Wastewater treatment

As an operator, you are responsible to your employer for maintaining an economical and efficient operating facility.

TRUE

An operator has an obligation to the great numbers of people who rely on down stream water supplies and are totally dependent on the operator's competence and trust worthiness for their welfare

TRUE

Today, the natural purification processes in rivers treat all the waste loads and keep rivers clean.

FALSE

Operators are water quality protectors on the front line of the water pollution battle.

TRUE

The main benefit of a successful wastewater treatment program is the protection of the public health.

TRUE

Without adequate, reliable records of every phase of operation, the effectiveness of your operation has not been documented (recorded).

TRUE

Your records showing a high-quality effluent will mean nothing to citizens visiting your plant unless your plant appears clean and well maintained and the effluent looks good.

TRUE

Safety is never an operator responsibility.

FALSE

Chief operators frequently have the responsibility of training new operators and must encourage all operators to work safely.

TRUE

The waste water treatment field is changing rapidly and operators, maintenance personnel, foremen, managers, instrumentation experts, and laboratory technicians are sorely needed.

TRUE

What is a treatment plant operator?

The final and essential link in maintaining and protecting the aquatic environment upon which all life depends on.

Why are wastewater treatment plants built?

To purify soiled water and prevent pollution.

How should wastewater treatment plant operators consider their job?

As a water quality protector on the front line of the water pollution control battle.

What is the primary objective of an operator operating a wastewater treatment plant?

To protect the receiving water quality by continuous and efficient plant performance.

How can a well-guided tour for other operators help an operator?

May allow the other operators to suggest helpful solutions to operational problems.

What types of employers might a wastewater treatment plant operator work for?

A city, sanitation district, or other public agency. A large industry that operates its own treatment plant. A private contractor retained to operate and maintain a municipal or industrial treatment plant.

Why do wastewater treatment plant operators need continuous training? Due to

Advanced or improved equipment. Increasing budgets. Increasing instrumentation. More facility tours. New treatment techniques.

Why should an operator be present or at least available during the construction period of a new plant?

To become familiar with the entire plant, including the equipment and machinery and their operation.

Operators are in the field of public relations and must be able to explain the purpose and operation of their plant to which groups?

City council or directors of the plant. Civic organizations. Officials of regulatory agencies. Representatives of news media. School classes.

Which factors are contributing to the increasing need for trained wastewater treatment plant operators?

More sophisticated treatment. Operator certification regulations. Population growth. Regulatory requirements. Retirement of many current operators.

All organic materials have one thing in common --- they all contain basic minerals.

FALSE

Most living creatures need oxygen to survive, including fish and other aquatic life.

TRUE

Initial efforts to control human wastes evolved from the need to prevent the spread of diseases.

TRUE

The bacteria that grow in the intestinal tract of diseased humans find the environment in the wastewater treatment plant or receiving waters favorable for their growth and reproduction.

TRUE

One of the primary functions of a treatment plant is the removal of solids from wastewater.

TRUE

Operators try to kill or inactivate pathogenic organisms by disinfection.

TRUE

The weight of non-settleable solids may be calculated by subtracting the weight of dissolved and total solids from the weight of settleable solids.

TRUE

The organic portion of the total solids can be very harmful to receiving waters.

TRUE

Operators should use a standard method for the measurement and evaluation of floatable solids.

FALSE

Nutrient cycles are very complex and involve chemical changes in living organisms.

TRUE

What is the definition of pollution?

Any interference with the beneficial reuse of water.

What is organic waste?

Waste material that may come from animal or plant sources.

What is inorganic waste?

Waste material such as sand, salt, iron, or calcium.

What happens to fish in receiving waters when bacteria use the entire supply of oxygen from the stream faster than it can be replenished by natural diffusion from the atmosphere?

They die.

The stabilization of a waste means which of the following?

To convert the waste to a form that resists change.

Many serious outbreaks of communicable diseases have been traced to which problem?

Direct contamination of drinking water or food supplies.

What is an operator's best defense against infections and diseases?

Good personal hygiene.

What is the objection to treated wastewater as containing nutrients?

Nutrients are capable of encouraging excess algae and plant growth in receiving water.

Why are floatable solids undesirable in the plant effluent?

The sight of floatable solids in receiving water indicates the presence of an adequately treated wastewater.

Why are ammonia and hydrogen sulfide undesirable in receiving waters?

They are odorous gases.

Substantial amounts of organic industrial waste come from which industries?

Dairy processing, meatpacking, tanning, vegetable and fruit packing.

Waste discharge is may contain what types of toxic substances?

Cyanide, and heavy metals.

Which substances are objectionable in treated wastewater discharges?

Highly acidic or alkaline (basic) substances. Pathogenic organisms. Taste and odor producing substances. Toxic substances

Weather any problems are caused by the discharge of treated wastewater in the receiving water depends on which factors?

Amount of flow in the receiving stream or volume of receiving lake that can be used for dilution. Quality of receiving water. Size of flow from the treatment plant. Type or degree of treatment. Uses of the receiving water.

Why do operators need to know how to control nutrient cycles?

To control odors. To protect receiving waters. To treat waste.

The length of time required for ways to reach your plant can affect treatment plant efficiency.

True.

Ponds are frequently constructed in rural areas where there is sufficient available land.

True.

The purpose of flow measuring devices is to treat waste.

False

All primary clarifiers, no matter what their shape, must have a means for collecting the settled solids and the floating solids.

True.

Both the trickling filter and the activated sludge treatment processes or anaerobic biological treatment processes.

True.

The activated sludge process is a biological process and it serves the same function as a trickling filter or rotating biological contactor.

True.

Incineration or burial of skimmings from the clarifiers will prevent treatment plant operational problems.

True.

Algae in ponds produce oxygen for the other organisms to use.

True.

Both industry and agriculture are discovering the treated effluent may be the most economical source of additional water.

True.

Aerobic and anaerobic sludge digestion processes produce stabilized or digested solids that ultimately must be disposed of in the environment.

True.

What is a sanitary sewer?

A pipe or conduit (sewer) intended to carry waste water or water-borne waste from homes, businesses, and industries to the treatment works.

When are pump stations normally installed?

When low areas of land must be sewered or where pipe depth under the ground service becomes excessive.

How can fluctuating flows from a large pump station be reduced?

By using variable speed pump or short pumping cycles.

What is the purpose of flow measuring devices?

To measure and record the flow rates and volumes of wastewater treated by the plant.

What is the purpose of pre aeriation?

To freshen the wastewater and to help remove oils and greases.

Why is treated wastewater disinfectant before it is discharge to receiving waters?

To prevent the spread of diseases.

Why are debris and trash usually removed from wastewater by a bar screen?

To protect equipment and reduce any interference with in-plant flow.

Why are most sewer pipes laid at a slope steep enough to maintain a wastewater flow of two feet per second (fps) (0.6m/sec)?

To prevent grit from settling in the pipes.

Why should grit be removed early in the plant treatment process?

Because grit is abrasive and will rapidly wear out pumps and other equipment.

The exact amount of BOD removal in a clarifier depends on which factor?

The amount of BOD contained in the settled material.

What happens when the clear surface water of the primary tank flows over the effluent weir at a high velocity?

Particles settling to the bottom or those already on the bottom may be picked up and carried from the tank.

How is oxygen provided for the organisms living in the biological slime that grows on the RBC media?

The atmosphere surrounding the media.

What are the two major types of bacteria present in a digester?

Acid formers and gas formers.

Why must the effluent from plants in some areas be dechlorinated or detoxified before discharge receiving water?

To protect aquatic life.

What is disinfection?

A process designed to kill or inactivate pathogenic organisms.

If hydrogen sulfide from the collection system reaches your plant, what impact would this have on the plant?

Concrete in the plant would be damaged. Odor problems could occur. The wastes could be more difficult to treat.

Wwaste water enters a treatment plant, it usually flows through a series of pretreatment or liminary treatment processes including which processes?

Grit removal. Screening. Shredding.

Why must operators know the quantity of waste water flow into a treatment plant?

To adjust aeriation rates. To adjust chlorination rates. To adjust pumping rates. To calculate loadings on treatment plant processes. To calculate treatment efficiency.

What are the disadvantages of using a weir to measure waste water flows entering a plant?

A relatively dead water space occurs just upstream of the weir. As solids accumulate upstream of the weir, the flow reading may become incorrect. Odors and unsightliness - can result from an upstream dead space. Organic solids may settle out upstream of the weir.

Which flow measuring devices are used to measure waste water flows in pipelines?

Magnetic flow meters. Venturi meters.

Why are digestion tanks mixed continuously?

To avoid the formation of thick scum blankets. To bring the food to the organisms. To provide a uniform temperature.

Scum blankets in a digester above the supernatant consist of which items?

Grease. Hair. Plastics. Rubber goods. Soap.

Advanced methods of waste treatment are used to reduce which items from wastewater?

Nutrient content.

Why do regulatory agencies require the disinfection of plant effluent prior to discharge?

To kill or inactivate pathogenic organisms. To protect the receiving water that is used for a drinking water supply. To protect the receiving water that is used for swimming or waiting.

How can solids removed from wastewater by pre treatment process be disposed of?

By dewatering and then directly burial in an approved sanitary landfill. By incineration with the remaining ash disposed of in a landfill.

There are many potential safety hazards around a wastewater treatment plant.

True.

Always wash your hands thoroughly before eating, smoking, or going home.

True.

Stand on a slippery surface while taking material from a bar screen.

False.

Strong's or sewer cleaning operations by maintenance crews make all the sudden surge of wastewater and debris and a resultant greater head loss through the screens.

True.

The totalizer records the total volume of screenings removed by the plant.

True.

When starting up comminutors and barminutors, always observe the unit to verify that it sounds normal and appears to be operating properly.

True.

When estimating the velocity in a grit channel using a stick or other float, the average velocity in the channel will be slightly higher than you estimate.

True.

A little organic matter in the grit removed from a grit channel usually indicates that proper velocities are being maintained in the channel.

True.

Treat an empty grit washer as a confined space and provide adequate ventilation

True.

Advanced preparation for emergencies can save a lot of extra work and make it possible to keep your plant operating efficiently under unfavorable conditions.

True.

Which problem is created by a treatment plant operating at reduced efficiency?

An increase in the pollution level of the effluent discharged into receiving water.

What is the purpose of screens, racks, comminutors, and grit removal devices?

To remove rocks, large debris, and grit.

Which injuries can a cure from pulling too hard when lifting inlet or outlet gates or pulling heavy, waterlogged debris from the racks?

Back injuries, hernias, and muscle strains.

What should the operator do after broken equipment has been repaired and placed in service again?

Observe the unit for proper operation.

The frequency of sharpening the cutting edges on the cutter of a barmminutor depends on which factor?

The type and abrasiveness of the wastewater being treated.

What is putrescible materia?

Material that will decompose under anaerobic conditions and produce nuisance odors.

Why should a grit channel be removed from service during the cleaning operation?

To prevent the grit from being washed into the downstream treatment processes.

Why should grit disposed of by burial be quickly covered with soil?

To prevent odors and attracting flies and rats.

Under what condition should the cyclone liner and screw conveyor of a cyclone grit separator be replaced?

When excessive wear prevents proper adjustments and the equipment no longer functions as intended.

What is detritus?

The heavy material present in wastewater such as sand, coffee grounds, eggshells, gravel, and cinders.