NWPTRT093
Assess and improve anaerobic digestion processes


Application

This unit describes the skills required to evaluate system performance and investigate and report on optimisation of anaerobic bioreactor processes.

This unit applies to those working as technical staff with a specific responsibility for optimising mixed, fixed and suspended media anaerobic bioreactor processes in wastewater treatment plants.

The skills and knowledge described in this unit must be applied within the legislative, regulatory and policy environment in which they are carried out. Organisational policies and procedures must be consulted and adhered to, particularly those related to measuring and testing, investigation and manufacturers' specifications.

Those undertaking this unit would work autonomously, performing sophisticated, tasks in a familiar context.

No licensing, legislative or certification requirements apply to unit at the time of publication.


Elements and Performance Criteria

ELEMENTS

PERFORMANCE CRITERIA

Elements describe the essential outcomes

Performance criteria describe the performance needed to demonstrate achievement of the element. Where bold italicised text is used, further information is detailed in the range of conditions section.

1. Evaluate anaerobic treatment process performance

1.1 Review existing process performance data.

1.2 Review existing operational processes with reference to manufacturer and plant designer specifications.

1.3 Identify the impact of incoming feed quality on anaerobic treatment processes.

1.4 Identify and coordinate any additional sampling and testing required for valid evaluation of current process performance.

2. Investigate anaerobic treatment plant configuration

2.1 Review existing fault reports and other relevant plant asset information.

2.2 Investigate the operational status of plant components with reference to manufacturers’ or plant designers’ specifications.

2.3 Carry out investigations to identify potential deficiencies.

3. Investigate the operational options for process optimisation

3.1 Review relevant fault and incident reports and remedial actions taken.

3.2 Investigate potential changes to operational processes to identify possible optimisation strategies.

4. Develop and record a plan for process optimisation

4.1 Determine plant configuration and revised operational processes for process optimisation.

4.2 Plan a trial to test the performance of the determined optimisation options.

4.3 Compile a report making recommendations on optimisation options.

Evidence of Performance

Evidence required to demonstrate competence must satisfy all of the requirements of the elements and performance criteria. If not otherwise specified the candidate must demonstrate evidence of performance of the following on at least one occasion.

coordinating anaerobic treatment process inspection, sampling and testing, including the following tests:

chemical oxygen demand (COD)

temperature

macro nutrients, including nitrogen or phosphorus

micro nutrients, including cobalt or iron

settling tests

pH

redox potential

volatile fatty acids

alkalinity

gas analysis

solids

performing mathematical calculations to provide data for the analysis and development of options and solutions, including at least one of:

COD removal

volatile solids reductions

solids retention time

interpreting a range of complex and technical documents, including at least one of:

regulatory, legislative, licensing and organisational requirements

codes and standards

specifications

organisational policies

evaluating system performance

reviewing existing anaerobic treatment process performance with reference to historical data, differences in feed water quality and plant configuration

identifying data deficiencies and organising additional data collection through appropriate sampling and testing

assessing fault reports and investigating the current operational status of anaerobic treatment process plant components

investigating current and potential chemical addition practices

planning trials to test the performance of the determined anaerobic treatment process optimisation options:

recirculation rates

addition of nutrients

temperature

pre-treatment to remove inhibitory or toxic substances

alkalinity and pH correction

flow or feed rate

mixing rate

sludge wastage rate

preparing reports with recommendations


Evidence of Knowledge

Evidence required to demonstrate competence must satisfy all of the requirements of the elements and performance criteria. If not otherwise specified the depth of knowledge demonstrated must be appropriate to the job context of the candidate.

principles that form the basis of anaerobic treatment processes including:

design parameters:

organic loading rate

solids retention time

hydraulic loading rate

temperature

mixing strategy

volatile solids reduction

recycle flow rates

detention time

chemical oxygen demand (COD) removal

volatile fatty acids to alkalinity ratio

intended plant configuration

feed water quality:

chemical oxygen demand (COD)

nutrients

pH and alkalinity

total and suspended solids

salt

inhibitory compounds

temperature

types of anaerobic treatment processes including:

up flow anaerobic sludge blanket reactors (UASB)

fluidised bed reactors

anaerobic digesters

high rate anaerobic lagoons (HRAL)

bulk volume fermenters (BVF)

anaerobic microbiology

pH

VFA: alkalinity ratio

nutrient requirements – macro and micro

gas production and characterisation

inhibitory substances

system layout

principles of anaerobic system maintenance

range of appropriate procedures (measuring and testing, investigation)

risk management principles relating to anaerobic treatment processes

chemical and nutrient dosing processes


Assessment Conditions

Competency should be assessed in an actual workplace or in a simulated environment, with access to equipment and infrastructure appropriate to the outcome. Competency should be demonstrated over time to ensure the candidate is assessed across a variety of situations.

Consideration must be given to holistic assessment for this unit. Refer to advice in the companion volumes.

Assessors must satisfy the NVR/AQTF mandatory competency requirements for assessors.


Foundation Skills

The foundation skills demands of this unit have been mapped for alignment with the Australian Core Skills Framework (ACSF). The following tables outline the performance levels indicated for successful attainment of the unit.

Further information on ACSF and the foundation skills underpinning this unit can be found in the Foundation Skills Guide on the GSA website.


Competency Field

Treatment