Wastewater Treatment Study Guide, Exams of Water and Wastewater Engineering

Download Wastewater Treatment Study Guide and more Exams Water and Wastewater Engineering in PDF only on Docsity! Wastewater Study Guide Texas Wastewater Treatment Study Guide Exam Questions Containing 200 Terms with Definitive Solutions 2024- 2025. (Dark Back Ground for better Visibility and eye Care) The name of the State Agency responsible for enforcing pollution control laws in Texas is - a. Texas Water Development Board Wastewater Study Guide b. Texas Water Commission c. Texas Section of EPA d. Texas Commission on Environmental Quality e. Texas Water Resource and Conservation Commission - Answer: D The term pathogenic means - a. Aerobic Bacteria b. Anaerobic Bacteria c. Fecal Matter d. Coliform Bacteria e. Capable of Causing Disease - Answer: E The minimum separation between sewer lines and potable water lines is - a. 5 feet b. 7 feet c. 9 feet d. 11 feet e. 24 feet - Answer: C A licensed wastewater operator is a professional who - a. Consistently does the best job possible b. Practices personal safety c. Strives to improve job knowledge d. Strives to keep the plant and collection system in the best appearance and working order Wastewater Study Guide b. Poly Vinyl Chloride (PVC) c. Ductile Iron d. Stainless Steel e. Both a & b - Answer: E Before entering a confined space a worker should - a. Use approved monitoring device and check for the presence of dangerous gases b. Ventilate the space with a blower c. Wear a safety harness and attach a life line d. Enter the confined space even if another co-worker in not present e. a, b, & c - Answer: E A properly designed and operated primary sedimentation tank should remove ______ percent of incoming BOD? a. 10 to 15 % b. 20 to 30 % c. 30 to 40 % d. 35 to 50% e. None of the above - Answer: C Which device may be used to determine the level of sewage in a lift station? a. Air bubbler tube b. Parshall Flume c. Altitude Valve d. Air Actuated Valve e. All the above - Answer: A Wastewater Study Guide What is the most important role of aerobic bacteria in the treatment of wastewater? a. Enhance organic matter b. Decompose organic matter c. Introduce workers to dangerous diseases d. Enhance oxygen production e. Produces Odor and Offensive Smells - Answer: B The hydraulic loading of a trickling filter may be determined by - a. BOD and depth of filter media b. Organic loading and filter volume c. Total pounds of BOD removed d. Total pounds of suspended solids applied daily e. Flow rate and filter area - Answer: E Which of the following is typically used to dewater sludge? a. Belt press b. Drying beds c. Solid bowl centrifuge d. Gravity thickener e. All the above - Answer: E Which of the following are the most important to providing adequate sewage treatment in a stabilization pond? Wastewater Study Guide a. Protozoa, rotifers and turtles b. Sunlight, algae, bacteria, and Time c. Aeration, Sedimentation, and Chlorine Contact d. Nitrification, Sedimentation, Recirculation, & Detention e. Blowers, Diffusers, & Ultraviolet Disinfection - Answer: B Offensive and objectionable odors which sometimes occur in trickling filters usually indicate that - a. The filter should be backwashed b. The flow is too great for the filter area c. Chlorinator is not working properly & algae is growing on the media d. Septic conditions are present e. All the above - Answer: D Dissolved Oxygen (DO) in the aeration tank of an activated sludge plant should be maintained at or about - a. 1 to 2 mg/L b. 2 to 3 mg/L c. 2 to 4 mg/L d. 4 to 6 mg/L e. 0.5 to 0.75 mg/L - Answer: C Which of the following would contribute to infiltration in a collection system? a. Breaks in the main lines b. High ground water levels Wastewater Study Guide Point source discharges are - a. Discharges that show up in the system and at the plant from an unidentified or explained source. b. Discharges that come from pipes or ditches that are monitored, controlled and inspected. c. Discharges that have Intermittent, dispersed flows having little or no control. d. Discharges that contribute greatly to the BOD and COD and typically come from dairies and farm related activities. e. None of the above - Answer: B Non-Point Source Discharges are - a. Discharges that have Intermittent, dispersed flows having little or no control. b. Discharges that come from pipes or ditches that are monitored, controlled and inspected. c. Discharges that come from municipalities, or industry. d. Discharges that are high in BOD & typically come from food establishments. e. None of the above - Answer: A The Texas Water Code establishes the protection of water quality and quantity of the state by - a. Limiting what farmers can use for irrigation. Wastewater Study Guide b. Establishing minimum standards for how close cattle or dairy operations can be to a lake or receiving stream. c. Setting stream standards, issues permits for discharges, identifies non-point source controls, and establishes water reuse. d. Making it almost impossible to meet effluent discharge standards. e. None of the above. - Answer: C The wastewater plant operator is primarily responsible for - a. Treating potable water to Safe Water Standards b. Treating wastewater discharged from the community c. Developing, implementing, and complying with budget d. Collection and Containment of all non-point source water e. Traffic law compliance while vehicles are on plant property - Answer: B Chapter ____ of the Texas Water Code is the state law controlling water pollution and _____ authority to control discharges in Texas. a. Chapter 30 & Texas Commission on Environmental Quality b. Chapter 30 & Texas Water Commission c. Chapter 26 & Texas Commission on Environmental Quality d. Chapter 26 & Texas Water Commission e. Chapter 290 & Texas Commission on Environmental Quality - Answer: C The Texas Commission on Environmental Quality can revoke an Operator's license if the operator - a. Causes a permit violation, Falsifies records, or Neglects their duty Wastewater Study Guide b. Causes a permit violation, is convicted of a Felony, or DWI c. Knowingly violates plant permit under authority of the mayor d. Causes an environmental impact event under direction of supervisor e. TCEQ cannot revoke a license once it has been issued - Answer: A If an accidental discharge, bypass, or spill (SSO) of wastewater occurs the responsible party MUST notify TCEQ regional offices within ______ hours. a. 12 hours b. 24 hours c. 36 hours d. 48 hours e. 72 hours - Answer: B Aerobic Bacteria require _______ in the water for their metabolism a. Nitrogen b. Hydrogen c. Oxygen d. Either aerobic or anaerobic conditions e. Cannot live with O2 present - Answer: C Anaerobic Bacteria require _______ in the water for their metabolism a. Nitrogen b. Hydrogen c. Oxygen d. Either aerobic or anaerobic conditions Wastewater Study Guide e. Carbon Dioxide, Methane, & Ammonia - Answer: A The majority of Dissolved Oxygen in raw sewage come from _________ a. Inorganic Decomposition b. Facultative Decomposition c. Organic Decomposition d. Organic Solids e. Potable Drinking Water - Answer: E Each person contributes approximately ______ lbs of BOD to the system daily. a. 0.17 b. 0.71 c. 1.7 d. 17 e. 17.4 - Answer: A Sources of wastewater include - a. Domestic, Storm Water, Commercial, Food Processing, Agricultural, & Industrial. b. Domestic, Storm Water, Commercial, Agricultural & Hazardous c. Domestic, Commercial, Agricultural, & Industrial d. Commercial, Storm Water, Food Processing, & Industrial e. Domestic, Commercial, Agricultural, & Industrial - Answer: A Wastewater Study Guide A sewer manhole provides access into the system for cleaning or service. A manhole is located - a. At changes in pipe composition, grade, direction & intersection b. At changes in pipe composition, grade, direction, & intersection c. At changes in alignment, diameter, grade, direction, & intersection d. At the discretion of the engineer & public works director e. Where a sewer clean out is not feasible - Answer: C New manholes must have an inside diameter of at least _______ feet and the entry access must be at least ______ inches. a. 3 feet and 24 inches b. 4 feet and 24 inches c. 4 feet and 30 inches d. 5 feet and 30 inches e. There is no current standard or requirement - Answer: B In the past _____ was used to construct manholes. This product is prohibited for construction or grading today. a. Concrete b. Fiberglass c. Poly Vinyl Chloride (PVC) d. Brick & Mortar e. Ductile Iron or Cast - Answer: D Vitrified clay and Poly Vinyl Chloride (PVC) are the most common pipe Wastewater Study Guide materials used for sewer lines but other materials are available such as - a. Ductile Iron, Cast Iron, Acrylonitrile Butadiene Styrene(ABS) Concrete, Polyethylene & Asbestos Concrete b. Stainless Steel, Galvanized, Fiberglass, Orangeburg & Copper c. Ductile Iron, Cast Iron, Stainless Steel, & Galvanized d. Poly, SDR-35, Orangeburg, C-900, & Schedule 80 PVC e. Both a & b - Answer: A In order to maintain two (2) feet per second velocity in a six (6) inch main line, the fall per 100 feet of pipe will be - a. 0.25 percent or 3 inches b. 0.33 percent or 4 inches c. 0.50 percent or 6 inches d. 0.75 percent or 8 inches e. 1.00 percent or 10 inches - Answer: C Whenever wastewater cannot flow to the treatment plant by _______ a _______ is typically used. a. Gravity / Lift Station b. Pressure / Pressure Pump c. Gravity / Booster Pump d. Pressure / Lift Station e. Gravity / Positive Displacement Pump - Answer: A The primary cause of stoppage in a collection system is _____ and ______ Wastewater Study Guide One common type of weir design for measuring flow is - a. B-Knotch b. C-Knotch c. Z-Knotch d. V-Knotch e. Inverted Siphon - Answer: D Inflow and Infiltration (I&I) typically refers to - a. Plant load & Filter Capacity b. Unaccounted for water in the system after heavy rains c. Unaccounted for load typically from a septic tank waste hauler d. The amount of chemical change in the system after heavy rains e. The direction of flow into the plant and flow through the various treatment processes - Answer: B If the _____ loading on the plant is high, the operator would need to ______ Dissolved Oxygen (DO) levels. a. Inorganic / Decrease b. Inorganic / Increase c. Organic / Decrease d. Organic / Increase e. Surface / Restrict - Answer: D A simple method for indicating when to waste sludge is - Wastewater Study Guide a. Mixed liquor suspended solids test b. Sludge volume index test c. Total Sedimentation Test d. BOD Test e. 30 minute settling test - Answer: E ________ are the smallest, most numerous, and most important of the activated sludge microorganisms. a. Bacteria b. Fungi c. Protozoa d. Amoebic e. Rotifers - Answer: A Organic loading refers to the pounds per day of _______ per acre feet or 1,000 cubic feet of filter media a. DO b. BOD c. TSS d. Filtered Solids e. Unsettleable Solids - Answer: B Hydraulic loading refers to the volume of ________, including recirculation, applied to the filter. a. Sludge Wastewater Study Guide b. Air or Oxygen c. Water d. Mixed Liquor e. Total Suspended Solids - Answer: C The most common type(s) of trickling filters are - a. Standard rate (1-4 mgd) & High rate (10-40 mgd) b. Standard rate (2-6 mgd) & High rate (12-50 mgd) c. Pressure rate (1-4 mgd) & Super High Rate (15-70 mgd) d. Sand (.5 to 2 mgd) & Higher rate (7-40mgd) e. Being replaced by Micro Filtration and are no longer being used - Answer: A Odors occur when treatment becomes - a. Aerobic b. Anaerobic c. Clogged d. Overloaded e. Infiltrated - Answer: B Organic loading of a stabilization pond is about _____ pounds of BOD/acre/day with a detention time of at least _____ days. a. 30 BOD / 30 Days b. 30 BOD / 45 Days c. 35 BOD / 30 Days d. 35 BOD / 35 Days Wastewater Study Guide b. Oxidizer / Oil & hydrocarbons c. Neutralizer / Ozone d. Oxidizer / microorganisms e. Disinfectant / microorganisms - Answer: B When added to water chlorine forms _________ & __________ acid. a. Muriatic & Hypochloric b. Sulfuric & Muriatic c. Hypochlorous & Sulfuric d. Hydochlorous & Hydrochloric e. Hydrochloric & Muriatic - Answer: D When ammonia is present in wastewater and reacts with chlorine ________ are formed. a. Chloramines b. Floc c. Methane gas d. Hydrogen Sulfide gas e. Nothing happens when the two are combined - Answer: A Effluent dosage of chlorine in the contact chamber must produce a total combine residual of - a. 0.5 mg/L after 15 minutes b. 0.5 mg/L after 20 minutes c. 1.0 mg/L after 10 minutes Wastewater Study Guide d. 1.0 mg/L after 20 minutes e. 2.0 mg/L after 20 minutes - Answer: D Besides disinfection, chlorine has other uses at the wastewater treatment plant such as - a. Reduce flies & need for other chemicals b. Reduces BOD, Odor, Algae growth, Helps with grease c. Reduces COD, Aids in Algae growth, & the need for other chemicals d. Good antiseptic scrub for floors in the office & lab e. Operators can take it home for household use - Answer: B TCEQ allows the reuse of wastewater, some of these uses include - a. Irrigation, Aquifer Recharge, Cooling Towers, & Fire Protection b. Irrigation, Cooling Towers & Fire Protection c. Irrigation, Consumption by livestock, Gardens d. Irrigation Only e. Effluent water must be evaporated or used for irrigation only - Answer: A All reclaimed water piping must be _______ in color. a. White b. Blue c. Red d. Brown e. Purple - Answer: E Wastewater Study Guide Before entering a manhole the operator should test for _________ and oxygen levels and ________ the manhole before entering. a. Methane & Washout b. Hydrogen Sulfide & Ventilate c. All Hazardous Gases & Ventilate d. Gases & Put on a SCBA & life line e. Chlorine & Wait for a co-worker - Answer: C How many gallons will a pump pumping 650-gpm produce in 24 hours? a. 15,600 b. 39,000 c. 93,600 d. 936,000 e. 9,360,000 - Answer: D If an operator does not have an electronic flow measuring device but knows that the population of his entity is 3,250 he could determine that approximately _______ gallons per day is being discharged to the collection system. a. 10,140 b. 42,250 c. 422,500 d. 1,014,000 e. Not enough information to compute - Answer: C Wastewater Study Guide a. Color of surface rocks b. Influent Dissolved Oxygen (DO) Removal c. Effluent pH d. Percent BOD Removal e. Total Suspended Solids (TSS) Removal - Answer: D Which of the following trickling filter problems could be reduced by increasing the recirculation ratio? a. Mudballs b. Filter Flies c. Filter Ponding d. pH Stabilization e. Both b & c - Answer: B What gases are produced by the controlled anaerobic digestion of wastewater sludge's? a. Methane & Sulfur Dioxide b. Methane & Carbon Dioxide c. Methane & Carbon Monoxide d. Hydrogen Sulfide & Carbon Dioxide e. Hydrogen Sulfide & Carbon Monoxide - Answer: B Which of the following diseases are caused by pathogenic organisms that may be present in raw wastewater? a. Hepatitis, Typhoid, Paratyphoid, Dysentery, Cholera Wastewater Study Guide b. Gastroenteritis, Polio, Hookworm, & Giardiasis c. Yellow fever, Scarlet fever, Smallpox, Chickenpox, Mumps, d. a & b only e. All the above - Answer: D During a heavy rain it is possible that manholes and lift stations may overflow, discharging waste materials into roadways or ditches. This type of discharge (SSO) would be - a. Considered an unauthorized discharge b. A violation of the Texas Water Code c. A bypass that must be reported within 24 hours d. Considered a health hazard e. All the above - Answer: E An effective way for the collection system worker to prevent infection by waterborn pathogenic organism is to - a. Wear protective clothing and avoid direct contact with wastewater b. Receive a vaccination and booster shot each year c. Wash hands with Antiseptic Soap & follow with Alcohol d. Keep exposure brief until antibodies are built up and immunity increases. e. All the above - Answer: A Which of the following will increase the chances that sewage will turn septic a. Cold weather Wastewater Study Guide b. High Dissolved Oxygen levels c. Stoppages in the main line d. High flow from infiltration after a rain e. Jet Roding mains following odor complaints - Answer: C Extensive use of garbage disposals (grinders) in a community would likely have the following effect on the collection system - a. Absolutely none b. Lower the overall BOD & pH c. Increase the amount of flow, solids, and grease d. Aid the operator in the treatment of septic conditions e. Give the lift stations a good cleaning and increase pumping capacity - Answer: C The minimum size for a gravity flow sewer line on city right-of-way and the minimum grade is - a. 4 inch and a grade of 0.25 percent b. 4 inch and a grade of 0.33 percent c. 6 inch and a grade of 0.33 percent d. 6 inch and a grade of 0.50 percent e. 8 inch and a grade of 0.25 percent - Answer: D Which of the following would be the most accurate way to find the average wastewater flow rate in an existing 10-inch sewer main? a. Internal Video Inspection b. Floating a ping-pong ball from one manhole to another and timing Wastewater Study Guide d. Excavating all the customers line e. All the above - Answer: A Which of the following sewer rehabilitation methods would most commonly be used to seal a number of joint leaks on a main with minimal interruption? a. Slip Lining b. Inversion Lining c. Internal Grouting d. Excavation and Replacement e. All the above - Answer: C Pre-treatment of wastewater would include - a. Coarse or Fine Screening b. Grinding and Grit Removal c. Grease Removal and Pre-aeration d. Adding Chlorine e. a, b, & c - Answer: E Primary treatment of wastewater would include - a. Settling tanks or basins b. Scum collection & removal c. Sludge collection & removal d. Chlorination e. a, b, & c - Answer: E Wastewater Study Guide Secondary treatment typically used today would include - a. Stabilization Ponds, Trickling Filters, Rotating Biological Contactors (RBC) & Activated Sludge b. Facultative Lagoons, Trickling Filters, & Imhoff Tank c. Rotating Biological Contactors (RBC), Imhoff Tank, & Facultative Lagoons d. Activated Sludge Process, Ponds, & Grit removal e. All the above - Answer: A Essential components of the wastewater collection system include - a. Sewer Mains & Piping, Lift Stations, Pumps, Grease & Sand Traps, & Manholes b. Sewer Mains & Piping, Lift Stations, Grease Traps & Sand Traps, c. Sewer Mains & Piping, Lift Stations, Pumps, Grease & Sand Traps, Manholes, & Grit Removal Equipment d. Sewer Mains, Piping, Lift Stations & Manholes e. Sewer Mains, Piping, Lift Stations, Manholes, Grit Removal, & Chlorination equipment - Answer: A Grit removal would be considered - a. A part of the Collection System b. A part of Primary Treatment c. A part of Secondary Treatment d. Overrated and is not cost effective to perform Wastewater Study Guide e. Job duties for the beginning operator - Answer: B The protozoa that causes dysentery would most likely be destroyed by - a. Aeration b. Sun Light & Algae Blooms c. Primary Treatment d. Disinfection e. Recirculation & Mixing with Influent - Answer: D Using final plant effluent in cooling towers would be - a. Strictly prohibited by TCEQ Rules & Regulations b. Beneficial way to reuse treated effluent c. Obnoxious due to algae & odor issues d. Acceptable but the water would have to be treated again before use e. Chlorinated to 50mg/L for 2 hours before using - Answer: B TCEQ may authorize discharge of untreated wastewater into or near a receiving stream in extreme cases. This is referred to as - a. Beneficial Nutrients in a receiving stream b. Avoiding Treatment c. Bypass d. Operator Screw Up e. Not possible without a hugh fine from TCEQ - Answer: C Enforcement action from TCEQ may be taken if pollution or waste violates Wastewater Study Guide Inorganic Solids (ash) are those that - a. Are determined by burning the residue from the Total Solids determination. b. Are beneficial to the operator and Aquatic life c. Consist of sand, grit, & minerals and can be suspended or dissolved d. Cannot be filtered out e. Cause filter plugging and increase maintenance costs - Answer: C Organic matter in wastewater can be _________ or __________ and makes up approximately __________ % of the total solids. a. Dissolved or Suspended / 40 % b. Dissolved or Suspended / 65 % c. Septic or Fresh / 85 % d. Domestic or Industrial / 45 % e. None of the above - Answer: B The typical pH of an influent entering the plant will vary from - a. 6.0 to 9.0 b. 6.5 to 7.5 c. 6.5 to 8.0 d. 6.5 to 9.0 e. 7.5 to 9.5 - Answer: C Acute toxicity occurs when - Wastewater Study Guide a. There is a slow die off of treatment organisms b. There is a rapid die off of treatment organisms c. A spill occurs and herbicides end up in the collection system d. Septic conditions exist due to blockage in the collection system e. Operators take extended leave with a "hottie - Answer: B Chronic toxicity occurs when - a. There is a rapid die off of treatment organisms b. Septic conditions exist due to blockage in the collection system c. Illegal dumping occurs typically from a private waste hauler d. Certain microorganisms become inactivated but others continue to work resulting in a sick biological process e. Operators are continually exposed to concentrated levels of unknown chemicals in the waste. - Answer: D A comminutor would be - a. A mechanical device that screens & cuts large solids in small particles b. A electrical device that channels inflow from on trough to another c. A hydraulic driven device that is used to recycle sludge d. A mechanical device that is used when bypassing secondary treatment e. A submersed mechanical air blower - Answer: A Detention time in wastewater typically refers to - a. The amount of time that it takes for sewage to make it through all treatment steps in the plant. Wastewater Study Guide b. The amount of time in the collection system from customer discharge until it reaches the treatment facilities. c. The amount of time it takes between starting and completing a BOD test. d. The time sewage is kept in a sedimentation basin e. The amount of time given an operator convicted of DWI. - Answer: D There are five (5) major components to a tricking filter and they are - a. Filter floor, Underdrain, Walls, Filter Media, & Distributor Arms b. Filter floor, Underdrain, Walls, Sand or Plastic Media, & Aerator c. Filter floor, Underdrain, Walls, Filter media, Loss of Head Gauge d. Filter Floor, Underdrain, Walls, Recycling Pump, Telescoping Valve e. Filter, Underdrain, Walls, Weirs, Media, & Distributor Arm - Answer: A Zoogleal Mass refers to - a. A thick layer of slime that is typically treated with high concentrations of chlorine to improve filter flow. b. A thick layer of jelly like slime where organisms, bacteria, fungi, protozoa, and ciliates thrive. c. A thin layer of plastic filter media that helps reduce flies, snails, and larva on the filter. d. A thick layer of grease that is placed on the distributing arms to prevent wear. e. A Church service typically offered prior to Good Friday - Answer: B Wastewater Study Guide b. 30 % c. 50 % d. 75 % e. Less than 25 % - Answer: C Aerated Lagoons rely on __________ to provide ________ and ________ a. Sunlight & Wind / Agitation & Mixing b. Mechanical aeration / Flow & Circulation c. Hydraulic power / Agitation & Circulation d. Mechanical aeration / Aeration & Mixing e. Injected liquid oxygen / Aeration & Circulation - Answer: D The most common method of dewatering and drying sludge is - a. Belt Press b. Drying Bed c. Methane fired furnaces d. High Speed Centrifugal Slinger e. Hydraulic Pressure Press - Answer: B Digester gas typically contains about ________ % _________ a. 50 to 60 % Carbon Monoxide b. 50 to 75 % Carbon Dioxide c. 60 to 70 % Methane d. 65 to 75 % Methane e. 50 % Hydrogen Sulfide - Answer: D Wastewater Study Guide The depth of sludge drawn to a drying bed should be - a. Approximately 4 inches b. Approximately 6 inches c. Approximately 9 inches d. Approximately 12 inches e. Approximately 18 inches - Answer: C Newly hired personnel have ________ to become licensed. a. 6 months b. 1 year c. 2 years d. 3 years e. There is no requirement from TCEQ - Answer: B Force Mains and fittings must have a pressure rating of at least - a. 80 psi b. 100 psi c. 125 psi d. 150 psi e. 200 psi - Answer: D Most pumping stations and electrical equipment used today in wastewater collection or treatment is _______ and typically either ______ or _______ volts Wastewater Study Guide a. A.C. (Alternating Current) & 220 or 440 b. D.C. (Direct Current) & 110 or 220 c. A.C. (Alternating Current) & 110 or 440 d. A.C. (Alternating Current) & 100 or 208 e. a & in some cases c - Answer: E To avoid electrical shock, the operator should ______________ if they are experiencing equipment failures or power related issues. a. Refer the problem to a trained electrical repairperson and do not attempt to check fuses or open the disconnect box. b. Retrieve a Volt / Ohmmeter and open the disconnect box to check for incoming voltage and to make sure fuses are not blown. c. Call the newbie and let him sort out what might be the problem d. Notify the power provider and let them send out a serviceman to assure the problem is not on the provider's side. e. Both a & d - Answer: E When using Hydraulic Hydro Jetting sewer cleaning equipment the operator will want to go from a _________ manhole and clean toward the stoppage to avoid ___________. a. Clear or open / Forcing sewage into customer homes or businesses b. Full or clogged / Adding unaccounted for water to treatment plant c. Clear or open / The possibility of personal contact with untreated sewage. d. TCEQ approved / The possibility of a sewer spill or overflow Wastewater Study Guide b. Aerobic c. Facultative d. Zoogleal Mass e. Chemically Demanding - Answer: B In the activated sludge process aeration tanks provide the space necessary to _______, ________, & _______ and return biological solids. a. Mix, Aerate, & Hold Influent b. Chlorinate, Aerate, & Settle c. Mix, Chlorinate, & Hold Influent d. Oxygenate, Settle, & Hold Effluent e. Mix, Aerate, & Hold Effluent - Answer: A In the active sludge process, Utilization is the process of - a. Food digestion that changes food source into waste b. Food supply that changes food sources into waste c. Food supply that is changed into a liquid state for use d. Microorganisms getting rid of unusable food source e. None of the above - Answer: C In the activated sludge process, Stabilization is - a. Food sources biologically converted to water, carbon dioxide, or cells b. Food sources that are changes into a liquid state for use c. The biological process whereby excess food supply is converted to waste. Wastewater Study Guide d. Wastes biologically converted to water, carbon dioxide, or new cells e. None of the above - Answer: D In the activated sludge process, the _______ is called the heart of the activated sludge process. a. Contact Stabilization b. Mechanical Bar Screen & Grit Removal c. Clarifier d. Sludge Recycling e. Sludge Waste - Answer: C In the activated sludge process, factors that will influence the operation of the final clarifier are - a. Loading, Solids applied, Settling, Thickness of solids, Rate of return & Wasting b. COD of solids applied, Sedimentation time, Thickness of sludge blanket, & Sludge wasting. c. Liquids applied, Settling time, Thickness of sludge, Recirculation, & Wasting d. Chlorine Contact time, Thickness of sludge, Rate of return & Wasting e. Time, Temperature, Loading, Settling, & Wasting - Answer: A In the activated sludge process, the clarifier will concentrate return sludge and waste sludge about ______ to _______ times the solids concentration of the mixed liquor. Wastewater Study Guide a. One (1) to Three (3) b. One (1) to Four (4) c. Two (2) to Three (3) d. Two (2) to Four (4) e. Two (2) to Five (5) - Answer: D In the activated sludge process, for the clarifier to do its job, the _______ must be retained long enough to allow ______ to settle and liquid to rise. a. Solids / Water b. Supernatant / Water c. Water / Solids d. Solids / Waste Sludge e. Solids / Floc - Answer: C In the activated sludge process, as more mixed liquor flows to the clarifier, the thickness of the sludge blanket will - a. Increase as solids accumulate b. Decrease as solids are used c. Stay constant d. Require more recycling & waste to drying beds e. Mixed liquor flow has no effect on the sludge blanket - Answer: A In the activated sludge process, biological solids from the bottom of the clarifier must be returned to the aeration basin for re-seed. This process is accomplished by - Wastewater Study Guide e. How long it takes for sludge to make it through all treatment processes - Answer: C In the activated sludge process, Gould Sludge Age (GSA) is calculated by a. Subtracting the total pounds of TSS in the aerator by the pounds of TSS entering the aerator as raw b. Dividing the total pounds of TSS in the aerator by the pounds of TSS entering the aerator as raw c. Adding the total pounds of TSS in the aerator by the pounds of TSS entering the aerator as raw d. Dividing the BOD of treated sludge in aerator by the BOD of sludge entering the aerator as raw e. Taking a sample of the sludge in the aerator and estimating in days how long it will take to break down - Answer: B In the activated sludge process, the term Mean Cell Residence Time (MCRT) refers to - a. The longer a cell is kept in the aeration the more resistant it becomes b. The number of times that a living cell is circulated c. The amount of time the living cells are kept in the plant d. The amount of time that it takes to draw sludge to a drying bed e. The amount of time that it takes from raw sludge entering the plant to processed sludge being wasted to dewatering. - Answer: C In the activated sludge process, daily observation of the aeration basin Wastewater Study Guide treatment processes are essential. The operator should pay close attention to - a. Temperature, Foaming, Color, & Inflow b. Inflow, Sludge floating, Recirculation, Chlorination, & Odors c. Flies, Snails, Foaming, Odors, & Effluent quality d. Surface turbulence, Foam, Odors, & Color e. The activated sludge plant requires very little maintenance or daily care - Answer: D In the activated sludge process, daily observation of the final clarifier is also essential. The operator should pay close attention to - a. Temperature, Sludge blanket, Weir Flow, Clarifier Sloughing, & Outflow b. Surface scum, Sludge blanket, Weir flow, Rising solids, & Clarifier overflow c. Floating solids, Sludge going over the weir, Rising solids, & Clarifier overflow d. Microorganisms, Surface scum, Weir flow, Rising solids, & Clarifier Overflow e. Color, Odor, Foaming, Surface scum, Weir flow, Rising solids, & Outflow quality - Answer: B In the activated sludge process, five (5) important control parameters are a. BOD level, Aerator solids level, Solids quality, Rate of returned sludge, & Wasting rate b. TSS levels of inflow, Aerator detention time, Solids quality, Rate of Wastewater Study Guide returned sludge, & Wasting rate c. Dissolved Oxygen level, Aerator solids level, Solids quality, Rate of returned sludge, & Wasting rate d. Total suspended solids, Total settled solids, Detention time, Sludge quality, amount of sludge sent to dewatering e. Floating solids, Dissolved Oxygen levels, Foaming, Odor, Weir Overflow - Answer: C In the activated sludge process, Dissolved Oxygen levels throughout the aeration basins are measured using a portable DO Meter. The operator should keep DO levels between _______ and _________. a. 0.5 mg/L and 1.5 mg/L b. 1.0 mg/L and 3.0 mg/L c. 1.75 mg/L and 5.0 mg/L d. 2 mg/L and 4.0 mg/L e. 2.5mg/L and 5.0 mg/L - Answer: D In the activated sludge process, "Classic Bulking" is a common problem typically caused by - a. Low density sludge b. High density sludge c. Low Detention Times d. Unexpected High BOD loading e. Dying microorganisms - Answer: A Wastewater Study Guide Shock loads, & Nutrient deficiencies c. Grease, chemicals, chlorine residual too high, BOD too low, need a constant supply & level of solids, Inflow & Infiltration & Nutrient deficiencies d. Inflow to a activated sludge plant has very little effect on operation but the operator should watch for illegal dumping of toxic materials e. No consistency, high flow & low flows create a surging in the plant which disrupts sludge sedimentation and causes bulking - Answer: B In the activated sludge plants, the operator will experience problems. Some of the common Operational problems include - a. Sludge quality, Foaming, Improper operating techniques b. Sludge consistency, Mechanical failures, Microorganisms die off c. Odors, Foaming, Operators not understanding lab analysis or how to correct deficiencies d. Recycling pumps and lines are typically undersized causing septic sludge, foaming, Operator training & Understanding of the plant e. Both a & d - Answer: A In the activated sludge plants, the operator will experience problems. Some of the common Environmental problems include - a. High temperatures, High pH, & Excessive algae growth b. Sunlight, Wind, temperatures & pH c. Temperature fluctuations , Odor discharges, & pH on effluent d. Low temperatures, Odors, System pH out of range, & sludge wasting Wastewater Study Guide e. Low temperatures, System pH out of range, & Excessive algae growth - Answer: E In the activated sludge plants, to properly set the clarifier return rate the operator must know three things - a. Waste sludge rate, Detention time, & TSS b. Return activated sludge rate, Sludge blanket thickness, & the Solids concentration of the return flow c. Inflow BOD, Detention time, Outflow DO level d. Return activated sludge rate, DO level in the final clarifier, & Total Solids in the return flow e. Sludge flows downhill, Keep your mouth shut around filter flies, & The Boss is a grouchy SOB. - Answer: B The typical sludge age for extended aeration plants is - a. 10 to 30 days b. 15 to 45 days c. 20 to 30 days d. 20 to 40 days e. 40 to 90 days - Answer: D In the activated sludge plant, good quality sludge will settle _______ & __________ over __________ minute period. a. Gently & Uniformly over 20 to 30 minutes b. Gently & Uniformly over 15 to 20 minutes Wastewater Study Guide c. Rapidly and ragged over 10 to 15 minutes d. Rapidly and uniformly over 10 to 20 minutes e. Evenly and stacked over 15 to 20 minutes - Answer: B In the activated sludge plant, old sludge quality will settle _________ & ___________ over ___________ minute period. a. Rapidly and ragged over 5 minutes b. Rapidly and ragged over 10 minutes c. Gently and ragged over 5 minutes d. Gently and ragged over 10 minutes e. Rapidly and uniformly over 5 minutes - Answer: A In the activated sludge plant, there are five (5) important nitrogen transformation processes that occur by microorganisms. They are - a. Assumption, Nitrification, Denitrification, Nitrogen Fixation, & Neutralization b. Binding, Ammonification, Nitrification, Denitrification, Nitrogen Fixation c. Assumilation, Ammonification, Nitrification, Denitrification, & Nitrogen fixation d. Ammonification, Nitrification, Denitrification, Absorption, & Neutralization e. Assumilation, Absorption, Ammonification, Nitrification, & Fixation - Answer: C ________ in the effluent from an activated sludge process is a pollutant and may create toxic conditions for aquatic life in the receiving stream Wastewater Study Guide operator should reduce the air SCFM to get DO into the proper range d. Too much sludge was drawn from the sludge blanket and in a few days the problem should correct itself e. Not enough sludge was drawn from the sludge blanket and more sludge should be sent to waste - Answer: C In the activated sludge system if the operator observed uneven surface aeration, dead spots or inadequate mixing in some areas, the operator would suspect - a. Plugged diffusers b. Not enough air in the treatment process so increase air SCFM to retain more DO c. Inflow greater than treatment capacity of unit d. Someone has dumped toxic chemicals and microorganisms are dying e. The power outage to the plant is effecting the decomposition rate - Answer: A In the activated sludge system, if the operator observes white thick billowing sudsy foam on the aeration tank, the operator would suspect - a. Low flow to the aeration tank and or not enough sludge wasting b. Low flow to the aeration tank and or excessive sludge wasting c. Overloaded aeration tank and or excessive sludge wasting d. Overloaded aeration tank and not enough sludge wasting e. Organics in the inflow have changed and the entire process will need to be recalibrated. - Answer: C Wastewater Study Guide In the activated sludge system, if the operator observes excessive air being used with no apparent change in organic or hydraulic loading, the operator would suspect - a. Sludge blanket is turning over, Plugged air diffusers & High inorganic loading b. Leaks in the system piping, Plugged air diffusers & High organic loading c. Short circuit in detention basin, Plugged air diffusers & High organic loading d. Plugged air diffusers, High organic loading, & Time to waste sludge e. Temperature has dropped, plugged air diffusers, & too much sludge was wasted - Answer: B During the month of July, the average daily flow of a wastewater treatment plant was 2,768,000 GPD, and the BOD was 417 mg/L. What is the total pounds of BOD contributed and what is the approximate population of the community served? a. 55 lbs / 3,256 population b. 962 lbs / 5,658 population c. 9,626 lbs. / 56,626 population d. 9,626 lbs / 163,650 population e. Not enough information to compute - Answer: C As an operator of a wastewater plant you are treating a flow of 21 MGD, what is the flow in gallons per minute? Wastewater Study Guide a. 1,458 b. 5,833 c. 8,750 d. 14,583 e. 87,500 - Answer: D The maximum safe withdrawal rate for a 150 lb. chlorine cylinder is - a. 25 lbs b. 30 lbs c. 35 lbs d. 40 lbs e. Draw as much as needed or until the cylinder lines freeze - Answer: D A dosage of 5 mg/L of chlorine is added to 2.0 MGD of wastewater. How many pounds of chlorine is added? (Hint: Chlorine= MG X 8.34 X dosage) a. 8.34 pounds b. 16.68 pounds c. 83.4 pounds d. 834 pounds e. None of the above - Answer: C The BOD inflow of a wastewater treatment plant is 260 mg/L and the BOD of the outflow effluent is 9 mg/L. What is the percentage of BOD removed? (Hint: Inflow - Outflow X 100 divided by inflow) a. .96