pieces.
Fill in the blank: The _______ is used to cool pellets from 170 degrees F to below 100 degrees F.
Pellet Cooler.
What is the purpose of adding a polymer to the DAFT
to help the suspended solids clump together. called flocculation
