CHEMICALLY MODIFIED EXCESSIVE SLUDGE AS AN ADSORBENT OF DYES

In the municipal wastewater treatment technology, the biological method based on the activated sludge process is most commonly used. The activated sludge consists of small flocs, which mainly include bacteria. During the purification process, the growth of microorganisms and their multiplication occurs. Whereby it is necessary to discharge the excess sludge outside the technological system to maintain the concentration of the activated sludge in bioreactor at the appropriate level. Currently, the excess sludge is subjected to the stabilization process (usually biologically) and then it is directed to e.g. agricultural use as fertilizer. In recent years, research is conducted on the use of excessive sludge in the sorption process as a waste sorbent. During the studies, experiments on the use of a chemically modified excess sludge (as an sorbent) to remove two dyes from aqueous solutions (Acid Red 18 and Acid Green 16) were conducted. Excessive activated sludge was thickened, dried at 105 °C and ground to a grain size < 0.49 mm. The sludge was then chemically treated using Fenton's reagent. Next, the adsorption process was carried out. The effect of pH, the effect of reaction time and sorption isotherm was determined. Parameters of three models of isotherms were calculated: Freundlich, Langmuir and Dubinin-Radushkevich.