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Describe wastewater treatment separation processes, and critical points
Level
5
Credits
6
Purpose
People credited with this unit standard are able to: describe the performance
of settlement, and air-based flotation systems used in wastewater treatment
separation processes; describe and interpret tests of separation processes;
describe performance optimising of separation processes; and identify critical
points, identify adverse effects, preventive actions, and corrective actions, of
separation processes.
Subfield
Water Industry
Domain
Wastewater Treatment
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 replaced unit standard 19180.
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
Definitions
Optimising – adjusting plant input variables to make the process as effective as possible to
achieve the desired output, taking into account the constraints of cost, human input,
effluent quality, and resource consent requirements.
Critical points – points in a process or in equipment where failure to function correctly can
lead to adverse effects which may affect the treatment process or other processes in the
treatment plant.
Wastewater includes stormwater and sewage systems.
 New Zealand Qualifications Authority 2016
24933 version 1
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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 performance of settlement used in wastewater treatment separation
processes.
Performance criteria
1.1
The mechanics of settlement are analysed and calculated in terms of flow,
particle velocity, time, temperature, and density.
1.2
Improvements to settlement tanks are described in terms of their individual flow
diagrams and characteristics.
Range
1.3
tanks include – circular, rectangular;
flow diagrams and characteristics include – horizontal and vertical
flow paths, tube and plate settlers, sedimentation tank dimension
ratios, detention times, scraper options, weir settings, effluent
quality.
Settlement tanks are described in relation to methods for improvements to
sludge collection.
Range
includes but is not limited to – optimise effectiveness of sludge and
scum removal, chemical addition.
Element 2
Describe the performance of air-based flotation systems used in wastewater treatment
separation processes.
Performance criteria
2.1
Air-based flotation systems are described in terms of optimising their operating
factors.
Range
2.2
bubble rise rates, loading rates, carry water pressure.
Air-based flotation systems are described in relation to methods for improving
sludge collection.
Range
surface removal options, beach design, weir design, chemical
addition, effluent quality.
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Element 3
Describe and interpret tests of separation processes.
Performance criteria
3.1
Separation processes are described in terms of the timing and types of tests to
be undertaken.
Range
3.2
tests include but are not limited to – organic content, suspended
solids, settled solids, settleability.
Test results are interpreted in relation to process variations.
Range
mass loading, flow, time.
Element 4
Describe performance optimising of separation processes.
Performance criteria
4.1
Results of monitoring are described in terms of the adjustments that may be
carried out.
Element 5
Identify critical points of separation processes, adverse effects, preventive actions, and
corrective actions.
Performance criteria
5.1
The critical points in separation processes are identified in accordance with
organisational procedures.
5.2
The adverse effects at each critical point are identified in terms of the causes or
the events leading to their occurrence.
5.3
The preventive and corrective actions for problems or events related to each
adverse effect 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