AWWA WSO Water Treatment Grades 3&4 Questions With Complete Solutions.

Which disinfectant would work best against cryptosporidium? - Ozone The pH of a water sample is greater that the pHs so the Langlier index? - Indicates the water is scale forming. When water high in calcium bicarbonate is softened by ion exchange - Sodium bicarbonate remains in the product water. Lime softening can effectively disinfect water because: - The pH level is higher than 10.5 A noncarbonate hardness compound is - MgSO4 What term refers to the reintroduction of carbon dioxide into water either during or after lime-soda ash softening? - Recarbonation ___________ is the oxidation of unprotected metal surfaces. - Corrosion What is the cause of carbonate hardness? - Calcium Bicarbonate Which two ions are most commonly associated with water hardness? - Calcium and Magnesium For noncarbonate hardness to be removed, what must be added to remove the noncarbonated calcium compounds? - Soda Ash If a water system collects at least 40 samples per month for the analyses of total coliforms, what percentage of total coliform positive samples are acceptable for the system to remain in compliance with the maximum contaminant level for total coliforms? - No more than 5%Water systems are required to achieve at least ____________ removal and/or inactivation of viruses between a point where the raw water is not subject to recontamination by surface water runoff and a point downstream before or at the first customer. - 4 log