Client: The Namibia Water Corporation Ltd (NamWater)
Industry: Potable Water
Region: Otjozondjupa Region, Namibia
Product: 3 x AGF42S Autonomous Gravity Sand Filter, ±10 MLD
Installation: 1988

Challenge

• The Okakarara Regional State Water Scheme extracts water from the Grootfontein – Omatako canal for supply to the town of Okakarara and surrounding communities.
• Water is transported via open canal to the Waterberg Potable Water Treatment Plant, where pretreatment and final polishing takes place.
• During the design phase, the process engineers looked for rapid gravity filters with a proven track record and that suited the remote, rural location of the plant. They required:
  • easy installation
  • simplicity of operation
  • low maintenance costs
  • easy maintenance functions
  • zero electrical energy consumption
  • effective filtration
  • high reliability
  • proven durability.

Application

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

Solution

• The inherent simplicity of our AGF Autonomous Rapid Gravity Filters met the requirements set by the design engineers.
• Easy installation:
  • Minimum civil works on site.
  • Fabrication under tightly controlled factory conditions.
• Simplicity of operation:
  • Complete autonomous function.
  • Backwashing initiates on a hydraulic signal built into the mechanical design.
  • Backwashing initiates only when needed.
• Low maintenance costs:
  • No peripheral equipment (backwash pumps, automatic valves, controllers, compressors / blowers) required.
  • Manpower limited to monitoring & periodic inspection functions.
• Easy maintenance functions:
  • Maintaining the integrity of the mechanical structure and periodic replacement of nozzles and sand.
• Zero electrical energy consumption:
  • Gravity flow through the filters.
• Effective filtration:
  • A proven track record of meeting and exceeding compliance standards.
• High reliability:
  • Simplicity imparts reliability.
  • No peripheral electronic or electric components.
  • No moving or rotating components.
• Proven durability:
  • Units in operation for 40+ years.
• 3 x AGF42S Autonomous Rapid Gravity Filters were installed, processing 140m³/h per unit at an average filtration velocity of ± 10 m/h.

Results

• The filters were installed and commissioned easily and rapidly despite the remote location.
• After 38 years of continuous operation, the AGF autonomous rapid gravity filters continue to produce high-quality filtrate.