1. 1 Water Quality Freshman Clinic II Number of typhoid deaths, Philadelphia 10000 6000 2000 800 200 0 188518951905191519251935 Filtration, 1905 Chlorination, 1905 Adopted from ASCE

2. 2 Safe Drinking Water Act of 1974 n Ensure public water supply systems meet minimum standards for protection of public health –Primary Regulations –Secondary Regulations http://www.epa.gov/safewater/mcl.html

3. 3 Primary Drinking Water Standards n Protection of human health –Maximum Contaminant Level Goal n Nonenforceable health goal n What we’d like to achieve –Maximum Contaminant Level n Set as close to MCLG as feasible (tech/cost) n Violation requires corrective action

4. 4 Primary Standards n Organics –Pesticides, Solvents, Fuels... n Inorganics –metals... n Radionuclides –Beta particles, alpha particles, radon... n Microbials –viruses, bacteria, protozoa, helminths

5. 5 Example Contaminants ContaminantMCLGMCL Health Effect Cause BenzeneZero 0.005 mg/L Risk of Cancer Factories, Gasoline, Landfills Cadmium 0.005 mg/L Kidney Damage Galvanized pipes, Erosion of natural deposits, Metal refineries, Batteries, Paints Alpha Particles Zero 15 picocuries/ Liter (pCi/L) Risk of Cancer Erosion of natural deposits Giardia Lamblia ZeroTT Gastrointestional Illness Human or animal fecal matter TT – Treatment Technology (filtration and disinfection, or alternative that achieves 99.9% removal/inactivation)

6. 6 Aside - Units n Concentration –mg/l (milligrams per liter) n milli = 1/1,000 –ug/l or  g/l (micrograms per liter) n micro = 1/1,000,000 –pCi/l (picocuries per liter) n pico = 1/1,000,000,000,000 n The curie is equal to 37 billion disintegrations per second, approximately the activity of 1 gram of radium

7. Microbial Pathogens n Tiny living organisms that cause disease n Can be –Viruses –Bacteria –Protozoa –Helminths n But not all viruses, bacteria, protozoa, and helminths are pathogens

8. 8 Measurement n Organics and Inorganics –measure for specific compound n HPLC, GC, GC-Mass Spec, AA, IC… n Radionuclides –Conduct gross tests, then specific tests n Microbes –Measure indicator organisms

9. Indicator organisms n Too difficult to identify all pathogens, so we use indicator organisms –May not be pathogens themselves n If you find indicator organisms –sample might be pathogen contaminated n If you don’t –very unlikely sample is contaminated

10. 10 Common Indicator Organisms n Total Coliform n Fecal Coliform n Escherichia coli n Common denominator is fecal coliform –found in intestines –evidence of fecal contamination http://www.cellsalive.com/ E. Coli

11. 11 Secondary Drinking Water Standards n Not health related n Not enforceable n Based on –Aesthetics n Color, odor, taste, foaming… –Cosmetic effects n Skin or tooth discoloration –Technical effects n Corrosivity, staining, scaling, sedimentation

12. 12 Examples of Secondary Standards PARAMETERGOALREASON Chloride 250 mg/L salty taste Copper 1.0 mg/L metallic taste; blue-green staining Corrosivity Non-corrosive metallic taste; corroded pipes/ fixtures staining Fluoride 2.0 mg/L tooth discoloration Foaming agents 0.5 mg/L frothy, cloudy; bitter taste; odor Iron 0.3 mg/L rusty color; sediment; metallic taste; reddish or orange staining pH 6.5 - 8.5 low pH: bitter metallic taste; corrosion high pH: slippery feel; soda taste; deposits Silver 0.1 mg/L skin discoloration; graying of the white part of the eye Sulfate 250 mg/L salty taste Total Dissolved Solids (TDS) 500 mg/L hardness; deposits; colored water; staining; salty taste

13. 13 Odor n Threshold odor number (TON) –Goal is < 3 TON –Determined by panels of “smellers” identifying the most dilute sample they can smell n A = ml sample n B = ml odor-free water TON = (A + B) / A another secondary standard Electronic Noses are finding more application

14. Color n Goal is < 15 color units n True Color –vegetable or organic extracts that are dissolved or too small to filter n Also called “natural color”, usually yellowish-brown n South Jersey rivers have lots of true color n Apparent Color –suspended matter, such as red clay –Can be filtered out another secondary standard

15. Color Measurement n Traditional –chemical solutions that produce color similar to natural color n Platinum Cobalt Color Units –start w/ 500 mg/L solution K 2 PtCl 6 –add sufficient cobalt chloride to provide proper tint –dilute to produce working standards n 1 mg/L of K 2 PtCl 6 = 1 platinum cobalt unit n Modern –Use a spectrophotometer

16. 16 Spectrophotometer Hach model DR/4000 UV VIS www.hach.com

17. 17 Light Absorbance n Many solutions absorb light n Amount of absorbance function of –chemicals in solution and their concentration –distance light travels through solution –wavelength of light

18. 18 Spectrophotometry n Widely used n Accurate and sensitive n Absorbance of light used to measure concentration of light absorbing compounds –If compound itself doesn’t absorb light, reactant is added that converts it to some other (light absorbing) compound Red solutions are red because they absorb blue light

19. 19 Beer-Lambert law n Amount of light absorbed is proportional to number of molecules of absorbing substance in light path n Absorbtion proportional to –concentration of chromogen (light absorbing compound) –length of light path through solution

20. 20 n I and I 0 = intensity of transmitted light in presence / absence of chromogen, respectively n c = concentration of chromogen n l = length of light path through solution n K = constant, characteristic for each absorbing substance at a specified wavelength of light and in a specific solvent (often water) n light transmission = I/I 0, usually reported as a percent n Absorbance (Abs) is used more frequently -log 10 (I/I 0 ) = K c l Abs = -log 10 (I/I 0 )

21. 21 Hach model DR/4000 UV VIS n Uses Deuterium Lamp and gas filled Tungsten Lamp n Narrows light down to a specific wavelength using a monochromator n Detects the difference in light through a solution photoelectrically and compares that difference electronically n The difference is expressed as percent transmission or absorbance www.hach.com

22. 22 n carefully made solution containers n plane, parallel sides ensure light path is same through all portions, making it possible to tabulate values of K for various substances in various solvents and wavelengths cells or cuvettes

23. 23 Color and Spectrophotometry n We can measure color in water samples using a specific wavelength of light n Measure true color of filtered water n Measure apparent color of unfiltered water

24. Turbidity n Clarity of water n Cause –Soil runoff, resulting in scattering of light by colloidal particles colloidal particles are 0.001 to 1  m colloidal particles are 0.001 to 1  m n Why do we care? –Clarity relates to cleanliness –Affects treatment success of disinfection n Measurement –light transmission with standard light source, 90 o detector, and glass container n Measured in NTU (Nephelometric Turbidity Units)

25. Some NTU Numbers n > 5 NTU's n < 0.1 NTU n Surface water typical values –11 NTU –16 NTU –26 NTU Detected visually Aesthetically objectionable Properly treated water Reservoir Lake River

26. 26 Turbidity Standard n Primary drinking water standard –Turbidity may never exceed 1 NTU, and must not exceed 0.3 NTU in 95% of daily samples in any month n Why primary? –Because water with low turbidity is less likely to be contaminated by pathogens and disinfects easier

27. 27 Hach 2100N Laboratory Turbidimeter www.hach.com

28. 28 Turbidimeter n Micro-processor-based model n Employs advanced optical and electronic design n Has two types of sensors –Scattering Sensor –Transmissive Sensor

29. 29 Turbidity Test

30. 30 Websites n EPA Office of Water –www.epa.gov/OW/ www.epa.gov/OW/ n Water Quality Company –www.hach.com n Frequently asked questions about water quality –www.sioxlan.com n Water Environment Federation –www.wef.org n American Water Works Association –www.awwa.org n Info on water treatment processes –www.culligan.com