World of Difference Award

The winner of the 2006 World of Difference Award is Aqua Enviro for their entry ‘Glass Media Reed Beds for Tertiary Treatment of Industrial Effluents’.

The entry describes the successful application of recycled glass in a form know as ‘cullet’, as the support media in a reed-bed wastewater treatment system. The support media has a dual role to play in that it both supports the growing rhizome system for the planted reeds and also conducts the effluent under treatment through the reed bed system. Traditionally this role has been filled using natural materials obtained by extraction from non-renewable sources.  Washed river gravel is generally the media with the most suitable properties.

In order to identify the potential for recycled glass, the properties of cullet from a number of suppliers were evaluated at a laboratory scale and a source identified that yielded similar hydraulic conductivity to the gravel more routinely employed. This recycled glass was then evaluated for its ability to support the growth of reeds and to achieve BOD and suspended solids removal in a large pilot facility treating the effluent from the Bernard Matthews turkey factory in Norfolk.

The initial trials have exceeded expectations and as a result of the performance of the reed bed treatment system, the aesthetics of the process in a natural landscape and the clear demonstration of sustainability by the use of a recycled material, otherwise destined for landfill, Bernard Matthews are committed to the design and construction of a full-scale system for tertiary treatment of the whole of their waste stream.

Around 2.5 million tonnes of glass are landfilled every year and the government has a target to recycle 70% of this waste. The potential annual market for reed beds in the industrial sector alone is estimated at a population equivalent of around 150,000. If just half of these beds were constructed using glass media, then this would meet 42% of the government’s recycling target.