Integrated osmosis systems and methods

摘要

Integrated, sequential stages of nanofiltration, forward osmosis, and reverse osmosis and related membranes provide an Integrated Osmosis structure, systems and methods. By optimally placing and using the desired characteristics of each membrane, performance and cost effectiveness not attainable individually is obtained. Integrated Osmosis systems provide high diffusive and osmotic permeability, high rejection, low power consumption, high mass transfer, and favorable Peclet number, by manipulating convection, advection and diffusion, low concentration polarization gradients, low reverse salt flux and effective restoration of performance after cleaning fouled membranes. Benefits include increased permeate recovery and decreased waste concentrate volume from reverse osmosis processes or other elevated osmotic pressure solutions. Integrated Osmosis first employs nanofiltration for selective harvesting of solutes, proffering a reduced osmotic pressure permeate. Forward osmosis dewaters the lowered osmotic pressure permeate generating a dilute draw solution which serves as feed to a reverse osmosis process. Reverse osmosis permeate provides freshwater and concentrate provides draw solution for the forward osmosis process.

主权项

1. An Integrated Osmosis water treatment method comprising the steps of:
providing a two pass RO high TDS concentrate feed from an RO stage having greater than about 60,000 ppm salinity; nanofiltering the two pass RO high TDS concentrate feed to selectively remove non-monovalent ions from the two pass RO high TDS concentrate feed to produce a lowered osmotic pressure solution; and passing the lowered osmotic pressure solution through at least one FO stage having at least one membrane while maintaining the lowered osmotic pressure solution at a constant temperature to avoid temporal variation and corresponding impact on flux, and also feeding a draw solution to the FO stage such that the temperature of the membrane rises to about 40-45° C., to produce a fresh water permeate.