CE3503 Environmental Engineering

1. CE3503 Environmental Engineering Water Treatment Dr. Martin T. Auer MTU Department of Civil & Environmental Engineering

2. Charge Neutralization

3. Bridging floc negatively- charged particle negatively- charged particle hydroxo- metallic complex

4. Particle Settling Velocities Source: Vesilind & Morgan

5. Chlorine Distribution sorption

6. Drinking Water Process Train

7. Equilibrium Chemistry

8. Iron and Manganese

9. Hardness

10. Granular Activated Carbon The most commonly used adsorbent is granular activated carbon (GAC). These irregular particles, 0.2-5 mm in diameter, are a char of carbon material (wood or coal). They are ‘activated’ or made more porous by exposure to steam at high temperature. Activated carbon has 1000 m2 of adsorbing surface area per gram (~ 1 teaspoon) or equivalent to that of a 40 acre farm in one handful! Source: Sontheimer et al. 1988 Source: Chemviron Carbon Source: Millenium Inorganic Chemicals

11. The Adsorption Process Organic chemicals are typically removed from a water supply prior to distribution through the process of adsorption: the physical-chemical attraction of a solid material for a chemical in solution. In adsorption, the chemical being adsorbed is termed the adsorbate and the solid to which it sorbs is the adsorbent. Effluent stream Influent stream

12. 6 (mg/L) 4 2 Concentration 0 0 2 4 6 8 Time (d) … tendency to sorb For adsorption to be effective, the chemical must sorb strongly. Poorly soluble (hydrophobic) compounds (e.g. the components of gasoline) adsorb more strongly than highly soluble (hydrophilic) compounds (e.g. table salt). Poorly sorbed Strongly sorbed

13. … application in water treatment In drinking water treatment, adsorption with GAC is accomplished using a packed bed column. The untreated water is introduced at the top of the column and trickles down through the GAC. Contaminants are removed en route and clean water emerges at the bottom of the column. In application, columns 6 feet in diameter and 30 feet in height are not uncommon. Carbon Bed GAC columns

14. … column operation Water flows thru the column and contaminants are adsorbed. With time, the GAC becomes saturated (sorption capacity is reached) and contaminants exit the bed (breakthrough). The exhausted carbon must then be replaced. Cin exhaustion Cout Ceq breakthrough

15. Asbestos/Arsenic/Metals Removal Sorption with Ferric sulfate: asbestos, arsenic, cadmium, chromium, copper, lead, mercury, molybdenum, selenium, silver Coagulation with Alum: asbestos, nickel, uranium

16. Reverse Osmosis

17. Ultrafiltration

18. Ultrafiltration polypropylene fiber 300 µm ID 500 µm OD

19. Ultrafiltration 0.2 µm nominal pore size

20. permeate flow epoxy seal Ultrafiltration Technology raw water in

21. Ultrafiltration banks of fiber bundles

22. Ultrafiltration contaminants backwashing

23. Home Water Treatment Reverse osmosis unit (salt) Softening by ion exchange (hardness)

24. Home Water Treatment • Three step process: • sieve and bottom filter – rust, sand, turbidity • activated carbon filter – chlorine, color and SOCs • ion exchange resin – metals Bottled Water: $8 /gallon Tap Mount: $0.25 / gallon Municipal: $0.0015 / gallon Achieves 99.99% removal of Giardia and Cryptosporidium cysts, but does not remove all pathogenic organisms.