AWWA Water Operator Certification Exam Prep 2024 With 520 Questions and Answers What is the most common disinfection by product when adding chlorine to water containing natural and inorganic matter? - ANSWER Chloroform What will most probably cause taste and odors, slime, and filter clogging? - ANSWER Blue-green Algae Why can rapid sand filters handle higher filtration rates compared to slow sand filters? - ANSWER Coarser sand Iron bacteria can interfere with ___________ because the bacteria produce _____________that prevents the stabilization chemicals from reaching the pipe surface. - ANSWER stabilization, a slime layer Hypochlorous acid is favored over hypochlorite ion when the pH is _____________and the temperature is ___________. - ANSWER low, low What filter has an unstratified media distribution? - ANSWER slow sand filters What is (are) the combine chlorine residual(s) at pH values ranging from 6.5 to 8.5? - ANSWER Monochloramine and dichloramine When iron alone is treated using manganese greensand filters, the chlorine feed rate should be about _________________. - ANSWER 1.0 to 1.2 times the iron concentration chlorination of water that has high concentrations of natural organic matter will produce - ANSWER THMs When disinfecting with chloramines, when can the ammonia be added to the process? - ANSWER Before, same time as, or after the chlorine What will settle out of the water in a short period of time? - ANSWER Very fine silt Point- of-use activated carbon filters are most effective for removing _________________. - ANSWER Chlorine Potassium permanganate is used as an oxidant for control of ____________________. - ANSWER Iron and manganese, organic precursors, and taste and odors What must an operator periodically check regarding the cyclone separator system? - ANSWER Storage bin or hopper to empty of sand and grit These types of chemicals chemically tie up scale-forming ions and are eventually ingested by consumers. - ANSWER Sequestering agents An operator should record filter ______________ measurements, condition, and depth of media on a ________ basis. - ANSWER bed expansion, quarterly Lime will precipitate noncarbonate hardness from the water, but it also orms noncarbonate salts that cause noncarbonate hardness. What are these salts? - ANSWER CaSO4 and CaCl2 What are absolute ratings based on with regard to membranes? - ANSWER Largest pore opening How ar manganese greensand beds regenerated? - ANSWER Backwashed with permanganate solution The most effective process for removing radon gas, when considering cost and footprint, would be ____________. - ANSWER packed tower aeration What is the primary advantage of placing a properly sized anthracite coal layer over manganese greensand? - ANSWER Longer filter run times What factor will cause problems for chlorination? - ANSWER Foreign substances In the lime-soda ash softening process, smaller plants find that ________ is less expensive to purchase; regardless of the size of the plant, ___________ needs to be mixed long enough because it dissolves rather slowly. - ANSWER calcium hydroxide, lime What does the optimal pH establish when applied to iron and manganese oxidation? - ANSWER Detention time A water plant using chloramines as a disinfectant has allowed sizable amounts of turbidity to enter the distribution system. If this occurs over a period of years, what will occur at the far end of the distribution system? - ANSWER Taste and odor will develop, Bacterial growth will be supported, and Nitrification The reduction of color would most likely occur after - ANSWER coagulation, flocculation, and sedimentation To eliminate hydrogen sulfide (H2S), the pH of the water should be lowered to ____________ or less before beginning aeration. - ANSWER 6.0 Permanganate reactions are largely dependent on ___________. - ANSWER pH What are the primary reasons that more small water stems are installing pressure filters? - ANSWER Because installation and operating costs are low Because lime slurries have a _________ and a ___________ in water, calcium carbonate will ____________ on anything the slurry touches. - ANSWER high pH, low solubility, preciptate It is recommended that the free chlorine residual at a customer's tap should be at least ________. - ANSWER 0.2 mg/L Microfiltration is considered to be intermediate between ___________ based on pore size. - ANSWER ultrafiltration and multimedia granular filtration After microscreening, there should be a significant reduction in ______________. - ANSWER Turbidity How can the problem of poorly formed floc be solved? - ANSWER Use of coagulant aid What chemical used in corrosion control gives off large quantities of CO2 when it comes in contact with an acid? - ANSWER Soda ash Alum requires _____________ to be present naturally or added fro proper coagulation, and about _____________ is required for each milligram of alum added per liter. - ANSWER alkalinity, 0.5 mg/L
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