An improved technique for reducing water wastage from micro-RO-membrane-based water purification systems: An experimental study

Abstract

While reverse osmosis (RO) has emerged as the leading technology for home-use and point-of-use (POU) water purification, this technology leads to water wastage as the reject. This wastage needs to be reduced, especially in water-stressed regions of the world. In this paper, we report an experimental study, which demonstrates that it is possible to operate a home-use RO-based water purification system, at ∼75% recovery, without significantly compromising the life of the membrane. The membrane element is ‘cleaned’ using a hydrostatic and osmotically driven backwash using the permeate produced in the system. This study examines the effect of the permeate volume used for the backwash, on the extent of salt removal from the membrane module. During this study, which involved the measurement of the total dissolved solids (TDS) of the backwash-effluent, it was observed that the backwash-effluent showed dual-minima in the effluent TDS. This paper further examines this dual-minima observed under different experimental conditions. Data generated suggest the causes for the dual-minima. HIGHLIGHTS Water savings from reverse osmosis systems.; Scale prevention in RO membranes.; Dual-minima in backwash TDS.; Backwash optimization.;

Keywords

• high-recovery ro
• home-use water purifier
• osmotic backwash
• pou water purification