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Describe wastewater sludge and biosolids management
Level
5
Credits
10
Purpose
People credited with this unit standard are able to describe: the volumes,
types, and characteristics of wastewater sludges produced by wastewater
treatment processes; stabilisation and dewatering methods used in
wastewater sludge treatment; and the environmental effects of applying
biosolids to land, and of heat treatment.
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 19185.
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
Definitions
Biosolids – sewage sludges or sewage sludges mixed with other materials that have
been treated and/or stabilised to the extent that they can be safely returned to the
environment.
Sludge – wastewater solids from separation processes including scum.
Wastewater includes stormwater and sewage systems.
 New Zealand Qualifications Authority 2016
24938 version 1
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Reference
New Zealand Water and Wastes Association, Guidelines for the safe application of
biosolids to land in New Zealand. August 2003. ISBN 1-877134-43-0.
Elements and performance criteria
Element 1
Describe the volumes, types, and characteristics of wastewater sludges produced by
wastewater treatment processes.
Range
wastewater sludges – primary sludges and scums, secondary sludges, digested
sludges.
Performance criteria
1.1
Wastewater treatment processes are described in terms of the volumes and
solids content of sludges produced.
1.2
Sludges produced in the various wastewater treatment processes are described
in terms of their characteristics.
Range
characteristics – suspended, dissolved, volatile.
Element 2
Describe stabilisation methods used in wastewater sludge treatment.
Range
primary sludge and scum, secondary sludge.
Performance criteria
2.1
Aerobic digestion of wastewater sludge is described in terms of the
microbiological activity.
Range
2.2
Anaerobic digestion of wastewater sludge is described in terms of the biological
process.
Range
2.3
may include but is not limited to – solids loading rates, biological
activity, oxygen requirements, temperature and mixing effects,
aeration methods, detention times;
evidence is required for at least three.
process outputs – volatile conversion rates, gas production;
process inputs – temperature, detention times.
The methods of heat treatment are described in terms of the processes.
Range
includes but is not limited to – incineration, vitrification.
 New Zealand Qualifications Authority 2016
24938 version 1
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Element 3
Describe dewatering methods used in wastewater sludge treatment.
Performance criteria
3.1
The measurement of dewatering factors of sludges is described in terms of
solids concentration and solids loading rate.
3.2
Conditioning techniques are described in terms of their methods of action and
effectiveness.
Range
3.3
addition of – elutriation, coagulants, lime, polymers.
The methods of thickening and dewatering biosolids are described in terms of
the processes.
Range
includes but is not limited to – drying beds, sludge gravity
thickeners, dissolved air thickeners, centrifuges, belt presses,
thermal drying.
Element 4
Describe the environmental effects of applying biosolids to land, and of heat treatment.
Performance criteria
4.1
The results of applying biosolids to land are described in terms of environmental
effects.
Range
4.2
methods – composting and soil additives, landfills, land
application;
effects of – nutrients, metals, pathogens.
The results of heat treatment are described in terms of environmental effects.
Range
effects of – ash, metals, odours, air dispersion plumes.
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