MA Wastewater Operator certification Grade 2 Latest Study Guide Exam 2026

Wastewater MA Wastewater Operator certification Grade 2 Latest Study Guide Exam 2026 General Wastewater Treatment: What is the pressure head caused by? - Correct Answer-Water elevation General Wastewater Treatment: What color should the piping be that contains reclaimed water? - Correct Answer-purple General Wastewater Treatment: What is the term for the height to which a column of water will rise in a well. - Correct Answer-piezometric surface General Wastewater Treatment: In general, what is the maximum practical lift of pumps - Correct Answer-15-25ft General Wastewater Treatment: Which one of the following valves is the best to use in throttling a flow situation? a. gate b. butterfly c. globe d. ball - Correct Answer-globe General Wastewater Treatment: Which one of the following devices is used to measure water depths in storage facilities? a. transducer b. Venturi meter c. magnetic sensor d. thermistor - Correct Answer-transducer Wastewater Treatment Facilities: The velocity in sanitary sewers is approximately: - Correct Answer-2 ft/s Wastewater Wastewater Wastewater Treatment Facilities: The distance between manholes ranges from - Correct Answer-300-500ft Wastewater Treatment Facilities: What should the flow velocity be through a grit channel - Correct Answer-1.0 ft/s Wastewater Treatment Facilities: Grit washers are used to______ a. remove some of the organic matter b. remove large pieces of wood c. remove rags and eggshells d. remove the odors - Correct Answer-remove some of the organic matter Wastewater Treatment Facilities: The most common flow-measure device for wastewater is a_____ - Correct Answer parshall flume Wastewater Treatment Facilities: The detention time for primary clarifiers usually has a range of_____hr/s - Correct Answer-1.5-2hr Wastewater Treatment Facilities: The effluent from which process is called mixed liquor dary clarification b. primary clarification c. sludge drying bed or pond d. activated sludge - Correct Answer-activated sludge Wastewater Treatment Facilities: Aerobic ponds usually range in depth from ___-____ft - Correct Answer-3-6ft Wastewater Treatment Facilities: Anaerobic ponds usually range in depth from___-___ft - Correct Answer-8-12ft Wastewater Treatment Facilities: Wastewater Wastewater Wastewater Another name for a waste stabilization pond is - Correct Answer-raw wastewater lagoon Wastewater sources & characteristics: Typically what average percent of total solids in a domestic wastewater, both dissolved and suspended, are inorganics - Correct Answer-50% Wastewater sources & characteristics: Typically, what average percent of total solids in domestic wastewater, both dissolved and suspended, are inorganics? - Correct Answer-50% Wastewater sources & characteristics: Approx. what % of the dissolved solids in wastewater are inorganics - Correct Answer 87% Wastewater sources & characteristics: Approximately what % of the dissolved solids in wastewater are organics - Correct Answer-12% Wastewater sources & characteristics: Which organism wold most probably be associated with moderate sludge age and effluent water quality - Correct Answer-free-swimming ciliates Wastewater sources & characteristics: Which organism would most probably be associated with high suspended solids and biochemical oxygen demand (BOD) - Correct Answer-amoebas Wastewater sources & characteristics: High suspended solids and BOD are most probably associated with which type of organisms? - Correct Answer-flagellates Wastewater sources & characteristics: What organism would most likely enhance the penetration of oxygen into the activated sludge - Correct Answer-rotifers Rocks/Screens/Comminutors & Grit Removal: Chlorine gas has a specific gravity of - Correct Answer-2.5 specific gravity Wastewater Rocks/Screens/Comminutors & Grit Removal: Proper flow velocity through a grit channel is indicated when the grit being removed contains a. no organics b. a little organic material c. about half the volume as the grit being removed d. about the same volume as the grit being removed - Correct Answer-a little organic material Sedimentation and Flotation: Surface loading and detention time is a clarifier are directly related to: - Correct Answer flow through a clarifier Sedimentation and Flotation: What is the expected range for the removal of settleable solids from a primary clarifier? - Correct Answer-95-99% Sedimentation and Flotation: What condition will occur if sludge is not pumped out of primary clarifiers at regular intervals? - Correct Answer-clarifier will become septic Sedimentation and Flotation: Secondary clarifiers are usually located after: a. primary clarifier b. an anaerobic digester c. a biological process d. preaeration - Correct Answer-a biological process Sedimentation and Flotation: Filter sloughings are a product of: - Correct Answer-biological action Sedimentation and Flotation: when one liquid is dissolved in another liquid it is called - Correct Answer-an emulsion Sedimentation and Flotation: Wastewater Wastewater Wastewater What is the optimum temperature for digester substances? - Correct Answer-90 degrees F Secondary Treatment: Which one of the following types of wastewater ponds listed below is not classified like the other three? a. polishing pond 2. oxidation pond c. aerobic pond d. raw sewage - Correct Answer-aerobic pond Secondary Treatment: What type of pond would receive wastewater form a secondary treatment system? - Correct Answer-polishing pond Secondary Treatment: The color of the bio-film on a rotating biological contactor undergoing nitrification would appear? - Correct Answer-reddish brown to golden Secondary Treatment: The color of the bio-film on a rotating biological contactor that has high sulfur concentrations would appear - Correct Answer-chalky white Secondary Treatment: Rotating biological contactors have all the following advantages except: a. high sludge production b. they can handle a large range of flows c. power requirements are low d. low operating costs, as they are east to run - Correct Answer-high sludge production Secondary Treatment: A wastewater [plant has a train of three rotating biological contactor (RBC) units. The color of the first RBC is___; the color of the second RBC is_____; and the color of the third RBS C is____ - Correct Answer-(1) gray (2) reddish brown (3) reddish brown Activated Sludge: Wastewater Wastewater Following the activated sludge what process modification is very sensitive to bulking? a. conventional modification b. extended aeration activate sludge c. complex mix aeration d. pure oxygen - Correct Answer-conventional modification Activated Sludge: What modified activated sludge process does not require primary treatment? ete mix aeration b. contact stabilization c. tapered aeration d. step aeration - Correct Answer-contact stabilization Activated Sludge: Primary treatment is not required in which modified activated sludge process? a. step aeration b. complete mix aeration c. tapered aeration d. extended aeration activated sludge - Correct Answer-extended aeration activation sludge Activated Sludge: Mixed liquor is a combination of what 3 things? - Correct Answer-activated sludge in an aeration tank + primary effluent + return sludge/raw wastewater Activated Sludge: In a small package, wastewater treatment plant, the operator should try to keep the dissolved oxygen in the aeration tank at approximately:____mg/L - Correct Answer-2.0 mg/L Activated Sludge: How much of the solids should be wasted each week in the summer form a package wastewater treatment plant for the best quality? - Correct Answer-5% Activated Sludge: Wastewater At what concentration level should dissolved oxygen be maintained during the initial start up of a oxidation ditch? _____? - Correct Answer-2.0 mg/L Activated Sludge: What should be the color of an oxidation ditch that is working properly? - Correct Answer-medium brown to dark brown Activated Sludge: Which one of the following ius the least important in the successful operation of an activated sludge plant? a. BOD b. food entering the process (solids) c. sludge age d. organisms available to treat the wastes - Correct Answer-BOD Activated Sludge: What is the critical factor in any method to control the aeration tank? a. BOD b. F/M c. COD d. DO - Correct Answer-F/M ratio Activated Sludge: What is the most accurate measure of the organisms present in an aerator for treating incoming wastes? - Correct Answer-MLVSS Activated Sludge: Most algae are in the____kingdom - Correct Answer-Protista Kingdom Activated Sludge: Bacteria are in the ______kingdom - Correct Answer-Monera Kingdom Activated Sludge: Grease should be cleaned from walkaways with a stiff brush and a. detergent b. bleach c. trisodium phosphate Wastewater Wastewater d. phosphate-free surfactant - Correct Answer-trisodium phosphate Activated Sludge: Which one of the following types of substance is not soluble in water and has the potential of creating explosive conditions? a. oils and greases b. toxic gases c. flammable oils d. organic toxicants - Correct Answer-flammable oils Activated Sludge: What substance can cause obstructions in the sewer system and may cause anaerobic decomposition where the substances accumulate? a. heavy metals b. oils and greases c. flammable oils d. settleable solids - Correct Answer-settleable solids Activated Sludge: Which one the following types of substances is corrosive and may interfere with biological treatment a. organic toxicants b. cyanide c. acids and alkalies d. heavy metals - Correct Answer-acids and alkalies Activated Sludge: Which one of the following types of substances can be toxic to wastewater plants using biological systems and may adversely affect potable water supplies downstream? a. heavy metals b. toxic gases c. cyanides d. acids and alkalies - Correct Answer-heavy metals Activated Sludge: Where would toxicants least likely cause a problem for a wastewater treatment plant? Wastewater Wastewater a. clarifier b. trickling filter c. sludge digester d. activated sludge - Correct Answer-clarifier Activated Sludge: If an activated sludge plant is hit with a high organic load, what will most like occur in the aeration tank? - Correct Answer-significant decrease in DO Activated Sludge: Of the following, which is the least important nutrient in wastewater treatment for microorganisms to reproduce? a. potassium b. nitrogen c. carbon in organic matter d. phosphorous - Correct Answer-potassium Activated Sludge: Adequate ___BOD, ____nitrogen, ____Phosphorous ratio for microorganisms to grow is usually a. 100:2:1 b. 100:5:1 c. 100:10:3 d. 100:12:5 - Correct Answer-100:5:1 Trickling Filters: Humus sludge is biomass from - Correct Answer-trickling filters Trickling Filters: excessive slime growths on a trickling filter may cause a condition on the the filter called - Correct Answer-ponding Trickling Filters: Another name for slime growth is - Correct Answer-zoogleal film Trickling Filters: Wastewater Wastewater If is not recommended to start up trickling filters in the _____(season) because bacteria are most ofter dormant at this time - Correct Answer-winter Trickling Filters: When the influent load to a wastewater treatment plant changes rapidly, the best test to control purposes is a. total solids b. DO c. BOD d. COD - Correct Answer-COD Trickling Filters: A problem with odors from trickling filters may be solved by: a. reducing the number if weeds b. using masking agents c. applying chlorine d. flooding the filter - Correct Answer-using masking agents Trickling Filters: What can be done to the trickling filter to solve high effluent suspended solids? a. flush out distributor arms b. decrease circulation c. reduce the number of weeds d. flood the filter - Correct Answer-decrease recirculation Rotating Biological Contactors: Approx. how much surface area of a rotating biological contactor is immerses in the wastewater? - Correct Answer-40% Rotating Biological Contactors: How many stages are usually present in the rotating biological contactor process? a. 3 stages b. 4 stages c. 6 stages d. 8 stages - Correct Answer-four stages Rotating Biological Contactors: Wastewater Wastewater Rotating biological contactors are adversely affected by temperatures below_____degree F - Correct Answer-55 degrees F Rotating Biological Contactors: How often should the oil be changed in the speed reducer of a rotating biological contactor? - Correct Answer-every 6 months Rotating Biological Contactors: How often should the motor bearings be greased in a rotating biological contactor unit? - Correct Answer-every 12 months Rotating Biological Contactors: How often should the mainshaft bearings be greased in a rotating biological contactor unit? - Correct Answer-every week Rotating Biological Contactors: How ofter should the drive bearings be greased in a rotating biological contactor unit? - Correct Answer-every week Rotating Biological Contactors: How often should the oil in the chain casing be changed? - Correct Answer-every 3 months Waste Treatment Ponds: Ponds used in series after a trickling filter are sometimes called? - Correct Answer polishing ponds Waste Treatment Ponds: A pond that contains algae and requires the use of compressor is classified as - Correct Answer-an aerobic pond Waste Treatment Ponds: A pond that depends on fermentation, is odorous, and is used mainly for processing industrial wastes is classified as - Correct Answer-an anaerobic pond Waste Treatment Ponds: Wastewater Wastewater A pond that contains oxygen in its upper layers and lacks oxygen in the bottom layer is classified as - Correct Answer-a facultative pond Waste Treatment Ponds: When is the pH in a waste pond the lowest? (Time of day) - Correct Answer-sunrise Waste Treatment Ponds: When is the pH in a waste pond the highest? (time of day) - Correct Answer-around 4:00 PM Waste Treatment Ponds: When is the dissolved oxygen in a waste pond the highest? (Time of day) - Correct Answer-around 400PM Waste Treatment Ponds: Regarding waste pond lab sampling, which parameter is sampled at the influent of the pond? a. pH b. BOD c. DO d. temperature - Correct Answer-BOD Waste Treatment Ponds: How far out from the water's edge should waste pond samples be collected? - Correct Answer-8 ft Waste Treatment Ponds: At what depth should samples be collected from a waste pond? - Correct Answer-1 ft Waste Treatment Ponds: The recommended minimum depth for a waste pond is" - Correct Answer-3 ft Sludge Digestion & Solids Handling: Saprophytic microorganisms are also called: - Correct Answer-acid formers Sludge Digestion & Solids Handling: Wastewater Wastewater Microorganisms that are methane fermenters will only produce in the pH range of - Correct Answer-6.6-7.6 Sludge Digestion & Solids Handling: Digestion is working properly if the volatile solids content of the raw sludge has been reduced by ___-___% - Correct Answer-50-60% Sludge Digestion & Solids Handling: An anaerobic sludge digester should be operated such that________________ - Correct Answer-acid formation is equal to methane formation Sludge Digestion & Solids Handling: The most common imbalance in the operation of an anaerobic sludge digester is - Correct Answer-excess acid fermentation Sludge Digestion & Solids Handling: The most important factor in the high-rate process of anaerobic digestion is: a. DO b. COD c. F/M ration d. mixing - Correct Answer-mixing Sludge Digestion & Solids Handling: Operators should, as a rule, never change the temperature in an anaerobic digester by more than___degrees F/day - Correct Answer-1 degree F/day Sludge Digestion & Solids Handling: What is the optimum temperature range of mesophile bacteria in anaerobic digestion? - Correct Answer-85-100 degrees F Sludge Digestion & Solids Handling: What is the purpose of a draft tube in an anaerobic sludge digester? - Correct Answer directs raw and digested sludge mixture to a heating area Sludge Digestion & Solids Handling: How often should the liquid level be checked on a digester to prevent overfilling? - Correct Answer-once/day Wastewater Wastewater Sludge Digestion & Solids Handling: Typically, an anaerobic digester will produce about 30%-35% by volume of which gas? - Correct Answer-CO2 Sludge Digestion & Solids Handling: How often should flame arresters be service on anaerobic digesters? - Correct Answer every 3 months Sludge Digestion & Solids Handling: how often should the thermal valves be dismantled for service? - Correct Answer once/year Sludge Digestion & Solids Handling: typically, how often should sediment and drip traps be drained in cold water? - Correct Answer-twice a day Sludge Digestion & Solids Handling: Draft tube propeller mixers are subject to corrosion from____ a. nitric acid b. phosphoric acid c. sulfuric acid d. hydrogen sulfide - Correct Answer-hydrogen sulfide Sludge Digestion & Solids Handling: What do corbels provide in an anaerobic digester? - Correct Answer-support for the floating cover when it is at its lowest point Sludge Digestion & Solids Handling: What do roller guides provide in an anaerobic digester? - Correct Answer-they prevent the cover from scraping the sidewall Sludge Digestion & Solids Handling: What do ballast blocks provide in anaerobic digesters? - Correct Answer-stability and proper cover buoyancy Sludge Digestion & Solids Handling: Wastewater Wastewater What do skirts provide in anaerobic digesters? - Correct Answer-they prevent foaming in the annular space Sludge Digestion & Solids Handling: the floating cover on an anaerobic should be inspected how often? - Correct Answer daily Sludge Digestion & Solids Handling: Bacteria in an anaerobic digester will effectively utilize: a. hair b. mineral oils c. gasoline products d. fats - Correct Answer-fats Sludge Digestion & Solids Handling: what would happen if too much sludge was added to an anaerobic digester? - Correct Answer-acid fermentaters would predominate and pH would decrease Sludge Digestion & Solids Handling: The best operation performance for an anaerobic digester is when it is feed a. several times a day b. twice per day c. once per day d. once every other day - Correct Answer-several times a day Sludge Digestion & Solids Handling: The least desirable control method for an anaerobic digester is the use of digester____ a. pH b. CO2 c. volatile-acid-alkalinity ratio d. temperature - Correct Answer-pH Sludge Digestion & Solids Handling: what would be the best solution if the volatile-acid-to-alkalinity ratio increased to 0.3 in a digester due to pumping thin sludge? - Correct Answer-thicken the raw sludge Wastewater Wastewater Wastewater Sludge Digestion & Solids Handling: If a single stage or primary tank has foam in the supernatant due to an "organic overload" in the digester, what is the best solution? - Correct Answer-reduce the feeding rate Sludge Digestion & Solids Handling: What would be the most probable cause for gas leaking through the pressure relief valve on the digester's roof? - Correct Answer-plugged gas line or closed valve Sludge Digestion & Solids Handling: If the manometer indicates the gas pressure in a digester is below normal, what would be the most probable cause? - Correct Answer-too much lime has been added, reducing gas production Sludge Digestion & Solids Handling: If the gas pressure in a digester is lower than normal, what is the most probable cause? - Correct Answer-gas line or hose is leaking Sludge Digestion & Solids Handling: If a wastewater treatment plant has four aerobic digesters operated in series, which tank will exert the highest oxygen demand? - Correct Answer-first tank Sludge Digestion & Solids Handling: Where is the best place to collect scum from wastewater plants that use aerobic digesters? - Correct Answer-primary clarifier Sludge Digestion & Solids Handling: What should the initial depth of sludge from a digester be when it is placed in a sludge drying bed? - Correct Answer-12-18 inches Sludge Digestion & Solids Handling: Operators should use special precautions when placing anaerobically digested sludge on a drying bed because sludge contains what gas? - Correct Answer-methane Sludge Digestion & Solids Handling: What does the wastewater industry call sludge that is only partially digested? Wastewater Wastewater a. gray b. yellow c. green d. brown e. black f. white - Correct Answer-green Odor Control: Hydrogen Sulfide will exist in a system depending on the presence or absence of_____ - Correct Answer-oxygen Odor Control: To what pH should wastewater be raised to halt sulfide production and inhibit sludge growth and biological slimes? - Correct Answer-above 9.0 Odor Control: If the head works in a wastewater treatment plant had an H2S odor, what would be the most likely solution? a. airstream treatment b. correct faulty plant operation c. add treatment chemicals d. remove sludge from grit channel - Correct Answer-add treatment chemicals Odor Control: If the primary sedimentation unit to a wastewater treatment plant has an H2S odor, what would be the most likely solution? a. improve housekeeping b. reduce turbulence c. increase mixing d. remove sludge digester - Correct Answer-remove sludge faster Odor Control: If the sludge drying beds had a decaying odor, what would be the most likely solution? a. increase air in aeration system b. improve operations before digester c. improve housekeeping around drying beds d. chemical addition with counter masking or masking agents - Correct Answer chemical addition with counter masking or masking agents Wastewater Odor Control: If the ponds or lagoons had an ammonia odor, what would be the most likely solution? - Correct Answer-add chemical treatment Enhanced Biological (Nutrient) Control: In the activated sludge system for the process control of effluent suspended solids, what is the primary controlling variable for the desired microbial population? - Correct Answer-the concentration of MLSS Disinfection: The process that uses heat to selectively destroy undesirable organisms is called: - Correct Answer-pasteurization Disinfection: Which chemical in the following list is the strongest disinfectant? a. chlorine b. hypochlorous acid c. hypochlorite acid d. hydrochloric acid - Correct Answer-hypochlorous acid Disinfection: What is the recommended withdrawal of chlorine in pounds from a 100 or 150 lb cylinder in a 24-hr period such that freezing does not occur? - Correct Answer-40 lb Disinfection: If there is a leak from a valve on a sulfur dioxide tank and the lead is found using ammonia, what color will the vapor fumes be? - Correct Answer-white Disinfection: What is the acceptable sulfur dioxide level in mg/L in wastewater plant effluent? - Correct Answer-0.5 mg/L or less Disinfection: What is the ultimate measure of effective chlorination? - Correct Answer-bacteriological result Wastewater Wastewater Solids removal from secondary effluent: Which one of the following methods would not be used to feed DRY chemicals? a. screw feeder b. vibrating trough c. rotating feeder d. plunger feeder - Correct Answer-plunger feeder Solids removal from secondary effluent: Which method would not be used to feed LIQUID chemicals? a. screw feeder b. vibrating trough c. rotating feeder d. plunger feeder - Correct Answer-screw pump Solids removal from secondary effluent: Which type of feeder would most likely feed clear solutions? a. rotameter b. decanter c. orifice d. positive displacement - Correct Answer-rotameter Solids removal from secondary effluent: What type of feeder would always feed a gas? - Correct Answer-direct feed Solids removal from secondary effluent: What is "the" major factor in predicting the performance of wastewater clarifiers? - Correct Answer-solids loading Effluent Disposal: What is the most probable cause for excessive algae in the effluent of a wastewater pond? - Correct Answer-temperature favoring the growth of a particular species of algae Effluent Disposal: If a secondary clarifier has floatable debris in the effluent, what is the most likely cause? - Correct Answer-the clarifier is hydraulically overloaded Effluent Disposal: Wastewater Wastewater Wastewater Because water samples sometimes require repeat or backup tests, the amount of sample that should collected for samples that are preserved and transported for any particular analysis should be at least____times the amount for those analysis - Correct Answer-two Effluent Disposal: Which one of the following parameters can be preserved for later lab analysis? a. nitrate b. pH c. temperature d. dissolved oxygen - Correct Answer-nitrate Wastewater Solids Processing: Which one of the following is not a major solids treatment method? a. thickening b. concentration c/ dewatering d. stabilization - Correct Answer-concentration Wastewater Solids Processing: A solids treatment thickening process method would be a. gravity b. filter presses c. composting d. chemical oxidation - Correct Answer-gravity Wastewater Solids Processing: One solids treatment thickening process would be: a. heat treatment b. flotation c. composting d. belt presses - Correct Answer-flotation Wastewater Solids Processing: Another solids treatment thickening process would be: a. sand drying beds b. vacuum filters c. solids concentration d. composting - Correct Answer-solids concentration Wastewater Wastewater Solids Processing: A solids treatment stabilization process method would be: a. flotation b. gravity c. vacuum filters d. incineration - Correct Answer-incineration Wastewater Solids Processing: A solids treatment dewatering process method would be" a. gravity d. incineration c. composting d. flotation - Correct Answer-incineration Wastewater Solids Processing: Which one of the following solids treatment methods can be classified as both stabilization and dewatering? a. incineration b. wet air oxidation c. lime stabilization d. chemical oxidation - Correct Answer-incineration Wastewater Solids Processing: Name the solids treatment method that has a solids buildup which forms a blanket on the bottom and forces the water out due to compression? - Correct Answer-gravity thickening Wastewater Solids Processing: What is the solids treatment method that aerated the recycles water from the unit under pressure? - Correct Answer-flotation thickening Wastewater Solids Processing: Typically, in the flotation thickening method, how much performance improvement (%) is the amount of solids for waste activated sludge realized when a polymer is added? - Correct Answer-1% Wastewater Solids Processing: Wastewater Wastewater Wastewater What is the solids treatment method that chemically treats the residual flow, then spread evenly over a porous belt? - Correct Answer-solids concentration Wastewater Solids Processing: The solids treatment method usually dewaters solids by mixing them with a bulking agent and then waiting for biological stabilization to occur? - Correct Answer composting Wastewater Solids Processing: The solids treatment method that usually dewaters solids by mixing them with a bulking agent, and then waiting for biological stabilization to occur is called________ - Correct Answer-lime stabilization Wastewater Solids Processing: What is the name of the solids treatment method that maintains a certain pH for at least 2 hrs, then with the final product which can then be applied directly to land is called______ - Correct Answer-thermal treatment Wastewater Solids Processing: What is the solids treatment method that uses a chemicals and mixes the recycled flow with the process residual flow in a reactor? - Correct Answer-chlorine oxidation Wastewater Solids Processing: What solid treatment method first uses chemicals as it conditions the solids and then later in the process, "throws" the solids out of the way is called_______ - Correct Answer-centrifuge Wastewater Solids Processing: This solids treatment method maximizes the reduction of moisture and solids is called_______ - Correct Answer-incineration Wastewater Solids Processing: What solids treatment method removes 100% of the pathogens, water, and organics (UV is not the answer) - Correct Answer-incineration Residual Solids Management: In general, secondary sludges: a. contain 20-25% nonvolatile inorganic matter Wastewater b. are more fibrous c. has less flocculant than primary sludges d. have a density significantly greater than water - Correct Answer-contain 20-25% nonvolatile inorganic matter Residual Solids Management: Name the type of centrifuge that uses a knife or plow insertion to scrap off the "cake" from its walls? - Correct Answer-basket centrifuge Residual Solids Management: which type of centrifuge uses an other screw conveyor to move the solids to the discharge point? - Correct Answer-scroll centrifuge Residual Solids Management: What is the ideal temperature range for methane-forming bacteria in anaerobic digesters? - Correct Answer-94-97 degrees F Residual Solids Management: what type of waste solids would most likely be sent to a rendering reclamation? a. screenings b. grit c. secondary sludge d. scum - Correct Answer-scum Residual Solids Management: which one of the following wastewater solids would most likely never end up on a dedicated land disposal (DLD) site? a. incinerated material b. screenings c. grit d. compost - Correct Answer-compost Residual Solids Management: If a sludge cake consists of 60% solids, where did it mostly likely originate from? - Correct Answer-drying lagoon Water and Wastewater Microbiology" Wastewater Wastewater What type of protozoa is typically associated with a poor treatment process and a young bio-solids age? - Correct Answer-flagellates Water and Wastewater Microbiology" The most common pathogen identified in waterborne disease outbreaks in the United States is_______ - Correct Answer-Giardia Water and Wastewater Microbiology" The major gas produced by aerobic decomposition is:_______ - Correct Answer-carbon dioxide Maintenance: If an induction motor is rated at 40 amps for a full-load current, what will be the most probable starting sequence amps required? - Correct Answer-200-320 amps Maintenance: Motor insulation material comes in four classes and the are based on_______ - Correct Answer-temperature limitation Maintenance: The current imbalance between legs of polyphase motors should never exceed____% - Correct Answer-5% Maintenance: The allowable voltage above or below the value stamped on a motor's nameplates is_____% - Correct Answer-10% Maintenance: The allowable frequency deviation above or below the value stamped on a motor's nameplate is_______% - Correct Answer-5% Maintenance: What would be the cause of a shorted-winding in a motor? - Correct Answer-foreign material in motor Maintenance: Wastewater Wastewater Wastewater What should be the air gap separation between a potable water pipe and the rim of a wastewater tank? - Correct Answer-at least two pipe diameters above the rim Safety: What is the only acceptable breathing device to wear while handling chlorine leaks? - Correct Answer-self-contained breathing apparatus Safety: What type of fire extinguishers should be used on electrical fires? - Correct Answer carbon dioxide Safety: What document provides a profile of hazardous substances and/or mixtures? - Correct Answer-material safety data sheet MSDS Safety: An atmosphere is defined as oxygen deficient if it contains less than what % oxygen by volume? - Correct Answer-19.5% Safety: What class of fire involves sodium and magnesium? - Correct Answer-class D Safety: What is the proper emergency chlorine kit for a 1-ton chlorine cylinder? - Correct Answer-emergency kit B Basic Chemistry: The specific gravity standard for gases is_______ - Correct Answer-air Basic Chemistry: The standard for gases has a density of - Correct Answer-1.29 g/L Basic Chemistry: How many steps are the in coagulation? - Correct Answer-3 steps Basic Chemistry: Wastewater Low-temperature water can be compensated for when using alum by______ - Correct Answer-increasing the alum dosage Basic Chemistry: When an electrolyte is dissolved in water to form an ion, the ion is said to be________ - Correct Answer-dissociated Basic Chemistry: Which one of the following species is ozone? a. O2 (+3) b. NO2 c. O3 d. N2O - Correct Answer-O3 Basic Chemistry: name the laboratory glassware that can be used to heat liquids in an open flame? - Correct Answer-flasks Basic Chemistry: When inserting glass tubing into a rubber hose or stopper, never use____for lubrication - Correct Answer-oil Basic Chemistry: Electrical units operating in areas exposed to flammable vapors should_______ - Correct Answer-be explosion-proof Basic Chemistry: Usually, what is the % accuracy of a graduated cylinder and burette? - Correct Answer 1% Basic Chemistry: The clarity of a trickling filter's effluent is considered good when the "Secchi" disk can be read at a level of___ft - Correct Answer-6ft Basic Chemistry: The clarity of the effluent from an activated sludge process is considered good when the "Secchi" disk cab be read at a level of_______ft - Correct Answer-6ft Wastewater Wastewater Basic Chemistry: The clarity of a chlorine contact basin's effluent is considered good when the "Secchi" disk can be read at a level of___ft - Correct Answer-6ft Wastewater