1. CalARP - Examination of Chemical Processes: Drinking Water Treatment
Presented by:
Paul Beswick - MWDSC Environmental Support Services
(213)
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. TO DISTRIBUTION SYSTEM
Typical Water Treatment Plant
PRE-CHLORINATION
Cl2
Kills disease causing organisms and helps control taste-and-odor causing substances.
DAF
FILTRATION
Filters out remaining suspended particles
CLEARWELL
Provides contact time for disinfection. Stores water for high demand.
NH3
CHLORAMINES
Kills disease causing organisms. Provides disinfectant residual for the distribution system.
SEDIMENTATION
Settles out larger suspended particles.
COAGULATION / FLOCCULATION
Gathers together fine light particles to form larger particles (floc) to aid the sedimentation and filtration processes.
FLASH MIX
Mixes chemicals with raw water containing fine particles that will not readily settle or filter out of the water.
NaOH
CORROSION CONTROL
Adjusts the pH of the treated water to inhibit corrosion of pipelines.

6. TO DISTRIBUTION SYSTEM
Typical Water Treatment Plant
FLASH MIX
Mixes chemicals with raw water containing fine particles that will not readily settle or filter out of the water.
COAGULATION / FLOCCULATION
Gathers together fine light particles to form larger particles (floc) to aid the sedimentation and filtration processes.
SEDIMENTATION
Settles out larger suspended particles.
Cl2
NH3
CHLORAMINES
Kills disease causing organisms. Provides disinfectant residual for the distribution system.
PRE-CHLORINATION
Cl2
Kills disease causing organisms and helps control taste-and-odor causing substances.
Cl2
NaOH
CORROSION CONTROL
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

7. Coagulation/Flocculation
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
DUAL-MEDIA
TRI-MEDIA
Medium
Sand
Coarse
Coal
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?