Different samples of rice husk ash (RHA) and sodium silicate were prepared and characterized using FTIR, NFTIR and XRD. The selected sample of RHA was obtained by calcination of untreated rice husk (RH) in a semi-closed system at 650 degrees C. Four novel polyinorganic coagulants were also prepared, namely, poly aluminum chloride silicate, poly hydroxy aluminum sulphate silicate, poly ferric chloride silicate and poly ferric aluminum chloride silicate. Applications were carried out for the removal of some pollutants from ground, sewage and industrial waste waters. It was found that the maximum percentages removal of Fe2+ and Mn2+ ions in ground water reached 99 and 97%, respectively, the maximum percentage removal of, Pb2+ ion in industrial waste water reached 97%. In addition, the maximum percentages removal of COD, BOD and TSS in sewage waste water reached 90, 92, and 93%, respectively. (C) 2010 Elsevier B.V. All rights reserved.