AWWA WQTC64026

This paper describes ongoing research into removal of specific salts and pollutants from high-pressure membrane concentrate by precipitative softening with sodium hydroxide and/or coagulation with iron salts. Because of its detrimental health and environmental effects, as well as its likelihood of concentrating in desalting process residuals, arsenic serves as an example of the many pollutants that might limit the disposal options for high-pressure membrane process residuals. In addition, removal of calcium and natural organic matter (NOM) will be explored. Simulated residuals will be treated at the bench-scale to discern the potential for pollutant reduction as well as to determine the removal mechanisms. The removal of dissolved salts and pollutants from a high ionic strength environment will also be modeled using existing computer algorithms such as PHREEQC Interactive Version 2.12.5 (USGS) and Visual MINTEQ ver 2.40 (Gustafsson, J. 2006) by combining information found in the literature with results obtained from bench-scale treatments conducted for this research. Actual process residuals will then be treated and the results compared with the model predictions to ascertain model validity. Includes 26 references, tables, figure.