north battle ford general

7/31/2019 North Battle Ford General

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Requirements to produce high

quality water

Stephen Stanley, Ph.D., P.Eng.

EPCOR Water Services


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Capable Plant Model

High Quality Treated Water

Operation (process control)

Capable Plant

Administration Design Maintenance


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Capable Plant

A capable plant means if it is managed,

operated and maintained properly, the plant

has the required infrastructure to meet allrequirements

Criteria for capable plant largely dependent

on regulation


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Capable Plant

Requirements constantly changing as new

information becomes available

turbidity requirements have gone from 5 NTUto 1 NTU to 0.5 NTU and now proposed to go

to 0.3 NTU

Requirements for a capable plant alsodependent on raw water source

ground water - disinfection

surface waters - filtration and disinfection


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Capable Plant - Giardia Example

Raw Water

Giarida Levels

Recommended Log

Reduction


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Capable Plant

Multi-barrier Approach

Water treatment uses the concept of multi-

barriers to meet treatment requirements

a number of treatment processes which are eachbarriers for contaminants

Giardia example for 4 log removal

Clarification 0.5 log removalFiltration 2.0 log removal

Disinfection 1.5 log removal


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Capable Plant - Cryptosporidium

One of the greatest challenges facing the

water industry

Regulations just starting (US EPA and

Canada)

Resistant to chlorine (loss of major barrier)

For conventional treatment must rely on

particle removal

UV and ozone disinfection effective


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Capable Plant - Regulation

Regulations generally based on the concept

of reducing the risk associated with water to

an acceptable levelother factors include available technology and

economics

Poorer standards result in greater risk thatpublic health can compromised

typically event related (when plant challenged)


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Capable Plant - Summary

Requirements of a capable plant dependent

on regulation

Also dependent on raw water source

Capability of plant restricted to design flow

rates

A capable plant only provides the ability to

produce high quality water if proper

administration, maintenance and operational

systems are in place


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Adminstration

Relates to having administrative policies,

and staffing and funding requirements

needed to produce high quality water

Requires a commitment from senior

administration to produce high quality water

Needs quality assurance and quality controlprograms to ensure high quality water

Must ensure adequate staffing and funding

are available


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Design

Design of a treatment facility must not only

meet requirements for the capable plant but

must also consider operational andmaintenance realities

Design should also consider technical

expertise required


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Maintenance

To make a capable plant sustainable, regular

maintenance must occur

Maintenance activities must consider

operational constraints and must be planned

accordingly

For critical systems redundancy may berequired


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Operations - Process Control

Water treatment of surface waters,

especially those treating river waters is a

very dynamic process raw water quality may vary from a turbidity of

1 NTU to over 1000 NTU

water demand may vary by 3 times Treatment plants must constantly vary

operating conditions (chemical doses,

flows, etc.)


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For process control require:

a measure of the state of the system

comparison of the current state to the desiredstate

an action (for example a change in chemical

dose) to return the system to the desired state


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Challenges in Process Control

Multiple and conflicting objectives

water quantity vs. water quality

disinfection vs. disinfection by-products

Multiple operating parameters

must simultaneously adjust more than one

chemical dose and operating conditions


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Long residence time in plant

if treated water turbidity increases and requires

change in coagulant dose at front of plant, canhave 3 to 5 hours of water in the plant that must

pass through before change will be noticed

requires intermediate assessment of treatment

process


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No standard methods to determine proper

chemical dosing

must rely heavily on operator experience

must ensure available tools are being used (jar

tests)


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Upsets can occur in water treatment

Must have clearly defined emergency

response plans

Should have programs such as a boiled

water notice in place

Can not wait for illness


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Production of High Quality

Water

Requires not only a capable plant but proper

administration, design, maintenance and

operations Failure in any of these areas significantly

increases the risk to public health


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The Challenge

Requirements for the production of high

quality of water is largely independent of

the size of the community The complexity of the treatment system is

largely dependent on the quality of the raw

water The challenge is implementing the

requirements in smaller communities

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