Removing Trace Organics by Reverse Osmosis Using Cellulose Acetate and Polyamide Membranes

Abstract

A full-scale (8-cfs [ 0.22-m3/s]) reverse osmosis (RO) water treatment plant equipped with conventional cellulose acetate membranes, and two pilot RO plants, equipped with polyamide membranes, were tested for their ability to remove total organic carbon and a broad range of trace organics, including volatiles, purgeables, neutrals, bases, phenols, and acids from lime-clarified secondary municipal wastewater. The full-scale RO system removed total organic carbon (TOC) by 89 percent to 0.95 mg/L at 84-percent water recovery, and the pilot RO systems removed TOC by 99 percent to 0.1 mg/L at water recoveries of 52 and 67 percent, respectively. The two membranes tested showed significant differences in their ability to reject trace organics. All membranes rejected branched, complex molecules but varied in their rejection characteristics for smaller molecules, such as chlorinated solvents. The latter group was rejected to a varying degree by polyamide membranes but passed through cellulose acetate membranes. The use of RO for trace organics removal is evaluated by comparing cumulative removals of different treatment schemes with and without RO treatment. Percent 84 52 67 *SF--Spread factor APRIL 1986 MARTIN REINHARD ET AL 163

Removal of trihalomethanes from drinking water by nanofiltration membranes

“…As reported by other researchers that, rejection of DBP compounds was influenced by compound physical chemical properties (e.g., molecular size, solubility, diffusivity, polarity, hydrophobicity, and charge), membrane properties (e.g., permeability, pore size, hydrophobicity, and charge), and membrane operating conditions (e.g., flux, transmembrane pressure, and recovery) [10,16,17,[25][26][27], both diffusion and partitioning are highly related to physical and chemical properties of compounds and membranes.…”

“…Reinhard et al stated that contaminant removal is dependent on the chemical characteristics of both membrane and contaminants [25]. Further, molecular characteristics effecting solute sorption include water solubility and hydrogen bonding ability.…”

“…Several people have cited a number of factors affecting removal of organics by NF membranes [10,16,17,25,26]. Reinhard et al stated that contaminant removal is dependent on the chemical characteristics of both membrane and contaminants [25].…”

Identification of organic residues in tertiary effluents by GC/EI-MS, GC/CI-MS and GC/TSQ-MS

“…A previous study of WF21 effluents (1979)(1980)(1981)(1982) found that none of the EPA priority pollutants were present at concentrations above Correspondence to: W.-H. Ding regulatory levels [1]. Other studies at WF21 focused on alkylphenol polyethoxylates surfactant residues, their chlorination and bromination during chlorine disinfection [2], and on removal of organics during reverse osmosis treatment [3]. Little is known about the identity and concentration of specific organics that remain after GAC contacting.…”

Micropollutant Degradation Mechanism

“…Considering that the molecular weights of almost all pesticides range from 200 to 400 Da, NF membranes are potentially useful for pesticide removal. Since NF membranes can simultaneously remove both hardness and pesticides, their application to the treatment of drinking water has been increased (Reinhard et al, 1986;Baier et al, 1987;Duranceau et al, 1992;Berg et al, 1997;Hofman et al, 1997;Van der Bruggen et al, 1998).…”