Wastewater Treatment and Collection System Management, Exams of Water and Wastewater Engineering

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Wastewater Class B Texas with 184 questions and answers exam The name of the State Agency responsible for enforcing pollution control laws in Texas - >>>Texas Commission of Environmental Quality The term pathogenic means - >>>Capable of causing disease The minimum separation between sewer lines and potable water lines is - >>>9 feet A licensed wastewater operator is a professional - >>>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 - >>>Filtering a sample The Biochemical oxygen Demand (BOD) of a sample is based on - >>>Measuring the dissolved oxygen (DO) used The results of Biochemical Oxygen Demand (BOD) sample taken at a treatment plant tells the operator - >>>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? - >>>Natural gas, gasoline fumes, hydrogen sulfide and carbon dioxide A preferred hydraulic method of cleaning sewer lines is - >>>Hydro Jet Cleaner Ways to reduce bad odors coming from a collection system - >>>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 - >>>ductile iron, Poly Vinyl Chloride (PVC) Before entering a confined space a worker should - >>>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 - >>>30-40% Devices that may be used to determine the level of sewage in a lift station - >>>air bubbler, floats, electrodes, Acoustic (sonic) What is the most important role of aerobic bacteria in the treatment of wastewater? - >>>decompose organic matter The hydraulic loading of a trickling filter may be determined by - >>>flow rate and filter area These can be used to dewater sludge - >>>belt press, drying beds, solid bowl centrifuge, gravity thickener Most important to providing adequate sewage treatment in a stabilization pond - >>>sunlight, algae, bacteria and time Offensive and objectionable odors which sometimes occur in trickling filters usually indicate - >>>septic conditions are present The majority of Dissolved Oxygen in raw sewage comes from - >>>Potable Drinking Water Each person contributes approximately ______ lbs of BOD to the system daily. - >>>0.17 Sources of waste water include - >>>domestic, storm water, commercial, food processing, agricultural and industrial A sewer manhole provides access into the system for cleaning or service. A manhole is located - >>>at changes in alignment, diameter, grade, direction and intersection New manholes must have an inside diameter of at least ______ feet and the entry access must be at least ____inches. - >>>4 feet and 24 inches In the past ____ was used to construct manholes. This product is prohibited for construction or grading today - >>>brick and mortar Verified clay and Poly Vinyl Chloride (PVC) are the most common pipe materials used for sewer lines but other materials are available such as - >>>ductile iron, cast iron, acrylontrile butadiene styrene (ABS) Concrete, polyethylene & asbestos concrete Whenever wastewater cannot flow to the treatment plant by _____ a _____ is typically used - >>>gravity/ lift station The primary cause of stoppage in a collection system is _____ and _____ - >>>grease/roots The _____pump is most commonly used in a lift station - >>>centrifugal A centrifugal pump must be ____ or it will not pump - >>>primed ______ gas is very toxic and deadens the sense of ______ - >>>Hydrogen Sulifide/smell ______ gas is colorless, odorless and heavier than air - >>>Methane ______ are the smallest , most numerous, and most important of the activated sludge microorganisms - >>>bacteria Organic loading refers to the pounds per day of ____ per acre feet or 1,000 cubic feet of filter media - >>>BOD Hydraulic loading refers to the volume of ____, including recirculation, applied to the filter - >>>water The most common type(s) of trickling filters are- - >>>Standard rate (1-4 mgd) and High Rate (10-40 mgd) Odors occur when treatment becomes - >>>anaerobic ____________gas is greenish-yellow, pungent, heaver than air and highly toxic - >>>chlorine One common type of weir design for measuring flow is - >>>V-Knotch Inflow and Infiltration (I&I) typically refers to - >>>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. - >>>Organic/Increase A simple method for indicating when to waste sludge is - >>>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. - >>>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. - >>>free oxygen Unstable anareobic sludge contains streaks of _________ or ________. - >>>gray/green Aerobic digestion is an ____process whereby the aerobic bacteria consume themselves - >>>Endogenous Approved disposal methods for digested, dewatered, sludge's are landfill, ____ and ____. - >>>Incineration & Land Application Landfill applied sludge must have a solids content of at least _________percent - >>>20 Calcium Hypochlorite (HTH) is a strong _______ and reacts violently with _________. - >>>Oxidizer/Oil & Hydrocarbons When added to water chlorine forms _____&_______acid - >>>Hydrochlorous and Hydrochloric When ammonia is present in wastewater and reacts with chlorine_________are formed - >>>Chloramines Effluent dosage of chlorine in the contact chamber must produce a total combined residual of - >>>1.0 mg/L after 20 minutes Excessive power consumption by a pump could be caused by - >>>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 ______. - >>>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. - >>>3 feet / 25 feet laterally A ____________ would be the best to determine if a storm drain is connected to a sanitary sewer line. - >>>Smoke Test _________ would most commonly be used to seal a number of joint leaks on a main with minimal interruption - >>>internal grouting Pre-treatment of wastewater would include: - >>>Coarse or fine screening, grinding and grit removal and grease removal and pre-aeration Primary treatment of wastewater would include - >>>settling tanks or basins, scum collection and removal, sludge collection and removal Secondary treatment typically used today would include - >>>Stabilization ponds, trickling filters, rotating biological contractors (RBC) & activated sludge Essential components of the wastewater collection system include - >>>Sewer mains & piping, Lift Stations, Pumps, Grease & Sand traps, & Manholes Grit removal would be considered - >>>A part of Primary Treatment The protozoa that causes dysentery would most likely be destroyed by - >>>Disinfection Using final plant effluent in cooling towers would be a - >>>Beneficial way to reuse treated effluent TCEQ may authorize discharge of untreated wastewater into or near a receiving stream in extreme cases. This is referred to as - >>>Bypass Enforcement action from TCEQ may be taken if pollution or waste violates the Texas Water Code. Violations of Water Code may include - >>>Unauthorized discharge, accidental discharge & health hazard Solids in wastewater are classified as - >>>Total (TR), Suspended (TSS), Dissolved (TDS), Settleable (SS), Non-setteable, Floatable, Organic and Inorganic Total Suspended Solids (TSS) are those that - >>>Can be filtered out Total Dissolved Solids (TDS) are those that - >>>cannot be filtered out Settable Solids (SS) are those that - >>>Settle out when left standing for extended periods of time Non-settleable Solids are - >>>Small particles that do not settle Volatile Solids (VSS) are those that - >>>Are determined by burning the residue from the Total Solids determination Inorganic Solids (ash) are those that - >>>Consist of sand, grit, & minerals and can be suspended or dissolved Organic matter in wastewater can be ______or________and makes up approximately _______% of the total solids - >>>Dissolved or Suspended / 65 The typical pH of an influent entering the plant will vary from - >>>6.5 to 8.0 Acute toxicity occurs when - >>>There is a rapid die off of treatment organisms Chronic toxicity occurs when - >>>Certain microorganisms become inactivated but others continue to work resulting in a sick biological process A mechanical device that screens & cuts large solids in small particles - >>>Cumminuter Detention time in wastewater typically refers to - >>>The time sewage is kept in a sedimentation basis There are five (5) major components to a trickling filter - >>>Filter floor, underdrain, walls, filter media, & distributer arms Zoogleal Mass refers to - >>>A thick layer of jelly like slime where organisms bacteria, fungi, protozoa and ciliates thrive. The efficiency of a trickling filter is measured in - >>>Percent BOD Removed Common operating problems with a trickling filter include - >>>Ponding, Filter files, Odors, Clogging of Nozzles, & Snails Wastewater Stabilization Ponds are an approved process for wastewater treatment. Organic loading of Stabilization Ponds is typically - >>>35 lbs BOD/Acre/Day with a minimum of 30 days detention time In the activated sludge process, the clarifier will concentrate return sludge and waste sludge about ___ to__ times the solids concentration of the mixed liquor - >>>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. - >>>water/ solids In the activated sludge process, as more mixed liquor flows to the clarifier, the thickness of the sludge blanket will - >>>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 - >>>Air lift pumps, centrifugal pumps, Diaphragm pumps, Screw pumps & Gravity Flow In the activated sludge process, no sludge process will work properly without - >>>Regular removal of excess solids In the activated sludge process, Mass Balance refers to - >>>Maintaining the balance between Return Sludge Flow, Return Sludge, Aeration tank volume, Mixed liquor suspended solids In the activated sludge process, the terms F/M ratio is important because this refers to - >>>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 ___________. - >>>Dividing/ Incoming BOD/ aeration tank In the activated sludge process, the term Gould Sludge Age refers to - >>>How long in days a pound of solids stays in the aerator In the activated sludge process, Gould Sludge Age (GSA) is calculated by - >>>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 - >>>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 - >>>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 - >>>Surface scum, Sludge blanket, Weir Flow, Rising solids, & Clarifier overflow In the activated sludge process, five (5) Important control parameters are - >>>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 _______. - >>>2 mg/L and 4.0 mg/L In the activated sludge process, "Classic Bulking" is a common problem typically caused by - >>>Low density sludge In the activated sludge process, Sludge Rising differs from "Sludge Bulking" and "Sludge Rising" is typically associated - >>>Nitrification - De-nitrification process In the activated sludge process, techniques used to reduce "Frothing & Foaming" typically include - >>>Adjusting sludge age, Reducing the amount of air, Spraying the frothing area with water, Applying de-foaming agents In the activated sludge process, floc is very important to the settling process. Floc is composed primarily of - >>>Bacteria, Protozoa, Microscopic Animals, & Fungi In the activated sludge plants, the operator will experience problems. Some of the common Treatment plant problems include - >>>Insufficent 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 - >>>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 - >>>Sludge quality, foaming, improper operating techniques In the activated sludge plants, the operator will experience problems. Some common Environmental problems include. - >>>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 - >>>Return activated sludge rate, Sludge blanket thickness, & the Solids concentration of the return flow The typical sludge age for extended aeration plants is - >>>20 to 40 days In the activated sludge plant, good quality sludge will settle _________& _______ over _________ minute period. - >>>Gently & Uniformly over 15 to 20 minutes In the activated sludge plant, old sludge quality will settle ________& _________ over ________ minute period. - >>>Rapidly and ragged over 5 minutes. In the activated sludge plant, there are (5) important nitroen transformation processes that occur by microorganisms. They are- - >>>Assumilation, Ammonification, Nitrification, Denitrification, & Nitrogen fixation.