7 Sources and Treatment Process Selection

River water

• Requires extensive treatment

• Highly variable quality

• Needs the greatest flexibility

Lakes

• Subject to seasonal changes

• Turning over — the bottom anaerobic/anoxic layer mixes with the top in Spring and Fall

• Anoxic layers release Fe(II), Mn(II), and H2S

• Late summer – algal blooms

Groundwater (deep wells)

• Safest

• Best quality

• Best temp, taste, and odor

• Simplest treatment

• Could have problems with hardness or arsenic

Groundwater well treatment

Well → Aeration → Detention tank (allows for complete oxidation) → sand filter (removes Fe and Mn) → add ammonia and fluosilicic acid

Shallow Well Treatment

Shallow well → Add alum and lime → flocculator clarifier → Add potassium permanganate → flocculator clarifier → Fluosilicic acid → dual media coal-sand filter → add chlorine

Lake Treatment

Lake → Intake with screen → Add Cl and activated carbon → Mixing tank and flocculator (alum) → Add activated carbon → Settling tank → sodium fluoride → sand filter → chlorine

River Treatment

River → screens → Presedimentation basins → baffled mixing basin → sedimentation basins → flocculator clarifier → blending tank → sedimentation basin → sand filter → add Cl and soda ash

Intake types

• Submerged or exposed

Intake structures may represent __ % of the cost of a facility

20%

Which intakes are better

Submerged