Recycling Possibilities of Sewage Sludge from Water Purification
Keywords:recycling, sewage sludge, glass-ceramics
AbstractThe 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 (KAlSi3O8), hematite (Fe2O3), quartz (SiO2) and corundum (Al2O3). The physical-chemical properties of novel materials correspond to the dense glass-ceramics composite while the material itself could be applied as building material.