TEXAS WASTEWATER CLASS B EXAM 2024 | ALL QUESTIONS AND CORRECT ANSWERS (VERIFIED ANSWERS), Exams of Water and Wastewater Engineering

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TEXAS WASTEWATER CLASS B EXAM 2024 | ALL QUESTIONS AND CORRECT ANSWERS (VERIFIED ANSWERS) | LATEST VERSION | ALREADY GRADED A+ Before entering a manhole the operator should test for ________and oxygen levels and ________the manhole before entering. ------CORRECT ANSWER---------------all hazardous gasses and ventilate When a municipal wastewater effluent has a high nitrate level and low ammonia level this most likely means ------CORRECT ANSWER--------------- the effluent has received a high degree of aerobic treatment Total solids in wastewater are the sum of ------CORRECT ANSWER---------- -----Settleable and volatile solids This treatment device is commonly used to separate and remove large solids from raw wastewater ------CORRECT ANSWER---------------A Mechanically raked bar screen ___________would have an adverse effect on the proper settling of solids in a clarifier. ------CORRECT ANSWER---------------A short circuiting flow pattern This test would give the best information on how efficiently a trickling filter was operating ------CORRECT ANSWER---------------Percent BOD Removal This trickling filter problem could be reduced by increasing the recirculation ratio ------CORRECT ANSWER---------------Filter files What gases are produced by the controlled anaerobic digestion of wastewater sludge's ------CORRECT ANSWER---------------Methane & Carbon Dioxide These diseases are caused by pathogenic organisms that may be present in raw wastewater ------CORRECT ANSWER---------------Hepatitis, typhoid, paratyphoid,dysentery, cholera, gastroenteritis, polio, hookworm and giardiasis During heavy rain it is possible that manholes and lift stations may overflow, discharge waste materials into roadways or ditches. This type of discharge (SSO) would be ------CORRECT ANSWER--------------- considered an unavoidable discharge, a violation of the Texas Water Code, a bypass that must be reported within 24 hours and considered a health hazard An effective way for the collection system worker to prevent infection by waterborn pathogenic organism is to ------CORRECT ANSWER--------------- Wear protective clothing and avoid direct contact with waste water _________will increase the chances that sewage will turn septic ------ CORRECT ANSWER---------------Stoppages in the main line Essential components of the wastewater collection system include ------ CORRECT ANSWER---------------Sewer mains & piping, Lift Stations, Pumps, Grease & Sand traps, & Manholes Grit removal would be considered ------CORRECT ANSWER---------------A part of Primary Treatment The protozoa that causes dysentery would most likely be destroyed by ------ CORRECT ANSWER---------------Disinfection Using final plant effluent in cooling towers would be a ------CORRECT ANSWER---------------Beneficial way to reuse treated effluent TCEQ may authorize discharge of untreated wastewater into or near a receiving stream in extreme cases. This is referred to as ------CORRECT ANSWER---------------Bypass Enforcement action from TCEQ may be taken if pollution or waste violates the Texas Water Code. Violations of Water Code may include ------ CORRECT ANSWER---------------Unauthorized discharge, accidental discharge & health hazard Solids in wastewater are classified as ------CORRECT ANSWER-------------- -Total (TR), Suspended (TSS), Dissolved (TDS), Settleable (SS), Non- setteable, Floatable, Organic and Inorganic Total Suspended Solids (TSS) are those that ------CORRECT ANSWER----- ----------Can be filtered out Total Dissolved Solids (TDS) are those that ------CORRECT ANSWER------- --------cannot be filtered out Settable Solids (SS) are those that ------CORRECT ANSWER--------------- Settle out when left standing for extended periods of time Non-settleable Solids are ------CORRECT ANSWER---------------Small particles that do not settle Volatile Solids (VSS) are those that ------CORRECT ANSWER--------------- Are determined by burning the residue from the Total Solids determination Inorganic Solids (ash) are those that ------CORRECT ANSWER--------------- Consist of sand, grit, & minerals and can be suspended or dissolved Organic matter in wastewater can be ______or________and makes up approximately _______% of the total solids ------CORRECT ANSWER------- --------Dissolved or Suspended / 65 The typical pH of an influent entering the plant will vary from ------ CORRECT ANSWER---------------6.5 to 8.0 Acute toxicity occurs when ------CORRECT ANSWER---------------There is a rapid die off of treatment organisms Chronic toxicity occurs when ------CORRECT ANSWER---------------Certain microorganisms become inactivated but others continue to work resulting in a sick biological process A mechanical device that screens & cuts large solids in small particles ------ CORRECT ANSWER---------------Cumminuter Detention time in wastewater typically refers to ------CORRECT ANSWER-- -------------The time sewage is kept in a sedimentation basis There are five (5) major components to a trickling filter ------CORRECT ANSWER---------------Filter floor, underdrain, walls, filter media, & distributer arms Zoogleal Mass refers to ------CORRECT ANSWER---------------A thick layer of jelly like slime where organisms bacteria, fungi, protozoa and ciliates thrive. The efficiency of a trickling filter is measured in ------CORRECT ANSWER-- -------------Percent BOD Removed stoppage to avoid _________. ------CORRECT ANSWER---------------Clear or open / Forcing sewage into customer homes or businesses The name of the State Agency responsible for enforcing pollution control laws in Texas ------CORRECT ANSWER---------------Texas Commission of Environmental Quality The term pathogenic means ------CORRECT ANSWER---------------Capable of causing disease The minimum separation between sewer lines and potable water lines is --- ---CORRECT ANSWER---------------9 feet A licensed wastewater operator is a professional ------CORRECT ANSWER---------------consistently does best job possible, practices personal safety, strives to improve job knowledge, strives to keep the plant and collection system in the best appearance and working order An important step in testing a sample for Total Suspended Solids is ------ CORRECT ANSWER---------------Filtering a sample The Biochemical oxygen Demand (BOD) of a sample is based on ------ CORRECT ANSWER---------------Measuring the dissolved oxygen (DO) used The results of Biochemical Oxygen Demand (BOD) sample taken at a treatment plant tells the operator ------CORRECT ANSWER---------------How the plant was operating 5 days ago Which of the following are dangerous gasses that are likely to be present in lift stations and manholes? ------CORRECT ANSWER---------------Natural gas, gasoline fumes, hydrogen sulfide and carbon dioxide A preferred hydraulic method of cleaning sewer lines is ------CORRECT ANSWER---------------Hydro Jet Cleaner Ways to reduce bad odors coming from a collection system ------CORRECT ANSWER---------------routinely cleaning slow running or low flow lines, adding chlorine or hydrogen peroxide to the collection system Types of pipe that are commonly used in wastewater collection system ----- -CORRECT ANSWER---------------ductile iron, Poly Vinyl Chloride (PVC) Before entering a confined space a worker should ------CORRECT ANSWER---------------Use approved monitoring device and check for the presence of dangerous gasses, ventilate the space with a blower, wear a safety harness and attach a life line A properly designed and operated primary sedimentation tank should remove _____ percent of incoming BOD ------CORRECT ANSWER----------- ----30-40% Devices that may be used to determine the level of sewage in a lift station - -----CORRECT ANSWER---------------air bubbler, floats, electrodes, Acoustic (sonic) What is the most important role of aerobic bacteria in the treatment of wastewater? ------CORRECT ANSWER---------------decompose organic matter The hydraulic loading of a trickling filter may be determined by ------ CORRECT ANSWER---------------flow rate and filter area These can be used to dewater sludge ------CORRECT ANSWER-------------- -belt press, drying beds, solid bowl centrifuge, gravity thickener Most important to providing adequate sewage treatment in a stabilization pond ------CORRECT ANSWER---------------sunlight, algae, bacteria and time Offensive and objectionable odors which sometimes occur in trickling filters usually indicate ------CORRECT ANSWER---------------septic conditions are present Dissolved Oxygen (DO) in aeration tank of an activated sludge plant should be maintained at or about ------CORRECT ANSWER---------------2 to 4 mg/L Chemical characteristics of sewage include ------CORRECT ANSWER------- --------solids, greases, dissolved oxygen, O2 Demand, pH, and gasses _________removes Total Suspended Solids (TSS) ------CORRECT ANSWER---------------filtration Inorganic solids include ------CORRECT ANSWER---------------sand, grit and minerals Organic solids include ------CORRECT ANSWER---------------organic materials from plants, animals or humans A good plant influent pH is about ------CORRECT ANSWER---------------7.2 Dangerous gases are produced during bacterial decomposition of organics in wastewater. The main gasses are ------CORRECT ANSWER--------------- Hydrogen sulfide, carbon dioxide and methane The majority of Dissolved Oxygen in raw sewage comes from ------ CORRECT ANSWER---------------Potable Drinking Water Each person contributes approximately ______ lbs of BOD to the system daily. ------CORRECT ANSWER---------------0.17 TEXAS WASTEWATER CLASS B EXAM 2024 | ALL QUESTIONS AND CORRECT ANSWERS (VERIFIED ANSWERS) | LATEST VERSION | ALREADY GRADED A+ Before entering a manhole the operator should test for ________and oxygen levels and ________the manhole before entering. ------CORRECT ANSWER---------------all hazardous gasses and ventilate When a municipal wastewater effluent has a high nitrate level and low ammonia level this most likely means ------CORRECT ANSWER--------------- the effluent has received a high degree of aerobic treatment Total solids in wastewater are the sum of ------CORRECT ANSWER---------- -----Settleable and volatile solids This treatment device is commonly used to separate and remove large solids from raw wastewater ------CORRECT ANSWER---------------A Mechanically raked bar screen ___________would have an adverse effect on the proper settling of solids in a clarifier. ------CORRECT ANSWER---------------A short circuiting flow pattern This test would give the best information on how efficiently a trickling filter was operating ------CORRECT ANSWER---------------Percent BOD Removal This trickling filter problem could be reduced by increasing the recirculation ratio ------CORRECT ANSWER---------------Filter files What gases are produced by the controlled anaerobic digestion of wastewater sludge's ------CORRECT ANSWER---------------Methane & Carbon Dioxide These diseases are caused by pathogenic organisms that may be present in raw wastewater ------CORRECT ANSWER---------------Hepatitis, typhoid, paratyphoid,dysentery, cholera, gastroenteritis, polio, hookworm and giardiasis During heavy rain it is possible that manholes and lift stations may overflow, discharge waste materials into roadways or ditches. This type of discharge (SSO) would be ------CORRECT ANSWER--------------- considered an unavoidable discharge, a violation of the Texas Water Code, a bypass that must be reported within 24 hours and considered a health hazard An effective way for the collection system worker to prevent infection by waterborn pathogenic organism is to ------CORRECT ANSWER--------------- Wear protective clothing and avoid direct contact with waste water _________will increase the chances that sewage will turn septic ------ CORRECT ANSWER---------------Stoppages in the main line Essential components of the wastewater collection system include ------ CORRECT ANSWER---------------Sewer mains & piping, Lift Stations, Pumps, Grease & Sand traps, & Manholes Grit removal would be considered ------CORRECT ANSWER---------------A part of Primary Treatment The protozoa that causes dysentery would most likely be destroyed by ------ CORRECT ANSWER---------------Disinfection Using final plant effluent in cooling towers would be a ------CORRECT ANSWER---------------Beneficial way to reuse treated effluent TCEQ may authorize discharge of untreated wastewater into or near a receiving stream in extreme cases. This is referred to as ------CORRECT ANSWER---------------Bypass Enforcement action from TCEQ may be taken if pollution or waste violates the Texas Water Code. Violations of Water Code may include ------ CORRECT ANSWER---------------Unauthorized discharge, accidental discharge & health hazard Solids in wastewater are classified as ------CORRECT ANSWER-------------- -Total (TR), Suspended (TSS), Dissolved (TDS), Settleable (SS), Non- setteable, Floatable, Organic and Inorganic Total Suspended Solids (TSS) are those that ------CORRECT ANSWER----- ----------Can be filtered out Total Dissolved Solids (TDS) are those that ------CORRECT ANSWER------- --------cannot be filtered out Settable Solids (SS) are those that ------CORRECT ANSWER--------------- Settle out when left standing for extended periods of time Non-settleable Solids are ------CORRECT ANSWER---------------Small particles that do not settle Volatile Solids (VSS) are those that ------CORRECT ANSWER--------------- Are determined by burning the residue from the Total Solids determination Inorganic Solids (ash) are those that ------CORRECT ANSWER--------------- Consist of sand, grit, & minerals and can be suspended or dissolved Organic matter in wastewater can be ______or________and makes up approximately _______% of the total solids ------CORRECT ANSWER------- --------Dissolved or Suspended / 65 The typical pH of an influent entering the plant will vary from ------ CORRECT ANSWER---------------6.5 to 8.0 Acute toxicity occurs when ------CORRECT ANSWER---------------There is a rapid die off of treatment organisms Chronic toxicity occurs when ------CORRECT ANSWER---------------Certain microorganisms become inactivated but others continue to work resulting in a sick biological process A mechanical device that screens & cuts large solids in small particles ------ CORRECT ANSWER---------------Cumminuter Detention time in wastewater typically refers to ------CORRECT ANSWER-- -------------The time sewage is kept in a sedimentation basis There are five (5) major components to a trickling filter ------CORRECT ANSWER---------------Filter floor, underdrain, walls, filter media, & distributer arms Zoogleal Mass refers to ------CORRECT ANSWER---------------A thick layer of jelly like slime where organisms bacteria, fungi, protozoa and ciliates thrive. The efficiency of a trickling filter is measured in ------CORRECT ANSWER-- -------------Percent BOD Removed stoppage to avoid _________. ------CORRECT ANSWER---------------Clear or open / Forcing sewage into customer homes or businesses The name of the State Agency responsible for enforcing pollution control laws in Texas ------CORRECT ANSWER---------------Texas Commission of Environmental Quality The term pathogenic means ------CORRECT ANSWER---------------Capable of causing disease The minimum separation between sewer lines and potable water lines is --- ---CORRECT ANSWER---------------9 feet A licensed wastewater operator is a professional ------CORRECT ANSWER---------------consistently does best job possible, practices personal safety, strives to improve job knowledge, strives to keep the plant and collection system in the best appearance and working order An important step in testing a sample for Total Suspended Solids is ------ CORRECT ANSWER---------------Filtering a sample The Biochemical oxygen Demand (BOD) of a sample is based on ------ CORRECT ANSWER---------------Measuring the dissolved oxygen (DO) used The results of Biochemical Oxygen Demand (BOD) sample taken at a treatment plant tells the operator ------CORRECT ANSWER---------------How the plant was operating 5 days ago Which of the following are dangerous gasses that are likely to be present in lift stations and manholes? ------CORRECT ANSWER---------------Natural gas, gasoline fumes, hydrogen sulfide and carbon dioxide A preferred hydraulic method of cleaning sewer lines is ------CORRECT ANSWER---------------Hydro Jet Cleaner Ways to reduce bad odors coming from a collection system ------CORRECT ANSWER---------------routinely cleaning slow running or low flow lines, adding chlorine or hydrogen peroxide to the collection system Types of pipe that are commonly used in wastewater collection system ----- -CORRECT ANSWER---------------ductile iron, Poly Vinyl Chloride (PVC) Before entering a confined space a worker should ------CORRECT ANSWER---------------Use approved monitoring device and check for the presence of dangerous gasses, ventilate the space with a blower, wear a safety harness and attach a life line A properly designed and operated primary sedimentation tank should remove _____ percent of incoming BOD ------CORRECT ANSWER----------- ----30-40% Devices that may be used to determine the level of sewage in a lift station - -----CORRECT ANSWER---------------air bubbler, floats, electrodes, Acoustic (sonic) What is the most important role of aerobic bacteria in the treatment of wastewater? ------CORRECT ANSWER---------------decompose organic matter The hydraulic loading of a trickling filter may be determined by ------ CORRECT ANSWER---------------flow rate and filter area These can be used to dewater sludge ------CORRECT ANSWER-------------- -belt press, drying beds, solid bowl centrifuge, gravity thickener Most important to providing adequate sewage treatment in a stabilization pond ------CORRECT ANSWER---------------sunlight, algae, bacteria and time Offensive and objectionable odors which sometimes occur in trickling filters usually indicate ------CORRECT ANSWER---------------septic conditions are present Dissolved Oxygen (DO) in aeration tank of an activated sludge plant should be maintained at or about ------CORRECT ANSWER---------------2 to 4 mg/L Chemical characteristics of sewage include ------CORRECT ANSWER------- --------solids, greases, dissolved oxygen, O2 Demand, pH, and gasses _________removes Total Suspended Solids (TSS) ------CORRECT ANSWER---------------filtration Inorganic solids include ------CORRECT ANSWER---------------sand, grit and minerals Organic solids include ------CORRECT ANSWER---------------organic materials from plants, animals or humans A good plant influent pH is about ------CORRECT ANSWER---------------7.2 Dangerous gases are produced during bacterial decomposition of organics in wastewater. The main gasses are ------CORRECT ANSWER--------------- Hydrogen sulfide, carbon dioxide and methane The majority of Dissolved Oxygen in raw sewage comes from ------ CORRECT ANSWER---------------Potable Drinking Water Each person contributes approximately ______ lbs of BOD to the system daily. ------CORRECT ANSWER---------------0.17 Sources of waste water include ------CORRECT ANSWER--------------- domestic, storm water, commercial, food processing, agricultural and industrial A sewer manhole provides access into the system for cleaning or service. A manhole is located ------CORRECT ANSWER---------------at changes in alignment, diameter, grade, direction and intersection New manholes must have an inside diameter of at least ______ feet and the entry access must be at least ____inches. ------CORRECT ANSWER--- ------------4 feet and 24 inches In the past ____ was used to construct manholes. This product is prohibited for construction or grading today ------CORRECT ANSWER------- --------brick and mortar Verified clay and Poly Vinyl Chloride (PVC) are the most common pipe materials used for sewer lines but other materials are available such as ----- -CORRECT ANSWER---------------ductile iron, cast iron, acrylontrile butadiene styrene (ABS) Concrete, polyethylene & asbestos concrete Whenever wastewater cannot flow to the treatment plant by _____ a _____ is typically used ------CORRECT ANSWER---------------gravity/ lift station The primary cause of stoppage in a collection system is _____ and _____ - -----CORRECT ANSWER---------------grease/roots The _____pump is most commonly used in a lift station ------CORRECT ANSWER---------------centrifugal A centrifugal pump must be ____ or it will not pump ------CORRECT ANSWER---------------primed ______ gas is very toxic and deadens the sense of ______ ------CORRECT ANSWER---------------Hydrogen Sulifide/smell ______ gas is colorless, odorless and heavier than air ------CORRECT ANSWER---------------Methane ______ are the smallest , most numerous, and most important of the activated sludge microorganisms ------CORRECT ANSWER--------------- bacteria Organic loading refers to the pounds per day of ____ per acre feet or 1,000 cubic feet of filter media ------CORRECT ANSWER---------------BOD Hydraulic loading refers to the volume of ____, including recirculation, applied to the filter ------CORRECT ANSWER---------------water The most common type(s) of trickling filters are- ------CORRECT ANSWER- --------------Standard rate (1-4 mgd) and High Rate (10-40 mgd) When ammonia is present in wastewater and reacts with chlorine_________are formed ------CORRECT ANSWER--------------- Chloramines Effluent dosage of chlorine in the contact chamber must produce a total combined residual of ------CORRECT ANSWER---------------1.0 mg/L after 20 minutes Besides disinfection, chlorine has other uses at the wastewater treatment plant such as ------CORRECT ANSWER---------------Reduces BOD, Odor, Algae growth, Helps with Grease TCEQ allows the reuse of wastewater, some of these include ------ CORRECT ANSWER---------------Irrigation, aquifer recharge, cooling towers and fire protection All reclaimed water piping must be _______in color ------CORRECT ANSWER---------------purple The Activated Sludge Process can produce a high degree of treatment. Typically one could expect a ______to_______% BOD removal ------ CORRECT ANSWER---------------90 to 99% The Activated Sludge plant has five (5) Critical Components. They are ------ CORRECT ANSWER---------------Oxygen supply, Aeration tanks, Clarifiers, Return & Waste The Activated Sludge process is an ________process. ------CORRECT ANSWER---------------Aerobic In the activated sludge process aeration tanks provide the space necessary to _______, ________, & _______ and return biological solids. ------ CORRECT ANSWER---------------Mix, aerate, & Hold Influent In the active sludge process, Utilization is the process where ------ CORRECT ANSWER---------------Food supply is changed into a liquid state for use In the activated sludge process, Stabilization is ------CORRECT ANSWER-- -------------Wastes biologically converted to water, carbon dioxide, or new cells In the activated sludge process, the _______ is called the heart of the activated sludge process. ------CORRECT ANSWER---------------Clarifier In the activated sludge process, factors that will influence the operation of the final clarifier are ------CORRECT ANSWER---------------Loading, solids applied, settling, thickness of solids, rate of return & Wasting In the activated sludge process, the clarifier will concentrate return sludge and waste sludge about ___ to__ times the solids concentration of the mixed liquor ------CORRECT ANSWER---------------two (2) to four (4) In the activated sludge process, for the clarifier to do its job, the ____ must be retained long enough to allow ______ to settle and liquid to rise. ------ CORRECT ANSWER---------------water/ solids In the activated sludge process, as more mixed liquor flows to the clarifier, the thickness of the sludge blanket will ------CORRECT ANSWER------------- --Increase as solids accumulate In the activated sludge process, biological solids from the bottom of the clarifier must be returned to the aeration basin for re-seed. This process is accomplished by ------CORRECT ANSWER---------------Air lift pumps, centrifugal pumps, Diaphragm pumps, Screw pumps & Gravity Flow In the activated sludge process, no sludge process will work properly without ------CORRECT ANSWER---------------Regular removal of excess solids In the activated sludge process, Mass Balance refers to ------CORRECT ANSWER---------------Maintaining the balance between Return Sludge Flow, Return Sludge, Aeration tank volume, Mixed liquor suspended solids In the activated sludge process, the terms F/M ratio is important because this refers to ------CORRECT ANSWER---------------Food to Microorganism Ratio ANSWER---------------Insufficent capacity, Equipment failures, Design inadequacies, Poor maintenance, & Inflow rates exceed plant capacities. In the activated sludge plants the operator will experience problems. Some of the common Influent problems include ------CORRECT ANSWER---------- -----Septic inflow, Organic overloading, and under loading, Hydraulic overloading, Solids washout during storm inflow, Toxic substances, Shock loads, & Nutrient deficiencies In the activated sludge plants, the operator will experience problems. Some common Operational problems include ------CORRECT ANSWER------------- --Sludge quality, foaming, improper operating techniques In the activated sludge plants, the operator will experience problems. Some common Environmental problems include. ------CORRECT ANSWER-------- -------Low temperatures, System pH out of range, & Excessive algae growth In the activated sludge plants, to properly set the clarifier return rate the operator must know three things ------CORRECT ANSWER--------------- Return activated sludge rate, Sludge blanket thickness, & the Solids concentration of the return flow The typical sludge age for extended aeration plants is ------CORRECT ANSWER---------------20 to 40 days In the activated sludge plant, good quality sludge will settle _________& _______ over _________ minute period. ------CORRECT ANSWER---------- -----Gently & Uniformly over 15 to 20 minutes In the activated sludge plant, old sludge quality will settle ________& _________ over ________ minute period. ------CORRECT ANSWER-------- -------Rapidly and ragged over 5 minutes. In the activated sludge plant, there are (5) important nitroen transformation processes that occur by microorganisms. They are- ------CORRECT ANSWER---------------Assumilation, Ammonification, Nitrification, Denitrification, & Nitrogen fixation. __________in the effluent from an activated sludge process is a pollutant and may create toxic conditions for aquatic life in the receiving stream ------ CORRECT ANSWER---------------Nitrogen Denitrification occurs in an activated sludge system when there is __________ to maintain the aerobic metabolism of the carbon stabilizing bacteria. ------CORRECT ANSWER---------------Insufficient Dissolved Oxygen The lack of _________ triggers the facuitative bacteria to change from aerobic and anaerobic ------CORRECT ANSWER---------------Dissolved Oxygen In the activated sludge system, "Hydraulic Wash Out" is ------CORRECT ANSWER---------------When the upward movement of the water in the clarifier exceeds the downward settling velocity In the activated sludge system, Hydraulic Wash Out can be controlled by --- ---CORRECT ANSWER---------------flow equalization, Additional clarifier capacity or inflow reduction In the activated sludge system, if the operator observed Boiling action, Violent turbulence throughout the aeration tank surface, Large air bubbles 1/2 inch or greater, the operator would suspect- ------CORRECT ANSWER- --------------Over aeration resulting in high DO and or floc shearing therefore the operator should reduce the air SCFM to get DO into the proper range In the activated sludge system if the operator observed uneven surface aeration, dead spots or inadequate mixing in some areas, the operator would suspect ------CORRECT ANSWER---------------Plugged diffusers In the activated sludge system, if the operator observes white thick billowing sudsy foam on the aeration tank, the operator would suspect ------ CORRECT ANSWER---------------Overloaded aeration tank and or excessive sludge wasting In the activated sludge system, if the operator observes excessive air being used with no apparent change in organic or hydraulic loading, the operator would suspect ------CORRECT ANSWER---------------Leaks in the system piping, Plugged air diffusers & High organic loading The maximum safe withdrawal rate for a 150 lb chlorine cylinder is ------ CORRECT ANSWER---------------40 lbs