Comparative studies of reverse osmosis membranes for wastewater reclamation

Interest in wastewater reclamation and reuse has increased considerably over the past several years in Spain. However, the implementation of involving membrane-based advanced treatment and groundwater recharge schemes is still limited. The goal of this paper is to show part of the studies conducted using an experimental pilot plant (output: 100 m3/d) in Chiclana de la Frontera, Province of Cadiz, southern Spain. The purpose pilot-plant study was to define the optimum conditions for physicochemical pretreatment of secondary effluents for successful reverse osmosis operation for groundwater recharge. The performance of cellulose acetate and two thin-film composite membranes was studied. Several pretreatment levels were used in order to optimise economic issues. Comparative analyses of the secondary effluent and the reclaimed wastewater for groundwater recharge were made in order to study the efficiency of the treatment sequence used and the feasibility of the processes studied. Membrane rejection characteristics are showed to be an important barrier to the presence of pollutants and micro-pollutants in reclaimed wastewater. Finally, the high quality of reclaimed wastewater allows it to be used with safety in groundwater recharge and other reuse applications without restrictions.