Recycling Possibilities of Sewage Sludge from Water Purification

Abstract

The sewage sludge from a water purification plant was analysed for recycling to the dense glass-ceramic materials. The sewage sludge containing aluminium compounds and circa 50 % of organic matter was used as a filler, but as the matrix of glass-ceramic was examined an illitic clay from Liepa deposit (Latvia). The raw materials were investigated by differential-thermal (DTA) and X-ray diffraction analysis (XRD). The dense glass-ceramic was produced from the water purification sewage sludge and limeless clay in ratio 10-40 : 90-60. The optimal values of bulk density (2.28 g/cm3) and thermal shrinkage (29 %) for novel materials were observed for glass-ceramic with the sludge additive at amount of20 wt %, obtained by sintering at temperature 1140 °C. The relationship between thermal treatment conditions and maximal treatment temperature was established. The following crystalline phases for novel materials were detected by XRD analysis: microcline (KAlSi 3 O 8 ), hematite (Fe 2 O 3 ), quartz (SiO 2 ) and corundum (Al 2 O 3 ). The physical-chemical properties of novel materials correspond to the dense glass-ceramics composite while the material itself could be applied as building material. DOI: http://dx.doi.org/10.5755/j01.sace.1.1.2617