INFLUENCE OF WASTEWATER TREATMENT TECHNOLOGY AND SLUDGE STABILIZATION ON THE SORPTION CAPACITY OF SEWAGE SLUDGE

This article investigates the influence of sewage sludge treatment processes and stabilizationmethods on metal-binding capacity and susceptibility to metal remobilization from sewagesludge. The materials (stabilized sewage sludge) were collected from two mechanical-biologicalsewage treatment plants located in an industrial area in southern Poland (Silesian Province):1) one with nutrient removal (nitrogen and phosphorus) and anaerobic sludge digestion (WWTPIII),and 2) a facility without nutrient removal and with aerobic sludge stabilization (WWTP-II).Concentrations of PTEs in sewage sludge samples were measured using the inductively coupledplasma optical emission spectrometry (ICP-OES). Sewage sludge from WWTP-III showeda significantly higher sorption capacity for Cu ions (20–50%) and Ni ions (50% to 2.5-fold) ascompared to sewage sludge from WWTP-II. However, sewage sludge from WWTP-II exhibiteda higher sorption capacity for Cd ions. The studied potentially toxic elements (PTEs), irrespectiveof anion type, formed unstable bonds with sewage sludge, which may lead to their desorption intothe environment. The high mobility of Cd, Cu, Ni and Zn ions in chloride and sulphate system, aswell as the low susceptibility to Cr ion release, should be considered in various applications of thetested sewage sludge.