WATER SUPPLY SYSTEM BASIC OPERATIONS Prepared by RCAP Solutions

WATER SUPPLY SYSTEM BASIC OPERATIONS Prepared by RCAP Solutions For PADEP

Introduction Basics of Water Supply 2

Drinking Water Sources Surface Water Groundwater 3

Surface Water: Advantages Easily accessible Large volumes of water Surface reservoirs for storage 4

Surface Water: Disadvantages Exposure to contaminants Expensive filtration 5

Groundwater: Advantages Less treatment Consistency Availability 6

Groundwater: Disadvantages Chemical contamination Hardness Multiple wells Location 7

Groundwater Treatment Processes 8

Groundwater Treatment Processes Not very complex Mainly disinfection Covered later 9

Surface Water Treatment Processes 10

Racks and Screens 11

Racks and Screens Prevent debris Pipes and pumps Straining pasta 12

Mixing 13

Mixing Coagulant Suspended particles 14

Coagulation and Flocculation 15

Coagulation and Flocculation Reduces solids Prevents bacterial “hiding” Like making cheese 16

Sedimentation 17

Sedimentation Presedimentation Basins Solids loading reduction Sludge removal 18

Filtration 19

Filtration Solids and floc removal Physical Chemical Biological 20

Types of Filtration Slow Sand Conventional Filtration 21

Types of Filtration Direct Filtration Diatomaceous Earth 22

Types of Filtration Membrane Filtration Bag and Cartridge Filters 23

Disinfection 24

Disinfection Disease-causing organisms Chlorine Ozone and Ultraviolet Radiation 25

Disinfection: Chlorine Chlorine Gas Sodium Hypochlorite 26

Disinfection: Chlorine Calcium Hypochlorite Chlorine may form carcinogens 27

Disinfection: Ultraviolet Light Penetrates most cell walls No toxic residuals Short contact times; easy to operate Unsuitable for some water sources 28

Disinfection: Ozone O3 Shorter contact time Capital costs O&M 29

Other Typical Treatment Processes Iron and manganese removal Corrosion control These are source dependent 30

Iron and Manganese Removal Various techniques Aeration Sequestration Ion exchange 31

Corrosion Control Prevents degradation Adjust water characteristics 32

Exercise Exercise!!! Complete the fill-in-the blank questions 33

Distribution System Facilities Pumps Storage facilities Transmission mains Valves and hydrants Meters 34

Pumps Provide lift Do not generally create pressure Major part of O&M costs 35

Storage Facilities Clear wells Stand pipes Elevated storage tanks 36

Clear Wells 37

Clear Wells Large concrete reservoirs Constant rate of operation 38

Stand Pipes Located on the ground Require little maintenance 39

Elevated Storage Tanks Supporting structures Use gravity Filled in off-peak hours 40

Transmission Mains System Design Branching systems Loop or grid systems 41

Transmission Mains Materials Cast iron Ductile iron Plastic (polyvinylchloride – PVC) 42

Valves and Hydrants Valves Wet barrel hydrants Dry barrel hydrants 43

Meters Throughout the system Used for billing and to identify loss Lowers usage Replacement program 44

Exercise Exercise time!!! Fill in the graphic and answer the questions 45

Summary Key points 46

References and Resources See your workbooks for details 47