Transcript CalARP - Examination of Chemical Processes: Drinking Water Treatment Presented by: Paul Beswick - MWDSC Environmental Support Services (213) 217-5533 [email protected] CalCUPA Forum Annual Conference -

CalARP - Examination of Chemical
Processes:
Drinking Water Treatment
Presented by:
Paul Beswick - MWDSC Environmental Support Services
(213) 217-5533 [email protected]
CalCUPA Forum Annual Conference - 2/4/03
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
Joseph Jensen Filtration Plant
Robert A. Skinner Filtration Plant
Typical Water Treatment Plant
FLASH MIX
Cl2
Mixes chemicals with raw
water containing fine
particles that will not
readily settle or filter out of
the water.
COAGULATION /
FLOCCULATION
SEDIMENTATION
Gathers together fine light particles
to form larger particles (floc) to aid
the sedimentation and filtration
processes.
Settles out larger
suspended particles.
Cl2
PRECHLORINATION
Kills disease causing organisms and
helps control taste-and-odor causing
substances.
CORROSION
CONTROL NaOH Cl
2
CHLORAMINES
Kills disease causing
organisms. Provides
disinfectant residual for
the distribution system.
NH3 Cl2
Adjusts the pH of the treated
water to inhibit corrosion of
pipelines.
FILTRATION
TO DISTRIBUTION
SYSTEM
CLEARWELL
Provides contact time for
disinfection. Stores water
for high demand.
Filters out remaining
suspended particles
DAF 9-20-00
Typical Water Treatment Plant
FLASH MIX
Cl2
Mixes chemicals with raw
water containing fine
particles that will not
readily settle or filter out of
the water.
COAGULATION /
FLOCCULATION
SEDIMENTATION
Gathers together fine light particles
to form larger particles (floc) to aid
the sedimentation and filtration
processes.
Settles out larger
suspended particles.
Cl2
PRECHLORINATION
Kills disease causing organisms and
helps control taste-and-odor causing
substances.
CORROSION
CONTROL NaOH Cl
2
CHLORAMINES
Kills disease causing
organisms. Provides
disinfectant residual for
the distribution system.
NH3 Cl2
Adjusts the pH of the treated
water to inhibit corrosion of
pipelines.
FILTRATION
TO DISTRIBUTION
SYSTEM
CLEARWELL
Provides contact time for
disinfection. Stores water
for high demand.
Filters out remaining
suspended particles
DAF 9-20-00
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.
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
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)
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.

Rapid Sand Vs High Rate Filter Media
RAPID SAND
Medium
Sand
DUAL-MEDIA
Coarse
Coal
Fine Sand
Gravel
TRI-MEDIA
Coarse
Coal
Medium
Sand
Fine Garnet
Gravel
Gravel
The Chlorination Process
Public Health benefits of chlorination
 Process flow
 Process components
 Chlorine safety/risk mitigation measures

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

Chlorination Public Health Benefit
The Chlorination Process
Chlorine Rail Car Unloading
• 90 Ton rail cars
Chlorine Trailer Unloading
• 17/19 Ton Trailers
Stationary Chlorine Tank
• 25 ton stationary tank
Chlorine Cylinder Storage
• 1 ton cylinders
Chlorine Evaporators
Chlorinators
Ejectors
Key Chlorine Safety Features

24 hour monitoring and access control

Leak Detectors

Automatic shut-off valves

Regular preventive maintenance

On-site emergency response capability
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.
Chlorine Trailer Manway
Remote emergency shut-off capability
•
Highly sensitive chlorine gas detector
•
Multiple Emergency Shut-off
Locations
Controlled from several strategic locations
•
Shut-off is immediate
•
Monel Flex Hose Connection
Durable/flexible connection
•
Inspected/replaced regularly
•
Chlorine Gas Monitoring
•Continuous monitoring, alarms locally and in
Control Room
•Sensors strategically placed throughout plant
•Calibrated regularly
Chlorine leak alarms
•Audio / Visual chlorine gas leak alarms
provide immediate notification to all plant
personnel.
Vacuum Operation
• Chlorine piped to points of use throughout
plant under vacuum
• Safest method of transmission
On-site Emergency Response
Capabilities
Emergency Responders
Chlorine “C” - kit
C-kit Installed in Trailer Manway
Emergency Responders
THANK YOU!
Questions?