Pilot‐scale study of Polyelectrolyte‐Enhanced UF for arsenic removal

Abstract

The removal of arsenic (As) from dilute aqueous solutions has become of greater interest as lower drinking standards are implemented. In polyelectrolyte‐enhanced ultrafiltration (PEUF), a cationic water‐soluble polyelectrolyte (poly‐diallyldimethylammonium chloride [QUAT]) binds the anionic arsenate species and is rejected by the membrane, which has a 10 kDa molecular weight cutoff (MWCO). In the research presented in this article, PEUF was used to treat water with As concentrations of 50–100 μg/L. The results demonstrated that PEUF was able to produce treated water that meets the proposed US Environmental Protection Agency maximum contaminant level of 10 μg/L. In this study, the PEUF process was scaled up with a spiral‐wound ultrafiltration module operated under steady‐state continuous flow conditions (i.e., permeate flux of 80 L/m2‐h, and a pressure drop of 60 psi, which is typical for large‐volume applications). The main process parameters considered in this study were the QUAT‐to‐As ratio, pH, and the presence of background electrolytes (i.e., sulfate). The As removal efficiency improved with increasing pH, which is an advantage when the As‐tainted water is at an elevated pH since most adsorption‐based As removal methods perform better at lower pH levels.

Polyelectrolyte-Enhanced Ultrafiltration (PEUF) Process for Low Level Arsenic Removal: Recovery of Polyelectrolyte from Retentate Stream

“…Further work demonstrated scale up in a continuous PEUF process achieving 94% arsenic removal from 50 ppb arsenic contaminated water, thus achieving the 10 ppb MCL standard for arsenic in drinking water [6]. The authors also reported analysis of the relative cost for purifying drinking water using PEUF and several traditional technologies.…”

“…Methods: Polyelectrolyte recovery experiments were conducted by adding divalent metal chloride solution to synthetic PDADMAC-arsenate complex solutions to precipitate arsenic oxyanions from the solution. Initial arsenic concentrations of 100 ppb were selected to be compatible with the levels of arsenic in the retentate from the continuous PEUF process [6]. Parameters varied include the temperature, the ratio of PDADMAC:arsenic, pH, and the degree of supersaturation.…”

Reactive red 120 retention through ultrafiltration enhanced by synthetic and natural polyelectrolytes

“…The effectiveness of PEUF with regard to anion retention has also been examined previously by a number of studies. For instance, chromate retention using ethoxylated polyethyleneimine, poly(diallyldimethylammonium) chloride, chitosan, and pectin as chelating polyelectrolytes, nitrate retention using poly(dimethylaminecoepichlorohydrin), poly(diallyldimethylammonium) chloride, and poly(dimethylamine-co-epichlorohydrin-co-ethylenediamine), and removal of anionic species such as arsenic and perchlorate, by employing poly(diallyldimethylammonium) chloride as the complexing agent, have been formerly appraised by several scientific explorations [20][21][22][23][24][25][26][27][28][29]. Meticulous retrospection of archival literature however manifests the parochial availability of studies dealing with the application of PEUF for bringing about effective retention of dyes from colour-contaminated effluent streams.…”