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Title / Optimise and manage coagulation and flocculation processes for drinking-water treatment
Level / 5 / Credits / 6
Purpose / People credited with this unit standard are able to: optimise the process of coagulation as used in drinking-water treatment; optimise and manage the process of flocculation as used in drinking-water treatment; and identify critical points and hazards, and identify and manage preventive and corrective actions, in coagulation and flocculation processes.
Classification / Water Industry > Water Treatment
Available grade / Achieved
Explanatory notes
1 References
Legislation relevant to this unit standard includes but is not limited to the Health Act 1956, and Resource Management Act 1991;
Ministry of Health Public Health Risk Management Plan Guides for Drinking-Water Supplies (PHRMPGs):
P5.1, Conventional coagulation /flocculation/sedimentation.
2 Definitions
Critical points – points in a process or in equipment where failure to function correctly can lead to a public health hazard.
Optimise – adjusting plant input variables to make the process as effective as possible in order to achieve the desired output, taking into account the constraints of cost, human input, water quality, and water demand.
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.
Outcomes and evidence requirements
Outcome 1
Optimise the process of coagulation as used in drinking-water treatment.
Evidence requirements
1.1 The coagulation process is optimised in terms of the impact of pH and alkalinity in a drinking-water treatment process.
1.2 Coagulants are evaluated and described in terms of their effectiveness and cost.
Range may include but is not limited to – aluminium sulphate, ferric chloride, poly-aluminium chloride, ferric sulphate, polyelectrolytes, aluminium chloral hydrate;
evidence is required for at least two.
1.3 Coagulant mixing is optimised and calculated in terms of the velocity gradient.
Range one of – flash mixers, drop structures, pumps, hydraulic mixers; temperature, coagulant dispersion, chemical reaction times.
1.4 Coagulant dosing control methods and pH and alkalinity control for coagulant dosing are optimised in terms of dose level assessment and control.
Range pH meters, turbidity and colour loading;
two of – jar test, streaming current meters, coagulant residuals;
control methods – dilution, filter performance, separation performance.
Outcome 2
Optimise and manage the process of flocculation as used in drinking-water treatment.
Evidence requirements
2.1 Flocculation is optimised in terms of its relationship to coagulation.
Range includes but is not limited to – contact zones, floc recycling, low turbidity use, adsorption.
2.2 Optimal floc formation is managed in terms of particle contact.
Range time, temperature, flocculator types.
2.3 Polyelectrolytes are evaluated in terms of use as flocculant aids.
Range may include but is not limited to – anionic, cationic, non-ionic, high and low molecular weights, dose levels, material quality standards.
2.4 The storage, handling and mixing of raw material is managed to optimise treatment efficiencies for flocculation.
Outcome 3
Identify critical points and hazards, and identify and manage preventive and corrective actions in coagulation and flocculation process.
Evidence requirements
3.1 The critical points in the coagulation and flocculation processes are identified in accordance with organisational procedures.
3.2 The hazards at each critical point are identified in terms of the causes of the events leading to their appearance, and the risk factors.
3.3 The preventive and corrective actions for events related to each hazard are identified and managed.
Replacement information / This unit standard and unit standard 18450 were replaced by unit standard 29971.This unit standard is expiring. Assessment against the standard must take place by the last date for assessment set out below.
Status information and last date for assessment for superseded versions
Process / Version / Date / Last Date for Assessment /Registration / 1 / 27 May 2002 / 31 December 2018
Review / 2 / 19 September 2008 / 31 December 2018
Review / 3 / 16 March 2017 / 31 December 2018
Consent and Moderation Requirements (CMR) reference / 0101
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 (CMR). 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.
Infrastructure ITOSSB Code 101813 / Ó New Zealand Qualifications Authority 2017 / / New Zealand Qualifications Aut