Water Treatment: Introduction Suzette R. Burckhard, PhD, PE Civil and Environmental Engineering South Dakota State University Engineering the Future 2014

Objectives Facts –Define MCL, MCLG, MRDL, MRDLG, Treatment Technique Application –Explain the basic treatment operations necessary to treat surface water and ground water to drinking water standards

Water Quality review Physical Characteristics –color, turbidity, temperature, taste, odor Chemical Characteristics –chemical components, concentrations, pH Microbiological –Coliforms, Legionella, Giardia lamblia, Cryptosporidium Radiological –radiation level (Curies)

Water Quality Standards Maximum Contaminant Levels (MCLs), MCL Goal Secondary MCLs Treatment Technology (TT) Maximum Residual Disinfectant Level (MRDL), MRDL Goal

Water classification Ground water –Constant composition –High mineral content –Low turbidity –Low or no color –May be bacteriologically safe –No dissolved oxygen –High hardness –H 2 S, Fe, Mn –Possible chemical toxicity

Water Classification Surface Water –Varying composition –Low mineral content –High turbidity –Color –Microorganisms present –Dissolved oxygen –Low hardness –Tastes and odors –Possible Chemical toxicity

Treatment Limited treatment plants –Filtering is minimum required treatment Coagulation plants –Surface water treatment Softening plants –Groundwater treatment Typical treatment steps –Acquire water to be treated (surface water and/or groundwater) –Add chemical to soften or coagulate SS (depends on source) –Mix water and chemical to allow full reaction –Settle out particles –Filter (polish) water –Disinfect –Distribute

Limited treatment plants High quality water sources Address a specific water quality issue –Disinfection –Corrosion control –Fluoridation –Iron/manganese removal –Softening

Coagulation plants Treat surface water Remove –Color, turbidity, taste and odors, bacteria Typical treatment steps –Screening –Rapid mixing –Flocculation –Sedimentation –Filtration –Disinfection then distribution

Softening plants Typically treat groundwater –Similar types of operations as coagulation but with different chemicals –Main purpose of treatment is to remove hardness Typical treatment steps –Chemical addition – rapid mixing –Reaction –Settling –Recarbonization –Filtering –Disinfection and distribution

Comparison of Softening and Coagulation Plant Operations