Sewage Treatment Chp. 14,15,16,18
Terms in this set (92)
Flow Measurement -
Used to ensure process efficiency, to provide information for hydraulic and organic loading, and for data needed to prepare regulatory compliance reports. Most common methods are:
Preliminary treatment depends on what?
collection system (e.g., combined sewer system that collect stormwaters and sanitary sewers).
Screening does what?
removes large solids from the flow (leaves, branches, roots, rocks, rags, can, etc.)
reduces solids to a size that can enter the plant without damage to equipment or process interruption - comminution and barminution devices.
rely on the weight of the grit and is separated out by processes that employs gravity/velocity aeration, or centrifugal forces
Used to ensure process efficiency, to provide information for hydraulic and organic loading, and for data needed to prepare regulatory compliance reports.
Most common methods of Flow Measurement are?
Fill and draw - measures the time required for liquid to fill a container of know volume divided by the time equals flow rate
Weirs and flumes
- both methods place a restrictive device in the open channel. The water that passes over the constriction or through the throat is directly proportion to the height of the water behind the constriction's opening
- Forces air through the waste stream to achieve and maintain the aerobic state. Freshens septic waste, Reduce odors, Reduce corrosion by stripping H2S, Improves solids separation and settling, Reduces BOD5
- The following are chemicals used in primary treatment:
What are the chemicals used in primary treatmeant?
Peroxides, acids and bases, mineral salts (ferric chloride, alum, etc.), bioadditives, and enzymes. The pretreatment chemical addition is dependent on the condition of incoming waters and desired outcome
- The two types feeders are dry feeders and solution feeders.
What are the most common types of feeders?
volumetric and gravimetric
are simpler and less expensive
are simpler and less expensive
are generally small positive-displacement metering pumps.
What are the 3 types of Feeders?
Reciprocating, vacuum, gravity
(piston-plunger or diaphragm feeders)
feed rotameter (drip feeders)
because of wide swings in influent levels and organic loading, flow equalization directs excessive flow into storage basins maintains adequate mixing and aeration during storage. The stored influent is then pumped backed into the treatment process during low flow periods.
What happens after preliminary treatment?
waste stream still contains suspended organic solid, settleable organic and floatable solids
Primary sedimentation (or clarification) removes?
90 to 95 % of settleable solids 40 to 50 % of suspended solids 25 to 35 % of BOD5
What's Process efficiency?
is controlled by detention time, temp, design and equipment conditions
is used in primary, secondary and advanced treatment processes
What does Waste water enter?
a settling tank or basin, and the velocity is reduce to about one foot per minute.
Once the solids settle what happens next?
they are removed as sludge which is pumped to a sludge processing area.
Oil, grease and other floating materials are handled how?
skimmed from the surface his process is controlled by monitoring the retention time, temp, and other equipment conditions.
combine settling, skimming, and unmixed anaerobic digestion in one prefabricated unit
Long detention time and no control for solids separation means what?
that septic tanks should not be used for large (i.e., industrial) applications
Two Story Tanks?
Solve the problem of solid separation in septic tanks
Plain Settling Tanks
Accomplish sediment removal either continuously or intermittently
After preliminary treatment and primary sedimentation what's the next step?
the wastestream is now call primary effluent.
What's Primary effluent?
still contains large amounts of dissolved food, waste, and other chemicals (nutrients), and is usually cloudy and gray in color.
is the moving force in primary treatment which removes pollutants that either float or settle. This constitutes about 50% of the raw pollutant load.
(i.e., biological processes) converts the remaining load to a more environmental friendly solid to be discharged.
Biological processes convert what?
dissolved, suspended, and colloidal organic wastes to more stable solids, which can either be removed by settling or harmlessly discharged to the environment.
Biological treated effluent contains?
not more than 30 mg/L BOD5 and/or 30 mg/L total suspended solids
Commonly used biological treatments are?
(i.e., microorganisms) processes
being used since 1800s
Rotating biological contactors
used in more recent years
are temperature sensitive but when working properly good for reducing BOD. Activated sludge - more expensive to operate because of energy requirement for pump and blowers.
Microorganism can convert organic wastes into?
stabilized, low-energy compounds producing Carbon dioxide (CO2), Stable Solids, More Microorganisms
Fixed film systems are?
(Trickling filters and Rotating biological contractors (RBCs)). Use biological growth (biomass or zoogleal slime) that forms on a media.
systems biological growth that mixes with the wastewater.
is delivered over the top of filter media by a fixed distributor system or rotating distribution arm contain a population microorganism.
a thin layer as it flows down through the filter media and over the microorganism layer on the media.
consumes the waste and aerobically decomposes it
slime mostly bacteria, but also contain algae, protozoa, worms, snail, fungi, and insect larvae
Trickling Filter Performance Classification
Standard rate filters: hydraulic loading 25 to 90 gpd/ft3, removes 80 to 85 % BOD5, removes 80 to 85 % TSS
High rate filter
hydraulic loading 230 to 900 gpd/ft3, 65 to 80 % BOD5, 65 to 80 TSS removal.
Hydraulic loading >900 gpd/ft3, 40 to 65 % BOD5, 40 to 65% TSS removal.
What goes about the media and spray the waste water?
How many feet deep must the media B?
3 to 20'
What supports the media and collect the waste water?
What do effluent channels do?
Carry the flow from the trickling filter to the secondary settling tank.
How many hours/what does detention time separate treated waste water?
2 to 4 hours of detention Tom this is call secondary settling
What's a center shaft?
Designed to support the weight of disk common however collapse the center shout has been a major problem
What's a drive system?
Can be a major problem if it does not provide uniform RBC movement.
What's a tank?
A large enough space to provide dealt to retention time variation
What prevents bow mass loss from several weather changes?
What provide 2 to 4 hours retention time to permit settling of light or biological solid?
What are the advantages of pond/lagoons?
Simple to Build and manage
Handles large fluctuations inflows
Produce a Holly purified effluent at lower cost
Negligible energy costs
What classified based on their location in the system karma by the waste they receive com and bar the main biological process occurring in the ponds?
What are raw sewage Stabilization ponds?
Effluent into pond receive no prior primary treatment.
Usually provide a minimum of 45 days or detection
How much BOD raw sewage receives?
<30 lbs of BOD5/day/acre
What are inflow and outflow structures?
Are designed to permit effluent selection of quality
What decomposes organics in the waste water?
What do oxidation ponds provide a?
Biological treatment common additional settling common and reduction of fecal coliform levels
What's the reason solids affect raw sewage stabilization pond?
It enters and produces in pawn eventually fill the pawn question more thus pond have to be cleaned or replace every 20 to 30 years
What are aerobic pond?
Oxygen are present throughout the pond dealing aerobic decomposition. These ponds are not while the use
What are polishing ponds?
Remove additional BOD 5, solid, fecal coliform and nutrients
What is a anaerobic pond?
No oxygen are present in pawn yielding anaerobic decomposition. These ponds are normally used to treat high strength industrial waste.
What's the most common pawn, also the upper portion is a aerobic, lower levels anoxic and anaerobic?
What's Mechanical on diffused air systems provide oxygen throughout the pawn?
What removes contaminants that are not removed by primary and secondary processes nitrogen common phosphorus, soluble COD, heavy metals?
Advanced Water Treatment (AWT)
What are advanced water treatments?
Expensive to build and operate
Demand highly trained operators
Smart produced difficult to depose
What accomplishes implement tation filtering step much light the drinking water filters?
Special woven steel wire cloth around a revolving drum captures solids
Why is it important to remove nitrogen?
It's important because in helps control algae Bloom in the receiving body
Ammonium is toxic to fish
Prevent additional BOD
What is microorganisms convert ammonium nitrogen to nitrate nice gin in a second step to nitrate is convert nitrogen gas?
What is the ammonia stripping process?
Raise pH to 10 and strip NH3 in a stripping tower
What's pollution problem from the water to the air?
What's phosphorus removal?
Biological treatment units only removes about 30% in municipal waste waters
What does adding phosphorus removal do?
Add chemicals such as alum, ferric chloride or lime with precipitate the phosphate ions. The phosphorus precipitates can be removed by settling out in a clarifier tank.
What allows high quality water to pass across membrane while stopping the passage of dissolved solids?
What chemicals does reverse osmosis remove?
Arsenic, Asbestos, atrazine, fluoride, lead, mercury, nitrate, radium and volatile organics-benzene, trichloroethylene, trihalomethanes, and radon.
Water is de-mineralized using ion selective membranes and electric field
What's inexpensive and effect of tertiary treatment of waste water?
What allows beneficial water and nutrient recycling?
What are the types of land treatment?
Irrigation, slow rate application mode
Infiltration, rapid infiltration mode
Overland flow mode