Wastewater D License Exam Questions & Answers

How many PPB equals one PPM? - ANSWERSOne thousand parts per billion equals one part per million If the bubbler system air supply line at the wet well is clogged, what will this cause the pump to do? - ANSWERSPressure build up in the supply line would signal more water column then there really was, causing the pump to run longer than necessary, possibly not kick off and run continually If the bubbler system air supply line at the wet well has a hole in it above the water level, what will this cause the pump to do? - ANSWERSIt would cause a low pressure reading showing a lower water level then there really is, or possible not even kicking on the pump What is the best way to keep within the operating budget? - ANSWERSkeep list of purchases and expenses to date during fiscal year comparisons should be made with budget allocations to avoid excess purchases review purchases monthly and compare to budget If a diaphragm pump has 2 check valves open, what will the pump do? - ANSWERSIt would not pump properly because 1 check valve should be shut while the other is open A suction lift pump on the inlet side normally reads 2in of mercury on the psi vacuum gauge but not reads 3in of mercury. What is the problem with the pump? - ANSWERSA higher vacuum than normal may indicate a partially plugged or restricted suction line. A lower vacuum may indicate a higher wet well level or a worn pump impeller or wearing rings. One mg per L equals how many pounds per 1 MG? - ANSWERS8.34 What is the proper way to put packing in a pump? - ANSWERScut the packing rope about 45 degree angle, place around shaft, be sure to offset/stagger the next joint from the previous How many drips of water should you have coming out of a packing seal? - ANSWERSno drip on a mechanical seal How many drips of water should you have coming out of a packing seal? 2 - ANSWERSwhat the operation and maintenance manual recommends A one horsepower motor that runs on 110 volts using 10 amps has what efficiency? - ANSWERSmost motors run from 80-95% efficiency A motor that has 440 volt supply is usually what phase of power? - ANSWERS3 phase NPDES - ANSWERSNational Pollutant Discharge Elimination System the regulatory agency document issued by either a federal or state agency which is designed to control all discharges of pollutants from point sources into US waterways - ANSWERSNPDES permit What is the name of our operating permit? - ANSWERSNPDES What is the best way to promote safety in the workplace? - ANSWERSthe supervisor needs to be safe and promote safety in such a manner to get the employees involved What is normally used to raise the pH in sludge? - ANSWERSlime What is the common device used to measure the effluent of a lagoon? - ANSWERSv notch weir What concentration of H2S is unsafe to humans? - ANSWERSdeath in a few minutes at 0.2%. Paralyzes respiratory center What is the minimum O2 concentration that is safe for workers to enter a manhole? - ANSWERSIf O2 is less than 19.5%, do not enter space without respiratory protection. Normal air contains 20.93% of O2. Normal air contains ______% of O2 - ANSWERS19.5% What knob is turned to control the usage of chlorine applied? - ANSWERSrotameter Can you store BOD at 4C for 48 hours? - ANSWERSyes What is the minimum velocity of the water flow for a grit chamber and the maximum flow? - ANSWERS1.0 feet per second minimum 1.5 feet per second optimum 2.0 feet per second maximum How many mg/L equals one grain per gallon? - ANSWERS17.1 mg/L Dissolved oxygen increases when the temperature __________ - ANSWERSdecreases You can tell if a clarifier scraper arm is working by what means? - ANSWERSthe simplest is to visual check to see if the scum scraper arm is moving properly check into foam If the sludge is thick or thin, then what does this tell you about the sludge scraper? - ANSWERSpossible answer is the flights are damaged or the speed of the scrapers(flights) need to be increased if sludge is too thick or slowed down if the sludge is too thin aging and maturing of a body of water - ANSWERSeutrophication eutrophication - ANSWERSaging and maturing of a body of water If the effluent from a treatment facility contained 5mg/L of BOD, what effect would this have on the receiving stream? - ANSWERSlittle effect If you are doing a test and add one drop of chemical at a time, what is this method called? - ANSWERStitration If doing a winkler or azide method after adding the first 2 chemicals and the contents of the bottle turn white, what does this mean? - ANSWERSno oxygen left in bottle, it has all been consumed How far from a well should a sewer main be? - ANSWERS300 feet a connection between a potable water system and a nonpotable water supply - ANSWERScross connection a disease causing bacteria - ANSWERSpathogenic What diseases are considered to be waterborne? - ANSWERSGiardia and Cryptosporidium Typhoid, Hepatitis, Cholera What are the 3 main components in fertilizer that are in sludge? - ANSWERSnitrogen, potassium, phosphorus application of the various soil and plant sciences to soil management and crop production, scientific agriculture - ANSWERSAgronomy If the filter fecal test is run, what color would the fecal coliform show up as? - ANSWERSblue What is another name for non-filterable solids? - ANSWERSsuspended solids If you switch any lead on a three phase motor, what is the result on the motor rotation? - ANSWERSit will reverse rotation What type of plant has these steps: MLSS in aeration, MLSS no aeration, MLSS in aeration? - ANSWERSstep feed aeration the electromotive force (EMF) and is the electrical pressure available to cause a flow of current (amperage) when an electrical current is closed - ANSWERSvoltage Where is the appropriate place to store a self contained breathing apparatus (SCBA)? - ANSWERSan approved casing hanging outside a chlorination room and unlocked How do you measure the amount of CL2 available in cylinders? - ANSWERSthe cylinders are on scales, you determine the beginning weight and subtract the remaining balance to give you the available Cl2 What is the chemical symbol for chlorine? - ANSWERSCl Two pumps are parallel to each other. Each one produces 300 gpm with 100 ft head. What would be the combined gpm? - ANSWERSover 300 gpm but less than 600gpm What is the purpose of thickening sludge? - ANSWERSto make it economically feasible What is the significant problem of having scum on the top of a pond? - ANSWERSit prevents sunlight from penetrating the algae How far should a sewer line be from a water main? - ANSWERS50' separation or 10' horizontal and 18'' separation of sewer lines to water lines when they cross or meet at joints What is the best way to get rid of algae? - ANSWERSthe first choice is chlorinating or alternative use is copper sulfate In what measurements is fecal reported? - ANSWERSthe MPN in Colony Forming Units (CFU) in per 100 mL MPN - ANSWERSmost probable number What is the purpose of disinfection? - ANSWERSto reduce pathogenic diseases for safer human contact What is the purpose of sterilization? - ANSWERSto kill all organisms and bacteria A piston pump is also called ......... - ANSWERSa reciprocating pump What pump is used for pumping sludge? - ANSWERSreciprocating pump What is the highest and lowest time of DO in a lagoon? - ANSWERSClass lecture states that 3pm is the highest and 3am is the lowest test states that 6pm is the highest point and 6am is the lowest What part of a centrifugal pump is used to discharge water? - ANSWERSVolute-collects wastewater discharged by pump impeller and directs flow to pump discharge What is the major cause of bearing failure in a motor? - ANSWERSimproper lubrication over lubricating an electric motor 1 horsepower equals how many watts? - ANSWERS746 A piston pump is a ___________ displacement pump. Never operate it against a ________ discharge pump, valve, and/or pipe. It could be damaged by excessive pressure. Also, the suction valve should be ____ when the pump is started. Otherwise an excessive suction or vacuum could develop and cause problems. - ANSWERSpositive closed open What is the BOD removal efficiency of a lagoon? - ANSWERS60-70% Why should you decant a digester? - ANSWERSto thicken biosolids so more economical to dispose of water Which of the following is not a form of the hydrologic cycle? a. evaporation b. precipitation c. absorption d. percolation - ANSWERSabsorption When should you lubricate motors? - ANSWERSwhat is recommended by the manufacturer