Primary Filter, Final Treated Effluent, Wastewater Treatment Plant

GraviFilter: Self-Cleaning Gravity Screen Filter

Client: Nelson Mandela Bay Municipality, Kelvin Jones Wastewater Treatment Works
Industry: Sewage Wastewater
Region: Eastern Cape, South Africa
Product: VA4, 125m³/h, 250µm
Installation Date: 2021


  • At Kelvin Jones Wastewater Treatment Works in Uitenhage, final treated effluent (clarifier overflow) is re-used.
  • Applications include spray water, irrigation water for agriculture and recreational facilities and process water for industrial clients
  • The clarifier overflow contains suspended solids that can block downstream spray nozzles or that are in excess of industrial/agricultural client acceptance standards
  • A travelling bridge sand filter provided tertiary filtration
  • The sand filter fell into early disuse and was bypassed permanently
  • The result was tertiary effluent that did not comply with client acceptance standards leading to a loss in revenue
  • Nelson Mandela Bay Municipality required efficient filtration that would deliver compliant, uninterrupted water supply to their customers
  • Maintenance and downtime needed to be at a minimum


  •  Final Filtration / Spray nozzle protection
  • Final Filtration / Industrial re-use


  • Perform on-site diagnostics to determine the needs at the plant
  • Provide a solution that is fit for purpose
  • Move from filtering “as fine as possible” to filtering “at the appropriate level”
  • Provide filtration that is suited to the removal of soft, organic and fibrous solids from process streams
  • The gentle, unforced filtration action of the GraviFilter is ideally suited to this application, preventing the break up of flocculated particles and organic matter
  • Water gravitates through the screen, avoiding the vulnerability of permanent blockage or damage to the screen.
  • Stapling of fibrous suspended solids is greatly reduced
  • The integral, continuous self-cleaning mechanism of the GraviFilter ensures uninterrupted filtration for extended periods of time
  • The client installed a GraviFilter model VA4 with integral, self-cleaning mechanism. 125m³/h. 250µm screens.


  • Travelling bridge sand filter permanently eliminated
  • Tertiary effluent that complies with client acceptance standards
  • Minimal maintenance
  • Downtime approximating zero
  • Regeneration of the revenue stream