Effect of feed temperature on permeate flux and mass transfer coefficient in spiral-wound reverse osmosis systems

Abstract

The objective of the present study was to analyze and model concentration polarization in spiral-wound seawater membrane elements. In particular, the influence of feed temperature, salinity and flow rate on permeate flow and salinity was evaluated. Membrane lifetime and permeate fluxes are primarily affected by the phenomena of concentration polarization (accumulation of solute) and fouling (i.e., microbial adhesion, gel layer formation and solute adhesion) at the membrane surface. Results show that the polymer membrane is very sensitive to changes in the feed temperature. There was up to a 60% increase in the permeate flux when the feed temperature was increased from 20 to 40°C. This occurred both in the presence and absence of solute. Surprisingly, the permeate flux appears to go through a minimum at an intermediate temperature. There was up to a 100% difference in the permeate flux between feed temperatures of 30 and 40°C. The differences were statistically significant ( p<0.05). A doubling of the feed flow rate increased the permeate flux by up to 10%, but only at a high solute concentration. Membrane parameters were estimated using an analytical osmotic pressure model for high salinity applications. A combined Spiegler—Kedem/film theory model described the experimental results. The modeling studies showed that the membrane transport parameters were influenced by the feed salt concentration and temperature.