Reverse Osmosis Modeling Study of Lead and Arsenic Removal from Drinking Water in Tarija and La Paz, Bolivia

Abstract

An investigation of primary water sources in two Bolivian basins identified the presence of heavy metals toxic to health that exceeded the permissible limits for drinking water. Lead deposited in the San Jacinto and Huacata–Tarija reservoirs within the Guadalquivir basin and arsenic in the Milluni–La Paz basin were identified. The work studies reverse osmosis (RO) to remove Pb and As. The main contribution of this research is the development and construction of a mathematical model based on the Spiegler–Kedem concentration polarization model using different concentrations of Pb and As. The model makes it possible to design high conversion facilities (>80%) and optimize the process from the point of view of energy efficiency in future works. The model was developed to also include an Arrhenius temperature adjustment factor that allows for an accurate prediction of the process performance. The experimentation was carried out in two RO pilot plants using polyamide membranes. The model fits correctly with a maximum relative error between the experimental and theoretical flows of 5.4% and 4.4%. Among the benefits of the study, it guarantees the rejection of metals greater than 99%, even at low pressures.