Results of commercial-scale trials in the UK into the use of recycled glass as a medium for filtration of industrial and domestic wastewater have shown it could cut the costs of treatment, as well as …
Results of commercial-scale trials in the UK into the use of recycled glass as a medium for filtration of industrial and domestic wastewater have shown it could cut the costs of treatment, as well as bringing environmental benefits. Water treatment specialists Aqua Enviro are conducting trials of recycled glass filtration medium (RGFM) in northern England with Croda Chemicals Europe, frozen fruit and vegetable processor JE Hartley, Yorkshire Water, and kitchen roll and tissue manufacturer Georgia Pacific UK. Interim results of the trials, funded by WRAP (the Waste & Resources Action Programme), have shown that using recycled glass as a filtration medium could improve the quality of effluent, compared to traditional sand. It could also help water companies and industry to meet tough new environmental targets and avoid fines, without incurring extra costs. The Environment Agency regulates the amount of suspended solids allowed in water discharged into watercourses. Suspended solids de-oxygenate water, thus harming fish habitat. Excessive growth of blanket weed caused by suspended solids can also affect river flow as silt and other particles accumulate in the weed. Mark Lowe, consultant, Aqua Enviro, said: “The results of trials of the RGFM trials have been positive and encouraging. Tests have shown the medium is more effective than sand at removing suspended solids in effluent and delivers better performance in backwashing. As a result, less frequent backwashing is required, leading to cost savings”. “Unlike sand, the recycled glass has shown no tendency to clog up, or “blind“, when faced with high loadings of suspended material, leading to fewer blockages”. RGFM is set to reduce suspended solids in water discharged by Croda Chemicals Europe into watercourses by up to 80%, from 250mg/l to 50mg/l, helping Croda to meet the standards of the Integrated Pollution Prevention and Control accreditation. It could also help Croda to cut operating costs, through lower cleaning and maintenance bills and lower capital outlay in the future, as the company will need a smaller membrane system to allow water reuse within the plant. Tissue, pulp, paper and packaging manufacturer Georgia Pacific UK has used RGFM to treat effluent water destined for reuse at its plant or discharge into the sewage system. RGFM has reduced levels of suspended solids, which can be as high as 280mg/l, by 80%. The trial has also shown that other benefits can be achieved by recycling the cleaned water back into the plant, including the fact that the effluent, once removed of other impurities, is still hot and does not require re-heating. At the JE Hartley vegetable processing plant, RGFM has also outperformed sand as a filtration medium. RGFM removed 80% of suspended solids from effluent compared to 32% for sand. Hartley“s is now considering upgrading its filtration process to incorporate RGFM in the future. Yorkshire Water has trialled RGFM at its sewage treatment plant in Brawby, Malton, which serves 10,000 households in the town. RGFM has proved more effective than sand and it has helped the utility to reduce suspended solids in the effluent, which is discharged into the River Derwent, by 70%. Performance on backwashing was also equal to or better that of sand. Mark Lowe said: “If the interim findings are confirmed in the final report, they will have implications for a wide range of industrial sectors treating wastewater … They could also highlight RGFM“s potential as a filtration medium for drinking water and in aquaculture applications, including fish farming, as well as for water used in swimming pools and spas.