19356 version 2
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Optimise and manage hardness and corrosion control for drinkingwater treatment
Level
5
Credits
5
Purpose
People credited with this unit standard are able to: manage the impact of
hardness and corrosion of water undergoing water treatment; manage pH
values in drinking-water treatment; optimise and manage processes to
control pH and alkalinity in water treatment; and identify critical points and
hazards, and identify and manage preventive and corrective actions, in pH
and alkalinity adjustment processes.
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
1
Reference
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.
 New Zealand Qualifications Authority 2016
19356 version 2
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Optimise – adjusting plant input variables to make the process as effective as
possible in order to achieve the desired output, taking into account the constraints of
cost, human input, water quality, and water demand.
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.
Drinking-water supply – the supply catchment, treatment plant, and distribution. The
drinking-water supplier has responsibility for managing the public health risks of the
drinking-water supply.
Elements and performance criteria
Element 1
Manage the impact of hardness and corrosion of water undergoing water treatment.
Performance criteria
1.1
Inorganics and organics present in untreated water are managed in terms of
their impact on water pH and alkalinity, and treatment processes.
Range
1.2
carbon dioxide, carbonate, bicarbonate, sulphates, chlorides,
organic colour, pH definition, hardness, alkalinity.
Water chemical treatment is optimised and managed in terms of its effects on
pH, alkalinity, hardness, and corrosion.
Range
may include but is not limited to – alum, hydrated lime, soda ash,
caustic soda, carbon dioxide, sulphuric acid;
evidence is required for at least one.
Element 2
Manage pH values in drinking-water treatment.
Performance criteria
2.1
The pH range of drinking-water is managed in accordance with the DrinkingWater Standards 2000 and 2005 and organisational procedures.
2.2
The impacts of water pH and alkalinity are monitored in terms of pipe corrosion,
plumbosolvency, and scale formation.
Range
includes but is not limited to – metal corrosion parameters,
Langelier Saturation Index, lead and copper levels, asbestos
cement pipe.
 New Zealand Qualifications Authority 2016
19356 version 2
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Element 3
Optimise and manage processes to control pH and alkalinity in water treatment.
Performance criteria
3.1
Chemical addition and removal techniques are optimised and managed in
relation to pH control in water treatment using a selected chemical.
Range
equipment – one of – dry powder feeders, mixing tanks, dosing
pumps;
operational issues – solution strengths, carry water, material
handling safety, chemical transfer, line and pump blockage,
chemical safety handling, powder feeder control, line cleaning;
management techniques – material handling safety, equipment
selection, equipment maintenance;
pH control methods – measurement, calibration, time lags,
feedback control loops.
Element 4
Identify critical points and hazards, and identify and manage preventive and corrective
actions, in pH and alkalinity adjustment processes.
Performance criteria
4.1
The critical points in pH and alkalinity control process 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 occurrence, and the risk factors.
4.3
The preventive and corrective actions for events related to each hazard are
identified and managed.
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.
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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