NZQA registered unit standard
Title
22112 version 3
Page 1 of 5
Demonstrate knowledge of wastewater composition, corrosion in sewers, odours, and odour control
Level
Purpose
4 Credits 4
People credited with this unit standard are able to demonstrate knowledge of: wastewater, and wastewater composition; wastewater source control; corrosion in sewers and related structures; the causes of odours, and techniques for minimising odours in sewers.
This unit standard is for people who supervise maintenance and operations in water reticulation, and people who work in specialist water reticulation activities.
Classification
Available grade
Water Industry > Water Reticulation
Achieved
Explanatory notes
1 Legislation and bylaws include but are not limited to – Health Act 1956, Resource
Management Act 1991, Local Government Acts 1974 and 2002, and Local
Government Trade Waste Bylaws.
2 References
National Guide to Sustainable Municipal Infrastructure (Canada), available for ordering from http://www.sustainablecommunities.fcm.ca/infraguide/.
Dr. Pomeroy, R. D. and Boon A. G., The Problem of Hydrogen Sulphide in Sewers ,
2 nd edition, 1992; available from http://www.mullalyengineering.com.au.
3 Definition
Water reticulation
– in this context refers to all pipe systems, pumping systems, and components that contribute to the collection and disposal of wastewater and stormwater.
Outcome 1
Demonstrate knowledge of wastewater, and wastewater composition.
Primary Industry Training Organisation
SSB Code 101558

New Zealand Qualifications Authority 2020

NZQA registered unit standard 22112 version 3
Page 2 of 5
Evidence requirements
1.1 Wastewater is described in terms of its general characteristics and reasons for variations of these characteristics.
Range pH, temperature, suspended solids, biochemical oxygen demand
(BOD), chemical oxygen demand (COD).
1.2 The presence of microbes in wastewater is described in terms of the potential impact on public health.
Range bacteria, virus, protozoa.
1.3 Wastewater is described in terms of specific characteristics in relation to source types.
2.1
Range organic kitchen waste, fats, grease, grit, sludge, trade waste chemicals.
Outcome 2
Demonstrate knowledge of wastewater source control.
Evidence requirements
A wastewater source control programme is described in terms of its features.
Range three of – bylaws, monitoring and enforcement programmes, educational and awareness programmes, codes of practice, trade waste charges, pollution prevention plans.
2.2 Wastewater source control is described in terms of the reasons for, and methods of implementation.
Range reasons include but are not limited to – prevent degradation to sewers by aggressive chemicals, minimise risk to public health and sewer maintenance personnel, protect wastewater treatment processes, control polluting effect on environment following treatment.
2.3 Wastewater sampling is described in terms of laboratory tests, and test requirements for sample quality.
Range tests include but are not limited to
– faecal coliform count, BOD,
COD, chemical composition; test requirements – identification details, sealing and storage of sample, timing for collection and delivery.
Primary Industry Training Organisation
SSB Code 101558

New Zealand Qualifications Authority 2020

NZQA registered unit standard 22112 version 3
Page 3 of 5
Outcome 3
Demonstrate knowledge of corrosion in sewers and related structures.
Evidence requirements
3.1 Corrosion is described in terms of the contributing physical and biological mechanisms occurring in wastewater pipes.
Range two of
– sewage retention time, septicity, humidity, flow turbulence, bacterial action, aerobic and anaerobic conditions, conversion of hydrogen sulphide to sulphuric acid.
3.2 Corrosion is described in terms of the techniques for its minimisation.
Range ventilation, acid-resistant pipe products, chemical additives.
3.3 Corrosion is described in terms of its effect on materials.
Range
Outcome 4 concrete, polyvinyl chloride (PVC), ceramic, polyethylene (PE).
Demonstrate knowledge of the causes of odours, and techniques for minimising odours in sewers.
Evidence requirements
4.1 Odours and odour nuisance are described in terms of the mechanisms which contribute to their occurrence in sewers.
Range three of – sewage retention time, septicity, low flow, flow turbulence, bacterial action, emission points.
4.2 Odour generating substances are described in terms of the reasons for their presence.
Range hydrogen sulphide (sewer gas), mercaptans, volatile organic compounds (solvents), substances generated by bacterial action under anaerobic conditions.
Primary Industry Training Organisation
SSB Code 101558

New Zealand Qualifications Authority 2020

NZQA registered unit standard
4.3
22112 version 3
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Odour management is described in terms of the prevention techniques and treatment systems for minimising or treating odours.
Range prevention techniques
– sewer cleaning; liquid treatment – aeration, dosing using hydrogen peroxide, lime, caustic soda, chlorine; evidence is required for two; treatment systems – toilet vent systems, gully traps, air admittance valves, odour dispersion and dilution via ventilation stacks, chemical and biological additives, odour neutralising liquid or gel dosing systems, activated carbon filters, biofilters, chemical scrubbers, ultra-violet treatment; evidence is required for two.
4.4 Olfactometry is described in terms of the procedures for measuring odour.
Planned review date 31 December 2016
Status information and last date for assessment for superseded versions
Process Version Date Last Date for Assessment
Registration 1 26 October 2005 N/A
Rollover and
Revision
2 20 February 2009 N/A
Rollover and
Revision
3 21 July 2011 N/A
Consent and Moderation Requirements (CMR) reference 0179
This CMR can be accessed at http://www.nzqa.govt.nz/framework/search/index.do.
Please note
Providers must be granted consent to assess against standards (accredited) by NZQA, before they can report credits from assessment against unit standards or deliver courses of study leading to that assessment.
Industry Training Organisations must be granted consent to assess against standards by
NZQA before they can register credits from assessment against unit standards.
Providers and Industry Training Organisations, which have been granted consent and which are assessing against unit standards must engage with the moderation system that applies to those standards.
Requirements for consent to assess and an outline of the moderation system that applies to this standard are outlined in the Consent and Moderation Requirements (CMRs). The
CMR 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.
Primary Industry Training Organisation
SSB Code 101558

New Zealand Qualifications Authority 2020

NZQA registered unit standard 22112 version 3
Page 5 of 5
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.
Primary Industry Training Organisation
SSB Code 101558

New Zealand Qualifications Authority 2020