Pilot-Scale Oxidative Technologies for Reducing Fouling Potential in Water Reuse and Drinking Water Membranes
Year Released: 2013
Type: Scientific Investigation
Funding Partner: Bureau of Reclamation
Total Investment: $621,658.59 (Cash: $441,739.99, In-Kind: $199,918.60)
Principal Investigators: Benjamin D. Stanford, Ph.D., Hazen and Sawyer, P.C., Aleksey N. Pisarenko, Ph.D., Southern Nevada Water Authority, Shane A. Snyder, Ph.D., University of Arizona, and R. David Holbrook, Ph.D, P.E., National Institute of Standards and Technology
Membranes are a widely used technology for water reuse applications, especially reverse osmosis (RO) and nanofiltration (NF) membranes, largely because of their ability to reject dissolved organic matter (DOM), salts, chemical contaminants, and biological contaminants from the product (permeate) stream. RO membranes will reject up to 99.9% of DOM and salts, depending on the molecular weight cutoff of the membrane material.
One of the major operational costs associated with RO and NF membrane systems is in the energy required to drive the water across the membrane. Membrane fouling can further exacerbate the energy demand by requiring higher feed pressures to meet production goals.
Goals and Objectives
The project investigates the potential for pilot-scale oxidative technologies (ozone and UV advanced oxidation) placed upstream of membrane treatment to reduce the organic fouling of RO membranes during drinking water treatment and reuse applications. Additionally, mechanisms associated with organic fouling with and without oxidative pretreatment were investigated along with relative energy costs associated with each technology.
This multiyear study was designed to evaluate the novel use of oxidative technologies as a pretreatment for RO membrane feed water to address issues associated with organic fouling. The study investigated 5 major hypotheses through bench-scale and pilot-scale testing at two water reclamation sites and one drinking water site in Las Vegas, NV. The hypotheses were used to focus research efforts and guide our analysis of the impact of oxidation on organic matter, membrane fouling, and trace organic contaminants in water reuse systems.
Findings and Conclusions
The results from this study provided compelling information regarding the benefits of ozone applied upstream of RO membranes for decreasing the aromatic, hydrophobic nature of EfOM and for providing a benefit toward minimizing organic fouling of membranes and for oxidation of TOrCs, which minimizes their presence in the RO permeate and in the brine stream with the exception of NDMA. The evidence regarding benefits in controlling membrane fouling was clearly observed in both the flat sheet and pilot-scale tests.