calarp - examination of chemical processes: drinking water treatment

CalARP - Examination of Chemical CalARP - Examination of Chemical Processes:Processes:

Drinking Water TreatmentDrinking Water Treatment

Presented by:Presented by:Paul Beswick - MWDSC Environmental Support ServicesPaul Beswick - MWDSC Environmental Support Services

(213) 217-5533 pbeswick@mwdh2o.com(213) 217-5533 pbeswick@mwdh2o.comCalCUPA Forum Annual Conference - 2/4/03CalCUPA Forum Annual Conference - 2/4/03

PurposePurpose

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 PlantJoseph Jensen Filtration Plant

Robert A. Skinner Filtration PlantRobert A. Skinner Filtration Plant

TO DISTRIBUTION SYSTEM

Typical Water Treatment Plant

PRE-CHLORINATION

Cl2

Kills disease causing organisms and helps control taste-and-odor causing substances.

DAF 9-20-00

FILTRATIONFilters out remaining suspended particlesCLEARWELL

Provides contact time for disinfection. Stores water for high demand.

Cl2

Cl2NH3

CHLORAMINESKills disease causing organisms. Provides disinfectant residual for the distribution system.

SEDIMENTATIONSettles out larger suspended particles.

COAGULATION / FLOCCULATIONGathers together fine light particles to form larger particles (floc) to aid the sedimentation and filtration processes.

FLASH MIXMixes chemicals with raw water containing fine particles that will not readily settle or filter out of the water.

Cl2NaOHCORROSION CONTROLAdjusts the pH of the treated water to inhibit corrosion of pipelines.

TO DISTRIBUTION SYSTEM

Typical Water Treatment Plant

PRE-CHLORINATION

Cl2

Kills disease causing organisms and helps control taste-and-odor causing substances.

DAF 9-20-00

FILTRATIONFilters out remaining suspended particlesCLEARWELL

Provides contact time for disinfection. Stores water for high demand.

Cl2

Cl2NH3

CHLORAMINESKills disease causing organisms. Provides disinfectant residual for the distribution system.

SEDIMENTATIONSettles out larger suspended particles.

COAGULATION / FLOCCULATIONGathers together fine light particles to form larger particles (floc) to aid the sedimentation and filtration processes.

FLASH MIXMixes chemicals with raw water containing fine particles that will not readily settle or filter out of the water.

Cl2NaOHCORROSION CONTROLAdjusts the pH of the treated water to inhibit corrosion of pipelines.

Coagulation/FlocculationCoagulation/Flocculation

COAGULATIONCOAGULATION– The feeding and rapid mixing of one or more The feeding and rapid mixing of one or more

chemicals coagulants into the water, thereby chemicals coagulants into the water, thereby beginning the formation of particles called beginning the formation of particles called floc.floc.

FLOCCULATIONFLOCCULATION– The gentle mixing of water and coagulants The gentle mixing of water and coagulants

to form larger, heavier, more settleable floc.to form larger, heavier, more settleable floc.

CoagulantsCoagulants Chemicals that consist of positively Chemicals that consist of positively

charged ions that neutralize the charged ions that neutralize the negative charges and promote negative charges and promote coagulation.coagulation.

The most commonly used coagulants The most commonly used coagulants in water treatment are:in water treatment are:– Aluminum Sulfate (Alum) AlAluminum Sulfate (Alum) Al22(SO(SO44))33

– Ferric Sulfate FeFerric Sulfate Fe22(SO(SO44))33

– Ferric Chloride FeClFerric Chloride FeCl33

Coagulant AidsCoagulant Aids Added to improve coagulation; to build Added to improve coagulation; to build

stronger, more settleable floc; to stronger, more settleable floc; to overcome temperature drops that slow overcome temperature drops that slow coagulation; to reduce the amount of coagulation; to reduce the amount of coagulant needed; and to reduce the coagulant needed; and to reduce the amount of sludge produced.amount of sludge produced.

Common coagulant aids:Common coagulant aids:– Activated SilicaActivated Silica– Weighting Agents (Bentonite clay)Weighting Agents (Bentonite clay)– Polyelectrolytes Polyelectrolytes (polymers)(polymers)

FiltrationFiltration The major purpose of filtration is to The major purpose of filtration is to

remove suspended material (turbidity) remove suspended material (turbidity) from water.from water.

Suspended materials are removed when Suspended materials are removed when water passes through a bed of granular water passes through a bed of granular material known as the filter media.material known as the filter media.

Turbidity removal is important for public Turbidity removal is important for public health; it interferes with disinfection by health; it interferes with disinfection by shielding microorganisms from the shielding microorganisms from the disinfectant.disinfectant.

Rapid Sand Vs High Rate Filter MediaRapid Sand Vs High Rate Filter Media

RAPID SAND DUAL-MEDIA TRI-MEDIA

MediumSand

Gravel

Gravel

Gravel

CoarseCoal

CoarseCoal

Fine SandMedium

Sand

Fine Garnet

The Chlorination ProcessThe Chlorination Process

Public Health benefits of chlorinationPublic Health benefits of chlorination Process flowProcess flow Process componentsProcess components Chlorine safety/risk mitigation measuresChlorine safety/risk mitigation measures

Chlorination Public Health BenefitChlorination Public Health Benefit A critical role protecting US drinking A critical role protecting US drinking

water supply from waterborne infectious water supply from waterborne infectious diseases for over 90 yearsdiseases for over 90 years

Cholera, typhoid, dysentery, hepatitis A Cholera, typhoid, dysentery, hepatitis A virtually eliminatedvirtually eliminated

In over 98% of disinfection systemsIn over 98% of disinfection systems Germicidal potency, residual disinfection Germicidal potency, residual disinfection

properties, efficiency, economyproperties, efficiency, economy

Chlorination Public Health BenefitChlorination Public Health Benefit

The Chlorination ProcessThe Chlorination Process

Chlorine Rail Car UnloadingChlorine Rail Car Unloading

• 90 Ton rail cars

Chlorine Trailer UnloadingChlorine Trailer Unloading

• 17/19 Ton Trailers

Stationary Chlorine TankStationary Chlorine Tank

• 25 ton stationary tank

Chlorine Cylinder StorageChlorine Cylinder Storage

• 1 ton cylinders

Chlorine EvaporatorsChlorine Evaporators

ChlorinatorsChlorinators

EjectorsEjectors

Key Chlorine Safety FeaturesKey Chlorine Safety Features

24 hour monitoring and access control24 hour monitoring and access control Leak DetectorsLeak Detectors Automatic shut-off valvesAutomatic shut-off valves Regular preventive maintenanceRegular preventive maintenance On-site emergency response capabilityOn-site emergency response capability

� Operator on duty 24 hours a day. Operator on duty 24 hours a day.

� Chlorine alarms are received in the Control Chlorine alarms are received in the Control Room.Room.

� Chlorine facilities are visually inspected Chlorine facilities are visually inspected every four hours.every four hours.

Control RoomControl Room

Chlorine Trailer ManwayChlorine Trailer Manway

�Remote emergency shut-off capabilityRemote emergency shut-off capability

�Highly sensitive chlorine gas detectorHighly sensitive chlorine gas detector

Multiple Emergency Shut-off Multiple Emergency Shut-off LocationsLocations

�Controlled from several strategic locationsControlled from several strategic locations

�Shut-off is immediateShut-off is immediate

Monel Flex Hose ConnectionMonel Flex Hose Connection

�Durable/flexible connectionDurable/flexible connection

�Inspected/replaced regularlyInspected/replaced regularly

Chlorine Gas MonitoringChlorine Gas Monitoring

� Continuous monitoring, alarms locally and in Continuous monitoring, alarms locally and in Control RoomControl Room

� Sensors strategically placed throughout plantSensors strategically placed throughout plant

� Calibrated regularlyCalibrated regularly

Chlorine leak alarmsChlorine leak alarms

� Audio / Visual chlorine gas leak alarms Audio / Visual chlorine gas leak alarms provide immediate notification to all plant provide immediate notification to all plant personnel.personnel.

Vacuum OperationVacuum Operation

� Chlorine piped to points of use throughout Chlorine piped to points of use throughout plant under vacuumplant under vacuum

� Safest method of transmissionSafest method of transmission

On-site Emergency Response On-site Emergency Response CapabilitiesCapabilities

Emergency RespondersEmergency Responders

Chlorine “C” - kitChlorine “C” - kit

C-kit Installed in Trailer ManwayC-kit Installed in Trailer Manway

Emergency RespondersEmergency Responders

THANK YOU!THANK YOU!

Questions?Questions?