wastewater

Describe a wet well lift station

A wet well lift station is a single chamber that collects wastewater. This type of lift station is commonly called a submersible lift station due to the pump and motor being completely submerged in the wet well. The submersible centrifugal pump is watertight and normally controlled by float switches. They are made to be easily removed for cleaning and maintenance using a rail system.

List the basic components of an activated sludge system.

A. Aeration tanks B. Blowers and diffusers or mechanical aerators C. Clarifiers D. Recycle activated sludge (RAS) and waste activated sludge (WAS) pumps

Describe common disinfection processes

A. Chlorination B. UV radiation

Discuss the wastewater characteristics and problems with industrial discharges into a treatment plant.

A. Dairy operations Many different types of dairy and whey products are produced in Wisconsin. Some dairy operations have their own wastewater treatment plant, but many discharge to the treatment plant in the community in which they are located. Industrial wastes from dairy facilities consist of various dilutions of milk entering the municipal collection system. One of the largest sources of dairy wastewater come from the wash waters and rinse waters of dairy tanks, trucks, equipment, pipelines, and floors. B. Food industry Food (meats, canned foods, snacks, etc.) is processed in many different ways, and the wastes from them can vary in composition. Because food industry wastewaters can be variable and are usually high in BOD, suspended solids, nitrogen compounds, phosphorus, chlorides, and vary in pH, it is important for operators to be familiar with the wastewaters from food processors in their community. C. Breweries Wisconsin is known for its many breweries and microbreweries. Brewery wastewater typically has a high concentration of BOD from the carbohydrates and protein used in the brewing process and in the cleaning of brewery vessels, pipes, and equipment. D. Metal finishing Wastewater from metal finishing has very little BOD associated with it, but has pollutants that can be toxic to fish and aquatic life and treatment plant microorganisms, even in small concentrations.

Discuss control measures necessary for industrial discharges.

A. Enforce sewer use ordinances B. Effective communication with industries C. Grease Control Program D. Monitoring

List and describe the common types of flow measurement devices.

A. Open channel flow Flow through an open channel can be measured by installing a structure in the channel. This structure is typically either a flume or weir. The most common type of flume is a Parshall Flume. The most common type of weir is either a 60° or 90° v-notch (triangular) weir. As water flows through a flume or weir, the level of water flowing through it is measured. The most common water level measurement device is an ultrasonic meter, but other devices such as pressure measurement, bubbler tubes, and staff gauges are also used. B. Pipe flow meters The most common way to measure the flow of wastewater through a pipe is a magnetic flow meter, commonly referred to as a magmeter. A magmeter operates on the principle of electromagnetic induction.

Explain the components of a sanitary sewer collection system.

A. Private building lateral sewer C. Force mains D. Lift (pump) stations E. Inverted siphon F. Manholes

Describe a good sampling location and procedure for collecting representative influent wastewater samples.

It is important that raw influent wastewater be sampled in a location where it is well mixed and represents the actual wastewater coming into the treatment plant. It is best to collect the sample after the headworks (after screenings and grit removal), as this is most representative of the BOD and TSS going into downstream treatment units.

Discuss the importance of wastewater flow measurement

It is very important to know how much influent is flowing and being treated in the plant. Treatment efficiency is dependent on loadings and detention time. It is also required to report how much final effluent flows into a receiving water body. To measure the influent entering a treatment plant from the community, flow measurements should be taken before sidestreams. To know the actual flow and loading to the treatment units, sidestreams need to be included in the flow measurements.

Trace the sequence of events from the time one flushes a toilet until treated wastewater reaches a receiving stream.

Potable water is provided by the water supply system into a building and is used to flush or drain wastes into the building's sanitary sewer pipes and into the wastewater collection system. Wastewater is conveyed through gravity sewers, lift stations, and force mains until it makes its way into the headworks of a wastewater treatment plant. The wastewater is then treated by both physical and biological unit operations and processes and then clean water is discharged into a receiving water body.

Discuss how a vortex-type (Pista®) grit chamber works.

Raw wastewater is introduced along the side of a cylindrical tank designed for vortex flow. The water and grit combination rotates slowly around the vertical access of the tank. The flow spirals gradually down the tank perimeter, allowing the heavier solids to settle to the tank bottom where they are then removed

Discuss how an aerated grit chamber works.

Raw wastewater is introduced into the end of an aerated grit chamber, which is typically rectangular in shape. Injected air creates a spiral flow of wastewater as it moves through the chamber. As the flow velocity diminishes along the tank, heavier grit particles gradually settle from the water. The settled solids are typically gathered at the tank bottom by a rake mechanism and removed by pumping.

Discuss the possible impacts of sidestreams or recycle flows back to the secondary process.

Sidestreams or recycle flows usually come from solids handling treatment or dewatering processes, such as decanting digesters or sludge storage tanks. Sidestreams may be high in BOD, suspended solids, ammonia, phosphorus, and sulfides or very low in temperature. It is best to return sidestreams slowly and regularly so microorganisms adjust and acclimate to this loading.

Describe the environmental factors that influence the health and growth of microorganism

The activated sludge wastewater treatment process must operate under proper environmental conditions to support a healthy, growing population of microorganisms. The operator must monitor the activated sludge process to ensure the right environmental conditions are being provided for the microorganisms. Efficient wastewater treatment plant performance will then be achieved. A. Food B. Flow C. Oxygen D. Temperature E. pH F. Nutrients G. Toxicity

Discuss energy usage in a wastewater treatment plant.

The aeration system of a wastewater treatment plant uses the largest percentage (over 60%) of the energy in the treatment process. Wastewater pumping is another large energy user (12%) at a wastewater plant. Energy usage can be reduced with cost savings by having energy-efficient aeration systems, blowers, motors, and pumps

inflow and infiltration (i/i)

any unwanted clearwater that leaks into a collection system. Generally, it consists of groundwater, rainwater, or snowmelt.

Discuss the difference between a time-proportional and flow-proportional composite sample.

are a collection of samples over time, usually after so many minutes. Flow-proportional composite samples are samples collected per unit of flow, after so many gallons. The frequency at which flow-proportional samples are collected is directly proportional to the flow, with more samples taken when flows are higher and less samples when flows are lower. Automatic flow-proportional composite samplers are required for almost all wastewater treatment plants, as they are the most representative means of collecting samples from continuous flowing treatment systems, especially for biochemical oxygen demand (BOD) and total suspended solids (TSS).

Discuss pond and lagoon systems

are earthen basins with a clay or synthetic liner to prevent leakage to groundwater. These systems are classified as secondary biological treatment and are an economical way to accomplish biological treatment.

Sidestreams

are flows generated within the plant, usually from solids processing that has been recycled back through the plant.

Describe the types of materials prohibited from discharge into collection systems and the reasons they should not be discharged.

are included in local sewer use ordinances. Generally, materials that can interfere with wastewater treatment, pass through the treatment system and cause a water quality violation, or accumulate in sludges, making the sludges toxic or hazardous are prohibited. Many of the industrial materials can be handled with proper pretreatment or segregation of waste streams that cannot be pretreated. A. Volatile organics, C. Acidic and alkaline wastes can damage the collection system or upset the treatment plant. Generally, a pH lower than 5.0 or greater than 10.0 should be neutralized prior to discharge to the collection system. D. FOG must be controlled at industrial and commercial sources with oil separators and grease traps to prevent maintenance problems in wet wells and at the treatment plant. E. High-strength loadings of BOD or suspended solids can organically overload the treatment plant. This can especially be a problem with batch dumping that causes large slug loads. Any batch type operation should be handled by flow equalization to prevent plant upsets. F. High temperature wastewaters can affect biological activity. G. Solid or viscous materials can cause sewer blockages. H. Any debris including rags or other materials can cause sewer blockages or pump clogging. I. Other toxic materials can impair or interfere with the treatment process.

Describe a stabilization pond system.

are large, non-aerated, and normally less than 10 feet deep. Algae growing in the ponds provide most of the oxygen to the bacteria to remove pollutants. Solids settle to the bottom of the pond and are further stabilized by bacteria.

combined sewer

are pipe conveyances that carry both wastewater and storm water in a single pipe. During dry weather conditions, combined sewers discharge to a wastewater treatment plant. In the past, combined sewers discharged directly to a water body during wet weather conditions. Today, the extra wet weather volume is stored until it can be returned to the wastewater treatment plant

Screenings

are the materials in wastewater removed with screens at the headworks of treatment plants. They include: sticks, stones, plastics, and personal hygiene products.

Biosolids

are the nutrient-rich, organic byproduct of a municipal wastewater treatment plant that is utilized as fertilizer

Discuss the impact FOG can have on a collection system and a treatment facility.

are waste byproducts of cooking. They are found in meats, dairy products, cooking oils, shortenings, food scraps, and sauces. FOG collects and can form grease plugs in sewer pipes if washed down the drain or through unmaintained grease traps at restaurants or institutions. The most common cause of sanitary sewer overflows (SSO) from sewer pipes are blockages caused by grease. If grease makes its way to the treatment plant, it can plug valves, meters, and pipes. It floats to tank surfaces and can create settling problems. Grease can also favor the growth of filamentous organisms that create surface foam and scum. Grease can involve costly and unpleasant clean-ups.

Discuss where a wastewater treatment plant operator would find information on conducting wastewater tests.

can be found in 'Standard Methods for the Examination of Water and Wastewater',

Describe an aerated lagoon system

can use surface aerators or subsurface diffusers to provide aeration and mix the wastewater. Aerated lagoons are usually deeper (more than 10 feet) and require shorter detention times (60 days) to effectively treat the wastewater. Aeration improves removal efficiency. Aerated lagoons are followed by non-aerated lagoons to allow settling of suspended solids before discharge

Discuss the effect of I/I on a collection system.

enters collection system pipes, it can exceed the flow capacity of the pipes and result in surcharging, basement backups, and sanitary sewer overflows (SSO). I/I in the collection system can also lead to very high flows entering the treatment facility and can lead to wastewater pumping and treatment problems. Too much flow going through aeration basins and clarifiers can wash out solids, creating a loss of treatment efficiency and resulting in permit violations.

biochemical oxygen demand (BOD).

expressed in mg/L, is a measurement of the organic strength of a sample by measuring the amount of oxygen consumed over a given period of time.

Describe the role microorganisms have in the activated sludge process.

have in the activated sludge process is to convert dissolved and particulate organic matter, measured as BOD, into cell mass. In a conventional activated sludge process, microorganisms use oxygen to break down organic matter (food) for their growth and survival. Over time, and as wastewater moves through the aeration basin, food (BOD) decreases with a resultant increase in cell mass (MLSS concentration).

Describe the purpose of the aeration system

in the activated sludge process provides oxygen to the microorganisms and mixes the contents of the aeration basins. The mixing brings the wastewater pollutants into contact with the microorganisms to treat the wastewater and reduce the pollutants

Pathogens

infectious microorganisms in wastewater that pose health risks.

Describe the differences between nitrification and denitrification in wastewater treatment.

is a biological process where nitrifying bacteria (nitrifiers) convert nitrogen in the form of ammonia (NH3) into nitrite (NO2-) and nitrate (NO3-) under aerobic conditions. Treatment plants that have ammonia limits on their permit will use nitrification to remove ammonia. Many plants that discharge to surface waters have ammonia limits to protect fish and aquatic life from ammonia toxicity. Denitrification is a biological process where bacteria convert nitrate (NO3-) and nitrite (NO2-) to nitrogen gas (N2) under anoxic conditions. Treatment plants that have total nitrogen limits will use denitrification to remove nitrogen.

Clarifier

is a circular or rectangular tank used to remove floatable and settleable solids in wastewater.

Aerobic

is a condition under which free and dissolved oxygen (DO) is available in an aqueous environment.

Anaerobic

is a condition under which free, dissolved, and combined oxygen is unavailable in an aqueous environment.

Anoxic

is a condition under which oxygen is only available in a combined form such as nitrate (NO3-), nitrite (NO2-), or sulfate (SO4-2) in an aqueous environment.

Discuss the Clean Water Act.

is a federal law created in 1972 with the main objective of chemically, physically, and biologically restoring and maintaining the nation's waters. It was created to stop the continuous dumping of pollutants, both point source and non-point source, into surface waters and wetlands.

weir

is a level control structure used to provide uniform flow

microorganism

is a living organism too small to be seen with the naked eye, but is visible under a microscope. They include: bacteria, viruses, fungi, or protozoa.

Discuss what photosynthesis is and how it aids the biological treatment of wastewater in stabilization ponds.

is a natural, chemical process in which green plants (algae in ponds) containing chlorophyll use carbon dioxide in the presence of sunlight to produce carbohydrates for growth. In wastewater treatment ponds, photosynthesis releases oxygen as a byproduct, which is used to sustain the bacteria that stabilize the suspended organic material in wastewater.

Hydraulic Retention Time (HRT)

is a period of time that wastewater remains in a tank. This term is also known as detention time.

Disinfection

is a process used to destroy most pathogens to a safe level in the effluent. Disinfection does not destroy all microorganisms

sanitary sewer overflow

is a release of wastewater from a sewage collection system or an interceptor sewer directly into a water of the state or to the land surface. All SSOs must be reported to the Department of Natural Resources within 24 hours of the occurrence.

treatment facility overflow

is a release of wastewater, other than through permitted outfalls, from a wastewater facility into a water of the state or the land surface. All TFOs must be reported to the Department of Natural Resources within 24 hours of the occurrence.

Flume

is a restriction in an open channel used to measure flow.

Discuss grab and composite influent sampling.

is a sample collected at a single instant in time. A composite sample is a collection of samples taken over a longer period of time (usually 24 hours) and mixed and stored in a larger container. A composite sample represents the average wastewater quality being received into a wastewater treatment plant. If samples collected over 24 hours are stored in a composite sampling jug or container, the jug or container must be shaken and well mixed before pouring the actual sample to be used for testing. Some samples, such as pH, dissolved oxygen (DO), and chlorine residual, must be grab samples because compositing and holding such samples would change the test results.

composite sample

is a sample prepared by combining a number of grab samples, typically over a 24-hour period.

Grab sample

is a single sample taken at a particular time and place that is representative of the current conditions

manhole

is a structure that provides access to a collection system. It is typically a round opening with an iron lid.

Discuss suspended growth systems (activated sludge).

is a suspension of wastewater and microorganisms in an aeration basin. The mixture of wastewater and microorganisms is referred to as mixed liquor suspended solids (MLSS). Aeration equipment provides dissolved oxygen (DO) to promote the growth of microorganisms that substantially remove organic material.

Aeration basin

is a tank where wastewater is aerated to achieve biological treatment.

wet well

is a tank where wastewater is collected. The wastewater is then pumped from the wet well. Wet wells are commonly found in lift stations and at the headworks of the wastewater treatment plant.

Secondary treatment

is a treatment process using biological processes that utilize bacteria to remove pollutants.

Tertiary treatment

is a treatment process using physical, chemical, or biological processes to remove suspended solids and nutrients in wastewater to accomplish a level of treatment greater than what can be achieved by secondary treatment.

Primary treatment

is a treatment process usually consisting of clarification by solid and liquid separation removing a substantial amount of suspended and floating matter.

Treatmeant unit

is an individual structure or equipment within a collection system or a wastewater treatment facility that is part of a treatment process.

lift station

is an underground chamber with pumps that is used to elevate (lift) wastewater to a higher grade. Lift stations are located within a collection system.

storm sewer

is an underground pipe system that collects rainwater from streets and conveys it to a place other than the wastewater treatment plant.

sanitary sewer or collection system

is an underground pipe system used to convey wastewater to a treatment facility.

Describe common equipment used in tertiary treatment.

is granular filtration. The overall efficiency in removing pollutants by filtration could exceed 95% removal of suspended solids and phosphorus. Other less frequently used methods of tertiary treatment are carbon adsorption and physical chemical methods. Common equipment used in filtration are: A. Filtering system B. Cleaning system

WPDES. Wisconsin pollutant discharges elimination system.

is issued to wastewater facility owners and contains facility effluent, biosolids and sludge limitations, conditions, and reporting requirements.

Describe the characteristics of influent domestic wastewater.

is less than 99% water and is gray in color with an earthy, musty odor. Typical influent wastewater concentrations are:

Explain why some treatment plants have total phosphorus limits.

is one of the key nutrients that contribute to eutrophication and excess algae and plant growth in rivers and lakes. The decomposition of excess plant matter reduces the level of DO in the receiving water which affects aquatic life.

Selector

is part of the treatment system that selects for a specific type of microorganism by providing an environment (anaerobic, anoxic, or aerobic) that favors its growth.

List flow measuring applications in a wastewater treatment plant.

is required in Wisconsin Pollution Discharge Elimination System (WPDES) permits for measuring influent and effluent flows, flow measurements are needed in many other places within the plant for proper process control. In an activated sludge plant, measuring return and waste activated sludge is extremely important as they are the key to successful operations. In-plant flow meters are used for measuring: A. Return activated sludge (RAS) B. Waste activated sludge (WAS) C. Recycle or recirculation flows D. Sidestream flows E. Sludge flows to digesters F. Sludge feed rates to sludge dewatering equipment G. Sludge withdrawal volumes from storage tanks

Waste activated sludge

is the activated sludge (excess biomass or cell mass) removed from the secondary treatment process. For most treatment plants, this will be a portion of the RAS flow stream.

Food to Microorganism Ratio

is the amount of food (BOD) provided to the microorganisms [mixed liquor volatile suspended solids (MLVSS) or mixed liquor suspended solids (MLSS)].

Headworks

is the beginning, or head, of a treatment plant where influent flow is measured and sampled and where preliminary treatment occurs.

Eutrophication

is the excessive growth of plant and algae in receiving waters due to dissolved nutrients and their decomposition

Grit

is the fine, abrasive particles removed from wastewater, such as sand and eggshells.

septage

is the high strength waste pumped out of septic tanks, sometimes disposed at wastewater treatment plants

Dissolved Oxygen

is the measure of the amount of oxygen dissolved in water

Total Suspended Solids (TSS)

is the measure of the total amount of solids suspended in a sample and is expressed in mg/L.

Describe how flow-proportional sampling works.

is the most representative method of collecting wastewater samples for wastewater coming into and being discharged from a wastewater treatment plant on a continuous basis. For most treatment plants in Wisconsin, flow-proportional sampling is a permit requirement. The volume of each sample collected is based on the flow, and this is accomplished by having a flow meter send a signal to an automatic composite sampler.

influent

is the raw (or untreated) wastewater entering a treatment process

Return activated sludge

is the settled activated sludge (biomass) collected in a final clarifier and returned to the secondary treatment process to mix with incoming wastewater. This returns a concentrated population of microorganisms back into the aeration basin.

sludge age

is the theoretical length of time a particle of activated sludge stays in the treatment plant, measured in days. In an activated sludge plant, sludge age is the amount (lbs) of MLSS divided by the suspended solids or excess cell mass withdrawn from the system per day [lbs per day of waste activated sludge (WAS)].

Process control

is the tools and methods used to optimize treatment plant operations.

Effluent

is the treated wastewater discharged from a treatment plant to the environment.

Discuss the tertiary treatment process

is to provide advanced wastewater treatment beyond secondary biological treatment. It results in a very high quality effluent, extremely low in biochemical oxygen demand (BOD), suspended solids, and nutrients. Wastewater treatment plants that have discharge limits less than 10 mg/L of BOD and total suspended solids (TSS) or have very low phosphorus limits, usually need to provide tertiary treatment.

Discuss the disinfection process

is to reduce the discharge of waterborne pathogenic organisms that cause illness. This is done to protect public health as related to surface drinking water supplies and recreational use of downstream areas. Seasonal disinfection provides disinfection during the months when recreational activities are using downstream areas. Disinfection consists of either chlorination tanks or ultraviolet (UV) radiation units in Wisconsin.

Discuss the secondary biological treatment process.

is to remove dissolved and suspended organic material from wastewater to produce an environmentally safe treated effluent and biosolids or sludge.

Discuss the preliminary treatment process

is to remove larger materials (rags, sticks, stones, plastics, personal hygiene products, etc.) and grit from the waste stream before it flows to downstream treatment units. This is done to significantly reduce the plugging and clogging of pumps and pipes, the abrasive action of grit on equipment, and the settling of these materials in down streams tanks and basins.

Discuss the final clarification process

is to settle secondary biological treatment solids and discharge clear effluent. The settled solids can be returned [recycle activated sludge (RAS)] to the aeration tank or wasted [waste activated sludge (WAS)] for biosolids or sludge processing.

Discuss the primary treatment process

is to settle wastewater solids and capture floatable substances [such as fats, oil, and grease (FOG)]. Some biochemical oxygen demand (BOD) is also removed in the settling of these solids. The solids that settle in primary clarifiers and the FOG skimmed off the surface are directly removed from the process.

Explain why some treatment plants have to meet ammonia nitrogen limits.

is toxic to fish and aquatic life, and its toxicity is dependent on temperature and pH. The actual limits for ammonia nitrogen are calculated based on stream flow, stream temperature, stream pH, and the type of fishery classification.

Discuss the importance of treating wastewater.

is treated for two main reasons: A. Protect public health by destroying pathogens B. Protect the environment by removing pollutants Pathogenic organisms are disease-causing microorganisms. They include various bacteria, viruses, and parasites. The discharge of waterborne human wastes will contain these organisms from ailing individuals and would be expected to be present in wastewater entering a wastewater treatment plant.

List and define common sources of I/I.

is unwanted clearwater that gets into the collection system. Clearwater is classified by how fast it gets into the collection system and is determined by weather and groundwater conditions. Common sources of clearwater (I/I) are: A. Roof leaders connected to the sanitary sewer B. Storm and sanitary crossovers C. Low lying manholes in roads or ditches subject to flooding D. Uncapped lateral connections E. Sump pumps and foundation drains F. Cracks and offset joints in the sanitary sewer G. Manhole cracks and defects H. Buried manholes I. Cracks and leaks in building sewers

Describe the sources of wastewater in a community

is used water that goes down the drain and flows to the wastewater treatment plant. Flows originate from domestic (household), industrial, and commercial sources. Some wastewater is trucked to the wastewater treatment plant as septage, holding tank waste, leachate, and some high strength industrial wastewater. In addition, clearwater (rain, snow, and groundwater) from inflow and infiltration (I/I) can get into the collection system.

Describe common equipment used in attached growth secondary (biological) treatment.

make use of microorganisms that attach themselves to a medium or substrate of some type. Common equipment used in attached growth systems such as trickling filters and biotowers are different types of media, pumps, distribution arm and piping, and underdrains. Common equipment used in attached growth systems such as RBCs are basins, shafts, circular plastic disks, motors, and drives and sometimes blowers and diffusers (for air driven shafts). A. Pumps and distribution piping B. Media C. Underdrain system D. RBC motors, drives, and shafts

Discuss the potential impacts of industrial and commercial discharges.

may vary in strength and volume. Slug loads are of special concern and can upset or pass through the treatment plant and out with the final effluent. High levels of BOD, TSS, phosphorus, ammonia, and FOG can effect treatment. High or low pH can also be a problem.

treatment process

means a physical, biological, or chemical action that is applied to wastewater to remove or reduce pollutants

Describe sanitary sewer overflows (SSO) and their causes.

occur for many different reasons. One of the main reasons sewers back-up and overflow is too much clearwater gets into the sewer pipes through infiltration or inflow (I/I) during wet weather events. Sewer pipes are designed for only a certain flow capacity and excessive I/I can exceed that capacity. As sewers age, sewer defects increase, allowing for more clearwater (I/I) to get into them.

Discuss attached growth systems (rotating biological contactor (RBC), trickling filter, and biotower).

some times referred to as a fixed-film process) utilizes microorganisms that are fixed in place on a solid surface (attached). As wastewater passes through and around the solid surface, the microorganisms remove the food (organic content) from the wastewater. This attached growth type aerobic biological treatment process creates an environment that supports the growth of microorganisms.

Explain how a wet well and dry well pumping station works.

the centrifugal pumps and other equipment are located in a separate chamber (dry well), with only the suction pipe being submersed in the wet well. The pump is turned on when the wastewater reaches a certain depth. If the wastewater continues to rise, more pumps will be turned on. The pumps are turned off when the wet well is empty or reach the minimal set point. It is important that the dry well be well ventilated and dehumidified to protect the equipment and ensure the safety of the operator.

Describe common equipment used in primary treatment

the purpose is to settle wastewater solids and capture floatable substances (such as FOG). Well-designed and operated primary facilities can expect removal efficiencies of 40% to 60% for suspended solids and 20% to 35% for BOD. Common primary treatment units are rectangular clarifiers, circular clarifiers, and DAF.

Describe common equipment used in preliminary treatment.

to remove larger, inorganic materials (rags, sticks, stones, plastics, personal hygiene products, etc.) and grit from the waste stream before it flows to downstream treatment units. A. Screening Common screening systems are manually cleaned bar screens, mechanically cleaned bar screens, and rotary fine screens. These processes simply remove debris which is then land filled. B. Grit removal Common grit removal systems are aerated grit chambers and vortex-type (Pista®) unit. An aerated grit chamber uses air that separates light from heavier solids (grit). A vortex-type (Pista®) unit consists of a cylindrical tank creating a vortex flow in which the heavier grit settles to the bottom.

Describe common equipment used in suspended growth secondary (biological) treatment.

used in suspended growth secondary biological treatment are aeration tanks, blowers, diffusers, final clarifiers, and sludge pumps. A. Aeration tanks B. Blowers C. Diffusers D. Final clarifiers E. Sludge pumps

Discuss the impact cleaning agents and products can have on a treatment plant.

used widely in communities and are important in ensuring public health. When used frequently and in large quantities at industries, businesses, schools, nursing homes, medical facilities, or restaurants, they have the potential to affect treatment. Many effective cleaners contain phosphates and thus can contribute a significant amount of phosphorus to wastewater. Wastewater treatment plants with phosphorus limits, especially those with stringent limits, will have to remove nearly all this phosphorus.