“…The S\S process could be applied both in laboratory and in situ showing good results against the risk with the remarkable benefit of immobilizing heavy metal inside natural minerals, such as clays and zeolite or soil-compatible materials. Among these, fly ash and red muds are widely used (Apak et al, 1998;Castaldi et al, 2010;Ciccu et al, 2003;Coruh & Nur Ergun, 2010;Dermatas & Meng, 2003;Garau et al, 2011;Glenister & Thornber, 1985;Gray et al, 2006;Lombi et al, 2002a;McPharlin et al, 1994;Summers et al, 1996). In particular, many authors show that amendment of contaminated soil with red mud results in a durable reduction in metal mobility and also in a smaller risk of metal remobilization if soil pH were to decrease (Gray et al, 2006;Lombi et al, 2002a).…”