Arsenic removal by RO and NF membranes

Bench-scale experiments were performed to assess the effectiveness of reverse osmosis (RO) and nanofiltration (NF) membranes in removing arsenic (As) from synthetic freshwater and source water. The authors examined the effects of operational conditions (applied pressure and feedwater temperature) and solution chemical composition (As oxidation state, pH, and presence of co-occurring inorganic solutes). Both As(V) and As(III) were effectively removed from synthetic freshwater by RO and tight NF membranes over a wide range of operational conditions. The relatively large molecular weight (>125 g/mol) of the As species governed their separation behavior. Applied pressure had little effect on As removal, but an increase in feedwater temperature decreased As removal by a small percentage. Removals of As(III) and As(V) were comparable, with no significant preferential rejection of As(V) over As(III). Variations in solution pH from 4 to 8 also did not affect the removal of As species by the membranes tested, despite changes in the speciation and charge of As(V). Co-occurring inorganic solutes had only a slight effect on As removal. Removal of As from source water was comparable to that obtained with synthetic freshwater, despite the presence of turbidity, natural organic matter, and a variety of co-occurring solutes.

[1]  Menachem Elimelech,et al.  Effect of solution chemistry on the surface charge of polymeric reverse osmosis and nanofiltration membranes , 1996 .

[2]  Frederick W. Pontius,et al.  Health implications of arsenic in drinking water , 1994 .

[3]  Shoji Kimura,et al.  Reverse Osmosis of Single and Mixed Electrolytes with Charged Membranes: Experiment and Analysis , 1991 .

[4]  T. D. Hodgson.  Selective properties of cellulose acetate membranes towards ions in aqueous solutions , 1970 .

[5]  Johnnie N. Moore,et al.  Partitioning of arsenic and metals in reducing sulfidic sediments , 1988 .

[6]  J. T. Byrd.  Comparative geochemistries of arsenic and antimony in rivers and estuaries , 1990 .

[7]  J. Schurz,et al.  Characterization of polymer surfaces by means of electrokinetic measurements , 1988 .

[8]  Joe Reid,et al.  Arsenic occurrence: USEPA seeks clearer picture , 1994 .

[9]  Frederick W. Pontius,et al.  Crafting a New Arsenic Rule , 1994 .

[10]  K. Bruland,et al.  Biogeochemistry of arsenic in natural waters: The importance of methylated species , 1991 .

[11]  Kim R. Fox,et al.  Controlling arsenic, fluoride, and uranium by point-of-use treatment , 1987 .

[12]  P. Huang,et al.  Oxidative power of Mn(IV) and Fe(III) oxides with respect to As(III) in terrestrial and aquatic environments , 1981, Nature.

[13]  D. L. Peck,et al.  Reconnaissance investigation of water quality, bottom sediment, and biota associated with irrigation drainage in the Salton Sea area, California, 1986-87 , 1990 .

[14]  F. Pontius.  Uncertainties drive arsenic rule delay , 1995 .

[15]  J. Ferguson,et al.  A review of the arsenic cycle in natural waters , 1972 .

[16]  D. Tallman,et al.  Arsenic species as an indicator of redox conditions in groundwater , 1979 .

[17]  Shoji Kimura,et al.  Calculation of ion rejection by extended nernst-planck equation with charged reverse osmosis membranes for single and mixed electrolyte solutions , 1991 .

[18]  T. Sorg,et al.  Reverse osmosis treatment to remove inorganic contaminants from drinking water , 1987 .

[19]  J. Skorupa,et al.  Reconnaissance investigation of water quality, bottom sediment, and biota associated with irrigation drainage in the Tulare Lake bed area, southern San Joaquin Valley, California, 1986-87 , 1988 .

[20]  L. Dresner.  Some remarks on the integration of the extended Nernst-Planck equations in the hyperfiltration of multicomponent solutions , 1972 .

[21]  A. Katchalsky,et al.  Thermodynamic analysis of the permeability of biological membranes to non-electrolytes. , 1958, Biochimica et biophysica acta.

[22]  R. J. Petersen,et al.  Composite reverse osmosis and nanofiltration membranes , 1993 .

[23]  N. Korte.  Naturally occurring arsenic in groundwaters of the midwestern United States , 1991 .

[24]  J. Martin,et al.  Biogeochemical processes affecting arsenic species distribution in a permanently stratified lake , 1989 .

[25]  Kim R. Fox,et al.  Field Experience With Point‐of‐Use Treatment Systems for Arsenic Removal , 1989 .

[26]  P. Huang,et al.  Role of Manganese in the Oxidation of Arsenite by Freshwater Lake Sediments , 1981 .

[27]  Thomas J. Sorg,et al.  Water treatment processes. III. Removing dissolved inorganic contaminants from water , 1986 .

[28]  M. Elimelech,et al.  Arsenic Removal by Enhanced Coagulation and Membrane Processes , 1996 .

[29]  Nic E. Korte,et al.  A review of arsenic (III) in groundwater , 1991 .

[30]  W. Richard Bowen,et al.  Characterisation and prediction of separation performance of nanofiltration membranes , 1996 .