Mechanical Rapid Gravity Sand Filter, Potable Water Treatment Plant – Alice

AGF Autonomous Gravity Sand Filter

Client: Amathole District Municipality
Industry: Potable Water
Region: Eastern Cape, South Africa
Product: AGF42S, 3 units, 97m³/h per unit @ 7m/h
Installation Date: 2000


  • Amathole District Municipality operates a 7MLD potable water treatment plant at Alice, a rural town in the Eastern Cape province in South Africa.
  • During the design phase, process engineers were looking for polishing filters that would ensure compliance with potable water standards for Turbidity and TSS.
  • They required:
    • easy installation
    • high efficiency
    • low maintenance costs
    • easy maintenance functions
    • zero electrical energy consumption
    • high reliability


  • Final Filtration / Mechanical Rapid Gravity Sand Filters (polishing filters) at Potable Water Treatment Plant.


  • The inherent simplicity of the Autonomous Gravity Sand Filters (AGF) addressed constraints presented by the rural location and it easily met the requirements set by the design engineers.
  • Easy Installation:
    • Minimum civil works on site.
    • Fabrication under tightly controlled factory conditions. • High efficiency:
    • AGF filters cycle autonomously between filtration and backwash cycles resulting in regular, thorough cleaning of the filter bed.
  • Low Maintenance Costs:
    • No peripheral equipment (backwash pumps, controllers, compressors) required.
    • Manpower limited to period oversight functions.
  • Easy Maintenance:
    • Maintaining the integrity of the mechanical structure and periodic replacement of nozzles and sand.
  • Zero Electrical Energy Consumption:
    • Gravity flow through the filters.
    • Complete Autonomous Function.
  • High reliability:
    • No moving or rotating components.
    • No peripheral components.
  • 3 x AGF42S Mechanical Rapid Gravity Sand Filters were installed, processing 97m³/h per unit at an average filtration velocity of 7m/h.


  • Since commissioning in 2000 the AGF filters have consistently provided efficient filtration.
  • Maintenance and operating costs have been kept to a minimum.
  • The filters continue to produce filtrate that complies with the drinking water standard.