Floating the idea of purifying water with glass beads

Floating the idea of purifying water with glass beads

Cranfield University is pioneering the use of glass beads in water treatment – a concept that could lead to dramatic energy savings in treating drinking, waste and industrial water.

The Sustainable Systems Department at this UK university is testing a new low carbon footprint technology, patented by inventor Barrie Woodbridge. This involves the use of small specially manufactured low density glass beads during the coagulation process to form a floating particle which can be easily removed from the water.

A three-year project, sponsored by UK Water Utilities, the organisation representing the country's water suppliers, aims to develop an energy-saving method that could be easily implemented in existing plants, initially for the treatment of ground and surface water. The glass beads are the same as those currently used in industrial and engineering practices to create lightweight solid structures.

While the main application of the proposed system will probably be the treatment of ground and surface water in the production of drinking water, the developers believe that it could eventually be adapted for use in the treatment of sewage water as well.

Traditional water treatment methods demand a high level of energy use, particularly as numerous processes have to be applied. These in turn lead to the development of a solid particle that grows until it has to be removed by sedimentation or flotation.

In contrast, the new system will incorporate glass beads into the clump of solids formed during the purification process, known as the floc. This revolutionary concept is an attractive proposition for the water industry as it offers significant energy savings, and moreover could be incorporated into existing treatment systems without serious plant renovations.

At present, particles are removed with micro-bubbles created by a compressor/saturator system. By attaching themselves to the floc aggregate, the bubbles float to the top of the water, enabling the solids to be removed.

In practical terms, the glass beads would be added at the coagulation stage of the treatment process. This could lead to potential energy savings in the region of 80 to 90% overall. In addition, as the glass beads are recycled back into the floc at the end of the process the whole system is made more sustainable.

“Our concept is to get rid of the bubble-generation system and incorporate these floating spheres into the floc instead,” explains Dr Peter Jarvis, of Cranfield’s Centre for Water Science. By replacing the need for any saturator system, the glass-spheres method could result in significant energy savings in water-purification processes.

To date, researchers have carried out small-scale tests using the beads. Their intention is to prove the concept and carry out a full-scale demonstration by the end of the project. This is an ambitious aim as this would be the first ever full-scale operation to use the glass-beads system.