Full advanced treatment (FAT) consisting of reverse osmosis (RO) and advanced oxidation process (AOP) has been widely used in indirect potable reuse (IPR) applications in California and some other states and is expected to be a major component of the direct potable reuse (DPR) trains in future. FAT has been proven very effective in reliably meeting all Federal and State primary and secondary drinking water MCLs as well as reducing all measured emerging contaminants below its detection or health goal limits. However, FAT requires relatively high capital and O&M expenditures. In addition, areas where RO concentrate (brine) disposal is not achieved thru a costeffective method (e.g. ocean discharge or blending it with other sources), implementing an RO based IPR/DPR projects may be cost prohibitive. In this paper, a low temperature membrane distillation is incorporated into a FAT train to treat and recover RO concentrate streams to achieve a near zero liquid discharge. Membrane distillation uses hydrophobic semi permeable RO membranes that allow passage of water vapor and gases while greatly rejecting TDS and any dissolved compounds. This process is operated under ambient pressure (e.g. ~1 atm) because driving force to move water vapor is the temperature differences between feed and permeate sides of the membranes. The results obtained from the demonstration and full-scale membrane distillation facilities have shown that 98.5-99.2% water recoveries are achievable with average TDS and TOC removal efficiencies of 99%. High rejection of TDS and TOC with membrane distillation may potentially allow blending of membrane distillation permeate with RO permeate from the FAT for potable water production contingent upon further demonstration and regulatory approval.
This presentation is available to AMTA Members only.
- Ufuk Erdal
- AMTA/AWWA Membrane Technology Conference, West Palm Beach, FL
- AMTA/AWWA Membrane Technology Conference
- Advanced treatment, DPR, IPR, Membrane Distillation, Potable Reuse, RO Concentrate