Colorado Wastewater (WW) Operator D Practice Exam

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• What does a chlorine demand test measure?
• In biological phosphorus removal, adding chemical additives near the end of the biological treatment is recommended to minimize sludge production.
• Nitrite concentration in a typical wastewater treatment plant effluent is less than 0.5 mg/L as NO2-N.
• Which of the following would be the safest action to take in the event of a major chlorine container leak?
• A lagoon has an average daily flow of 0.25 MGD. How many gallons per day is that?
• A cylindrical tank with 44,450 L capacity holds approximately how many US gallons?
• Name the two nitrifying bacteria.
• After chlorine, the most common effluent wastewater disinfection technique or agent used in the US today is
• Which unit is used to express the resistance to electrical current in circuits?
• What is the weight of the dry sample (dish plus dry sample minus dish)?
• Racks, screens, comminutors and grit removal are examples of which type of wastewater treatment?
• Which factor causes the greatest friction loss in a pipe?
• What is the primary operational concern for using a float-level indicator in an open channel?
• What types of wastes generally are prohibited from discharge to wastewater treatment plants?
• Tanning is the process of:
• When chlorine reacts with H2S gas, the H2S is
• Which device is used to reduce voltage in electrical circuits?
• Which statement best describes a device that uses compressed air to elevate wastewater in a vertical rise?
• Which inorganic compound would be classified as inorganic given the definition that inorganic compounds do not include organic carbon?
• When ventilating a manhole with a portable blower, what minimum distance should the blower be from the opening?
• A treatment plant uses sulfur dioxide to dechlorinate effluent. An operator needs to adjust the sulfonator so that the dosing concentration is 1.5 mg/l more than the chlorine residual. Based on the following information, what should the sulfonator feed rate be: design flow = 5 mgd; chlorine dosage rate = 4 mg/l; chlorine residual = 0.9 mg/l
• Which of the following is a correct statement about the separation distance requirement for sludge land spreading?
• What is breakpoint chlorination?
• What is the approximate pounds per day of raw BOD entering a system with 1.5 MGD flow and 150 mg/L BOD?
• If dairy wastewater BOD is around 1,000 mg/L, but can be as high as 10,000 mg/L, which statement best describes its range?
• The in-stream process of cutting and screening solids contained in wastewater flow is called what?
• What is the BOD concentration after primary treatment if the influent BOD is 150 mg/L and primary treatment reduces it by 30%?
• Overgreasing a plug valve assembly is most likely to cause leakage at which interface?
• A centrifugal pump is pumping 200 gpm against a 40 ft total pumping head. The output power of the pump is approximately ______ hp.
• Which correction factor should be applied to DO meter readings to account for atmospheric conditions?
• If the COD value is 126 mg/L, the BOD value would be approximately 84 mg/L.
• The flow to a trickling filter is 2.5 MGD. The filter diameter is 100 ft and media depth is 4 ft. The recirculation rate is 0.75 to 1. Calculate the hydraulic loading rate in gallons per day per square foot.
• Which term refers to the maintenance action that assesses flushing intensity in trickling filter systems?
• Air requirements in an activated sludge tank are governed by which factor?
• An organization described as decentralized would have authority distributed
• Compared with activated sludge, trickling filters are not easily upset by shock loads, perform consistently, and are capable of taking considerable abuse. True/False?
• The slime layer on a trickling filter is called:
• Which two nutrients are commonly deficient in industrial wastewater, leading to nutrient limitation?
• In wastewater disinfection, hypochlorination refers to the use of ________ hypochlorite.
• The mechanism used to remove dewatered sludge from the belt of a belt filter press is commonly referred to as what?
• The slime layer on a trickling filter is an example of a biofilm.
• The CBOD5 results are reported when a nitrification inhibitor is used.
• Three properties of hydrogen sulfide include:
• Interferences are substances in a sample that can cause false ____________ and false ________.
• Alkalinity is defined as the __________ capacity of water.
• A pump is delivering at a less than expected rate of discharge. Which of the following possible causes is incorrect?
• Which statement best describes the major gases in digester gas?
• What conditions determine the backwash rate for a pressure filter?
• Nitrifiers grow slower than other bacteria, sludge ages longer than ____ days are often needed.
• Which value best represents the total daily load of suspended solids at the plant if the influent is 100 mgd and 110 mg/L, ignoring the side-stream?
• When Cr+3 is precipitated under alkaline conditions, which compound is typically formed?
• Which statement best describes common practice for reducing hexavalent chromium to trivalent chromium in wastewater treatment?
• Which device prevents backflow in a centrifugal pump system?
• Acids should never be added to chlorine solutions because they
• If fine-bubble diffusers are used to introduce air into a biological reactor, the surface of the tank will typically have what type of appearance?
• The reduction rate for Cr+6 _____________ with increasing pH.
• Which of the following is not a basic backflow prevention device?
• Trickling filters and RBCs are ________ processes; Activated sludge is a ________ process.
• What does a manometer measure?
• The height of water above a point measured in either pounds per square inch or height is called _____________.
• Power in an electrical circuit is defined as the product of voltage and current.
• The main function of a lubricant is to keep moving materials separate from each other.
• In a circular clarifier, what is the function of the centrally located drive unit?
• For a blower located in an area with very fine particles, which filtration method is preferred?
• What piece of laboratory glassware is used mainly to mix chemicals and measure approximate volumes?
• IFAS stands for Integrated fixed-film activated sludge.
• An activated sludge plant has a flow of 2 MGD with influent BOD of 240 mg/L. If the primary clarifiers remove about 30% of influent BOD and the target F/M ratio is 0.4, how many pounds of MLVSS should be maintained? (Round to the nearest pound.)
• A ground fault interrupter on an electrical circuit system is used to ______.
• If a 100-mgd flow of wastewater is dosed at a rate of 12 mg/L, the chlorine feed should be closest to what daily rate (lb/d)?
• Racks, screens, comminutors and grit removal are all examples of which type of wastewater treatment?
• One BTU is the unit of measure required to raise the temperature of 1 lb of water by 1 degree F.
• A Venturi flowmeter is based on which principle?
• For a wastewater to be balanced and to not be nutrient limited, the BOD to N to P ratio should be what?
• Breakthrough occurs when the
• What is the surface area, in square feet, of a circle with a diameter of 90 feet?
• Cavitation is the formation and collapse of a gas pocket or bubble on the blade of a pump's impeller. True or False?
• 9/5(degrees C) + 32 equals ______.
• According to the NEC, ground wires should be colored GREEN. Which of the following lists only non-green colors?
• Besides the multiple-hearth incinerator what is the other most common type of sludge incinerator in the U.S.?
• One ton chlorine cylinders: you should
• Which of the following best indicates proper mixing in an aeration tank?
• In a centrifugal blower, surging occurs when the discharge pressure is
• Sample refrigerators should be set at what temperature, plus or minus 2 degrees C?
• Organic loading rates for a well-mixed and heated digester typically range between:
• CCSS stands for:
• The flow-through rate in grit channels is usually about how many feet per second?
• In the lift station problem, which pump's check-valve lifting arm is up?
• In the cyanide to cyanate conversion using chlorine gas, what is the ratio of chlorine to cyanide used?
• If chlorine costs $0.21 per pound, what is the daily cost to chlorinate a 5 MGD flow rate at a chlorine dosage of 2.6 mg/L?
• A white or gray biomass on an RBC unit indicates _____?
• Common metals can be removed from wastestreams by ____________ precipitation.
• Detention time in hours in a final clarifier given diameter 95 ft, depth 11 ft, and flow 7.0 MGD.
• When cyanide is treated with chlorine gas, what product is formed?
• When using sodium bisulfite to reduce hexavalent chromium, which chemical must be added?
• Because dairy wastes contain a lot of floatable fats and greases, this unit process is often utilized as a pretreatment step.
• Which property describes water's buffering or acid-neutralizing capacity?
• Detention time for a small pond: a 0.5 acre pond with 5 ft depth receives 0.1 MGD. Detention time is approximately how many days?
• Which of the following lists includes key factors in activated sludge nitrification?
• What is the typical role of chelating agents in electroless plating?
• The final effluent dissolved oxygen of a properly operating trickling filter plant typically falls within 1.25 to 2.0 mg/L. This statement is:
• The process in which a tank or reactor is filled, water is treated, then the tank is emptied, and the cycle repeats is called which?
• In a conventional activated sludge plant, oxygen demand is highest at which location?
• If you need to raise your voice to be heard by someone less than 2 ft away, chances are you should be wearing hearing protection. True or False?
• Which statement best explains why pretreatment is often applied to dairy waste streams?
• Which is an appropriate location to collect a final effluent sample for a chlorine residual test?
• What is the stated advantage of using sodium hydrosulfite for manual addition of chemicals to reduce hexavalent chromium?
• Using the same pipe scenario as in the second question, what is the flow rate in cubic feet per minute?
• Kaldes is one example of an IFAS. Ringlace is another. Which statement best reflects this?
• Which parameter is a primary concern when evaluating metal finishing wastewater toxicity?
• A two-stage trickling filtration system consists of:
• A fluid with SG 1.05 weighs approximately how many pounds per gallon?
• What does VSS stand for in wastewater analysis?
• The results of a 5-day BOD test should be reported as CBOD5 when ____ is used.
• In the BOD test example, what is the bottle volume used?
• A breakpoint chlorination yields which residual?
• The primary function of secondary clarifiers is to:
• Which quality control samples are used to measure accuracy and precision?
• Rapidly closing a valve in a piping system can cause a phenomenon known as water hammer.
• _____ is the relationship in time between two waveforms of the same frequency.
• Which statement best describes a BTU?
• When using sulfide to precipitate metals, why must the pH be kept above 8?
• What is the purpose of heating and mixing a primary digester?
• Determine the required chlorinator setting in lb/day for a plant with 5.5 MGD flow, target residual 2.5 mg/L, and average chlorine demand 2.5 mg/L.
• What are the characteristics for chlorine as used in pollution control?
• Which chemical is used in the zero calibration solution for a membrane DO test?
• Hydraulic loading to a pond is generally expressed as gal/day/ft2. True or False?
• A total residual is also referred to as a _____ residual.
• What is the weight of the dish with ash?
• The flow velocity in a 6-in diameter pipe is twice that in a 12-in diameter pipe if both are carrying 50 gal/min of wastewater.
• Which precipitation method is the most efficient when a wastestream contains complexed metals?
• All those combinations of elements that do not include organic carbon are called what?
• Before snails and filter flies can establish themselves in a trickling filter, which condition must exist?
• What is the approximate volume of the cylindrical tank in cubic feet?
• The germicidal UV energy is typically at which wavelength?
• Control charts are only effective if they are ___________ and __________.
• When a centrifugal pump loses prime, which problem is most likely?
• A single-piston reciprocating pump has a 6 inch diameter piston with a 6 inch stroke. It makes 16 discharge strokes per minute. The pumping rate is approximately how many gallons per minute?
• The fusible plug on a chlorine cylinder melts at about ______ degrees.
• Which type of load is the Step feed activated sludge process particularly good at handling?
• Which of the following is a modification of the activated sludge process?
• The metals commonly treated in electroplating and metal finishing wastestreams include:
• This toxic metal compound is utilized in the tanning process.
• What equipment is typically used to control positive displacement blowers?
• The rotating biological contactor rotates to move media into and out of wastewater.
• In the digester example, what is the percent volatile solids (VS) used?
• Tannery wastewater is high in BOD, TSS, and this salt.
• Which sugar is metabolized by fecal coliform bacteria?
• What is the typical BOD removal efficiency range for primary treatment?
• What is surging in a centrifugal blower?
• Which disinfection method is currently the most common after chlorine in US wastewater effluent?
• Sulfide precipitation of common metals is sometimes preferred over hydroxide precipitation because it is which?
• A water holding tank has a bottom pressure gauge reading 15 psi. The tank is 15 ft in diameter and 40 ft high. Approximately how many feet of water does this pressure correspond to?
• When snow covers the surface of a trickling filter, which statement reflects the recommended action?
• What residual is attained after breakpoint chlorination?
• Which chemical is used to precipitate Cr+3 after reduction, based on the provided material?
• Which condition would least likely contribute to rising sludge in secondary clarifiers?
• A centrifugal pump delivering 320 gpm against 40 ft head has an approximate horsepower value of:
• A primary clarifier removes suspended solids from a flow of 2.7 MGD, with influent TSS 230 mg/L and primary effluent TSS 110 mg/L. How many pounds per day of suspended solids are removed?
• The volume of a primary anaerobic digester is 40,000 cubic feet. The raw sludge feed rate is 6000 lbs dry sludge per day and the volatile solids content is 78%. What is the organic loading rate in lbs VS/cubic foot/day?
• A digester operated in a temperature range of 115-125 degrees F is in the ________ range
• An activated sludge plant receives 2 MGD with influent BOD 240 mg/L. If the desired F/M ratio is 0.4 and primary clarifiers remove 30% of influent BOD, how many pounds of MLVSS should be maintained?
• Cr+6 must be converted to Cr+3 before precipitation.
• Generally, standard recoveries should be within which tolerance for the BOD test?
• Influent flow to the aeration basin is 5 MGD with a BOD concentration of 200 mg/L. If the yield is 0.7 lb of sludge produced per pound of BOD removed, how many pounds of sludge must be wasted per day?
• Scraper boards used to remove settled sludge to the collection hopper are called ________.
• Which statement about phosphorus in conventional activated sludge biomass is correct?
• Hexavalent chromium must be removed from the wastestream before metal precipitation can be done for this reason:
• Fecal coliforms are a subset of which larger group of bacteria?
• A limitation of the hydroxide precipitation process for treating common heavy metals includes:
• Counted plates should have at least this many colonies, but no more than this.
• If your facility cannot tolerate power loss even for short periods, then you need an emergency generator that can _____.
• One volume of liquid chlorine will yield about ____ volumes of chlorine gas.
• What is the primary purpose of a Parshall flume in open-channel flow measurement?
• Given the following, what is the F/M ratio of this activated sludge process? Tank dimensions: 80ft long x 20ft wide x 12ft deep, Average flow rate is 300 gpm, Plant influent BOD is 180 mg/L, Primary effluent BOD is 150 mg/L, MLSS is 1350 mg/L.
• When treating wastewaters with two or more common metals with different optimal pH levels for precipitation, which approach should be used?
• Rain or storm water that enters the sewer system through drains is called:
• Which chemical is used for dechlorination in wastewater treatment processes?
• Alkalinity is defined as the __________ capacity of water.
• Which document provides safety information for potentially hazardous materials?
• For a surface aerator, the oxygen transfer efficiency increases as submergence is decreased. Choose the correct statement.
• Chlorine residual is equal to chlorine applied minus chlorine demand.
• Under the new federal sludge regulations, what minimum separation distance from waters is required when land applying sludge?
• A tank measures 40 ft long, 25 ft wide, and 12 ft high. How many gallons of liquid are in the tank?
• In anaerobic digestion, tube in bath, tube in tube, and spiral plate are all types of what?
• Which statement is accurate regarding solids removal in wastewater treatment?
• In confined space entry, the permit provisions must be fulfilled and certified by signing. True or False?
• What type of in situ maintenance is recommended for most flexible membrane diffusers?
• Nitrogen and phosphorus must be removed from the effluent before farmers can irrigate with the treated effluent. True or False?
• Denitrification in the clarifier blanket is most commonly associated with which of the following phenomena?
• Hexavalent chromium is reduced to the trivalent form most efficiently at which pH?
• What is the typical pH used for reducing Cr+6 to Cr+3?
• IFAS stands for Integrated fixed-film activated sludge.
• The fusible plug on a chlorine cylinder melts at about what temperature?
• In addition to oxygen, nitrifiers consume bicarbonate alkalinity and produce carbonic acid. True or False?
• What is the weight of the empty dish?
• Why must cyanide be removed from a wastestream before metal precipitation can be performed?
• What is the circumference of a clarifier with a diameter of 50 feet?
• Oxygen deficiency becomes a concern when the oxygen level in a confined space is less than 19.50%.
• Before performing a membrane electrode DO test, the zero calibration uses a reading on a sample containing an excess of _____ and a trace of cobalt chloride, CoCl2.
• In Parshall flume measurement, which option describes its defining features?
• The unit of electrical resistance; resistance to the flow of electrical current.
• Destabilization of a sludge particle by decreasing the magnitude of the repulsive electrostatic interactions between particles is called what?
• An example of a 'single-use' plan is a
• Screening is an essential pretreatment step for combined tannery wastes. It removes these substances and prevents clogging downstream.
• Regardless of shape, 1 ac-ft of media in a trickle filter is equal to how many cubic feet?
• Which formula is used to calculate the volume of a wet well?
• In the jar test example, how much sludge volume was tested?
• Following coagulation, the next step in a physical-chemical treatment is called
• In water quality testing, coliform bacteria are used as what?
• The end product of denitrification is nitrogen gas.
• If you observe a slow constant drip from a pump shaft packing seal, what is your first action?
• What might cause a white filamentous growth in an RBC system, resulting in poor BOD removal efficiency?
• Which biomass characteristic on RBC units indicates filamentous bacteria dominance?
• What type of pump is typically used to feed ferric chloride for solids handling purposes?
• Duplicates in quality control are used to assess which aspect of data quality?
• Total and fecal coliform are pathogenic.
• If a 100-mgd plant doses at 12 mg/L, what is the chlorine feed setting in pounds per day (nearest 100 lb/d)?
• Which device on an anaerobic digester allows air to enter the tank if solids move rapidly or conditions change to prevent vacuum?
• Which statement best describes a safety advantage of ultraviolet disinfection over chlorine?
• What units are used to report BOD results in the example?
• Which term best describes the use of coliforms as a standard in measuring disinfection effectiveness?
• Chlorine applied minus ____ equals chlorine residual
• An ammonia concentration of 1500-3000 mg/L is _________ to a digester.
• If your 1 ton chlorine cylinder is leaking, what type of Chlorine Institute repair kit should be used?
• In a confined space entry, the permit provisions are fulfilled by certification through signing the permit.
• What is the maximum holding time for a sample to be analyzed for pH?
• Which is not a chemical used to precipitate phosphorus from a wastewater effluent?
• Which statement correctly describes oxygen demand for BOD removal?
• The two qualities in a final effluent that most affect performance of ultraviolet disinfection system are UV transmission and ____________.
• A positive-displacement sludge pump should never be placed into operation
• Which type of meat packing waste is suitable for land disposal?
• A manometer with a scale of 0 to 5 inches reads 1 inch; should the aeration blower inlet filter be replaced?
• The casing surrounding a pump impeller that collects the water discharged by the impeller is called a __________.
• Which instrument is used to measure pressure in a system?
• In the jar test example, what was the total solids percentage of the sludge?
• Convert 18 degrees Celsius to Fahrenheit
• If the influent suspended solids are 100 mg/L and the effluent suspended solids are 8 mg/L, what is the removal efficiency?
• After Cr+6 is reduced to Cr+3, the chromium is precipitated at which pH range using which reagent?
• What is the primary reason for limiting nitrate concentrations in receiving waters?
• Personnel should not work alone on energized equipment above which voltage?
• A ______ pH will increase the rate of release of dissolved hydrogen sulfide from wastewater.
• A fluid with a specific gravity of 1.05 weighs _____ lb/gal.
• The process of layering water by temperature in a body of water is called
• In Kjeldahl nitrogen analysis, organic nitrogen is determined by subtracting which nitrogen fraction from the total Kjeldahl nitrogen?
• Which electrical component is used to step voltage down in a control circuit?
• Which gas produced in anaerobic digesters can be used as fuel?
• Hexavalent chromium reduction to the trivalent form is typically done at this pH level
• The tiny fly commonly associated with trickling filter systems belongs to which genus?
• What is the approximate volume of the final clarifier with diameter 95 ft and depth 11 ft?
• What percent reduction is specified for vector attraction reduction?
• Which of the following indicates that the impeller of a centrifugal pump may be worn or damaged?
• If the influent suspended solids are 200 mg/L and the effluent suspended solids are 16 mg/L, what is the removal efficiency?
• Chloramines are ____?
• Pulmonary capacity tests are required before operators can be cleared for using respiratory equipment. These tests should be performed at a minimum of once every...?
• In chlorine dosing calculations, the dosage rate is expressed in which unit?
• Why is the sludge returned from the secondary clarifier to the aeration tank in activated sludge used for nitrification?
• What is a common symptom of a faulty level control causing pumps to run continuously in a lift station?
• Both of these quality control samples can be used to measure accuracy and precision.
• In processing systems, what term describes devices that transfer heat from one fluid to another?
• Under normal conditions, the maximum amount of chlorine gas that can be drawn from a 150-lb cylinder is
• Which factor is the primary determinant of air requirements in an activated sludge tank?
• LEL stands for what in gas detection terminology?
• In the BOD example, what is the observed DO depletion (IDO minus FDO)?
• Coliform bacteria and the procedures used to test for them are divided into the two categories of _______.
• According to Article 250 of the US National Electric Code (NEC), what color should ground wires be?
• What is the primary purpose of a ground fault interrupter in an electrical circuit?
• The organic nitrogen level is determined by performing a _______ nitrogen analysis and then subtracting the ammonia nitrogen concentration.
• Taking samples at different locations along the length and width of a reactor (aeration tank) as well as at different depths and analyzing them for solids concentration will verify whether or not you have what?
• In disinfection verification, which type of bacteria is commonly used as an indicator?
• What is the approximate volume, in MGD, of flow treated in a grit chamber that is 7 ft wide and 4 ft deep if a stick moves 24 ft in 30 seconds?
• In what order will bacteria break down the following oxygen-containing compounds: sulfate, carbon dioxide, and nitrate? That is, which sequence represents the source of bound oxygen requiring the least energy?
• What is the maximum holding time for a properly preserved sample for BOD analysis?
• It is advantageous to denitrify following nitrification as nearly half of this may be recovered.
• This term refers to a false positive caused by dirty glassware or sampling equipment.
• Which dilution practice is unsafe when handling concentrated acids?
• How often should inactive valves be exercised?
• In the jar test example, what was the polymer solution strength?
• Water use in the brewery industry is exceptionally high averaging ______ gallons of water for every gallon of beer produced.
• The safe application of biosolids to land requires control of disease-causing organisms called ____ and _____, such as mosquitoes and flies, that may carry these organisms.
• The device used to vent air into an anaerobic digester to prevent vacuum is called:
• For vector attraction reduction, the new sludge rules require a reduction in volatile solids across a digester process before land application. What percent reduction is specified?
• Which of the following causes leaking between the segment and body of a plug valve?
• In the BOD bottle, the ring of water surrounding the stopper is called what?
• Untreated sludge drawn from a primary sedimentation tank normally would contain 1000 to 3000 mg/L of settleable solids. True or False?
• Which hazardous chemical listed is a hydrocarbon?
• The dark gray/black sludge area near the aeration tank can indicate the introduction of what condition?
• In the BOD test example, what is the sample volume used?
• Which of the following is not an example of a sludge stabilization method?
• Hydrogen sulfide has which odor?
• One volume of liquid chlorine will yield about how many volumes of chlorine gas?
• What characteristics are associated with quality activated sludge?
• A primary anaerobic digester has a volume of 40,000 ft3. How many gallons is this volume?
• A sludge draw-off of 8000 gallons contains 6% solids. Approximately how many pounds of solids are pumped?
• Chlorine gas is how many times heavier than air?
• Flow measuring device that relies on fixed geometry to relate depth to discharge is a
• Coliform bacteria are
• What is the most critical control parameter for an aerobic digester?
• In a conventional effluent chlorination system the chlorine residual measured is mostly in the form of ______.
• A plant has a 90-ft diameter sludge tank with a sidewall depth of 20 ft. The tank also has a conical bottom that is 8 ft deep. The tank has a sludge liquid level of 15 ft (sidewater depth). How many gallons of sludge liquid are in the tank?
• In ultraviolet disinfection, which factor besides UV transmission is most important in final effluent?
• Which value represents the drinking water standard for NO3-N in mg/L?
• The chair-and-flight system in a rectangular secondary clarifier is used to:
• Hydrogen sulfide has which relative density compared with air?
• What does mgd stand for?
• Samples for TSS may be held for up to this many days prior to analysis if they are kept at 4C.
• In the BOD test, the calculated BOD for a sample with IDO 8.5 mg/L, FDO 5.1 mg/L, sample used 9 mL, and total sample volume 300 mL is which value?
• The melting temperature range for the chlorine cylinder fusible plug is approximately?
• For a piston pump with a diameter of 10 in, a stroke length of 6 in, and 30 strokes per minute, what is the pumping rate in gpm?
• A sudden increase in chlorine demand at a plant is most likely due to
• Given the following data, determine the percent volatile suspended solids of this sample.
• Which maintenance method is commonly used to restore performance of flexible membrane diffusers without removal?
• How long should samples be refluxed before COD analysis?
• Regarding the agronomic rate for biosolids application, the statement that it concerns the amount of phosphorus required by crops or vegetation and the excess that may enter groundwater is:
• A 42-inch diameter pipe is flowing at 6.5 ft/s. What is the flow rate in cubic feet per second?
• A digester receives a 12,000 gal/d load with 4% total solids. How many pounds of solids are pumped to the digester per day?
• Before repairing a pump's electrical circuit, which action should you take?
• Which surface appearance is typical when using fine-bubble diffusers?
• In sludge settling tests, which condition is indicated by a high SVI?
• Flow that enters the wastewater collection system through cracks and loose joints in the sewer line is called what?
• What is the pounds per day of suspended solids contributed by the 1-mgd side-stream with 1200 mg/L suspended solids?
• An example of a 'single-use' plan is a(n)
• What is the status of the force main pressure in the described lift station scenario?
• Which safety action is essential before starting work on electrical equipment to prevent accidental startup?
• The formation and collapse of gas pockets or bubbles on the blade of a centrifugal pump's impeller is known as what?
• Which of the following is a likely benefit of a planned maintenance program?
• One major hazard associated with chlorine gas in water treatment is that it is
• Which statement is true about hydroxide precipitation's handling of chromium species?
• Which two broad categories are used in coliform testing?
• Invisible light waves used for disinfection are called which type of radiation?
• In a system with multiple metals having different optimal pH for precipitation, which metal should be precipitated first?
• How is the F/M ratio defined in an activated sludge system?
• Which combination is commonly used to neutralize highly alkaline wastewater?
• Which statement about chlorine gas density is correct?
• What is the approximate number of gallons in one cubic foot?
• Which statement best describes a modification or alternative to the conventional activated sludge process?
• A BOD sample is incubated 5 days at __ degrees C.
• Lbs/day of suspended solids removed by a primary clarifier given flow 2.7 MGD, influent TSS 230 mg/L, primary effluent TSS 110 mg/L.
• What is the total chlorine dosage (in mg/L) required to achieve a target residual of 2.5 mg/L when the chlorine demand is 2.5 mg/L?
• The most critical criterion for determining when a mixed filter should be backwashed is:
• Given the following data, determine the excess solids (in lbs) that should be wasted from this activated sludge system. Target F:M = 0.6 per day, MLVSS = 2500 mg/L, BOD loading= 18,140 lb/day, Volume of aeration basin = 2 million gallons
• Coliform testing procedures are divided into two categories. Which two categories are they?
• The rate at which heat is produced in a load is the
• This titrant is used for hardness analysis in water samples.
• Rain or storm water that enters the sewer system through french drains, roof drains or similar sources is called what?
• Combined tannery wastes typically have a TSS concentration around which value?
• The daily pounds of hypochlorite solution required to deliver a chlorine dosage of 13.2 mg/L at 5.6 MGD with a 65% solution is closest to which value?
• Why should exhaust air be taken from floor level in a chlorine tank room?
• Calculate the pounds per day of BOD entering the trickling filter. Raw wastewater flow is 1.5 MGD, raw wastewater BOD is 150 mg/L, and 30% of BOD is reduced in primary treatment.
• When chlorine reacts with hydrogen sulfide gas, what happens to the hydrogen sulfide?
• Approximately how many gallons would 600 ft of 6 inch pipe hold?
• In tertiary denitrification, what is the main purpose of adding methanol?
• Combustible gas detectors measure gases and vapors in terms of which limit?
• The pressure against which a pump must operate is measured in terms of:
• Which of the following is the most probable cause of filter ponding?
• A single sample of wastewater taken at one time from one place is called a _________ sample.
• Which statement best describes UV disinfection in terms of effluent properties?
• Ten States Standards recommend wet wells be ventilated at which rate when continuous and which rate when intermittent?
• Which statement correctly describes nitrification's effect on alkalinity?
• Which gas is produced as the end product of denitrification?
• Trickling filter hydraulic loadings are expressed in:
• What is the weir overflow rate (gal/d per ft of weir) for a 50-foot diameter clarifier when the daily plant flow is 1 mgd?
• What is the most important factor when conditioning solids for dewatering?
• Hexavalent chromium reduction to trivalent is most efficient at pH 3. Which of the following is the correct statement?
• Leakage between the segment and body of a plug valve is most likely caused by
• This unit process consists of collecting uneven flows of wastewater in a large tank and then controlling the flow rate out of that tank and into the downstream wastewater treatment processes?
• Under good mixing conditions, the optimal chemical feed point for phosphorus removal with minimal chemical sludge production is at or near the end of the biological treatment.
• Tanning is the process of converting animal hides into leather.
• Wastewater from dairy processing plants usually has a BOD around _________, but can be as high as 10,000 mg/L.
• Rotating biological contactors consist of multiple plates of support media attached to a central shaft. The rotation of this shaft moves the media into and out of wastewater. This statement is:
• What direction does air flow through a trickling filter when the influent is warmer than the ambient air?
• Before denitrification can take place, there must be presence of food (BOD), absence of oxygen, and presence of nitrate.
• When abnormal indicators are present, the frequency of process monitoring should:
• Why do nitrifiers require longer sludge age than other bacteria?
• 1 acre equals how many square feet?
• During plant rounds, an operator notices that the secondary effluent is cloudy. The operator should:
• What is the primary purpose of check valves used with centrifugal pumps?
• Brine, the principal waste from oil production, is primarily associated with which contaminant?
• A treatment plant that receives wastewater from a large canning industry may expect what problems to occur in the secondary treatment process?
• The standard unit for grit channel flow-through rate is which of the following?
• The two major gasses found in digester gas are ________ and ________.
• Typically, primary treatment has a BOD removal efficiency in the range of what?
• Biological phosphorus removal requires the presence of this type of chamber just ahead of the aeration basins.
• Friction in a pipeline causes:
• In-plant measurements are more important than receiving-water measurements because they measure the plant's efficiency. True/False?
• One volume of liquid chlorine yields about how many volumes of chlorine gas?
• What is the specific gravity of hydrogen sulfide?
• Which two tests are commonly compared to evaluate wastewater sample biodegradability in the material?
• To prevent back injuries, which precautions should be followed?
• Bacteria in wastewater generally function well at a pH near 7.0. True or False?
• What does BOD stand for in wastewater testing?
• A small area of dark gray/black sludge in an aeration tank can be due to aeration equipment failure or ____.
• During nitrification, nitrifiers consume bicarbonate alkalinity and produce carbonic acid. Which acid is produced?
• Which ratio represents a balanced BOD to nitrogen to phosphorus relationship?
• A trickling filter receiving 15 million gal/ac/d would be classified as which type of filter?
• What constant is used to convert mgd and mg/L to pounds per day in chlorine dosing calculations?
• Forklift accidents are particularly dangerous because of the tremendous weight of the forklift.
• If you need a chlorine residual of 1 mg/L, how many pounds of chlorine must be applied each day if the flow is 2.5 mgd and the chlorine demand is 15 mg/L?
• A jar test conducted on 1 liter of secondary sludge with 1.5% total solids requires 50 ml of a 0.10% solution of dry polymer for flocculation. Determine the polymer dosage in lb/ton of solids.
• The tiny gnat-sized fly found on a trickling filter is called the _____ fly.
• "Flammable" liquids have a flash point _________ 100 degrees F.
• Besides throttling the inlet valve, what type of control is used for a centrifugal pump?
• What does MLVSS stand for in activated sludge systems?
• What percent of dissolved oxygen saturation is represented by an actual concentration of 8.2 mg/L when the saturation concentration is 9.4 mg/L?
• What is the common name for commercial sodium carbonate?
• In wastewater activated sludge, excessive dissolved oxygen levels can cause what?
• Which statement is true about the composition of dry air at sea level?
• Which method is commonly used to control the speed of positive displacement blowers?
• Which statement correctly describes the effect of nitrification on pH?
• Nitrification consumes alkalinity.
• In the jar test example, how much polymer solution was used?
• A plastic float travels 10 feet in 4.2 seconds in a wastewater channel that is 2.4 feet wide and 1.8 feet deep. What is the flow rate in cubic feet per second?
• What is the primary use of an Imhoff cone in wastewater testing?
• Which valve type is installed on discharge piping to prevent backflow when the pump stops?
• Bacteria release chemicals called ________ that break down the food particles adsorbed to the cell wall so that they can be absorbed by the microorganism.
• A process in which a tank is filled, the water treated, then the tank is emptied, and the process repeated is called ______.
• Calculate the percent reduction in flows achieved by an industrial water conservation program if wastewater flows are reduced from 350 gpm to 220 gpm.
• What is the approximate volume of flow (MGD) treated in a 7' wide, 4'deep grit chamber, if a floating stick moves 24' in 30 seconds?
• What is the chemical formula for sulfurous acid?
• In an unseeded BOD test with bottle volume 300 mL, sample volume 6.0 mL, IDO 9.0 mg/L, and FDO 4.0 mg/L, what is the BOD value in mg/L?
• In a conventional activated sludge process, how much oxygen is required per pound of BOD removed?
• An operator may refuse to work with a hazardous substance under which condition?
• When purchased materials are received by the utility they should be:
• A device used on an anaerobic digester that allows air to enter the tank if solids are drawn out too rapidly or the level changes suddenly relative to the floating cover is called:
• Over-lubricating horizontal pump bearings can lead to which primary problem?
• What calibrated device developed for measuring flow in an open channel consists of a contracting length, a throat with a sill, and an expanding length?
• For a 1 ton chlorine cylinder leak, which repair kit type should be used?
• A device that causes the wastewater in a vertical riser pipe to rise to an outlet using compressed air is called an
• A device used for quick, uniform dispersal of a chemical throughout a liquid is called a what?
• When fixed-film processes such as RBCs and trickling filters are placed after the secondary clarifiers, they are said to be which type of process?
• If centrifugal pump loses prime after starting, what is the most probable cause?
• What is the correct formula to compute detention time in a clarifier?
• Cavitation in a pump typically results in which outcome?
• An organizational structure in which authority is pushed down to lower levels is described as
• When manually lifting any object, what should you do?
• A _____ is installed on pump discharge piping to prevent water from flowing back across a pump when it is off.
• A treatment plant receives 100 million gallons per day of secondary influent containing 110 mg/L suspended solids. A side-stream from a 1-mgd dewatering plant with 1200 mg/L suspended solids is returned to the plant. What is the total suspended solids load on the secondary treatment plant, in pounds per day?
• A downstream DO drop with no upstream drop indicates decreased plant removal efficiency of biochemical oxygen demand.
• Nitrosomonas & Nitrobacter are ______ ______, needing oxygen to survive.
• An air gap device is used to:
• After a snowstorm, patches of snow and ice on the top of a trickling filter are observed. What is the proper course of action?
• Raw wastewater flow is 1.5 MGD with a BOD of 150 mg/L. After primary treatment, BOD is reduced by 30%. How many pounds per day of BOD enter the trickling filter?
• Which process best describes making sludge particles come together by neutralizing their charges?
• It is usually easier and cheaper to treat a small amount of concentrated waste than a large volume of dilute waste.
• After drying, filter papers and crucibles should be stored in a ______ to prevent moisture uptake from the atmosphere.
• One MGD equals approximately how many cubic feet per day?
• Control limits are meaningless unless these are also in place.
• Determine the organic loading to an anaerobic digester given digester volume 50,000 ft3, feed sludge 8,000 lbs/day, %TS 4.5%, VS 74%.
• The programming or instructions that a computer uses to do its job is called __________.
• In hardness analysis, EDTA is best described as what?
• When working in confined spaces where flammable gases may be present, use only tools made of ____.
• Sodium hypochlorite is manufactured by the reaction of gaseous or liquid chlorine with a solution of _________ _________ to produce a liquid containing NaOCl.
• Which gas is associated with rotten egg odor in wastewater environments?
• In the digester volume problem, what were the digester dimensions?
• Biological phosphorus conditioning occurs in what zone?
• How many days does a standard BOD test run?
• Many industrial wastes contain high concentrations of BOD, but not enough of these two essential elements.
• After drying, filter papers and crucibles should be stored in a __________ to prevent moisture uptake from the atmosphere.
• Typical volatile acids concentrations in a anaerobic digester range from:
• In a two-pump wet well where lag pump is clogged, what is the most likely cause of a problem where the wet well level stays excessively high despite the lead pump running?
• Coliform bacteria are:
• The reverse-acting actuator on a control valve is pneumatic. The valve is 50% open. As you decrease the input signal to the valve, it opens 60%. The valve is functioning normally. True/False?
• What is the most accurate flow measuring device?
• Which factor has the greatest impact on friction loss per unit length in a pipe?
• In the BOD test, the ring of water surrounding the stopper is referred to as the what?
• In comparing COD and BOD results for the same sample, which statement is true?
• Can a Venturi flowmeter be used to measure flow from a centrifugal untreated wastewater pump that starts at 25 gal/min and has a maximum of 100 gal/min?
• The device used for quick, uniform dispersal of a chemical throughout a liquid is called:
• The UV dose represents the product of the rate of energy emission (lamp intensity) and the time the organisms are exposed to the germicidal energy at 254 nm. This can be expressed by the equation: Dose = intensity x time (d=It)
• Ultraviolet disinfection uses light at what wavelength to effectively kill microorganisms without significantly altering the wastewater effluent properties?
• In a 30-minute activated sludge settleability test, the Imhoff cone used should be 1000 mL.
• Calculate the cross-sectional area of a channel with width 2.4 ft and depth 1.8 ft.
• The rotational speed of an air-driven RBC is controlled by:
• Which statement about chlorine cylinder safety is true?
• The fecal coliform membrane filter test is incubated at ___ degrees C and produces blue or blue-green colonies.
• Screening in tannery waste pretreatment removes which materials to prevent downstream clogging?
• What type of air filter would be preferable for a blower located in an area where there are very fine particles in the air?
• The Sk or SpülKraft factor is a measure of this:
• A sludge tank has a 90-ft diameter, sidewall depth 20 ft, and a conical bottom 8 ft deep. If the sludge liquid level is 15 ft, approximately how many gallons of sludge liquid are in the tank?
• A trickling filter receiving 15 million gal/ac/d would be classified as which type of filter?
• In a two-stage trickling filtration system, the two filters may be used in series directly or separated by a clarifier between them.
• When high pH wastewater needs neutralization, which chemicals are commonly used?
• Alkalinity is defined as the ___________ capacity of a water.
• BOD values for the influent to a domestic wastewater plant are usually this fraction of the COD value?
• Complexed metals are metals with which characteristic?
• BOD values are typically reported in which units?
• The typical reason metal finishing wastes are treated chemically rather than biologically?
• Which of the following is not typically corrected in dissolved oxygen measurements?
• What chemical is added to an effluent fecal coliform sample to neutralize residual chlorine?
• Calculate the chlorine demand given: flow rate 120 mgd; chlorine feed rate 8000 lb/d; chlorine residual 1.0 mg/L after contact time.
• A cylinder with diameter 10 ft and height 20 ft has approximately how many cubic feet of capacity?
• Which of the following best describes the function of a ground fault interrupter (GFCI)?
• If an anaerobic digester (100 ft diameter by 20 ft high) has 3' of grit on the bottom and 2' ft of scum on top, what fraction of the usable volume is lost?
• Coliforms are used as indicator bacteria in disinfection verification because which statement is true?
• Rotating Biological Contactor (RBC) units are an example of which type of biological treatment process?
• Phosphorus reporting forms PO4-P and P differ by approximately what factor?
• Phosphorus results may be reported as ____ or ____. They differ by a factor of nearly 3.
• A chlorine demand test will show the:
• Without mineral additions for phosphorus removal, the expected percent phosphorus removal in an activated sludge system is
• In the described lift station problem, the lag pump's check-valve lifting arm is in what position?
• Under snow and ice cover, BOD levels in ponds will normally:
• A total residual is also referred to as a ______ residual.
• The device designed to prevent suction collapse by allowing air into the digester when solids move abruptly is known as what?
• Which chemicals may be used to neutralize highly alkaline wastewater?
• Unlike chlorine, UV does not leave what in treated water?
• Some characteristics of water, such as pH and dissolved oxygen, change so quickly that they need to be measured immediately. T/F?
• Valves should be closed slowly to prevent:
• Which of the following is a correct minimum separation distance from waters when land applying sludge?
• Sulfide precipitation may be used to directly precipitate hexavalent chromium. True or False?
• In CBOD5 testing, the nitrification inhibitor should be used to prevent nitrification.
• In natural systems, which element most often limits the growth of algae and other organisms?
• How often should packing on a gate valve be replaced?
• The flow of air through a trickling filter is ______ during cold weather.
• During UV disinfection, the final effluent is irradiated at which wavelength?
• Thermophilic digestion occurs at what temperature range (in °F)?
• BOD samples should be evaluated for these two parameters prior to setting up the analysis.
• To deliver 1,459 lb/d of chlorine using a 65% hypochlorite solution, approximately how many pounds per day of solution are required?
• In the fecal coliform membrane filter test, which color colonies indicate a positive result?
• Convert 1 US gallon to liters.
• A cylindrical tank is 10 ft in diameter and 20 ft tall. What is its approximate capacity in liters?
• Daily maintenance procedures for a rectangular secondary clarifier include:
• What is the status of the low-level and high-level pressure switches in the described scenario?
• If an area of 2 acres is considered, how many square feet is that area?
• Batch processes are used to treat metal wastes because they are:
• Conditions in which oxygen is absent but nitrate is present are referred to as what?
• A sudden drop in the dissolved oxygen level in a stream downstream of a WWTP outfall, with no upstream drop, indicates a decrease in the plant's removal efficiency of biochemical oxygen demand.
• The formation of layers of different temperature in a body of water is called what?
• The optimum pH for nitrification is between.
• Complexed metals are metals that tend to remain in solution due to their ability to form organic complexes. Which option best describes this property?
• Which document provides safety information for potentially hazardous materials?
• An activated sludge that settles poorly and has an SVI greater than 250 mL/g is described as which condition?
• Coliform bacteria are:
• What is the principal waste from oil production?
• Meat packing wastes are well suited for treatment by these types of processes.
• A digester temperature target is 98.8 deg F +/- 1 deg F. If the temperature indicator reads 37.0 deg C, is the temperature within acceptable limits?
• Nitrification requires 4.33 pounds of oxygen per pound of ammonia nitrogen.
• In BOD dilution water, 1 mL of magnesium sulfate, ferric chloride, phosphate buffer, and calcium chloride are added per liter of DI water. These reagents are utilized as?
• Fixed-film processes after secondary clarifiers are classified as which type of treatment?
• If the recirculation ratio is 1:1, how does the total flow to the trickling filter compare to the incoming flow?
• If the flow is 7,000,000 gpd and a uniform dose of 1.2 mg/L is applied, how many pounds of chlorine will be used per day?
• Disaster plans should be developed in case of which event?
• The amount of chlorine used per day from a 1 ton cylinder is normally determined by
• The common metals usually treated in electroplating and metal finishing wastestreams are:
• Name the interference substance for the COD test.
• Metal finishing wastes are usually treated chemically rather than biologically because
• _________ = flow, mgd x chlorine dosage, mg/L x 8.34 lb/gal.
• Which chemical is not listed as used for CIP in dairy processing plants according to the source of material?
• Exhaust air from a chlorine tank room should be taken from which location?
• Which activated sludge process treats shock loads of dairy waste most efficiently?
• At concentrations less than _____, chlorine gas is not detectable by the human sense of smell.
• Which of these chemicals is NOT used to reduce cyanide to cyanate?
• The destruction of the larger portion of microorganisms with the probability that all pathogens are killed is called
• Brewery wastes are nearly always lacking these essential elements.
• The conductivity of wastewater indicates the quantity of dissolved material present. True or False?
• If the influent flow increases from 1.5 MGD to 2.0 MGD, and the BOD after primary remains the same, how does the pounds per day entering the trickling filter change?
• Dairy wastes are often ______ limited.
• Compute the lagoon's detention time given surface area 6.0 acres, average depth 3.0 ft, and average daily flow 0.25 MGD.
• As water temperatures decrease, the disinfecting action of chlorine:
• In the digester example, what is the percent solids (TS) used?
• Tannery waste is high in BOD, TSS, and this:
• For surface aerators, keeping the device less submerged will generally do what to oxygen transfer efficiency?
• Chelating agents are used in electroless plating processes to
• The maximum rate for withdrawing gaseous chlorine from a 1-ton tank at room temperature is:
• Forklift-related accidents are particularly dangerous primarily due to the forklift's weight.
• Trickling filter organic loadings are expressed in:
• Chlorine residual is chlorine applied minus chlorine demand.
• Flow that enters the wastewater collection system through cracks and loose joints in the sewer line is called:
• In the process of UV disinfection, the final effluent is irradiated by light at a wavelength of
• Chloramines are formed when chlorine reacts with which type of compounds?
• If the sewer rate is $5.50 for the first 500 cu ft and all wastewater generated over the minimum is billed at a rate of $0.25 per 100 cu ft, how much would a customer generating 1200 cu ft be billed?
• In a wet-well lift station scenario, what is the most likely cause of a problem where pumps run continuously despite automatic controls?
• The component that surrounds the impeller and collects the discharged water is called the __________.
• Proper disinfection kills all organisms.
• A trickling filter allows the flow to slowly trickle through a filtration bed in order to remove large particulates by screening them. T/F?
• Which industry is associated with nutrient deficiency as a secondary treatment problem for its wastewater?
• Which organism is NOT involved in nitrification?
• Which of the following is not an example of a flow measuring device?
• A digester receives a 9,000 gal/d load containing 6% total solids. How many pounds of solids are pumped to the digester per day?
• Which characteristic is a major concern for metal plating wastewater?
• The in-stream process of cutting and screening solids in wastewater flow is called what?
• Which document is designed to provide information on hazards and safe handling procedures for chemicals?
• A wastewater plant with 50 mgd flow dosed at 12 mg/L would require approximately how many pounds per day of chlorine feed?
• The alarm for the fire detector in the Belt Filter Press Control Room requires you to take which type of fire extinguisher?
• Which DO value would be typical for the final effluent of a properly operating trickling filter plant?
• In BOD dilution water, the four reagents added per liter are used as what category?
• Why is ultraviolet disinfection becoming more popular?
• What is the daily volume in cubic feet for a flow of 2.7 MGD?
• The slope of a sewer line is equal to the length of pipe divided by the vertical elevation difference. True or False?
• Which statement describes the hazard associated with sulfide precipitation when pH is not kept high enough?
• Solids gas-handling systems are kept under positive pressure to prevent atmospheric air from entering the system and creating a possible explosion. T/F?
• A digester receives a 10,000 gal/d load containing 5% total solids. How many pounds of solids are pumped to the digester per day?
• Friction in a pipeline causes:
• Turbidity generally indicates the quantity of ______ material in a flow stream, particularly at low solids concentrations.
• Combined tannery wastes can average _____________ mg/L of TSS and 1000 mg/L of BOD.
• When a great deal of authority is delegated on many levels, an organization may be described as:
• The activated sludge process removes soluble BOD from wastewater by
• A recirculation of 1:1 means which of the following?
• Distilled water must be used for dilutions in most analyses to prevent this problem.
• When using a progressing cavity pump to pump sludge, in what condition must the pump intake be to insure safe operation?
• In an anoxic activated sludge process, oxygen for facultative bacteria is provided by...?
• Which property makes hydrogen sulfide particularly hazardous in the workplace?
• If chlorine costs $0.21 per pound, what is the daily cost to chlorinate a 5 MGD flow at a dosage of 2.6 mg/L?
• The time it takes for a unit volume of wastewater to pass completely through a primary clarifier is called ______.
• _____(which can be used for disinfection) may be mechanically produced by photochemical or electrical methods resembling the natural processes.
• What is the average detention time in a clarifier with diameter 80 ft, depth 12.2 ft, and flow of 5 MGD?
• When planning to work on or near electrical equipment, be sure to always ______.
• E. Coli results must always be higher or lower than fecal coliform results?
• The two technologies for biological phosphorus removal are main stream and sidestream.
• Calculate the F:M ratio for an aeration system with influent flow volume 1 MG/d, average BOD to the aeration tank 140 mg/L, aeration tank capacity 250,000 gal, MLSS concentration 2,000 mg/L.
• Centrifugal pump parts include a(n)
• Detention time in a stabilization pond with influent flow rate 0.785 MGD, depth 4.5 ft, and area 17 acres is approximately how many days?
• Which problem is addressed by using distilled water for dilutions in most analyses?
• Chloramines are formed when chlorine combines with ammonia; they are referred to as
• In the described lift station scenario where the lag pump is clogged, which pump is clogged?
• What happens when denitrification takes place in the clarifier blanket?
• In a confined space entry, the entry supervisor must ensure that all confined space entry permit provisions have been fulfilled and certify the same by signing the permit. True or False?
• What is the most common preservation method for water samples before analysis?
• What is the correct order of nitrification?
• What is the percent reduction in TSS across the primary clarifier if influent TSS is 230 mg/L and effluent 110 mg/L?
• Which of the following statements accurately reflects the separation distance requirement for land applying sludge?
• In the context of anoxic nitrification, NO3 denotes what chemical species?
• Which residual is also referred to as a combined residual?
• If velocity in a channel is 2.38 ft/s and the flow area is 4.32 ft2, what is the flow rate in ft3/s?
• In an unseeded BOD test, which statement is true?
• How many days is the BOD sample incubated in the described test?
• The percent of oxygen in air at sea level is ______%.
• Air flow through a trickling filter when the influent is warmer than the air temperature is:
• Which statement about the agronomic rate is correct?
• A cylindrical tank is 10 ft in diameter and 20 ft in height. What is the approximate capacity in liters?
• When sodium bisulfite is used to reduce hexavalent chromium, which chemical must be added?
• Process-unit efficiency can be determined if the operator knows which information?
• In disinfection, compounds of organic or inorganic nitrogen and chlorine are called ______.
• A plant blower operates at 5000 cubic feet per minute continuously for one day. How many cubic feet of air are delivered in that day?
• If water is added to concentrated acid instead of acid into water, what happens?
• Which range represents typical organic loading rate for a well-mixed and heated digester?
• In preliminary treatment, which component is designed to remove grit?
• To ensure counting reliability, counted plates should have at least 20 and no more than 60 colonies.
• What is the electrical controls mode in the described lift station scenario?
• Control charts are only effective if they are ___________ and __________.
• For tertiary denitrification, which supplemental carbon source is often added?
• Which two parameters are used in the data to determine excess solids to waste?
• Sulfide precipitation can achieve lower metals concentrations in the final effluent than hydroxide precipitation. True or False?
• The 'rotten egg' odor near a trickling filter generally indicates
• The cross-sectional area of a channel is needed for flow calculations. Which of the following is the correct area for a channel 2.4 ft wide and 1.8 ft deep?