Re-use of mud from process waste water purification plant in ceramic tile production

Turkey is the fifth biggest ceramic tile exporter of the world. Considering the expectation that the Turkish tile sector continues to expand, further studies both on the improvement and the development of the tile formulations are necessary in order to make the producers advantaged in the world market while maintaining the capital and running costs at reasonably competitive levels as well. In addition to such studies, waste management in tile manufacturing has also become an important issue. Accordingly, the industrial use of wastes in the traditional ceramic industry has been intensively investigated in recent years. The present paper describes a research project carried out on the possible re-use of filter-pressed mud (sludge) from waste water treatment plant of a local tile company in commercial wall, floor and porcelain tile formulations. In order to achieve this aim, firstly the complete characterisation of the mud was carried out. Then, the particular focus was given to the effect of the waste material in increasing amounts (up to 10 wt. %) on the thermal behaviour and physical and technological properties of the re-formulated tile bodies. During the studies, a range of characterisation techniques, namely XRF, XRD, SEM in combination with EDS, DTA, TGA and non-contact dilatometry, were employed. The results showed that it was possible to use the waste material in tile production without deteriorating the relevant technological properties of the dried and fired bodies.