24974 version 1
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Demonstrate knowledge of coagulation and flocculation processes
Level
3
Credits
6
Purpose
People credited with this unit standard are able to describe the processes of
coagulation, and flocculation as used 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 by NZQA and industry.
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
None.
 New Zealand Qualifications Authority 2016
24974 version 1
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Elements and performance criteria
Element 1
Describe the process of coagulation as used in water treatment.
Performance criteria
1.1
The process of coagulation is described in terms of the characteristics of fine
particles.
Range
1.2
Coagulants are described in terms of their type, and effectiveness.
Range
1.3
coagulant mixing – coagulant dispersion, time, temperature;
available techniques – flash mixers, drop structures, pumps,
hydraulic mixers.
Coagulant dosing control methods are described in terms of dose level
assessment, control, and optimisation.
Range
1.5
includes but is not limited to – aluminium sulphate, aluminium
chloral hydrate, ferric chloride, poly-aluminium chloride, ferric
sulphate, polyelectrolytes.
The importance of rapid coagulant mixing and the available techniques are
described in terms of the factors that influence chemical reaction times.
Range
1.4
includes but is not limited to – colloidal substances, organics, silts,
clays, metal oxides, surface charges, nett charges, colour,
particulate matter, charge neutralisation;
characteristics – size, weight, density.
includes but is not limited to – jar test, streaming current meters,
pH meters, turbidity and colour loading, coagulant residuals,
process control.
Optimum coagulation dose rates are determined using a jar test.
Element 2
Describe the process of flocculation as used in water treatment.
Performance criteria
2.1
Flocculation is described in terms of its relationship to coagulation, and floc
sizes.
2.2
Floc particle growth is described in terms of mixing methods.
Range
temperature, flocculator types.
 New Zealand Qualifications Authority 2016
24974 version 1
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2.3
Polyelectrolytes are described in terms of their suitability for use as flocculant
aids.
Range
typical dose levels and features, charge distribution, size, shape,
charge.
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.
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