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Waterworks sludge into commercial ceramic product as an alternative disposal solution


Waterworks Sludge or Water Treatment Residue (WTR) is the solid waste matter which accumulates as the result of the drinking water purification process undertaken at waterworks. This material is composed of a mixture of microscopic organic and inorganic particulate matter. In the past it has been disposed of to sewers (if available) or mechanically dewatered to produce a 'cake' for disposal to land or landfill. Current EU directives now demand a more responsible disposal strategy for the future. Initial examination of this by-product by Staffordshire University showed it to be compatible with the traditional raw materials used by ceramic manufacturers in the clay-based building products and refractory industries. This manufacturing sector is also facing its own environmental problems as it is coming under increasing pressure in relation to its quarrying activities needed for its raw materials supply. Consequently, the possibility of introducing by-product materials such as WTR as a way of conserving traditional ceramic raw materials offers considerable benefits to such manufacturers. Over a 27 month period a collaborative investigation has been carried out by Staffordshire University and CERECO (a Greek ceramic research organisation) on behalf of a consortium of SME ceramic manufacturers from within in the United Kingdom, the Republic of Ireland and Greece who collectively produce a wide range of bricks, pipes, tiles and refractory products. During the first part of the project in association with collaborating B Proposer water companies, a large number of separate waterworks were sampled over an extended period of time and the products characterised using physical, chemical and ceramic evaluation procedures. The positive results of this preliminary investigation led to subsequent full-scale trials at the SME factories which resulted in successfully establishing the technical and practical ability of replacing a proportion of this by-product (0.5-8% dry weight-for-weight) for their normal raw material feedstocks, while still maintaining standard product specifications. The results of this project demonstrates a positive contribution to the future conservation of traditional ceramic raw materials as well as pointing the way forward for an innovative and more environmentally acceptable recycling route for WTR than the current landfill disposal strategy now widely practiced by the water industry in EU member states.