Wastewater Treatment and Sewer System Operations, Exams of Water and Wastewater Engineering

Download Wastewater Treatment and Sewer System Operations and more Exams Water and Wastewater Engineering in PDF only on Docsity! Wastewater Class B Texas Exam Questions and Answers 2024 Update. The name of the State Agency responsible for enforcing pollution control laws in Texas - Correct answer Texas Commission of Environmental Quality The term pathogenic means - Correct answer Capable of causing disease The minimum separation between sewer lines and potable water lines is - Correct answer 9 feet A licensed wastewater operator is a professional - Correct answer consistently does best job possible, practices personal safety, strives to improve job knowledge, strives to keep the plant and collection system in the best appearance and working order An important step in testing a sample for Total Suspended Solids is - Correct answer filtering a sample The Biochemical oxygen Demand (BOD) of a sample is based on - Correct answer measuring the dissolved oxygen (DO) used The results of Biochemical Oxygen Demand (BOD) sample taken at a treatment plant tells the operator - Correct answer how the plant was operating 5 days ago Which of the following are dangerous gasses that are likely to be present in lift stations and manholes? - Correct answer Natural gas, gasoline fumes, hydrogen sulfide and carbon dioxide A preferred hydraulic method of cleaning sewer lines is - Correct answer Hydro Jet Cleaner Ways to reduce bad odors coming from a collection system - Correct answer routinely cleaning slow running or low flow lines, adding chlorine or hydrogen peroxide to the collection system Types of pipe that are commonly used in wastewater collection system - Correct answer ductile iron, Poly Vinyl Chloride (PVC) Before entering a confined space a worker should - Correct answer Use approved monitoring device and check for the presence of dangerous gasses, ventilate the space with a blower, wear a safety harness and attach a life line A properly designed and operated primary sedimentation tank should remove _____ percent of incoming BOD - Correct answer 30-40% Devices that may be used to determine the level of sewage in a lift station - Correct answer air bubbler, floats, electrodes, Acoustic (sonic) What is the most important role of aerobic bacteria in the treatment of wastewater? - Correct answer decompose organic matter The hydraulic loading of a trickling filter may be determined by - Correct answer flow rate and filter area These can be used to dewater sludge - Correct answer belt press, drying beds, solid bowl centrifuge, and gravity thickener Most important to providing adequate sewage treatment in a stabilization pond - Correct answer sunlight, algae, bacteria and time Offensive and objectionable odors which sometimes occur in trickling filters usually indicate - Correct answer septic conditions are present Dissolved Oxygen (DO) in aeration tank of an activated sludge plant should be maintained at or about - Correct answer 2 to 4 mg/L Contributes to the infiltration in a collection system - Correct answer breaks in the main lines, high ground water levels, heavy rains, hydro jet cleaning plugged mains When a centrifuge pump loses prime the - Correct answer pump is no longer moving liquid A Rotating Biological Contactor (RBC) is - Correct answer fixed firm biological treatment process Needs to be checked regularly to properly operate an activated sludge treatment plant - Correct answer aeration equipment and mixed liquor solids Point source discharges are - Correct answer discharges that come from pipes or ditches that are monitored, controlled and inspected Non-point discharges are - Correct answer discharges that have intermittent, dispersed flows having little or no control The Texas Water Code establishes the protection of water quality and quantity of the state by - Correct answer setting stream standards, issues permits for discharges, identifies non-point source controls, and establishes water reuse. The wastewater plant operator is primarily responsible for - Correct answer treating wastewater discharged into the community One common type of weir design for measuring flow is - Correct answer V-Notch Inflow and Infiltration (I&I) typically refers to - Correct answer unaccounted for water in the system after heavy rains If the ____ loading on the plant is high, the operator would need to ____Dissolved Oxygen (DO) levels. - Correct answer Organic/Increase A simple method for indicating when to waste sludge is - Correct answer 30 minute settling test Organic loading of a stabilization pond is about ____ pounds of BOD/acre/day with a detention time of at least ___ days. - Correct answer 35 BOD/ 30 Days Anaerobic digesters are covered to keep out ____, and to trap useful methane which can be used to keep the digester warm. - Correct answer free oxygen Unstable anaerobic sludge contains streaks of _________ or ________. - Correct answer gray/green Aerobic digestion is a ____process whereby the aerobic bacteria consume themselves - Correct answer Endogenous Approved disposal methods for digested, dewatered, sludge's are landfill, ____ and ____. - Correct answer Incineration & Land Application Landfill applied sludge must have a solids content of at least _________percent - Correct answer 20 Calcium Hypochlorite (HTH) is a strong _______ and reacts violently with _________. - Correct answer Oxidizer/Oil & Hydrocarbons When added to water chlorine forms _____&_______acid - Correct answer Hydrochlorous and Hydrochloric When ammonia is present in wastewater and reacts with chlorine_________are formed - Correct answer Chloramines Effluent dosage of chlorine in the contact chamber must produce a total combined residual of - Correct answer 1.0 mg/L after 20 minutes Besides disinfection, chlorine has other uses at the wastewater treatment plant such as - Correct answer Reduces BOD, Odor, Algae growth, Helps with Grease TCEQ allows the reuse of wastewater, some of these include - Correct answer Irrigation, aquifer recharge, cooling towers and fire protection All reclaimed water piping must be _______in color - Correct answer purple Before entering a manhole the operator should test for ________and oxygen levels and ________the manhole before entering. - Correct answer all hazardous gasses and ventilate When a municipal wastewater effluent has a high nitrate level and low ammonia level this most likely means - Correct answer the effluent has received a high degree of aerobic treatment Total solids in wastewater are the sum of - Correct answer Settle able and volatile solids This treatment device is commonly used to separate and remove large solids from raw wastewater - Correct answer A Mechanically raked bar screen ___________would have an adverse effect on the proper settling of solids in a clarifier. - Correct answer a short circuiting flow pattern This test would give the best information on how efficiently a trickling filter was operating - Correct answer Percent BOD Removal This trickling filter problem could be reduced by increasing the recirculation ratio - Correct answer Filter files What gases are produced by the controlled anaerobic digestion of wastewater sludge's - Correct answer Methane & Carbon Dioxide? These diseases are caused by pathogenic organisms that may be present in raw wastewater - Correct answer Hepatitis, typhoid, paratyphoid, dysentery, cholera, gastroenteritis, polio, hookworm and giardiasis During heavy rain it is possible that manholes and lift stations may overflow, discharge waste materials into roadways or ditches. This type of discharge (SSO) would be - Correct answer considered an unavoidable discharge, a violation of the Texas Water Code, a bypass that must be reported within 24 hours and considered a health hazard An effective way for the collection system worker to prevent infection by waterborne pathogenic organism is to - Correct answer Wear protective clothing and avoid direct contact with waste water _________will increase the chances that sewage will turn septic - Correct answer Stoppages in the main line Extensive use of garbage disposals (grinders) in a community would likely have the following effect on the collection system - Correct answer Increase the amount of flow, solids, and grease The minimum size for a gravity flow sewer line on city right-of-way and the minimum grade is - Correct answer 6 inch and a grade of 0.50 percent The most accurate way to find the average wastewater flow rate in an existing 10-inch sewer main is - Correct answer obtaining actual flow data & verifying with field data What is the greatest advantage for using fiberglass manholes in areas with high groundwater? - Correct answer fiberglass is not subject to infiltration A __________ pump would most likely be used when discharging into a 10" diameter pressure sewer main. - Correct answer Centrifugal Excessive power consumption by a pump could be caused by - Correct answer Worn bearings and worn impeller Trench safety is a great concern in Texas. OSHA requires that anytime an excavation is greater than __ feet deep it must be protected by ______. - Correct answer 5 feet / an approved Trench Box, Shoring, or Sloping In an excavation if a ladder is used as a means of exit, it must extend ________feet above the ground and be secured and within ____ feet laterally of anyone in the excavation. - Correct answer 3 feet / 25 feet laterally A ____________ would be the best to determine if a storm drain is connected to a sanitary sewer line. - Correct answer Smoke Test _________ would most commonly be used to seal a number of joint leaks on a main with minimal interruption - Correct answer internal grouting Pre-treatment of wastewater would include: - Correct answer Coarse or fine screening, grinding and grit removal and grease removal and pre-aeration Primary treatment of wastewater would include - Correct answer settling tanks or basins, scum collection and removal, sludge collection and removal Secondary treatment typically used today would include - Correct answer Stabilization ponds, trickling filters, rotating biological contractors (RBC) & activated sludge Essential components of the wastewater collection system include - Correct answer Sewer mains & piping, Lift Stations, Pumps, Grease & Sand traps, & Manholes Grit removal would be considered - Correct answer a part of Primary Treatment Most pumping stations and electrical equipment used today in wastewater collection or treatment is ________ and typically either _______ or _________ volts - Correct answer A.C. (Alternating Current) & 220 or 440 and in some cases A.C. (Alternating Current) & 100 or 208 To avoid electrical shock, the operator should ________ if they are experiencing equipment failures or power related issues - Correct answer Refer the problem to a trained electrical repairperson and do not attempt to check fuses or open the disconnect box and Notify the power provider and let them send out a serviceman to assure the problem is not on the provider's side. When using Hydraulic Hydro Jetting sewer cleaning equipment the operator will want to go from a _______ manhole and clean toward the stoppage to avoid _________. - Correct answer Clear or open / Forcing sewage into customer homes or businesses The Activated Sludge Process can produce a high degree of treatment. Typically one could expect a ______to_______% BOD removal - Correct answer 90 to 99% The Activated Sludge plant has five (5) Critical Components. They are - Correct answer Oxygen supply, Aeration tanks, Clarifiers, Return & Waste The Activated Sludge process is a ________process. - Correct answer Aerobic In the activated sludge process aeration tanks provide the space necessary to _______, ________, & _______ and return biological solids. - Correct answer Mix, aerate, & Hold Influent In the active sludge process, Utilization is the process where - Correct answer Food supply is changed into a liquid state for use In the activated sludge process, Stabilization is - Correct answer Wastes biologically converted to water, carbon dioxide, or new cells In the activated sludge process, the _______ is called the heart of the activated sludge process. - Correct answer Clarifier In the activated sludge process, factors that will influence the operation of the final clarifier are - Correct answer Loading, solids applied, settling, thickness of solids, rate of return & Wasting In the activated sludge process, the clarifier will concentrate return sludge and waste sludge about ___ to__ times the solids concentration of the mixed liquor - Correct answer two (2) to four (4) 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. - Correct answer water/ solids In the activated sludge process, as more mixed liquor flows to the clarifier, the thickness of the sludge blanket will - Correct answer Increase as solids accumulate 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 - Correct answer Air lift pumps, centrifugal pumps, Diaphragm pumps, Screw pumps & Gravity Flow In the activated sludge process, no sludge process will work properly without - Correct answer Regular removal of excess solids In the activated sludge process, Mass Balance refers to - Correct answer maintaining the balance between Return Sludge Flow, Return Sludge, and Aeration tank volume, and mixed liquor suspended solids In the activated sludge process, the terms F/M ratio is important because this refers to - Correct answer Food to Microorganism Ratio In the activated sludge process, the F/M Ratio is calculated by ______ the pounds of _________ by the pounds of MLVSS in the ___________. - Correct answer Dividing/ Incoming BOD/ aeration tank In the activated sludge process, the term Gould Sludge Age refers to - Correct answer how long in days a pound of solids stays in the aerator In the activated sludge process, Gould Sludge Age (GSA) is calculated by - Correct answer dividing the total pounds of TSS in the aerator by the pounds of TSS entering the aerator as raw In the activated sludge process, the term Mean Cell Residence Time (MCRT) refers to - Correct answer the amount of time the living cells are kept in the plant In the activated sludge process, daily observation of the aeration basin treatment processes are essential. The operator should pay close attention to - Correct answer Surface turbulence, Foam, Odors, & Color In the activated sludge process, daily observation of the final clarifier is also essential. The operator should pay close attention to - Correct answer Surface scum, Sludge blanket, Weir Flow, Rising solids, & Clarifier overflow In the activated sludge process, five (5) important control parameters are - Correct answer Dissolved Oxygen level, Aerator solids level, Solids quality, Rate of returned sludge, & wasting rate 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 _______. - Correct answer 2 mg/L and 4.0 mg/L In the activated sludge process, "Classic Bulking" is a common problem typically caused by - Correct answer Low density sludge In the activated sludge process, Sludge Rising differs from "Sludge Bulking" and "Sludge Rising" is typically associated - Correct answer Nitrification - De-nitrification process In the activated sludge process, techniques used to reduce "Frothing & Foaming" typically include - Correct answer Adjusting sludge age, Reducing the amount of air, Spraying the frothing area with water, Applying de-foaming agents In the activated sludge process, flock is very important to the settling process. Flock is composed primarily of - Correct answer Bacteria, Protozoa, Microscopic Animals, & Fungi In the activated sludge plants, the operator will experience problems. Some of the common Treatment plant problems include - Correct answer insufficient capacity, Equipment failures, Design inadequacies, Poor maintenance, & Inflow rates exceed plant capacities. In the activated sludge plants the operator will experience problems. Some of the common Influent problems include - Correct answer Septic inflow, Organic overloading, and under loading, Hydraulic overloading, Solids washout during storm inflow, Toxic substances, Shock loads, & Nutrient deficiencies In the activated sludge plants, the operator will experience problems. Some common Operational problems include - Correct answer Sludge quality, foaming, improper operating techniques In the activated sludge plants, the operator will experience problems. Some common Environmental problems include. - Correct answer Low temperatures, System pH out of range, & Excessive algae growth In the activated sludge plants, to properly set the clarifier return rate the operator must know three things - Correct answer Return activated sludge rate, Sludge blanket thickness, & the Solids concentration of the return flow The typical sludge age for extended aeration plants is - Correct answer 20 to 40 days In the activated sludge plant, good quality sludge will settle _________& _______ over _________ minute period. - Correct answer Gently & Uniformly over 15 to 20 minutes