Waste water Grade 1- Questions with Verified Answers (100% Pass)

Waste water Grade 1- Questions with Verified Answers (100% Pass) Concentration of clhorine gas in excess of 1000 ppm are? - Answers Fatal after a few breaths Routine weir maintenance should include checking the? - Answers Volume of the basin What chemical is used for dechlorination - Answers Sulfur oxide When a secondary clarifier becomes septic which of the following should be checked first? - Answers Sludge withdrawal rate Which form of solids is most difficult to remove in a gravity treatment process? - Answers Precipitated In a chemical feed system, which of the following is most likely to be used? - Answers Rotary lobe Which of the following is added to bacteriological sample bottles to remove residual chlorine from a sample? - Answers Sodium thiosulfate An operator observes a dense and somewhat greasy scummy layer of deep tan or dark brown foam on the aeration tank. Which of the following is the most likely explanation for this situation? - Answers Old mixed liquor solids A facultative wastewater treatment pond receives domestic waste with no industrial discharges. Over the last few days, the operator has noticed an increase in odor and a pinkish color developing in the ponds. Which of the following is the most likely explanation? - Answers An anaerobic condition id developing Which of the following is most important to ensure confidence in analytical testing results? - Answers Quality control results The rotation of the shaft is reversed after a three-phase motor has been repaired. Which of the following actions should be taken? - Answers Change location of two of the three leads An operator is most likely to be exposed to which of the following hazardous gases in plant operation? - Answers Chlorine, hydrogen, sulfide, oxygen and nitrogen Which of the following is a common open channel flow measuring device for waste water - Answers Parshall flume The most common cause of motor failure is? - Answers Bearing failure What safety hazard is created by a polymer spill - Answers Slippery conditions How much larvicide should be spread over the lagoon surface if the weight of the larvicide is 8.5lbs/gal. The lagoon surface area is 5 acres. The lagoon is 3 feet deep, and recommended dosage is 1lb/10,000ft? - Answers 2.6 gal Most odor from ponds is caused by? - Answers Algae When checking the accuracy of a flow meter using a v-notch weir, the head should be measured at a point? - Answers Upstream at a distance 3 to 4 times the maximum weir heard A gravity grit removal system operates beat with a wastewater velocity of - Answers 2.0 fr/sec A sample of raw wastewater has a carbonaceous biochemical oxygen demand (cbod) concentration of 450 ppm. This most likely indicates? - Answers Wastewater containing high organic load In a small town, wastewater is pumped is pumped from a lift station with a pump having a capacity of 200 gpm. The station receives 180,000 gal of water during an average day. How many hours of run time will this pump have per day? - Answers 15 hr The most commonly used device to measure large wastewater flow is a? - Answers Parshall flume Chlorine is very corrosive when compined with? - Answers Water What is the proper way to mix water and acid? - Answers Add acid to water The simplest device used to measure flow in open channels is - Answers A weir Which of the following methods describes an effective safety program? - Answers Participants must recognize hazards and learn safe procedures Which of the following is the primary reason to use a mechanical seal? - Answers Reduced maintenance Failure to frequently remove solids from a manually cleaned bar screen is most likely to cause an increase in? - Answers Influent grit Aerobic digesters typically reduce VS by - Answers 40 to 50% The results of a 30 minute settleable solids test is 400 mL/l. What is the SVI if the MLSS concentration 2000 mg/L? - Answers 205 Sampling during which of the following Sequencing batch reactor cycles will provide the most accurate MLSS concentration results? - Answers Settle decant When there is an imbalance of current between the hot and neutral conductors of a circuit, the ground fault circuit interrupter (GFCI) - Answers Opens the circuit When the aeration is turned off, the clear water that forms on top of the aerobic digester is called the? - Answers Supernatant The difference in the amount of chlorine applied to a flow and the residual chlorine remaining after the given contact time is called? - Answers Demand An operator notices excessive wear on the coupling between the pump and the motor flanges. This is most likely caused by? - Answers Misalignment Over the last seven days, maintenance log show a consistent increase of pump inlet vacuum along with increased run time for one of two pump stations centrifugal pumps. Which of the following most likely is the cause - Answers The suction line has become clogged Which of the following chemicals is beneficial in creating the problem that causes a facultative pond to change from a deep bright green to a dull gray color? - Answers Sodium chloride Floating surface aerators are secured using a? - Answers Power cable The electrical current draw rate is measured in? - Answers Amps Before starting up a new pump, an operator should do which of the following first? - Answers Ensure all the equipment is locked out and tagged out Who is responsible for ensuring that safety rules are followed throughout a treatment plant? - Answers Each employee Which of the following is most commonly used to determine the stabilization of solids anaerobic digester? - Answers Methane gas production Which of the following is most important precaution while working on rotating equipment? - Answers Following lockout/tag out procedures for the machinery. Add a flow of 2.0 MGD (7570 M/day) what is the we're over flow rate of a 60 foot open (18.3 m) diameter primary clarifier? - Answers 708 GPD/FT (8786 lpd/m) TSS removal performance in a primary clarifier or sedimentation basin has been declining over the course of several days. The effluent is getting increasingly dark, almost black and fowler smelling over the same period. Which of the following is the most likely cause of these issues? - Answers Insufficient aeration Which is the following waste water characteristics affect grease in scum removal efficiency -