Management of hydroxide sludge waste using hygroscopic gravimetric method and physico-chemical characterization

Abstract The hygroscopic analysis of hydroxide sludge materials has been considered as an efficient key to manage this type of waste. This analysis is then completed by drying, valorization, transport, and storage or valorization procedure. The main aim of this study is to investigate, compare, and determine the sorption isotherms of sludges based on experimental tests through the use of the static gravimetric method. These tests were conducted under three temperatures of 30, 40 and 50 °C of the hydroxide sludge issued from three drinking water treatment plants located in Morocco. The physico-chemical characterization showed that the hydroxide sludge mainly consisted of silica, aluminum oxide, iron, calcium, magnesium, and potassium. Furthermore, the experimental data and the sorption equations were modeled and analyzed based on six models (Oswin, Enderby, Peleg, LESPAM, Henderson and GAB). The results obtained revealed that increasing temperature causes moisture content decrease. Moreover, it was concluded that the Peleg model is the most appropriate one to describe the sorption curves of hydroxide sludge that has the highest correlation coefficient.