Rapid gravity filters offer a very robust and proven water purification solution with low operating and maintenance costs. They are commonly used as part of a multiple-stage treatment system.

Each of Colloide's filters are engineered to meet the specific performance requirements of individual water treatment plants. The company has a wealth of experience in providing new RGF solutions and upgrading existing RGFs. Filters can be provided within concrete structures or as prefabricated systems.

Rapid gravity filters are designed as a single or multi media solution to meet the application with an overall depth of 500-3000mm. Common media include silica sand, manganese dioxide, anthracite and activated carbon.

The water travels downwards through the filter bed, the solids are captured by the filter media and the clean water is discharged through the base of the filter. As a result of the filter capturing these solids, over time the filter will start to block at which point it will be taken off-line for a backwash in order to ‘clean’ the filter before returning it to service - a process which  takes approximately 20 minutes to complete. Colloide uses a state-of-the-art backwashing process to achieve this clean.

The filters are generally PLC-controlled with an operator interface panel or PC used to allow the operator to view the plant operation and change parameters.

Features

  • Colloide offers a variety of filter underdrain systems - from conventional lateral type to monolithlic floor, to modern dual lateral type

  • Variations in filter media available to suit each application

  • Colloide’s technical knowledge and experience enable it to provide alternative backwash regimes to suit each application, with a focus on extending run times and reducing backwash water

  • Our RGF is based on a very proven and reliable process

  • RGFs are available as packaged filters which can be built off-site, or as concrete filters which have their shells constructed on-site installed by Colloide

Applications

Potable water

  • Roughing filters

  • Post clarification filtration

  • Direct filtration

  • Carbon filtration on the back end of works

These filters provide an effective barrier to many drinking water contaminants, with excellent removal of turbidity, metals, microorganisms and colour.

Wastewater

When used for wastewater treatment, the solids removal reduces BOD / COD levels in the treated wastewater. These RGFs may also be used for nitrate (NO3-N) removal and / or phosphate removal.