18450 version 3
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Describe the management of coagulation and flocculation processes
Level
5
Credits
6
Purpose
People credited with this unit standard are able to describe: the optimising of
the process of coagulation as used in water treatment; the links between
coagulation and flocculation and optimising the process of flocculation as
used in water treatment; and the identification of critical points, hazards,
preventive actions, and corrective actions of coagulation and flocculation
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.
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.
Optimising – 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.
 New Zealand Qualifications Authority 2016
18450 version 3
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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 the optimising of 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
Optimising coagulation is described in terms of the pH and alkalinity level of the
water in the treatment process.
Range
1.3
includes but is not limited to – aluminium sulphate, ferric chloride,
poly-aluminium chloride, ferric sulphate, polyelectrolytes,
aluminium chloral hydrate.
The importance of rapid coagulant mixing and the available techniques are
identified and calculated in terms of the velocity gradient.
Range
1.6
elevated coagulant dosing, organics removal, disinfection byproducts minimisation, pH correction.
Coagulants are described in terms of their effectiveness and cost.
Range
1.5
optimum alkalinity levels, coagulant pH shifts, optimum pH levels,
pH adjustment processes, alkalinity control.
Enhanced coagulation is described in terms of the process objectives.
Range
1.4
colloidal substances, organics, silts, clays, metal oxides, surface
charges, colour, particulate matter, charge neutralisation;
characteristics – size, weight, density.
includes but is not limited to – coagulant dispersion, factors that
influence chemical reaction times, flash mixers, drop structures,
pumps, hydraulic mixers, time and temperature.
Coagulant dosing control methods are identified and described in terms of dose
level assessment, control and optimisation.
Range
includes but is not limited to – jar test, streaming current meters,
pH meters, turbidity and colour loading, coagulant residuals,
process control.
 New Zealand Qualifications Authority 2016
18450 version 3
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1.7
Chemical residuals from the coagulation process are described in terms of their
public health and environmental significance.
Range
sources, monitoring.
Element 2
Describe the links between coagulation and flocculation, and optimising 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
Optimising flocculation is described in terms of the effect of pH change on the
solubility of aluminium hydroxide and ferric species in the processed water.
2.3
Optimal floc particle formation is described in terms of mixing methods and
time.
Range
2.4
temperature, flocculator types, contact zones, adsorption.
Polyelectrolytes are identified and described in terms of their suitability for use
as flocculant aids.
Range
anionic, cationic, non-ionic, typical dose levels.
Element 3
Identify the critical points, hazards, preventive actions, and corrective actions of
coagulation and flocculation processes.
Performance criteria
3.1
The critical points in coagulation and flocculation processes are identified in
accordance with organisational procedures.
3.2
The hazards at each critical point are identified in terms of the causes of the
events leading to their appearance, and the risk factors.
3.3
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.
 New Zealand Qualifications Authority 2016
18450 version 3
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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