Silica fouling revisited

摘要

The potential for silica scale formation in reverse osmosis (RO) systems is thought to limit recovery in many installations, which may unnecessarily increase costs. In the past, the standard industry design guideline has been to limit the maximum silica concentration to about 120 mg/l in the concentrate at 25℃ (77℉) based on solubility data, such as ASTM D4993-89, and operational problems observed at field sites. However, data reported in this paper indicate that the nominal 120 mg/l silica limit can be significantly exceeded in many cases, but that silica scaling could occur at lower concentrations in other cases. The effect of variables, such as the presence of iron or other heavy metals, are discussed.