Water Treatment

Water Treatment

Pumice Rapid Gravity Filter

In water treatments we recommend our Pumice Filtration Media as it is a specially selected lava rock for this application. Our pumice filtration media is used extensively throughout the UK and Worldwide as a filtration media for DMF pre-treatment prior to RO and SWRO.

We have supplied into new installations and existing plants where our pumice has been proven as an alternative to anthracite and at a much lower capital cost.
All pumice filters employ the same basic principle; a rapid gravitational filtration of raw water through a granular media. Pumice can be used in single, dual or multi media filters in conjunction with sand and gravel depending on the quality of water to be treated.

Water Treatment using lava rock

The versatility of pumice enables it to be used to solve difficult filtration problems. Filtration can be achieved within a rapid gravity or pressure filter, with optimum filtration performance ensured through regular backwashing via nozzles in the filter floor.

Advantages of using Pumice Filtration Media over conventional granular filter media
Reduced pressure loss through the filter: the unique nature of pumice allows increased solids retention capacity, higher particulate loadings and therefore much increased filter run times without a deterioration in filtrate quality.

Reduced headloss: this filtration in depth avoids the build up of particulates within the top section of the filter bed reducing headloss across the filter.

Reduced backwash rates: pumices lightweight nature (approximately 400kg per cubic metre) means lower backwash rates are needed to fully expand the filter bed. This generates substantial savings in the operating costs of the filtration plant as backwash consumption requirements are typically 30% lower than using traditional media.

Increased bed expansion: the lightweight nature of pumice filtration media gives increased bed expansion over traditional media using the same backwash rate. Again this generates substantial savings in energy and water usage, which equates to a reduction in pumping requirements and enables a downsizing of the filtration plant.

Can be used at elevated temperatures: pumice can be used at temperatures ranging from 0-40 degrees celcius.

Can be used in saline or fresh water: pumice has been proven to work successfully in saline or fresh water conditions.

High filtrate quality: Using our Pumice Media we would expect the following filtration performance:

  • Suspended Solids < 1 mg/l
  • SDI < 2
  • Turbidity < 1 NTU

Applications for Pumice Filtration Media

Desalinisation / Desalinization; pumice filtration media is used in the pre-treatment of saline or brackish water prior to desalination. This preliminary treatment removes the coarse particulates prior to the next stage of treatment typically a membrane filtration process.

Seawater Reverse Osmosis and Reverse Osmosis; seawater reverse osmosis (SWRO) and reverse osmosis (RO) are desalination processes that produce potable water by forcing pre-treated seawater against a semi-permeable membrane, producing pure water on one side and concentrated brine on the other. The brine returns to the sea, while the potable water is stored or distributed for human consumption.

Potable Water Filtration: pumice filtration media is widely used in multimedia filters to treat potable water intended for human consumption.

Portable water filtration


Typical Grades
Pumice Filtration Media No.3:        0.2 – 0.5mm
Pumice Filtration Media No.5:        0.8 – 1.3mm
Pumice Filtration Media No.6:        1.2 – 2.4mm
Pumice Filtration Media No.8:        2.0 – 3.5mm

All our pumice filtration media has British Standard approval (BS EN 12906-1999) and UK Drinking Water Inspectorate approval. Additionally our pumice filtration media is NSF-61 approved and meets all the chemical and physical testing requirements for AWWA B-100 and DIN EN 12906.

Should you require any further technical information or details on some of the many plants we have supplied, please feel free to contact us and our Process Engineer will assist.