quiz 7 Flashcards
Which parameter is often higher in untreated groundwater as compared to untreated surface water?
Hardness
Which parameter is considered a secondary drinking water standard?
Odor
What is the sequence of processes used in conventional surface drinking water treatment plants?
coagulation, flocculation, sedimentation, filtration, disinfection
What is the major purpose of coagulation-flocculation-sedimentation in a surface drinking water treatment plant?
removal of particles
Which chemical is NOT a coagulant that is commonly used in a surface drinking water treatment plant?
Magnesium hydroxide
What media are usually used for granular media filtration?
sand
What is the major purpose of adsorption in a surface drinking water treatment plant?
Removal of natural or synthetic organic molecules and chlorine
Which chemical compound is settled/precipitated by precipitative softening for hardness removal?
CaCO3
Which chemical is NOT a disinfectant?
Amine
Which process provides residual disinfection?
chlorination
Which compound is a much stronger disinfectant?
Hypochlorous acid
Under certain conditions, which carcinogenic chemicals may be formed as chlorination by-products?
Halo-acetic acids
What is the purpose of secondary (residual) disinfection?
to prevent pathogen re-growth in the distribution system
How is CT defined in the context of disinfection?
concentration of disinfectant * contact time
Which membrane process is able to remove small particles, dissolved material, and sodium and chloride?
Reverse-osmosis
