Colorado Wastewater (WW) Operator D Practice Exam

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