1 Virginia Water Treatment Plant under construction

2 Water Treatment Package Plant

3 Water Treatment l Purpose? »Provide Water that is acceptable for... l Topics for Today »Water Source »Unit Operations Human Consumption and Industrial use

4 Water Source l The better the water source, the less treatment needed l Example - Glassboro »Source - Groundwater »Until recently, just disinfection residual »Now, also iron and manganese removal

5 Unit Operations l Pretreatment l Suspended Solids Removal l Pathogen Removal/Destruction l Taste/Odor Removal/Destruction l Hardness Removal l Iron and Manganese Removal l Toxins/Organics Removal l Disinfection Residual l Fluoridation

6 Pretreatment l Get water to point where typical plant can handle it l May not be needed »Screens, Presedimentation, Chemical Treatment, Aeration...

7 Suspended Solids Removal l Improve water clarity (we want <0.1 NTU) l Improve effectiveness of disinfection »Sedimentation üCoagulants (chemicals) destabilize colloidal (very small) particles üFlocculation (gentle mixing) help solids stick together so they settle faster üParticles settle out in quiescent tank

8 Empty Flocculation/ Sedimentation tank Similar Flocculation/ Sedimentation tank In use

9 Suspended Solids Removal (cont.) »Granular Media Filtration üWater passed through bed of sand, anthracite (coal), and/or activated carbon üRemoves most of remaining particles l colloidal, floc l protozoa, worm eggs »Membrane Filtration üNot common, depending on type, can remove molecules! Ultrafiltration Membrane strands

10 Source: Granular Sand Filtration Tank

11 Pathogen Removal/Destruction l Disease Prevention (we want 0 pathogens) »Removal - sedimentation and filtration »Destruction - Disinfection by chlorination, ozone, or UV »Concentration & contact time critical »If done improperly, generates carcinogens »most effective with clear water

12 WELLSVILLE, NY, WATER TREATMENT PLANT Construction of clearwell (500,000 gallons) Minimum of four hour contact time with disinfection chemicals before leaving plant

13 Taste/Odor Removal/Destruction l We want good tasting & smelling water »Destruction - oxidation by chemicals üChlorine Dioxide, Potassium Permanganate, Ozone... »Destruction by microbes (rare) »Removal üadsorption to activated carbon üaeration (if offensive compounds are volatile, generally not the case for surface water)

14 Hardness Removal l Hardness - Most commonly Ca & Mg, also caused by Fe, Sr, Al,… l causes excess soap consumption, soap scum, & precipitates »Removed by precipitation »Removed by ion exchange

15 Iron and Manganese Removal l Causes staining of clothes and plumbing, precipitates »Precipitation by Aeration »Precipitation by Chemical Oxidation »Ion Exchange

16 Toxins Removal l We don’t want toxic water (MCLs) »Proper selection of water source »Proper design of plant to not MAKE toxins through disinfection process »Treatment (uncommon)- aeration / oxidation / adsorption / Biodegradation...

17 Disinfection Residual l We don’t want water to get contaminated by pathogens in distribution system »Residual consists of chlorine compounds »Not allowed to fall below 0.2 mg/L for more than 4 hrs

18 Fluoridation l We want good teeth »Add fluoride compounds if enough not naturally present »Too much will cause mottling

19 Groundwater Treatment Wells Disinfection Iron Chelation Aeration (Fe & Mn) Clarification Sand Filtration Disinfection Flocculation (Fe & Mn) Clarification Sand Filtration Disinfection Fluoridation

20 Surface Water Treatment Lake River Screen Rapid Mix Flocculation Clarification Sand filtration Disinfection Screen Presedimentation Rapid Mix Flocculation Clarification Sand filtration Disinfection Fluoridation

21 What do Our Water Filters do? l Remove suspended solids l Remove Pathogens l Kill Pathogens l Remove taste/odor/toxins(?)

22 How do they remove Suspended Solids?

23 How do they Remove Pathogens?

24 How do they Kill Pathogens?

25 Overal Pathogen Protection Level?

26 How do they remove taste/odor/toxins?