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Level 4
Credits 15
Purpose This unit standard is intended for people who are responsible for the design, installation, monitoring, and regulation of on-site domestic wastewater systems.
People credited with this unit standard are able to demonstrate knowledge of: the primary treatment process for domestic wastewater; secondary treatment processes for domestic wastewater; disinfection treatment processes for domestic wastewater; nutrient reduction treatment processes for domestic wastewater; alternative treatment systems for domestic wastewater; and soil treatment processes for domestic wastewater.
Subfield Water Industry
Domain
Status
Status date
Date version published
Wastewater Treatment
Registered
17 October 2008
17 October 2008
Planned review date
Entry information
31 December 2011
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 Legislation relevant to this unit standard includes but is not limited to the Resource
Management Act 1991, Building Act 2004 and relevant Building Codes, Health Act
1956, and Historic Places Act 1993.
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2 Rules and requirements for wastewater include but are not limited to those found in regional and district plans, and regulatory authority requirements.
3 The standards applicable to this unit standard are:
AS/NZS 1547:2000 On-site domestic wastewater management ;
AS/NZS 1546.1:2008 On-site domestic wastewater treatment units – Septic tanks ;
AS/NZS 1546.2:2008 On-site domestic wastewater treatment units
–
Waterless composting toilets ;
AS/NZS 1546.3:2008 On-site domestic wastewater treatment units – Aerated wastewater treatment systems ;
Available at http://www.standards.co.nz.
4 References
On-site Wastewater Systems: Design and Management Manual (Technical
Publication 58), 3rd edition (Auckland Regional Council: August 2004), available from http://www.arc.govt.nz.
Guidelines for on-site sewage systems in the Wellington Region (WRC/RP-G-00/47),
(Greater Wellington Regional Council: February 2001), available at http://www.gw.govt.nz.
On-site wastewater guidelines for the Manawatu-Wanganui Region (20/EXT/381)
(Horizons Manawatu: November 2000), available at http://www.horizons.govt.nz.
Guidelines for new on-site wastewater management systems (Marlborough District
Council: July 2005), available at http://marlborough.govt.nz.
It is recommended that the assessor uses design guidelines issued by the regional or local authorities in the candidate’s locality.
5 In the context of this unit standard tertiary treatment processes refers to disinfection and nutrient reduction.
6 Credit for this unit standard does not qualify the candidate to work in a drainlaying situation that comes under the drainlayer’s licence requirements issued under the
Plumbers, Gasfitters, and Drainlayers Act 2006 and any subsequent amendments:
Element 1
Demonstrate knowledge of the primary treatment process for domestic wastewater.
Performance criteria
1.1 The primary treatment process is described in terms of the process by which septic tanks operate from inflow of raw wastewater to the discharge of treated wastewater to the land application system.
1.2 The primary treatment process is described in terms of the solids and scum stratification, and the requirements for effective settlement of solids.
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1.3 The primary treatment process is described in terms of the factors that determine system performance.
Range process factors include but are not limited to
– wastewater flow volume, wastewater contaminant concentrations, climatic conditions, retention time, sludge accumulation, outlet solids control device or outlet filter; household factors include but are not limited to
– garbage grinders, oils and grease, household cleaning chemicals.
1.4 The primary treatment process is described in terms of the public health and environment risks.
1.5
Range risks
– system performance, lack of maintenance; amenity – land access constraints, odour, pest nuisance.
Septic tanks are described in terms of their types, design features, and suitability for situations.
Range includes but is not limited to – construction materials, water tightness, lids, vents, inlet-outlet levels, effluent outlet filters, baffles, partitions, multiple chambers; types – compartmental traditional, two stage (or dual).
1.6 Septic tanks are described in terms of their operation and maintenance requirements, and benefits.
Range septic tanks
– with an outlet filter, without an outlet filter, for blackwater only, for greywater only.
1.7
Element 2
Domestic wastewater grease traps are described in terms of their function, design, operation, maintenance, and recommended volume for specified situations.
Demonstrate knowledge of secondary treatment processes for domestic wastewater.
Range includes but is not limited to – activated sludge, biofilter, intermittent sand filters, recirculating sand filter, textile filter, membrane biological reactor.
Performance criteria
2.1 Secondary treatment processes are described in terms of their process, design and operation.
,
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2.2 Secondary treatment processes are described in terms of their suitability for situations.
Range land disposal options, fluctuations in numbers of occupants, periods of occupation, continuity of power supply, isolated locations.
2.3 Secondary treatment processes are described in terms of their recommended organic and hydraulic loading specifications, advantages, disadvantages, and impacts on design.
2.4 Risks to the secondary treatment processes are described in terms of the impact on public health and the environment, and associated mitigation measures.
Range includes but is not limited to – lack of maintenance, overloading, underloading, power outages; start up
– initial, after an absence; examples of mitigation measures – storage, high water level alarms, remote telemetry.
2.5 The installation, maintenance, and monitoring requirements of secondary treatment processes are described in accordan ce with designer’s and manufacturer’s specifications.
Range includes but is not limited to monitoring for – odours, total suspended solids, organics and nutrient concentration bacterial levels, effluent quality variables, frequency of maintenance, alarms, sludge removal, dissolved oxygen.
Element 3
Demonstrate knowledge of disinfection treatment processes for domestic wastewater.
Range disinfection
– chlorine, ultraviolet, ozone.
Performance criteria
3.1 Disinfection treatment processes are described in terms of the way in which they operate to reduce micro-organisms following secondary treatment, and prior to application to land.
3.2
Range micro-organisms – pathogens, indicators.
Disinfection treatment processes are described in terms of the risks and associated mitigation measures.
Range maintenance risks include but are not limited to
– lack of, requirements for, timeframe; other risks – reliability, monitoring, power failure or UV lamp failure, lack of contingency plans, lack of effectiveness against pathogens, by-products formation.
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3.3
3.4
Disinfection treatment processes are described in terms of their components.
Disinfection treatment processes are described in terms of their advantages and disadvantages.
3.5 Disinfection treatment processes are described in terms of the factors affecting their effectiveness.
Range includes but is not limited to – total suspended solids, transmittance, biochemical oxygen demand (BOD), turbidity, maintenance; factors affecting chlorine disinfection – residual chlorine, ammonia, chloramines; factors affecting ultraviolet disinfection – wastewater flow within the reactor, radiation intensity, wastewater quality.
3.6 The operation and maintenance of disinfection treatment processes are described in a ccordance with designer’s and manufacturer’s specifications.
Element 4
Demonstrate knowledge of nutrient reduction treatment processes for domestic wastewater.
Range nitrification, denitrification, phosphorus absorption.
Performance criteria
4.1 Nutrient reduction treatment processes are described in terms of the way in which they operate to reduce nutrients following secondary treatment, and prior to application to land.
4.2 Nutrient reduction treatment processes are described in terms of their components.
4.3 Nutrient reduction treatment processes are described in terms of their advantages and disadvantages.
4.4 Nutrient reduction treatment processes are described in terms of the factors affecting their effectiveness.
Range must include but is not limited to – input nitrogen levels, recycle ratios, carbon source, anoxic conditions.
4.5 The operation and maintenance of nutrient reduction treatment processes are described in accordance with designer’s and manufacturer’s specifications.
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Element 5
Demonstrate knowledge of alternative treatment systems for domestic wastewater.
Performance criteria
5.1 Alternative treatment systems are described in terms of their types, benefits, design, performance, operation, maintenance, and conditions required for effective operation.
5.2
Range composting, vermiculture, wetland treatment, peat beds.
Composting and vermiculture treatment systems are described in terms of public health and ecosystem risks, and mitigating factors.
Range safe use and disposal of composted material, solids handling, holding periods and safe storage of solids while maturing, effect of temperature on maturation, pest and vector control.
5.3 Wetland treatment is described in terms of configuration and construction.
Range includes but is not limited to – pre-treatment requirements, hydraulic retention times, depths, flow, die-off of natural vegetation, effect on pathogens and microbial indicators, biological oxygen demand (BOD), total suspended solids (TSS) and nutrients, typical quality of wastewater from wetlands, protection of plants at start up, vector attraction.
Element 6
Demonstrate knowledge of soil treatment processes for domestic wastewater.
Performance criteria
6.1 Soil treatment processes are described in terms of soil chemistry and wastewater interactions.
6.2 Soil treatment processes are described in terms of soil microbiology and wastewater interactions.
6.3 Soil treatment processes are described in terms of wastewater nutrients, and plant and vegetation interactions.
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.
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