24937 version 1
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Describe lagoon type wastewater treatment processes, and critical
points
Level
5
Credits
4
Purpose
People credited with this unit standard are able to: describe anaerobic lagoon
wastewater treatment processes; describe aerated lagoon wastewater
treatment processes; describe and interpret tests of lagoon type wastewater
treatment processes; describe performance optimising of lagoon type
wastewater treatment processes; and identify critical points of lagoon type
wastewater treatment processes, adverse affects, preventive actions, and
corrective actions.
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 19184.
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.
 New Zealand Qualifications Authority 2016
24937 version 1
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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.
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.
Wastewater includes stormwater and sewage systems.
Elements and performance criteria
Element 1
Describe anaerobic lagoon wastewater treatment processes.
Performance criteria
1.1
The concept of an anaerobic lagoon is described in terms of the anaerobic
process.
Range
1.2
The methods of anaerobic lagoon processing are described in terms of
structures and flows.
Range
1.3
anaerobic processes – high strength wastes, treatment capacity
per volume, gases emitted, Biochemical Oxygen Demand (BOD)
loading, anaerobic bacteria.
structures include but are not limited to – lagoons, ponds, covers;
methods include but are not limited to – gas collection, batch
loading, continuous loading.
Anaerobic micro-organism reactions in anaerobic lagoons are described in
terms of temperature.
Range
anaerobic micro-organisms – thermophilic, mesophilic.
Element 2
Describe aerated lagoon wastewater treatment processes.
Performance criteria
2.1
The concept of an aerated lagoon is described in terms of the aerobic process.
Range
2.2
dissolved oxygen levels, aerobic bacterial activity.
The layouts of aerobic lagoons are described in terms of flow configurations and
effects.
Range
flow configuration – continuous flows, batch flows, modules;
effects – detention time, mixing, pH effects, oxygen balance
calculations, loading.
 New Zealand Qualifications Authority 2016
24937 version 1
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2.3
The methods of aeration used for aerobic lagoons are described in terms of
their efficiency.
Range
methods – air blowers, spargers, water pumps, liquid to air
interface, specific surface area, power efficiencies.
Element 3
Describe and interpret tests of lagoon type wastewater treatment processes.
Performance criteria
3.1
Anaerobic and aerated lagoon performance is described in terms of the timing
and types of tests to be undertaken.
Range
3.2
tests include but are not limited to – temperature, methane and
carbon dioxide emissions, dissolved oxygen, pH, indicator
organisms, Biochemical Oxygen Demand (BOD), suspended
solids, phosphorus, nitrogen.
Test results are interpreted in relation to process variations.
Range
includes but is not limited to – loading.
Element 4
Describe performance optimising of lagoon type wastewater treatment 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 lagoon type wastewater treatment processes, adverse effects, and
preventive and corrective actions.
Performance criteria
5.1
The critical points in lagoon type wastewater treatment 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 effects are identified.
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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