17897 version 2
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Demonstrate knowledge of water treatment disinfection processes
Level
4
Credits
6
Purpose
People credited with this unit standard are able to describe: the purpose of
disinfection in water treatment; and the chlorination, ozonation, and ultraviolet disinfection processes, in water treatment.
Subfield
Water Industry
Domain
Water Treatment
Status
Registered
Status date
19 September 2008
Date version published
19 September 2008
Planned review date
31 December 2013
Entry information
Open.
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
Reference
Drinking-Water Standards for New Zealand, Ministry of Health, Wellington, 2000 and 2005.
 New Zealand Qualifications Authority 2016
17897 version 2
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Elements and performance criteria
Element 1
Describe the purpose of disinfection in water treatment.
Performance criteria
1.1
The types of pathogens present in untreated water are identified and described
in terms of their occurrence and the risk posed to human health.
Range
1.2
viruses, bacteria, protozoa.
The description identifies the effectiveness of disinfection in terms of public
health protection and Drinking-Water Standards for New Zealand.
Range
dose, time, residual.
Element 2
Describe chlorination processes in water treatment.
Performance criteria
2.1
Chlorination theory is described in terms of disinfection of water supplies.
Range
2.2
Disinfection of water supplies is described in terms of chlorination methods, and
the way in which they are sourced.
Range
2.3
breakpoint, chlorine compounds, residuals, Ct values, pathogen
vulnerability, pH effects.
methods – chlorine gas, sodium and calcium hypochlorite, mixed
oxidants, pool tablets, chlorine di-oxide, chlorination;
source – on-site-electrolytic generation, supplied.
Chlorination by-products are described in terms of the Drinking-Water
Standards for New Zealand.
Range
chlorinated organics, chloramines, chlorite, chlorate.
Element 3
Describe ozonation processes in water treatment.
Performance criteria
3.1
Ozonation theory is described in terms of disinfection of water supplies.
Range
includes but is not limited to – residuals, ozone half-life, pH effects,
Ct values, vulnerability of pathogens, nil residual, ozone
properties.
 New Zealand Qualifications Authority 2016
17897 version 2
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3.2
Disinfection of water supplies is described in terms of ozonation methods.
Range
3.3
includes but is not limited to – on-site generation, ozone
contactors and diffusers, air filtration, oxygen sources; ozone
vapour destruction.
Ozonation by-products are described in terms of the Drinking-Water Standards
for New Zealand.
Range
includes but is not limited to – bromine compounds.
Element 4
Describe ultra-violet (UV) disinfection processes in water treatment.
Performance criteria
4.1
UV radiation is described in terms of the way in which it achieves disinfection in
water supplies.
Range
4.2
dose, flow, transmittance, intensity, design configuration, cell
disruption, vulnerability of pathogens, nil residual, turbidity.
UV disinfection is described in terms of the operation, limitations, and
maintenance of its components.
Range
components – lamps (medium pressure, low pressure), ballast,
transmittance meter, intensity sensor;
limitations of components – air entrapment, component failure,
component longevity, water quality;
limitations of lamps – lamp fouling;
maintenance – cleaning (chemical, mechanical), calibration.
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.
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.
 New Zealand Qualifications Authority 2016
17897 version 2
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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