CalARP - Examination of Chemical Processes: Drinking Water Treatment

1. CalARP - Examination of Chemical Processes:Drinking Water Treatment Presented by: Paul Beswick - MWDSC Environmental Support Services (213) 217-5533 pbeswick@mwdh2o.com CalCUPA Forum Annual Conference - 2/4/03

2. Purpose • Present an overview of drinking water treatment processes and chemicals • Highlight role of CalARP Regulated Substance(s) (RS) in water treatment • Identify RS process risks and discuss risk mitigation measures

3. Joseph Jensen Filtration Plant

4. Robert A. Skinner Filtration Plant

5. Typical Water Treatment Plant FLASH MIX COAGULATION / FLOCCULATION SEDIMENTATION Mixes chemicals with raw water containing fine particles that will not readily settle or filter out of the water. Cl2 Gathers together fine light particles to form larger particles (floc) to aid the sedimentation and filtration processes. Settles out larger suspended particles. Cl2 PRE-CHLORINATION Kills disease causing organisms and helps control taste-and-odor causing substances. CHLORAMINES Kills disease causing organisms. Provides disinfectant residual for the distribution system. CORROSION CONTROL Cl2 NH3 Cl2 NaOH Adjusts the pH of the treated water to inhibit corrosion of pipelines. FILTRATION Filters out remaining suspended particles CLEARWELL TO DISTRIBUTION SYSTEM Provides contact time for disinfection. Stores water for high demand. DAF 9-20-00

6. Typical Water Treatment Plant FLASH MIX COAGULATION / FLOCCULATION SEDIMENTATION Mixes chemicals with raw water containing fine particles that will not readily settle or filter out of the water. Cl2 Gathers together fine light particles to form larger particles (floc) to aid the sedimentation and filtration processes. Settles out larger suspended particles. Cl2 PRE-CHLORINATION Kills disease causing organisms and helps control taste-and-odor causing substances. CHLORAMINES Kills disease causing organisms. Provides disinfectant residual for the distribution system. CORROSION CONTROL Cl2 NH3 Cl2 NaOH Adjusts the pH of the treated water to inhibit corrosion of pipelines. FILTRATION Filters out remaining suspended particles CLEARWELL Provides contact time for disinfection. Stores water for high demand. TO DISTRIBUTION SYSTEM DAF 9-20-00

7. Coagulation/Flocculation • COAGULATION • The feeding and rapid mixing of one or more chemicals coagulants into the water, thereby beginning the formation of particles called floc. • FLOCCULATION • The gentle mixing of water and coagulants to form larger, heavier, more settleable floc.

8. Coagulants • Chemicals that consist of positively charged ions that neutralize the negative charges and promote coagulation. • The most commonly used coagulants in water treatment are: • Aluminum Sulfate (Alum) Al2(SO4)3 • Ferric Sulfate Fe2(SO4)3 • Ferric Chloride FeCl3

9. Coagulant Aids • Added to improve coagulation; to build stronger, more settleable floc; to overcome temperature drops that slow coagulation; to reduce the amount of coagulant needed; and to reduce the amount of sludge produced. • Common coagulant aids: • Activated Silica • Weighting Agents (Bentonite clay) • Polyelectrolytes (polymers)

10. Filtration • The major purpose of filtration is to remove suspended material (turbidity) from water. • Suspended materials are removed when water passes through a bed of granular material known as the filter media. • Turbidity removal is important for public health; it interferes with disinfection by shielding microorganisms from the disinfectant.

11. Rapid Sand Vs High Rate Filter Media RAPID SAND DUAL-MEDIA TRI-MEDIA Coarse Coal Medium Sand Coarse Coal Medium Sand Fine Sand Fine Garnet Gravel Gravel Gravel

12. The Chlorination Process • Public Health benefits of chlorination • Process flow • Process components • Chlorine safety/risk mitigation measures

13. Chlorination Public Health Benefit • A critical role protecting US drinking water supply from waterborne infectious diseases for over 90 years • Cholera, typhoid, dysentery, hepatitis A virtually eliminated • In over 98% of disinfection systems • Germicidal potency, residual disinfection properties, efficiency, economy

14. Chlorination Public Health Benefit

15. The Chlorination Process

16. Chlorine Rail Car Unloading 90 Ton rail cars

17. Chlorine Trailer Unloading 17/19 Ton Trailers

18. Stationary Chlorine Tank 25 ton stationary tank

19. Chlorine Cylinder Storage 1 ton cylinders

20. Chlorine Evaporators

21. Chlorinators

22. Ejectors

23. Key Chlorine Safety Features • 24 hour monitoring and access control • Leak Detectors • Automatic shut-off valves • Regular preventive maintenance • On-site emergency response capability

24. Control Room • Operator on duty 24 hours a day. • Chlorine alarms are received in the Control Room. • Chlorine facilities are visually inspected every four hours.

25. Chlorine Trailer Manway • Remote emergency shut-off capability • Highly sensitive chlorine gas detector

26. Multiple Emergency Shut-off Locations • Controlled from several strategic locations • Shut-off is immediate

27. Monel Flex Hose Connection • Durable/flexible connection • Inspected/replaced regularly

28. Chlorine Gas Monitoring • Continuous monitoring, alarms locally and in Control Room • Sensors strategically placed throughout plant • Calibrated regularly

29. Chlorine leak alarms • Audio / Visual chlorine gas leak alarms provide immediate notification to all plant personnel.

30. Vacuum Operation • Chlorine piped to points of use throughout plant under vacuum • Safest method of transmission

31. On-site Emergency Response Capabilities

32. Emergency Responders

33. Chlorine “C” - kit

34. C-kit Installed in Trailer Manway

35. Emergency Responders

36. THANK YOU!Questions?