24900 version 1
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Describe the management of chlorine and chlorine dioxide disinfection
processes
Level
5
Credits
8
Purpose
People credited with this unit standard are able to describe for chlorine and
chlorine dioxide disinfection processes: mechanisms, variables which
determine their effectiveness, design features, the equipment used, methods
of application, safety considerations, and operating issues; and identify
critical points, hazards, preventive actions, and corrective actions of chlorine
and chlorine dioxide disinfection processes.
Subfield
Water Industry
Domain
Drinking-Water
Status
Registered
Status date
19 September 2008
Date version published
19 September 2008
Planned review date
31 December 2013
Entry information
Open.
Replacement information
This unit standard, unit standard 24901, and unit
standard 24902 replaced unit standard 18453.
Accreditation
Evaluation of documentation and visit by NZQA, industry
and teaching professional in the same field from another
provider.
Standard setting body (SSB)
Primary Industry Training Organisation
Accreditation and Moderation Action Plan (AMAP) reference
0179
This AMAP can be accessed at http://www.nzqa.govt.nz/framework/search/index.do.
Special notes
1
References
Legislation relevant to this unit standard includes but is not limited to the Hazardous
Substances and New Organisms Act 1996.
 New Zealand Qualifications Authority 2016
24900 version 1
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Ministry of Health Public Health Risk Management Plan Guides for Drinking-Water
Supplies (PHRMPGs):
P7.1, Chlorine disinfection;
P7.2, Chlorine dioxide disinfection.
Drinking-Water Standards for New Zealand, Ministry of Health, Wellington, 2000 and
2005.
2
Definitions
Critical points – points in a process or in equipment where failure to function correctly
can lead to a public health hazard.
Organisational procedures – instructions to staff, and procedures which are
documented in memo or manual format and are available in the workplace. These
requirements include but are not limited to – site specific requirements,
manufacturers’ specifications, product quality specifications, and legislative or
regulatory requirements.
Elements and performance criteria
Element 1
Describe chlorine and chlorine dioxide disinfection process mechanisms, variables which
determine their effectiveness, and design features.
Performance criteria
1.1
Chlorine and chlorine dioxide disinfection processes are described in terms of
the mechanisms by which chlorine compounds inactivate micro-organisms.
1.2
Chlorine disinfection is described in terms of the variables which determine the
effectiveness of the process.
Range
1.3
includes but is not limited to – Freely Available Chlorine (FAC),
Total Available Chlorine (TAC), contact time, temperature, pH,
turbidity, organic loading, chloramine, chlorine demand.
Chlorine and chlorine dioxide disinfection processes are described in terms of
their design features.
Range
typical sizes, configurations.
Element 2
Describe the equipment used, methods of application, and safety considerations for
chlorine and chlorine dioxide disinfection processes.
Performance criteria
2.1
Chlorine and chlorine dioxide disinfection processes are described in terms of
storage and delivery mechanisms of chlorine which can contribute to under or
over dosing.
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24900 version 1
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2.2
Chlorine and chlorine dioxide disinfection processes are described in terms of
monitoring equipment.
2.3
Chlorine and chlorine dioxide disinfection processes are described in terms of
safety considerations when handling.
2.4
Disinfection of water supplies is described in terms of the source compounds of
chlorine, and their production and properties.
Range
chlorine gas, sodium and calcium hypochlorite, chlorine dioxide,
on-site electrolyte generation, mixed oxidants.
Element 3
Describe operating issues associated with chlorine and chlorine dioxide disinfection.
Performance criteria
3.1
Chlorine and chlorine dioxide disinfection is described in terms of operating
issues.
Range
impact of contact time, continuity of power and chemical supply,
dose rate adjustment and control, alarm response, drinking-water
standard transgression, corrosion, disinfection by-product
formation, equipment failure, safety of public, equipment
calibration and servicing, record keeping.
Element 4
Identify critical points, hazards, preventive actions, and corrective actions of chlorine and
chlorine dioxide disinfection processes.
Performance criteria
4.1
The critical points in the disinfection processes are identified in accordance with
organisational procedures.
4.2
The hazards at each critical point are identified in terms of the causes of the
events leading to their appearance, and the risk factors.
4.3
The preventive and corrective actions for events related to each hazard are
identified.
Please note
Providers must be accredited by NZQA, or an inter-institutional body with delegated
authority for quality assurance, before they can report credits from assessment against
unit standards or deliver courses of study leading to that assessment.
Industry Training Organisations must be accredited by NZQA before they can register
credits from assessment against unit standards.
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Accredited providers and Industry Training Organisations assessing against unit standards
must engage with the moderation system that applies to those standards.
Accreditation requirements and an outline of the moderation system that applies to this
standard are outlined in the Accreditation and Moderation Action Plan (AMAP). The
AMAP also includes useful information about special requirements for organisations
wishing to develop education and training programmes, such as minimum qualifications for
tutors and assessors, and special resource requirements.
Comments on this unit standard
Please contact the Primary Industry Training Organisation standards@primaryito.ac.nz if
you wish to suggest changes to the content of this unit standard.
 New Zealand Qualifications Authority 2016