RT Journal Article T1 Combining coagulation, softening and flocculation to dispose reverse osmosis retentates A1 Ordóñez Sanz, Ruth A1 Moral, Ana A1 Hermosilla Redondo, María Daphne A1 Blanco Suárez, María Ángeles AB The concentrated stream of a reverse osmosis unit was treated by coagulation, softening and flocculation to reduce conductivity and refractory organic matter content. Different polyaluminium chlorides and one ferric salt were used as coagulants, lime was added as softener, and two polymers (anionic and cationic polyacrylamides) were tested as flocculants. Coagulants reduced significantly the presence of refractory compounds by themselves, although conductivity increased. Lime addition decreased conductivity forming precipitates of CaCO3 and Mg(OH)2. When coagulation was combined with flocculation without adding lime, the anionic flocculant was more effective than the cationic one because the specific high hardness of water supplied enough Ca2+ and Mg2+ to promote the formation of bigger flocs, bridging the slightly negative coagula and anionic groups of the polymer; although they also reduced the efficiency of the cationic polyacrylamide. None of the tested flocculants showed any effect on conductivity and refractory organic matter reduction when lime was added. PB Elsevier SN 1226-086X YR 2012 FD 2012 LK https://hdl.handle.net/20.500.14352/44333 UL https://hdl.handle.net/20.500.14352/44333 LA eng NO Ordóñez, Ruth, et al. «Combining Coagulation, Softening and Flocculation to Dispose Reverse Osmosis Retentates». Journal of Industrial and Engineering Chemistry, vol. 18, n.o 3, mayo de 2012, pp. 926-33. DOI.org (Crossref), https://doi.org/10.1016/j.jiec.2011.08.004. NO Comunidad de Madrid NO Ministerio de Ciencia, Innovación y Universidades (España) NO European Commission DS Docta Complutense RD 30 dic 2025