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A comprehensive set of questions and answers for levels 1 and 2 exam preparation in wastewater treatment plant operations. It covers various aspects of wastewater treatment, including solids measurement, pond operation, activated sludge process, disinfection, and pump maintenance. A valuable resource for students and professionals seeking to enhance their knowledge and understanding of wastewater treatment principles and practices.
Typology: Exams
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An Imhoff cone is used to measure________solids. A. suspended B. colloidal C. volatile D. settleable - CORRECT-ANSWERSD. settleable (Operation of Wastewater Treatment Plants, Volume 1 by Kenneth D. Kerri) The function of sodium nitrate, when added to a waste stabilization pond - CORRECT-ANSWERSSodium nitrate may be used to minimize odor problems during brief overload conditions in an un-aerated waste stabilization pond. (pg 31 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) The normal color of a wastewater treatment pond, especially during the summer months - CORRECT-ANSWERSGreen, due to the growth of algae near the pond surface (pg 32 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) typical F/M ratio in the conventional activated sludge process - CORRECT- ANSWERS.2-.5 F/M (pg 32 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) Excessive tan "greasy" foam can indicate what in the activated sludge process? - CORRECT-ANSWERSPossible Nocardia infestation (pg 36 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy)
White crispy billowy foam can indicate what in the activated sludge process?
This chemical, when present in wastewater effluent, can cause serious interference with disinfection - CORRECT-ANSWERSnitrite, produced during nitrification, can cause high chlorine demand (pg 58 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) The most commonly used chemical for effluent dechlorination - CORRECT- ANSWERSsulfur dioxide (pg 60 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) The characteristics (values present) of typical domestic raw sewage: BOD Suspended Solids Total Solids - CORRECT-ANSWERSBOD= 150-250 mg/L Suspended Solids= 175-275 mg/L Total Solids= 1000 mg/L or .1% (pg 69 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) The relationship between the COD and BOD levels in raw domestic sewage - CORRECT-ANSWERSCOD is approximately 2.2 times the BOD content (pg 69 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) Standard bottle volume for BOD5 test - CORRECT-ANSWERS300 ml What should be done if the pH and DO in a wastewater stabilization pond are dropping dangerously low? - CORRECT-ANSWERSCheck the loading. The loading may need to be reduced or stopped. Recirculating the water from a healthy pond to the problem pond should help the situation. Recirculation from outlet to inlet areas is beneficial for seeding, DO, and mixing. (question 9.6L, Operation of Wastewater Treatment Plants, Volume 1 by Kenneth D. Kerri) What factors would you consider when developing an operating strategy for wastewater stabilization ponds? - CORRECT-ANSWERS1. Maintain constant water elevations in the ponds
(Module #24, Gas Chlorination, Pennsylvania Department of Environmental Protection) True or False: Both gas and liquid chlorine can be drawn from one ton cylinders. - CORRECT-ANSWERSTrue. Ton containers most commonly have two outlet connections, the top one for gas withdrawal and the bottom one for liquid withdrawal. It is very important that the two valves be aligned vertically so that one valve may be used for gas and the other for liquid. The reason being that each valve is connected to a steel tube, commonly called an eduction pipe, that extends to the outer edge of the inside container. This way, when they are in vertically alignment one can be used solely for gas, and the other one solely for liquid. (Chlorine Handling Manual, Hydro Instruments) What is "Static Head?" - CORRECT-ANSWERSWhen water is not moving, the vertical distance (in feet or meters) from a reference point to the water surface is the static head. The total vertical distance that a pump raises water. (Water Programs glossary, Sacramento State) What is "Friction Head?" - CORRECT-ANSWERSFriction head is the head required to overcome the friction losses in the piping, valves, and fittings in the system prior to delivery. The smaller the size piping the greater the friction head loss. (Centrifugal Pump Selection Part 1: Total Head, Gate, Inc.) What is "Velocity Head?" - CORRECT-ANSWERSThe velocity head is energy of a liquid as a result of its motion at some velocity. The velocity at the suction of the pump is different from the velocity at the discharge of the pump because the sizing of the suction and discharge piping is different. (Centrifugal Pump Selection Part 1: Total Head, Gate, Inc.) True or False: Methane is a colorless and extremely flammable gas that can explode when mixed with air - CORRECT-ANSWERSTrue True or False: Chlorine gas is explosive. - CORRECT-ANSWERSFalse. Chlorine itself is not flammable, but it can react explosively or form explosive compounds with other chemicals. Chlorine gas is highly toxic.
What is the function of a shaft sleeve in relation to pumps? - CORRECT- ANSWERSIt is a replaceable wearing surface that protects the pump shaft. (pg 79 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) Distributes seal water uniformly around the pump shaft. - CORRECT- ANSWERSLantern Ring (pg 80 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) True or False: A supply line from a public water source is connected to furnish water for the pump packing of a centrifugal pump at a WWTP. This situation is a cross connection hazard. - CORRECT-ANSWERSTrue. Should a supply line be connected directly to the pump, a serious cross-connection hazard will be created, which is potentially capable of permitting hazardous materials to enter the water system. Accepted practice requires that an air gap be provided at the service connection with a small pump drawing from the receiving tank to supply the water seal. (Backflow Prevention and Cross-Connection Control, State of Ohio EPA) The flow of electric current is measured in this unit. - CORRECT- ANSWERSAmperes or "amps" (pg 81 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) A three phase pump motor is rotating the wrong direction after repairing and replacing it. What is a likely solution to this problem? - CORRECT- ANSWERSSwitch any two of the three electrical leads to the motor. (pg 81 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) What are the advantages of mechanical seals on pumps? - CORRECT- ANSWERSMechanical seals are much more durable than packing seals and are the better choice for long-term operation of pumps. Also, packing gland style seals leak much more than mechanical seals. A _____ flume is widely used for measuring wastewater flow. - CORRECT- ANSWERSParshall
(Operation of Wastewater Treatment Plants, Volume 1 by Kenneth D. Kerri) Velocity of flow in a grit channel must be reduced to a range of ____ to _____ fps in order for grit to properly settle. - CORRECT-ANSWERS.7 to 1.4 fps (Operation of Wastewater Treatment Plants, Volume 1, 3. by Kenneth D. Kerri) With respect to grit removal systems, grit is traditionally defined as particles larger than 0.21mm (0.008 in) (65 mesh) and with a specific gravity of greater than ______. - CORRECT-ANSWERSspecific gravity of grit is 2.65 or greater (EPA Wastewater Technology Fact Sheet, Screening and Grit Removal) Mechanically cleaned bar screens feature bars set at _____ to _____ degrees from vertical. - CORRECT-ANSWERSBars set at 0 to 30 degrees from vertical. (EPA Wastewater Technology Fact Sheet, Screening and Grit Removal) Manually cleaned bar screens feature bars set at _____ to _____ degrees from vertical to facilitate cleaning. - CORRECT-ANSWERSBars set at 30 to 45 degrees from vertical to facilitate cleaning. Primarily used in older or smaller treatment facilities, or in bypass channels. (EPA Wastewater Technology Fact Sheet, Screening and Grit Removal) The BOD test measures the amount of oxygen that is consumed while a sample of wastewater is incubated in the dark at a temperature of _____ °C for _____ days (± _____ hours) - CORRECT-ANSWERSThe BOD test measures the amount of oxygen that is consumed while a sample of wastewater is incubated in the dark at a temperature of 20 °C for 5 days (± 3 hours) (USGS Book 9-A7 (Third Edition) Five-Day Biochemical Oxygen Demand) What do we mean by Total Dissolved Solids (TDS) in wastewater? - CORRECT-ANSWERSAll the solids that cannot be filtered out of the water (New Mexico Wastewater Systems Operator Certification Study Manual) What do we mean by Total Suspended Solids (TSS) in wastewater? - CORRECT-ANSWERSAll the solids that can be filtered out including: settleable solids and non-settleable solids (colloids) (New Mexico Wastewater Systems Operator Certification Study Manual)
The wastewater in a sewer line should move at a speed that will prevent the deposition and buildup of solids in the sewer; this is called a "scouring velocity". A minimum velocity of _____ fps provides this scouring or self- cleaning velocity. - CORRECT-ANSWERSThe wastewater in a sewer line should move at a speed that will prevent the deposition and buildup of solids in the sewer; this is called a "scouring velocity". A minimum velocity of 2 fps provides this scouring or self-cleaning velocity. (New Mexico Wastewater Systems Operator Certification Study Manual) Wastewater treatment ponds: Facultative ponds are _____ feet deep - CORRECT-ANSWERSFacultative ponds are 4-8 feet deep (New Mexico Wastewater Systems Operator Certification Study Manual) Wastewater treatment ponds: Anaerobic ponds are _____ feet deep - CORRECT-ANSWERSAnaerobic ponds are >14 feet in depth (New Mexico Wastewater Systems Operator Certification Study Manual) Typical Primary Clarifier Efficiencies: Settleable Solids expected removal efficiency _____% to _____% - CORRECT-ANSWERSTypical Primary Clarifier Efficiencies: Settleable Solids expected removal efficiency 95% to 99% (New Mexico Wastewater Systems Operator Certification Study Manual) Typical Primary Clarifier Efficiencies: Suspended Solids expected removal efficiency _____% to _____% - CORRECT-ANSWERSTypical Primary Clarifier Efficiencies: Suspended Solids expected removal efficiency 40% to 60% (New Mexico Wastewater Systems Operator Certification Study Manual) Typical Primary Clarifier Efficiencies: Total Solids expected removal efficiency _____% to _____% - CORRECT-ANSWERSTypical Primary Clarifier Efficiencies: Total Solids expected removal efficiency 10% to 15% (New Mexico Wastewater Systems Operator Certification Study Manual) Typical Primary Clarifier Efficiencies: Biochemical Oxygen Demand (BOD) expected removal efficiency _____% to _____% - CORRECT-ANSWERSTypical Primary Clarifier Efficiencies: Biochemical Oxygen Demand (BOD) expected removal efficiency 20% to 50%
(New Mexico Wastewater Systems Operator Certification Study Manual) Sludge septicity in the primary clarifier can be recognized when: A. sludge gasification causes large clumps of sludge to float on the water surface. B. Primary clarifier foam is black C. The Specific Oxygen Uptake Rate (SOUR) in the primary clarifier is greater than 3000 mg O2/L/hr D. The sludge contains from 4.0 to 8.0 percent dry solids in TS laboratory testing E. All of the above - CORRECT-ANSWERSA. sludge gasification causes large clumps of sludge to float on the water surface. Pump cavitation may be caused by: A. Loss of discharge pressure due to open hy-drants or line breaks B. Closed suction valve C. Obstruction in the suction line D. Low suction head due to drop in water level E. All of the above - CORRECT-ANSWERSE. All of the above (New Mexico Wastewater Systems Operator Certification Study Manual) A minimum dissolved oxygen (D.O.) level of _____ mg/L is recommended in the aeration tank for most basic types of activated sludge processes. - CORRECT-ANSWERSA minimum dissolved oxygen (D.O.) level of 1.0 mg/L is recommended in the aeration tank for most basic types of activated sludge processes. Maintaining > 1.0 mg/L of D.O. contributes to establishing a favorable environment for the organisms, which produces the desired type of organism and the desired level of activity. (New Mexico Wastewater Systems Operator Certification Study Manual) If the D.O. in the aeration tank is allowed to drop too low for long periods, undesirable organisms, such as ____________________________ may develop and overtake the process. - CORRECT-ANSWERSIf the D.O. in the aeration
tank is allowed to drop too low for long periods, undesirable organisms, such as filamentous type bacteria may develop and overtake the process. (New Mexico Wastewater Systems Operator Certification Study Manual) Typical operating parameters for conventional activated sludge systems: Detention time in aeration basin = _____ hrs - CORRECT-ANSWERSTypical operating parameters for conventional activated sludge systems: Detention time in aeration basin = 4-8 hrs (New Mexico Wastewater Systems Operator Certification Study Manual) Total solids consist of _____ and _____ solids, both of which contain organic and inorganic matter. - CORRECT-ANSWERSTotal solids consist of dissolved and suspended solids, both of which contain organic and inorganic matter. (Operation of Wastewater Treatment Plants, Volume 1 by Kenneth D. Kerri) Typical operating parameters for conventional activated sludge systems: MLSS in aeration basin = _____-_____ mg/L - CORRECT-ANSWERSTypical operating parameters for conventional activated sludge systems: MLSS in aeration basin = 1000-4000 mg/L What is the main difference between sludge from primary and secondary clarifiers? - CORRECT-ANSWERSThe main difference between the sludge from primary and secondary clarifiers is that the primary sludge is usually denser than secondary sludge. (Operation of Wastewater Treatment Plants, Volume 1, question 5.0A by Kenneth D. Kerri) What are some causes of floating sludge (bulking) in a primary clarifier? - CORRECT-ANSWERS• Sludge decomposing in tank, lifted by gasification
What are some causes of black and odorous septic wastewater in primary clarifier effluent? - CORRECT-ANSWERS• Improper sludge removal
(Operation of Wastewater Treatment Plants, Volume 1, section 6.4B by Kenneth D. Kerri) The tiny, gnat-sized filter fly is known also as _____? - CORRECT- ANSWERSPsychoda (Operation of Wastewater Treatment Plants, Volume 1, section 6. by Kenneth D. Kerri) Trickling filter flies can be controlled by what methods? - CORRECT- ANSWERS1. Increasing the recirculation rate
For rotating biological contactors, what is the approximate percentage of media surface immersed in wastewater while in operation? - CORRECT- ANSWERS40% (Operation of Wastewater Treatment Plants, Volume 1, section 7. by Kenneth D. Kerri) Why is the RBC process divided into four or more stages? - CORRECT- ANSWERSThe RBC process is divided into four or more stages to increase the effectiveness of a given amount of media surface area. Organisms on the first-stage media are exposed to high levels of BOD and reduce the BOD at a high rate. As the BOD levels decrease from stage to stage, the rate at which the organisms can remove BOD decreases and nitrification starts. (Operation of Wastewater Treatment Plants, Volume 1, section 7.0B by Kenneth D. Kerri) Nitrification in nature is a two-step oxidation process of ammonium (NH4+) or ammonia (NH3) to nitrate (NO3−) catalyzed by two ubiquitous bacterial groups. The first reaction is oxidation of ammonium to nitrite by ammonia oxidizing bacteria represented by the (a.)______ genus. The second reaction is oxidation of nitrite (NO2−) to nitrate by nitrite-oxidizing bacteria, represented by the (b.) ______ genus. - CORRECT-ANSWERS(a.) Nitrosomonas, (b.) Nitrobacter _______ is an aerobic process in which bacteria change the ammonia and organic nitrogen in wastewater into oxidized nitrogen (usually nitrate). The second-stage BOD is sometimes referred to as the "nitrogenous BOD" (first- stage BOD is called the "carbonaceous BOD"). - CORRECT- ANSWERSNitrification is an aerobic process in which bacteria change the ammonia and organic nitrogen in wastewater into oxidized nitrogen (usually nitrate). The second-stage BOD is sometimes referred to as the "nitrogenous BOD" (first-stage BOD is called the "carbonaceous BOD"). (Operation of Wastewater Treatment Plants, Volume 1, section 7. by Kenneth D. Kerri) ______ is the anoxic biological reduction of nitrate nitrogen to nitrogen gas. - CORRECT-ANSWERSDenitrification is the anoxic biological reduction of nitrate nitrogen to nitrogen gas. In secondary clarifiers the nitrogen bubbles produced as a result of denitrification can attach to the biological floc and float the floc to the surface. This condition is often the cause of rising sludge. (Operation of Wastewater Treatment Plants, Volume 1, section 7. by Kenneth D. Kerri)
The ________ stage is a stage of decomposition that occurs in the biological treatment processes when aerobic bacteria, using dissolved oxygen, change carbon compounds to carbon dioxide. - CORRECT-ANSWERSThe carbonaceous stage is a stage of decomposition that occurs in the biological treatment processes when aerobic bacteria, using dissolved oxygen, change carbon compounds to carbon dioxide. (Operation of Wastewater Treatment Plants, Volume 1, section 7. by Kenneth D. Kerri) If the DO is too high in an aeration basin, ____________ may form and the secondary clarification process may not be able to remove the _________. - CORRECT-ANSWERSIf the DO is too high in an aeration basin, "pinpoint" floc may form and the secondary clarification process may not be able to remove the "pin" floc. (Operation of Wastewater Treatment Plants, Volume 1, section 8. by Kenneth D. Kerri) At what point of the day do wastewater stabilization ponds have the lowest pH? - CORRECT-ANSWERSLate night & early morning. Diurnal variations of both pH and dissolved oxygen are found in wastewater treatment ponds. During the day, algae use carbon dioxide which raises the pH while at night they produce carbon dioxide and the pH is lowered. (Operation of Wastewater Treatment Plants, Volume 1, section 9. by Kenneth D. Kerri) How is oxygen produced by algae? - CORRECT-ANSWERSAlgae produce oxygen from the oxygen in the carbon dioxide molecule (CO2) through photosynthesis (Operation of Wastewater Treatment Plants, Volume 1, section 9.3A by Kenneth D. Kerri) True or False: A facultative treatment pond is seeded with specially selected algae to optimize the treatment process for the climate and conditions. - CORRECT-ANSWERSFalse. Algae simply appear in a pond on their own without seeding. They are found in soil, water, and air and multiply under favorable conditions. (Operation of Wastewater Treatment Plants, Volume 1, section 9.3B by Kenneth D. Kerri)
What does a definite green color in a treatment pond indicate? - CORRECT- ANSWERSA definite green color in a pond indicates a flourishing algal population and is a good sign. (Operation of Wastewater Treatment Plants, Volume 1, section 9.5C by Kenneth D. Kerri) When should a wastewater treatment pond be started? - CORRECT- ANSWERSPonds should be started during the warmer months because higher temperatures are associated with efficient treatment processes. (Operation of Wastewater Treatment Plants, Volume 1, section 9.5B by Kenneth D. Kerri) What should be done if the pH and DO in a pond are dropping dangerously low? - CORRECT-ANSWERSCheck the loading. The loading may need to be reduced or stopped. Recirculating the water from a healthy pond to the problem pond should help the situation. Recirculation from outlet to inlet areas is beneficial for seeding, DO, and mixing. (Operation of Wastewater Treatment Plants, Volume 1, section 9.6L by Kenneth D. Kerri) What is the maximum daily withdrawal rate of chlorine gas used for wastewater disinfection, from a one ton cylinder? - CORRECT-ANSWERS lbs. The maximum withdrawal rate of chlorine gas from a 100/150 pound cylinder is 40 pounds per day; for a ton container, this rate is 400 pounds per day. True or False: pH generally will be affected significantly by a clarifier. - CORRECT-ANSWERSFalse. pH generally will NOT be affected significantly by a clarifier. (Operation of Wastewater Treatment Plants, Volume 1, comprehensive review questions # by Kenneth D. Kerri) True or False: Be sure to overlubricate clarifier equipment. - CORRECT- ANSWERSFalse. Be sure to NOT overlubricate clarifier equipment. (Operation of Wastewater Treatment Plants, Volume 1, comprehensive review questions
by Kenneth D. Kerri) True or False: Trickling filters with plastic media may be loaded at much higher rates than those with rock media without developing plugging, ponding, fly, or odor problems. - CORRECT-ANSWERSTrue.
(Operation of Wastewater Treatment Plants, Volume 1, comprehensive review questions # by Kenneth D. Kerri) True or False: When starting a trickling filter, slime growth will start to develop on the filter media immediately. - CORRECT-ANSWERSFalse. It will only appear after several days. (Operation of Wastewater Treatment Plants, Volume 1, comprehensive review questions # by Kenneth D. Kerri) Which treatment units in a wastewater treament plant are designed and operated to remove sludge and scum? A. Headworks basins B. Pre-aeration treatment units C. Preliminary treatment units D. Primary treatment units - CORRECT-ANSWERSD. Primary treatment units (Operation of Wastewater Treatment Plants, Volume 1, comprehensive review questions # by Kenneth D. Kerri) When evaluating trickling filter operation records, operators should adjust the process according to which main principle?
(Operation of Wastewater Treatment Plants, Volume 1, comprehensive review questions # by Kenneth D. Kerri) How can foaming be controlled in an aeration tank?
first aliquot of a composite sample is collected (i.e. when the composite sampler starts collecting a composite sample). (PA Dept. of Environmental Protection, BOD doc) Drying oven temp to determine Total Solids in sample - CORRECT- ANSWERS103-105 degrees C ("Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) Drying oven temp to determine Total Dissolved Solids (TDS) in sample - CORRECT-ANSWERS180 +/- 2 degrees C ("Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) Drying oven temp to determine Total Suspended Solids (TSS) in sample - CORRECT-ANSWERS103-105 degrees C ("Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) Chemical used to dechlorinate samples for BOD testing - CORRECT- ANSWERSSodium Sulfite (pg 76 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) At a WWTP, what can the following color codes on piping indicate? Brown Orange Green Blue Gray Yellow Purple - CORRECT-ANSWERSBrown=Sludge Orange=Natural Gas/Digester Gas Green=Compressed air Blue=Water Gray=Wastewater Yellow=Chlorine Purple=Reuse (pg 83 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) Classification of fires; used to determine the type of extinguisher: Wood, paper, rubbish, etc.
Oil, solvents, gasoline, etc. Electrical - CORRECT-ANSWERSWood, paper, rubbish, etc.= Class A Oil, solvents, gasoline, etc.= Class B Electrical= Class C (pg 83 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) The volume of screenings typically removed from raw sewage per million gallons (MG) - CORRECT-ANSWERS.5-5 cu. ft. per MG (pg 7 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) The name of the flow equation used to estimate flow in gravity sewers. - CORRECT-ANSWERSManning equation. The cfs flow can be calculated when pipe diameter, depth of flow, pipe slope, and pipe roughness are provided. (pg 9 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) What is CMOM? - CORRECT-ANSWERSChecklist and guide developed by the EPA to evaluate a wastewater Collection system's Management, Operation, and Maintenance activities (pg 12 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) Primary goal of CMOM program - CORRECT-ANSWERSBetter management and operation and to prevent sanitary sewer overflows. (pg 12 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) Typical removal efficiency of BOD in primary treatment - CORRECT- ANSWERS20-30% (pg 13 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) Typical removal efficiency of Total Suspended Solids (TSS) in primary treatment - CORRECT-ANSWERS40-60% (pg 13 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy)
Typical removal efficiency of Settleable Solids in primary treatment - CORRECT-ANSWERSgreater than 90% (pg 13 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) What is the percentage of Total Solids in typical primary clarifier sludge? - CORRECT-ANSWERS3-7% (pg 15 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) What is the percentage of Volatile Solids in typical primary clarifier sludge? - CORRECT-ANSWERS65-75% (pg 15 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) Mixing of an anaerobic digester has two important functions. - CORRECT- ANSWERS1. Distribution of food throughout the digester
The optimal range of pH for anaerobic digestion - CORRECT-ANSWERS6.8 - 7.2 (pg 17 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) Symptoms that indicate an anaerobic digester is approaching "sour" condition - CORRECT-ANSWERSTotal alkalinity of the sludge decreases (first indication) Volatile Acid content of the sludge increases Methane gas production decreases, while CO2 content of gas increases pH drops below 6 and possible foaming (pg 18 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) Gasses that make up anaerobic digester gas - CORRECT-ANSWERSMethane approx 70% Carbon Dioxide approx 30% Hydrogen, nitrogen, and hydrogen sulfide are also present in small amounts. (pg 19 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) operational temp of most (mesophilic) anaerobic digesters - CORRECT- ANSWERS90-100 degrees F (pg 21 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) The pH of an aerobic digester can be lowered by these byproducts of aerobic biological activity - CORRECT-ANSWERSCarbon Dioxide, produced during normal aerobic respiration Nitric Acid, produced during the process of nitrification (pg 22 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) Pathogens associated with sewage sludge - CORRECT-ANSWERSSalmonella bacteria
Enteric (intestinal) viruses Helminth ova (eggs of parasitic worms) (pg 26 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) Polymer terminology: "aging" - CORRECT-ANSWERSThe 30-90 minutes required for polymer to unfold and activate in freshly prepared feed solutions (pg 28 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) Polymer terminology: feeding polymer "neat" - CORRECT-ANSWERSpolymer fed directly, without dilution (pg 28 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) Regulations that govern the use and disposal of sewage sludge - CORRECT- ANSWERS40 CFR (Code of Federal Regulations) Part 503, often referred to as "Part 503." (pg 28 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy) Organic loading to a wastewater treatment pond is expressed in these units - CORRECT-ANSWERSPounds of BOD per day per acre (pg 29 "Wastewater Treatment Flash CERT!" 2013 second edition, Daniel W. Lundy)