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SOUTH AFRICAN QUALIFICATIONS AUTHORITY 
REGISTERED UNIT STANDARD THAT HAS PASSED THE END DATE: 

Monitor and control anaerobic and aerobic sludge digestion processes 
SAQA US ID UNIT STANDARD TITLE
116994  Monitor and control anaerobic and aerobic sludge digestion processes 
ORIGINATOR
SGB Water Sector 
PRIMARY OR DELEGATED QUALITY ASSURANCE FUNCTIONARY
-  
FIELD SUBFIELD
Field 12 - Physical Planning and Construction Civil Engineering Construction 
ABET BAND UNIT STANDARD TYPE PRE-2009 NQF LEVEL NQF LEVEL CREDITS
Undefined  Regular  Level 5  Level TBA: Pre-2009 was L5  8 
REGISTRATION STATUS REGISTRATION START DATE REGISTRATION END DATE SAQA DECISION NUMBER
Passed the End Date -
Status was "Reregistered" 		 2018-07-01  2023-06-30  SAQA 06120/18 
LAST DATE FOR ENROLMENT LAST DATE FOR ACHIEVEMENT
2024-06-30   2027-06-30  

In all of the tables in this document, both the pre-2009 NQF Level and the NQF Level is shown. In the text (purpose statements, qualification rules, etc), any references to NQF Levels are to the pre-2009 levels unless specifically stated otherwise.  

This unit standard does not replace any other unit standard and is not replaced by any other unit standard. 

PURPOSE OF THE UNIT STANDARD 
The qualifying learner achieving this unit standard in combination with context expertise standard(s) will be able to develop a thorough knowledge of the sludge digestion processes. This competence will enable the learner to manage these processes and to achieve efficient management and operation of a wastewater works. This knowledge will contribute towards the protection of the environment in accordance with legislation and regulations. Achieving this Unit Standard will enhance the efficiency of the qualifying learner and advance his / her own expertise and employability in water and other related sectors. 

LEARNING ASSUMED TO BE IN PLACE AND RECOGNITION OF PRIOR LEARNING 
Knowledge of advanced treatment for wastewater, wastewater related legislation, anaerobic/aerobic digesters and Occupational Health and Safety Act, computer literacy, mathematical calculations NQF level 4. 

UNIT STANDARD RANGE 
  • Explosive mixture: Mixture of methane in the air in the explosive range of 5 to 15% (v/v).
  • Types of digesters: Aerobic, anaerobic, primary, secondary.
  • Problems: Temperature change, pH change, volatility and alkalinity change, reduction of volatile solids, change in gas production. 
    		•

    Specific Outcomes and Assessment Criteria: 

    SPECIFIC OUTCOME 1 
    Explain and monitor the sludge digestion process. 

    ASSESSMENT CRITERIA     

    ASSESSMENT CRITERION 1 
    Biological activity and processes in the digestion process are described. 

    ASSESSMENT CRITERION 2 
    Effects of heating and operating temperature ranges on the process efficiency are explained. 

    ASSESSMENT CRITERION 3 
    Effects of mixing on the process efficiency is evaluated and monitored. 

    ASSESSMENT CRITERION 4 
    Solids/hydraulic loading rates are calculated and monitored and the effects thereof interpreted. 

    ASSESSMENT CRITERION 5 
    The sludge flow path options in the digestion process are described and advantages/disadvantages evaluated. 

    ASSESSMENT CRITERION 6 
    Relevance of volatile acids and alkalinity concentrations and their ratio in the digester are explained. 

    ASSESSMENT CRITERION 7 
    Importance of pH stability in digestion operation is explained. 

    ASSESSMENT CRITERION 8 
    Effects of industrial effluents, (e.g. heavy metals) on processes and sludge disposal options are evaluated and monitored. 

    ASSESSMENT CRITERION 9 
    Supernatant withdrawal rates and quality monitoring are explained. 

    ASSESSMENT CRITERION 10 
    Consequences of anaerobic digestion of waste activated sludge (struvite formation) are explained and control measures identified. 

    ASSESSMENT CRITERION 11 
    The performance of a digester is monitored and evaluated with respect to the criteria. 

    SPECIFIC OUTCOME 2 
    Explain and monitor the heating process for anaerobic sludge digestion. 

    ASSESSMENT CRITERIA     

    ASSESSMENT CRITERION 1 
    Principles and methods of sludge heating using boilers and heat exchangers are described. 

    ASSESSMENT CRITERION 2 
    Heat losses from digesters and raw sludge heat requirements are calculated, evaluated and process changes identified. 

    SPECIFIC OUTCOME 3 
    Explain and monitor biogas production and biogas usage. 

    ASSESSMENT CRITERIA     

    ASSESSMENT CRITERION 1 
    Mechanisms of biogas production are explained. 

    ASSESSMENT CRITERION 2 
    Biogas usage options are explained. 

    ASSESSMENT CRITERION 3 
    Gas production due to volatile solids reduction is calculated, monitored and compared to actual gas production. 

    ASSESSMENT CRITERION 4 
    Gas composition, quality and criteria for explosive mixture is evaluated and monitored. 

    ASSESSMENT CRITERION 5 
    Gas storage, pipework and safety devices are explained. 

    ASSESSMENT CRITERION 6 
    Biogas production, composition and usage is monitored and evaluated with respect to the performance of the digester. 

    ASSESSMENT CRITERION 7 
    Problems and variances are identified, analysed and appropriate corrective action is taken. 

    SPECIFIC OUTCOME 4 
    Monitor and control digester performance. 

    ASSESSMENT CRITERIA     

    ASSESSMENT CRITERION 1 
    Sludge solids mass balance is calculated and interpreted. 

    ASSESSMENT CRITERION 2 
    Problems are identified and appropriate corrective action is taken within own scope of responsibility. 

    ASSESSMENT CRITERION 3 
    Problems and variances outside own scope of responsibility are identified and reported to senior management. 

    SPECIFIC OUTCOME 5 
    Monitor maintenance and safety awareness of digestion process. 

    ASSESSMENT CRITERIA     

    ASSESSMENT CRITERION 1 
    Digester cleaning methods are explained. 

    ASSESSMENT CRITERION 2 
    Safety regulations with regard to boilers and gas emissions (boilers and biogas) are monitored for compliance with relevant legislation. 

    ASSESSMENT CRITERION 3 
    Digester shut down and start up procedures are described. 


    UNIT STANDARD ACCREDITATION AND MODERATION OPTIONS 
  • Anyone assessing a learner or moderating the assessment of a learner against this unit standard must be registered as an assessor with the relevant ETQA.
  • Any institution offering learning that will enable the achievement of this unit standard must be accredited as a provider with the relevant ETQA.
  • Assessment and moderation of assessment will be overseen by the relevant ETQA according to the ETQA's policies and guidelines for assessment and moderation.
  • Moderation must include both internal and external moderation of assessments at exit points of the qualification, unless ETQA policies specify otherwise. Moderation should also encompass achievement of the competence described both in individual unit standards as well as the integrated competence described in the qualification. 
    		•

    UNIT STANDARD ESSENTIAL EMBEDDED KNOWLEDGE 
    Learners should have a knowledge and understanding of:
  • Wastewater treatment.
  • Cleaning of digesters.
  • Pumps, sludge thickening equipment.
  • Relevant sections of the Occupational Health and Safety Act and Regulations.
  • Description and evaluation of digestion processes: aerobic, anaerobic, high rate, low rate, mesophilic, cryophilic, thermophilic, heated, unheated.
  • Tank design considerations.
  • Effects of sludge thickening on digestion (ie. pre-treatment).
  • Difference between primary and secondary sludge digesters. 
    		•

    UNIT STANDARD DEVELOPMENTAL OUTCOME 
    N/A 

    UNIT STANDARD LINKAGES 
    N/A 


    Critical Cross-field Outcomes (CCFO): 

    UNIT STANDARD CCFO IDENTIFYING 
    Identify and solve problems in which responses display that responsible decisions using critical and creative thinking have been made.

    Assessment criteria:
  • The performance of a digester is monitored and evaluated with respect to the criteria 1.1 to 1.10.
  • Gas production due to volatile solids reduction is calculated, monitored and compared to actual gas production.
  • Gas composition, quality and criteria for explosive mixture is evaluated and monitored.
  • Problems and variances are identified, analysed and appropriate corrective action is taken.
  • Problems are identified and appropriate corrective action is taken within own scope of responsibility.
  • Problems and variances outside own scope of responsibility are identified and reported to senior management.
  • Safety regulations with regard to boilers and gas emissions (boilers and biogas) are monitored for compliance with relevant legislation. 
    		•

    UNIT STANDARD CCFO WORKING 
    Work effectively with others as a member of a team, group, organisation, and community.

    Assessment criteria: All. 

    UNIT STANDARD CCFO ORGANISING 
    Plan, organise and manage oneself and one's activities responsibly and effectively.

    Assessment criteria: All. 

    UNIT STANDARD CCFO COLLECTING 
    Collect, analyse, organise and critically evaluate information.

    Assessment criteria:
  • The performance of a digester is monitored and evaluated with respect to the criteria 1.1 to 1.10.
  • Gas production due to volatile solids reduction is calculated, monitored and compared to actual gas production.
  • Gas composition, quality and criteria for explosive mixture is evaluated and monitored.
  • Problems and variances are identified, analysed and appropriate corrective action is taken.
  • Problems are identified and appropriate corrective action is taken within own scope of responsibility.
  • Problems and variances outside own scope of responsibility are identified and reported to senior management.
  • Safety regulations with regard to boilers and gas emissions (boilers and biogas) are monitored for compliance with relevant legislation. 
    		•

    UNIT STANDARD CCFO COMMUNICATING 
    Communicate effectively using visual, mathematical and/or language skills in the form of oral and/or written presentation.

    Assessment criteria: All. 

    UNIT STANDARD CCFO SCIENCE 
    Use science and technology effectively and critically, showing responsibility towards the environment and health of others.

    Assessment criteria: All. 

    UNIT STANDARD CCFO DEMONSTRATING 
    Demonstrate an understanding of the world as a set of related systems by recognising that problem-solving contexts do not exist in isolation.

    Assessment criteria: All. 

    UNIT STANDARD ASSESSOR CRITERIA 
    N/A 

    REREGISTRATION HISTORY 
    As per the SAQA Board decision/s at that time, this unit standard was Reregistered in 2012; 2015. 

    UNIT STANDARD NOTES 
    Integrated assessment

    When conducting assessments, assessors must ensure that they are familiar with the full text of the unit standards being assessed. Assessors must ensure that the assessment covers the specific outcomes, critical cross-field outcomes and essential embedded knowledge by developing assessment activities and tools, which are appropriate to the contexts in which the learners are working. These activities and tools may include self-assessment, peer assessment, formative and summative assessment. It may be more effective and efficient to assess a number of unit standards together in an integrated way, thus reducing the overall number of assessments and ensuring that commonalties that exist between a number of unit standards are captured in a way that makes sense for assessment. 

    QUALIFICATIONS UTILISING THIS UNIT STANDARD: 
      ID QUALIFICATION TITLE PRE-2009 NQF LEVEL NQF LEVEL STATUS END DATE PRIMARY OR DELEGATED QA FUNCTIONARY
    Elective  59201   National Certificate: Generic Management  Level 5  Level TBA: Pre-2009 was L5  Passed the End Date -
    Status was "Reregistered"     		 2023-06-30  As per Learning Programmes recorded against this Qual 


    PROVIDERS CURRENTLY ACCREDITED TO OFFER THIS UNIT STANDARD: 
    This information shows the current accreditations (i.e. those not past their accreditation end dates), and is the most complete record available to SAQA as of today. Some Primary or Delegated Quality Assurance Functionaries have a lag in their recording systems for provider accreditation, in turn leading to a lag in notifying SAQA of all the providers that they have accredited to offer qualifications and unit standards, as well as any extensions to accreditation end dates. The relevant Primary or Delegated Quality Assurance Functionary should be notified if a record appears to be missing from here.
     
    NONE 


    All qualifications and part qualifications registered on the National Qualifications Framework are public property. Thus the only payment that can be made for them is for service and reproduction. It is illegal to sell this material for profit. If the material is reproduced or quoted, the South African Qualifications Authority (SAQA) should be acknowledged as the source.