The scope of work for this thesis includes: (1) characterization of silica and other scaling compounds in coal seam gas (CSG) water, and (2) study of the removal of silica from aqueous solution using activated alumina.In the first phase of this research, coal seam gas water from a full scale water treatment facility was characterized with spectroscopic and other analytical techniques. Silica and other scaling compounds, all of which were present in dissolved and non-dissolved forms, were characterized. Transmission electron microscopic analysis showed the existence of spherical siliceous particles with a size range of 10-100 nm and aggregates of 1 to 10 microns in CSG brine.Elemental characterization confirmed that the particulate matters in CSG brine consist of the following elements in decreasing order: K, Si, Sr, Ca, B, Ba, Mg, P, and S. A plant-wide silica characterization showed that the ratio of particulate to dissolved silica varies as CSG water passes through the various process units and nearly one-third of the total silicon in the RO brine was present in particulate form. In search for the origin of particulate matters, it was found that RO brine is super-saturated with respect to several carbonate and sulphate based mineral salts and precipitation of such salts during the RO process should take place and could be responsible for subsequently capturing silica in the solid phase. However, the precipitation of crystalline carbonates and sulphates is complex. X-ray diffraction analysis did not confirm the presence of common calcium carbonates or sulphates but instead showed the presence of a suite of complex minerals, to which amorphous silica and/or silica rich compounds could have adhered. A filtration study showed that majority of the siliceous particles were less than 220 nm in size, but could still be potentially captured using a low molecular weight ultrafiltration membrane.In the second phase of this research, the potential of activated alumina for removing silica from aqueous solution was studied. Equilibrium, kinetics, and column study were performed to investigate the silica removal efficiency of activated alumina. pH studies showed that a pH of 8.8 is optimum for removal of silica using activated alumina. The equilibrium data fits the well-known Langmuir and Freundlich isotherms. The maximum monolayer adsorption capacity was found to be 17.63 mg/g at pH 8.8. A second order kinetic model fitted the experimental data better than a first order model. Analysis of the kinetic data with Weber-Morris intraparticle diffusion model suggests both external and internal mass transfer controls the overall adsorption process. It was also found that as initial silica concentration increases, external mass transfer becomes important and cannot be ignored in the overall mass transfer process. From the continuous column study, it was surprising to find that feed flow rate did not affect the overall performance of the column between 1 mL/min (2.25 bed volume/hr) and 4.2 mL/min (9.65 bed volume/hr).This th...