The ratio of food to organisms is a primary control in theactivated sludge process.
Activated sludge forms a lacy network or floc mass that entrapsmany materials not used as food.
The activated sludge process is incapable of handling theminor variations in flows or wastewater characteristics andproduce the desired quality of effluent.
Collection system maintenance activities can affect treatmentplant operation.
Mechanical aeration devices are the most common type ofaeration system used in the activated sludge process.
For your own safety and to avoid damaging equipment,always read the manufacturers' manuals and thoroughlyunderstand them before operating or maintaining any pieceof equipment.
Before starting any blower, be sure all inlet and dischargevalves are closed throughout the system.
To check out pumps, first lock out and tag the pump motor at the power panel so it cannot be started.
A thin sludge in a secondary clarifier will require a lower return flow percentage than a thick sludge.
In the activated sludge treatment process, the warmer the weather the less active the organisms, so the sludge age can be lowered by reducing the MLSS (mixed liquor suspended solids).
Less air will be required when aeration tank solids increase in concentration and activity.
The mixed liquor volatile suspended solids (MLVSS) is a measure of the organisms in the aerator available to treat the incoming waste.
At an activated sludge plant, the sight, smell, and touch observations often are the first indications that problems are developing and frequently offer indications of appropriate corrective action.
An activated sludge plant can accept quite a shock load now and then without adverse effects to the system, but it cannot survive a continuous series of shock loads.
Rising sludge is the same as bulking sludge.
Always read and understand manufacturers' literature before starting, operating, maintaining, or shutting down equipment.
Step-feed aeration distributes the oxygen demand from the waste water over the entire aerator instead of concentrating it at the outlet end.
The flexibility of sequencing batch reactors is shown by their ability to achieve nitrogen and phosphorus removal with simple operational modifications.
Since there are no continuous flows through a sequencing batch reactor (SBR), there is little opportunity for solids losses.
The presence of stalked ciliates indicates a stable activated sludge process that produces a low turbidity effluent.
What are filamentous organisms?
Organisms that grow in a thread or filamentous form
What is the purpose of air filters?
To remove dust and dirt from air before it is compressedand sent to various plant processes
Why is the discharge line from the blower equipped with an air relief valve?
To protect the blower from excessive back pressure andoverload
What are the purposes of air header valves?
To adjust the air flow to the header assembly and toblock the air flow to the assembly when servicing theheader or diffusers
Why should flow control gates on aeration tanks be painted?
For rust and corrosion protection
What problem can develop if the base plate nuts or bolts become loose on a blower (compressor)?
The whole alignment will be thrown out on start-up
How can an excellent effluent be produced by the activatedsludge process
The operator must have a plan of operation or an operationalstrategy and understand how the microorganismsremove wastes from the water being treated
What is a quick way to determine the quality of a plant effluent
The turbidity test
Why does an operator need to keep accurate records at an activated sludge plant?
To find the desirable operating range in terms of efficiencyof waste removal and cost of operation
What is flocculation?
The gathering together of fine particles after coagulationto form larger particles by a process of gentle mixing
How can septic sludge be produced?
When any type of sludge remains too long in suchplaces as hoppers and channels
Constructing a sequencing batch reactor (SBR) plant usuallycosts less than a conventional activated sludge plantdue to the elimination of which item
Why should samples collected for microscopic observation be collected when the Sludge Volume Index (SVI) grab sample is taken?
To correlate microscopic observations with changes inthe SVI
Where should a micro sample be collected in an aeration tank?
Where the microorganisms (bugs) should be hungry
When waste water enters an activated sludge plant, the activated sludge. processes remove which pollutants?
1. Coarse or heavy solids (grit)
2. Debris, such as roots, rags, and boards
3. Floatable and settleable material
For the activated sludge process to work properly, the operator must control which items?
Dissolved oxygen in the aeration tanks
Number of organisms
Which items are the sources of variations that affect the operation of the activated sludge plant?
Changes in collection system flows
Changes in waste water characteristics
In-plant operational variables
What are the purposes of aeration in the activated sludgeprocess
To provide dissolved oxygen
To provide mixing of the mixed liquor and wastewaterin the aeration tank
What information should be included on a lockout tag attachedto an aerator power breaker
The date the aerator was locked out
The name of the person who locked out the aerator
What are the main reasons an operator should completely check a new plant's equipment and structures before start up?
To be reasonably sure that everything will function properly when the plant is put into service
To familiarize the operator with plant equipment and locations of piping
Why is the proper operation ol equipment important? Becauseproper operation
Helps prevent operators from being injured
Prolongs the life of equipment
Reduces the cost of repairs and replacement
When checking out a new activated sludge plant, whichitems should be checked when inspecting the secondaryclarifiers?
1. 'Clarifier tank for sand and debris12. Control gates for operationI 3. Inlet baffles and discharge weirs for levelI 4. Scum control mechanismIs. Squeegee blades on the collector plows for proper distancefrom the floor of the tank
If the return sludge rate is too low in an activated sludge plant, which undesirable conditions may develop?
Accumulation of sludge in the clarifier creates a deep sludge blanket, which will allow solids to escape in the effluent
If aeration is sufficient to produce nitrate in the aeration tanks, denitrification may occur resulting in rising sludge and subsequent effluent solids
Septic sludge could develop if the detention time in thesecondary clarifier is too long
Which daily observations should be recorded by the operators at an activated sludge plant?
Aeration tank-turbulence, color, and amount of surface foam and scum
Influent-color and level of inflow
Secondary clarifier-effluent clear or turbid, type of solids on surface, and influent
When the lab data varies widely from one day to the next,which items should be checked
Lab procedures for errors
Time samples were collected
Which problems may be caused by septic sludge?
Septic sludge causes foul odors
Septic sludge rises slowly
Septic sludge sometimes rises in clumps
Small amounts of septic sludge can upset an aerator
Sludge going septic in a secondary clarifier may develop from which causes?
Clarifier collection mechanism is turned off, thus the sludge is not being moved to the draw-off hopper
Return sludge pump is off or a valve is closed
Return sludge rate is too low, thus holding the solids inthe final clarifier too long and allowing them to becomeseptic
Sludge draw-off lines are plugged, obstructed, or usedinfrequently
Which items contribute to abnormal conditions in the operation of air headers?
Upward water current drag forces exerted on the header
What items are advantages of the contact stabilization system with its off-scream reservoir of organisms in an aeration tank?
Avoids a complete kill of microorganisms when toxic wastes reach the plant
Avoids a complete solids wash-out when high flowsoccur
Which types of microorganisms are typically present in an activated sludge mixed culture of microorganisms?
Which microorganisms would be expected to predominate in a good settling activated sludge?
Waste Water Ch.11
flash cards for the waste water class c test for florida