In the activated sludge process, the oxidation may be by chemical or biological processes.
The removal of organisms from the activated sludge treatment process (sludge wasting) is a very important control technique.
In an air distribution system, an air metering device should be located in a straight section of the air main on the suction side of the blower.
In an aeration tank, the higher the food to microorganism (F/M) ratio, the more food and therefore a lower dissolved oxygen (DO) is needed.
When considering a major process change, first review the plant data and then make only one major change at a time.
Microbiology is another tool for operators to use in controlling the activated sludge process.
The psychrophilic bacteria in anaerobic digesters appear to be able to survive temperatures well below freezing with little or no harm.
Mixing is very important in a digester because it greatly speeds up the digestion rate.
Operators should make every effort to pump as thick a sludge to the digester as possible.
The withdrawal rate of sludge from a digester should be faster than a rate at which the gas production from the system is able to maintain a positive pressure in the digester.
Aerobic sludge digestion completes the oxidation of volatile materials in the digester.
The proper discharge of plant effluent is the final process for the operator.
The principles for collecting samples for measuring dissolved oxygen are the same as for measuring temperature.
Site-specific safety procedures should be confirmed with your local safety regulatory agency.
Always get air into the confined space before you enter to work and maintain the ventilation until you have left the space.
The sense of smell is reliable for evaluating the presence of dangerous gases.
Moving parts that create a contact hazard to employees must be guarded.
When applying protective coatings in a clarifier, you can create an atmospheric hazard.
In the laboratory, separate flammable, explosive, or special hazard items for storage in an approved manner.
Hard hats, safety footwear, eye protection, and hearing protection apply to all personnel in designated areas and specific jobs.
When you are performing plant maintenance, you must recognize tasks that may be beyond your capabilities or repair facilities, and you should request assistance when needed.
The horizontal pump suction piping slopes downward toward the pump.
Fuses are used to protect operators, wiring, main circuits, branch circuits, heaters, and motors.
Electric motors are the machines most commonly used to convert electrical energy into mechanical energy.
Valves, elbows, and other items that could disrupt the flow ahead of a meter can upset the accuracy and reliability of a flowmeter
Safety is just as important in the laboratory as in the rest of the treatment plant.
The shorter the time that elapses between sample collection and analysis, the more reliable will be the analytical results.
The COD test is used to measure the strength of that are too toxic for the BOD test.
Probably the most frequent use of computers is for word processing.
Wastewater flows and other characteristics that can be sensed by instruments can be monitored by computers.
When installing any computer program, be sure to check to see that it is doing what you expect it to do.
Collection of data without analysis, interpretation, and use of results is a waste of time and money.
Operators are likely to draw the line of best fit slightly differently as each operator will visualize a slightly different line (slope).
Well-kept records will make the task of writing treatment plant cost and efficiency reports much easier.
Records at most wastewater treatment facilities are kept daily and summarized on a monthly basis.
You and your plant operation are partially judged by the information contained in your report, its style, and its appearance.
The utility manager must provide a safer, cleaner work environment while constantly training and retraining operators to understand new technologies
Establishing safe work procedures for new employees is a very important function of management.
Good communication is an essential part of good management skills.
Every utility needs an effective operations and maintenance program.
The supervisor who has the responsibility for directing work activities must be safety conscious.
operator must think, act, and promote safety if the utility is to achieve a good safety record.
Why must the proper dissolved oxygen (DO) level be maintained in an aeration tank?
So filamentous organisms will thrive and the sludge floc will settle properly
So pinpoint floc will develop and be removed by the secondary clarifier
So the contents of the aeration tank will be thoroughly mixed
So the solids will settle properly and the plant effluent will be clear
Why should weirs installed at the outlet or effluent end of the aeration tank be level?
To comply with the plant's plans and specifications
To keep the aeration tank balanced
To prevent short-circuiting and an uneven distribution of solids in the effluent
To provide a uniform appearing tank
How can the mixed liquor suspended solids in the aeration tank be increased?
By increasing the influent flows
By reducing the aeration tank capacity
By reducing the effluent flows
By reducing the sludge wasting rate
What is bound water?
A high-molecular-weight substance that is formed by either natural or synthetic processes
Clouds of billowing sludge that occur throughout secondary clarifiers and sludge thickeners when the sludge does not settle properly
The gathering together of fine particles after coagulation to form larger particles by a process of gentle mixing
Water contained within the cell mass of sludges or strongly held on the surface of colloidal particles
What are raw sludge and scum?
Settled sludge solids that are removed from the bottom and the floating scum removed from the top of the aerators
Settled sludge solids that are removed from the bottom and the floating scum removed from the top of the clarifiers
Settled sludge solids that are removed from the bottom and the floating scum removed from the top of the digesters
Untreated solids and scum that are removed from the bar screens
What is the purpose of a vacuum relief valve on an anaerobic sludge digester?
Prevents a spark or flame from entering the digester
Prevents air from entering the digester or digester gas from escaping
Relieves excessive pressures in the digester so the water seal will not be blown out
Relieves excessive vacuums so the digester cover will not collapse
Which item is the key to successful digester operation?
pH
Recirculated sludge
Temperature
Volatile acid/alkalinity relationship
Successful operation of a surface discharge system depends on which factor?
Adequate budgets to meet the essential O & M requirements
All operators being properly certified
Conscientious operators using proper techniques for sampling and analysis
Qualified regulators understanding the plant's O & M requirements
What type of emergency operating equipment should be available for pumped discharge systems when there is a loss of power?
Standby generators
Standby monitors
Standby operators
Standby pumps
What is a representative sample?
A collection of individual samples obtained at regular intervals, usually every one or two hours during a 24-hour time span
A collection of samples combined with other samples in proportion to the rate of flow when the sample was collected
A sample portion of material, water, or wastestream that is as nearly identical in content and consistency as possible to that in the larger body being sampled
A single sample of water collected at a particular time and place that represents the composition of the water only at that time and place
What is the best protection against the risk of infections and infectious diseases?
Immunization program
Personal hygiene
Personal protective equipment (PPE)
Personnel safety courses
What is the ideal method of dealing with any high-noise environment?
The elimination or reduction of all sources through feasible engineering or administrative controls
The scheduling of work in the high-noise environment when the equipment is not operating
The selection of operators with a high level of noise tolerance to work in the high-noise environment
The use of generous compensation packages when loss of hearing results
What is the apparent cause of drowning when someone falls into a diffused aeration tank?
A strong undertow pulls the person under
The aerator is too deep for a person to stand on the bottom
The air in the water causes the person to sink to the bottom
There is nothing to grab hold of to keep afloat or to pull oneself out of the aerator
If your hands may come in contact with wastewater or sludge during sampling, how can you prevent the spread of disease?
Dry hands in the sunlight when you have finished sampling
Wear disposable, impervious gloves
Wear heavy leather gloves
Wear light, flexible, cotton gloves
Which materials are consumed by a Class B fire?
Combustible metals, such as magnesium, sodium, zinc, and potassium
Energized electrical equipment, such as starters, breakers, and motors
Flammable and combustible liquids, such as gasoline,oil, and grease
Ordinary combustibles, such as wood, paper, and cloth
Why is a good maintenance program essential for a wastewater treatment plant?
So operators can maintain their operator maintenance certificates
So operators will have time to conduct plant tours
To arrange for equipment vendors to observe their products
To operate continuously at peak design efficiency
How can pipelines that carry chlorine gas be purged to remove moisture?
By using cold water
By using dry air or nitrogen
By using methane gas
By using moist air
Why do very few maintenance operators do the actual electrical repairs or troubleshooting?
Because cost-effective training programs are rarely available for maintenance operators
Because highly trained technicians are readily available at a lower cost than maintenance operators
Because this is a highly specialized field and unqualified people can seriously injure themselves and damage costly equipment
Because union regulations and negotiations forbid maintenance operators from performing this work
What is voltage? Voltage is
A measure of power units used to rate electrical machines or motors or to indicate power in an electric circuit
A practical unit of electrical resistance
The electrical pressure available to cause a flow of current when an electric circuit is closed
The measurement of current or electron flow and is an indication of work being done
What is a fuse?
A device that allows a motor to be run continuously at its rated horsepower without causing damage to the insulation system
A protective device having a strip or wire of fusible metal which, when placed in a circuit, will melt and break the electric circuit when subjected to an excessive temperature
A switch that is opened automatically when the current or voltage exceeds or falls below a certain limit
An expression representing an electrical connection to earth or a large conductor that is at the earth's potential or neutral voltage
When two or more pumps of the same size are installed, why should they be operated alternately?
To ensure that all the pumps will fail simultaneously and can be replaced all at once
To equalize wear, keep the motor windings dry, and distribute lubricant in the bearings
To keep the load on the foundation and flow in the pipes balanced
To minimize electricity consumption and system electrical hazards
What do flow measurement transmitter instruments do?
Compare received signals with other values and send corrective or adjusting signals when necessary
Measure the variable flow indicator and convert this value to a usable number
Pick up the transmitted signal and convert it to a usable number
Send the flow variable to another device for conversion to a usable number
Why should operators review the plans and specifications for pumps and lift stations?
To be sure adequate provisions have been made for the station pumps, equipment, and instrumentation to be easily and properly operated and maintained
To review the plans and specifications to ensure receipt of low bids
To suggest contractors who could do an acceptable job
To verify and confirm the consulting engineers' calculations
In chemistry, to what does normality (N) refer?
Solution hazard
Solution strength
Solution toxicity
Solution volume
What does the digester supernatant solids test measure?
The degree of liquid-solids separation occurring when mixing is stopped in the digester
The effectiveness of the digester mixing procedures
The percent of settleable solids being returned to the plant headworks
The strength of the supernatant that is removed from the digester
Why should chlorine residual be removed before final discharge to a receiving stream?
For protection of aquatic vegetation from toxic chemicals
For protection of fish and other aquatic life
For protection of swimmers from skin rashes
For protection of water supplies from TTHMs
What is aseptic?
A plastic tube that contains an exact amount of chemical or reagent
A representative portion of a sample. Often, an equally divided portion of a sample
A solution or liquid whose chemical makeup neutralizes acids or bases without a great change in pH
Free from the living germs of disease, fermentation, or putrefaction. Sterile
What is the first question an operator should ask when considering the possibility of using a computer or expanding the use of computers?
How can I find a computer course to improve my computer skills?
How can I find funds in the budget to help me?
How can I get the computer staff to assist me?
How can I use a computer to help me do a better job?
What does a SCADA system do?
Collects, stores, and analyzes information about all aspects of O & M, transmits alarm signals when necessary, and allows fingertip control of alarms, equipment, and processes
Provides standby power to operate critical pumps when power systems fail
Scans plant facilities and reports unusual conditions to plant security
Surveys stakeholders and system users and reports
What is the median?
The difference between the largest and smallest measurement
The measurement that occurs most frequently
The middle measurement when the measurements are ranked in order of magnitude (size)
The sum of all measurements divided by the number of measurements.
What is a normal distribution of data?
The geometric mean describes the distribution
The mean, median, and mode values are different
The mean, median, and mode values will be be approximately the same
The percentile plotting points are different
What is the main means by which operators who have information communicate with those who need it?
Committee meetings
Professional conferences
Report writing
Telephones
Recorded data should enable the operator to determine how to perform which task?
Develop tailgate safety sessions
Operate and maintain the plant
Promote qualified operators
Schedule plant tours
What is planning?
Deciding who does what work and delegating authority to the appropriate operators
Determining the goals, policies, procedures, and other elements to achieve the goals and objectives of the agency
Guiding, teaching, motivating, and supervising operators and utility staff members
Taking the steps necessary to ensure that essential activities are performed so that objectives will be achieved as planned
What is authority?
Answering to those above in the chain of command to explain how and why you have used your authority
The act in which power is given to another person in the organization to accomplish a specific job
The power and resources to do a specific job or to get that job done
When a manager gives power or responsibility to an employee, the employee ensures that the manager is informed of results or events
How do you measure financial stability for a utility?
By calculating the benefit/cost ratio for the utility
By calculating the net revenue for the utility
By calculating the operating ratio and the coverage ratio
By calculating the rate of return on the utility's assets
What is the operating ratio?
A measure of the ability of the utility to pay the principal and interest on loans and bonds in addition to any unexpected expenses
A measure of the total revenues divided by the total operating expenses
The amount of money required annually to pay the interest on outstanding debts
The rate of return on the funds expended on facilities
What is SCADA?
A computer analytical system that continuously monitors water quality changes in the system
A computer budgeting system that records and monitors costs and revenues
A computer intelligence system that eliminates many tasks performed by operators
A computer-monitored alarm, response, control, and data acquisition system used to monitor and adjust the operation of equipment
What is the purpose of a safety policy statement?
To comply with OSHA regulations
To create the proper atmosphere to impress insurance companies
To let employees know that the safety program has the full support of the agency and its management
To let the media and the public know that the agency is safety conscious
When wastewater enters an activated sludge plant, the preliminary treatment processes remove which pollutants?
Coarse or heavy solids (grit)
Debris, such as roots, rags, and boards
Floatable and settleable material
Nutrients
Soluble or finely divided suspended materials
Which items can cause an unsuitable environment for the activated sludge process?
Failure to supply enough oxygen
High concentrations of acids, bases, and other toxic substances
Maintaining proper solids (floc mass) concentration in the aerator
Proper adjustment of the waste sludge pumping rate
Uneven flows of wastewater, which can cause overfeeding or starvation
What information should be recorded when testing pumps?
Date of the test
Location of the pump
Name of the operator
Pump discharge (flow)
Pump discharge pressure
Which plant changes could cause an activated sludge plant to become upset?
Changes in operators' shifts
Changes in the sampling program
Flow or waste changes
High solids in the digester supernatant
Temperature changes
Which items are possible causes of sludge bulking?
Filamentous organisms growing from one floc mass to another
Low DO
Low nutrient concentrations
Low pH
Production of a highly jelly-like, waterlogged sludge that has a very low sludge density
Which items should be checked before starting a new sequencing batch reactor (SBR) plant?
Be sure the plant has an up-to-date O & M manual and a set of as-built plans (record drawings)
Check and flush pipe systems and remove any refuse or debris left in them during construction
Ensure protective safety guards are installed on rotating equipment, open tanks, and channels
Make sure tanks are clean; be sure all debris, boards,ladders, and tools have been removed
To the extent possible, operate and test all equipment before admitting wastewater for treatment
Operators can achieve good digester operation by controlling which items?
Loading rate or food supply (organic solids)
Mixing
Reproduction rate of acid formers and methane fermenters
How can a scum blanket be controlled in a digester?
By adequate mixing
By chemicals
By heat
By methane fermenters
By volatile acids
Where does struvite scale sometimes form?
In anaerobic digesters
In downstream chlorination equipment
In downstream digested sludge concentration equipment
In downstream digested sludge handling equipment
In downstream effluent weirs
When operators are making their rounds inspecting their plant, they should be alert and investigate and record which items? Anything that
Feels different (hotter or vibrating more)
Looks different or unusual
Smells different
Sounds different
Tastes different
What types of problems are encountered when operating aerobic digesters?
Floating sludge
Fluctuating BODs
Odors
Scum
Wet solids
When reviewing the specifications for sludge digestion and solids handling facilities, which items should operators check?
Adequate supply of equipment operation and maintenance manuals
Equipment warranties and responsibility for acceptance testing
Instrumentation—remote and local control board items and recorders are provided
Paints and protective coatings
Performance requirements and capabilities
Prior to discharge to surface waters, why must wastewater be treated?
To prevent nuisances due to odors or unsightliness
To prevent the wastewater from interfering with the many uses of surface waters
To produce documentation for the record keeping system
To protect the health of the people who may come in contact with it
To provide water for discharge sampling and analysis
Which operating procedures should be developed for the start-up of a plant?
Inspect the discharge line, where possible
Look at the water surface over the diffuser or outfall pipe
Observe the flow entering the discharge system for visible pollutants
Open all appropriate valves
Start the pumps (unless it is a gravity system)
Which items are probable causes of floatables in pond effluents?
Excessive floatables and scum on the surface
Excessive solids accumulated on the bottom have gasified and floated to the surface
Excessive velocity or insufficient detention time
Outlet baffle is not at the proper location
Temperature or weather conditions may favor a particular species of algae
Under what conditions may the frequency of sampling be increased?
When the lab is not meeting QA/QC requirements
When the lab staff have the opportunity to analyze more samples
When the receiving waters are not meeting established water quality standards
When the treatment plant effluent is not meeting discharge requirements
When the treatment plant staff increases and more time is available to collect more samples
A confined space may be defined as any space that meets Which conditions?
Allows more than one employee to fit into the space and work
Has limited or restricted means for entry or exit
Is large enough and so configured that an employee can bodily enter and perform assigned work
Is not designed for continuous employee occupancy
Requires employees to wear personal protective equipment (PPE)
The hazard warnings on containers of hazardous chemicals at your plant should contain emergency guide information on which specific categories?
Flammability
Health
Permeability
Reactivity
Which items could be included in your plant's fire prevention plan?
Develop written response procedures for reacting to a fire situation, to include evacuation
Provide periodic cleanup of weeds or other vegetation in and around the plant
Provide required service on all fire detection and response equipment (inspection, service, hydrostatic
Regulate the use, storage, and disposal of all combustible materials/substances
Routinely inspect fire doors to ensure proper operation and unobstructed access
The primary use for polymers in wastewater treatment is the conditioning of sludge to facilitate removal of water in which subsequent treatment processes?
Aerobic digesters
Belt filter presses
Centrifuges
Dissolved air flotation thickeners
Gravity belt thickeners
Working safely in the laboratory involves which basic safety procedures and practices?
Always check labels on bottles to make sure that the proper chemical is selected
Never handle chemicals with your bare hands
Never use laboratory glassware for a cup or food dish
Use care in making rubber-to-glass connections
Use proper safety goggles or a face shield in all tests where there is danger to the eyes
Which paperwork items can be helpful in identifying the causes of accidents and developing corrective procedures?
Accident report forms
Facility plans and specifications and plant inspection reports
Plant's safety policy
Plant's safety rules
Supervisors' guidelines on how to promote and implement a safety plan
What could cause a pump to run dry?
Excessive leakage when pumping against a high head
Holes (spacing) being too large in the suction intake screen
Impeller rotating too fast and causing cavitation
Lack of proper priming when starting
Loss of suction when operating
Which items are primary sources of unsatisfactory AC brush and ring performance?
Disturbing external condition
Improper load or service condition
Mechanical fault in the machine
Poor machine design
Poor preparation and care of the machine
When performing pump station electrical equipment maintenance tasks, which items should be checked and inspected annually?
All panel instruments
All switch gear and distribution equipment
Enclosures
Fuses and circuit breakers
Wiring integrity
Which items are causes of motor malfunction or failure?
Bearing failures
Contaminants
Old age
Overload (thermal)
Single phasing
When troubleshooting any motor control that has developed trouble, the qualified maintenance operator should be able to do which of the following?
Examine all unusual factors
Find the cause of the problem
Know what should happen when a switch is pushed
Make a visual inspection
Repair the problem and eliminate the cause, if possible
Plugged pipelines are encountered in lines transporting which types of materials and liquids?
Digested sludge
Effluent
Grit
Raw sludge
Which factors will cause sludge lines to plug more often?
When industrial wastes are discharged after a fine screening process
When plant effluent and reclaimed effluent are pumped through the lines
When RAS (return activated sludge) and WAS (waste activated sludge) are pumped through the lines
When scum and raw sludge are pumped through the same line
When stormwaters carry in grit and silt that are not effectively removed by the grit removal facilities
When examining lift station prints, operators should ensure adequate provisions have been made for which items?
Floors should be sloped to provide drainage, where needed, and drains should be located in low spots
Overhead clearances of power lines, trees, and roofs should be adequate for a crane to remove large equipment
The alarm system should signal high water levels in the wet well and water on the floor of the dry well
There should be room to use hydrolifts, cranes, and high-velocity cleaners, as needed
There should be sufficient room to set up portable pumping units or other necessary equipment in cases of major station failures or disasters
When working with chemicals and other materials in the wastewater treatment plant laboratory, which hazards can be minimized by using proper techniques and equipment?
Burns
Electric shock
Infectious materials
Poisons
Toxic fumes
Why must hydrogen sulfide gas be measured in the atmosphere?
Because it causes corrosion
Because it causes odors
Because it increases the fuel value of sewer gas
Because it is flammable and explosive under certain conditions
Because it is toxic to your respiratory system
Which precautions should be considered when measuring the chemical oxygen demand (COD) of a sample?
Flasks and condensers should be clean and free from grease or other oxidizable materials
The standard ferrous ammonium sulfate solution is unstable and should be standardized daily
The wastewater sample should be well mixed
Use a wide-tip pipet to ensure a representative sample is added
Use extreme caution and safety precautions when handling the chemicals used for the test
Which precautions should be considered when using a dissolved oxygen (DO) probe?
Dissolved inorganic salts, such as found in seawater, can influence the readings from a probe
Do not place the probe directly over a diffuser because you want to measure the dissolved oxygen in the water being treated, not the oxygen in the air supply to the aerator
Keep the membrane in the tip of the probe from drying out
Periodically check the calibration of the probe
Reactive compounds, such as reactive gases and sulfur compounds, can interfere with the output of a probe
Sulfate ions in wastewater are indirectly responsible for which serious problems?
Indigestion
Laxative effects
Odor
Sewer corrosion problems
Toxic gas
Which items are general types of computer applications in wastewater treatment plants??
Communications
Data analysis
Recordkeeping
Report generation
Systems monitoring
If the proper lab results are entered into the computer, the computer can calculate and print out which items?
Chemical dosages
F/Ms (Food to Microorganism ratios)
MCRTs (Mean Cell Residence Times)
Percent removals
Suspended solids, BOD, or COD loadings
Which programs are typically included in general purpose software packages?
Database management
Graphics
Plant template
Spreadsheet
Word processing
Which items can typically be monitored, recorded, and controlled by computers in a wastewater treatment plant?
Aeration basin dissolved oxygen
Anaerobic sludge digester gas production
Chlorine contact time
Influent flow control gates and valves
Secondary clarifier sludge pumping
When preparing to plot data in a bar graph, what information must first be determined?
Class midpoint
Distribution of data
Measurement frequencies
Spread of data
Width of the class interval
Why are records important?
They are needed to fill unused space in storage rooms and filing cabinets
They are needed to show the type and frequency of maintenance and to evaluate the effectiveness of maintenance programs
They can indicate plant efficiency, performance, past problems, and potential problems
They can provide data upon which to base recommendations for modifying plant operation and facilities
They may be needed in damage suits brought against the district or municipality
A list of the minimum daily records kept at a fairly large treatment plant with digester tanks may include which items?
Chlorine use (lbs or kg)
Influent and effluent temperatures
pH of influent and effluent
Precipitation and air temperature
Raw wastewater flow (MGD from totalizer)
Which items are basic principles common to good report writing?
Know the purpose and objective of your report
Know your subject
Omit any recommendations
Organize the report to present your ideas in a logical order
Tailor your report to the person or persons to whom it is directed
Which items are guidelines for preparing a report?
Arrange the ideas in a logical sequence
Begin writing
Gather material needed to support the ideas to be presented in the report
List ideas and topics you plan to cover in the report
Prepare conclusions and recommendations after writing the main body of the report
The utility manager's staffing responsibilities include which tasks?
Evaluating employee performance
Issuing orders and instructions
Providing opportunities for advancement for operators and staff
Selecting and training employees
Teaching classes
Which items are important steps in the process of hiring and selecting a new operator?
Advertising the position
Avoiding unacceptable pre-employment inquiries
Interviewing applicants
Paper screening
Selecting the most qualified candidate
Which items may serve as a guide for both the employee and the supervisor when dealing with a confrontation regarding employee performance issues?
Aim for a permanent solution
Create a private environment
Keep your language appropriate
Listen very carefully
Maintain an adult approach
The total revenue of a utility comes from revenue generated by which sources?
Chemicals
Hook-up charges
Interest income
Taxes or assessments
User fees
What is predictive maintenance?
A method of establishing baseline performance data
Monitoring performance criteria over a period of time
Observing changes in performance so that failure can be predicted and maintenance can be performed on a planned, scheduled basis
The same as corrective maintenance
The same as proactive maintenance
How can a supervisor be partially or fully responsible for an accident?
By causing unsafe acts to take place
By disregarding an unsafe work environment
By overlooking or failing to consider any number of safety hazards
By requiring operators to follow safe procedures
By requiring work to be performed in haste