Membrane fouling, chemical cleaning and separation performance assessment of a chlorine-resistant nanofiltration membrane for water recycling applications

Abstract

The effectiveness of hypochlorite cleaning for fouling mitigation of a prototype chlorineresistant nanofiltration (NF) membrane was assessed for direct filtration of a secondary treated effluent. The chlorine resistance and separation performance of the prototype NF membrane were also compared to commercial NF and reverse osmosis membranes. The prototype chlorine resistant NF membrane did not show any changes in permeability and conductivity rejection after exposing a NaOCl solution for up to 5×10 4 ppm-h. By contrast, a considerable deterioration in rejection was observed for the other two commercial membranes. Direct filtration of a secondary treated effluent by the prototype NF membrane resulted in a progressive permeability reduction by up to 25% after 10 h of filtration. The membrane permeability was fully restored by hypochlorite cleaning with a 2,000 ppm NaOCl solution for 1 h. Effective permeability recovery by hypochlorite cleaning was demonstrated with multiple hypochlorite cleaning cycles. Membrane fouling and hypochlorite cleaning were also simulated using solutions containing a model foulant (sodium alginate, humic acids or bovine serum albumin). Among them, an insufficient permeability recovery was observed for membrane fouling caused by humic acids. Further research is recommended to develop an improved hypochlorite cleaning protocol to control various membrane fouling.

Optical and Electrochemical Characterization of Nanoporous Alumina Structures: Pore Size, Porosity, and Structure Effect

“…Lately, other applications of NPASs such as spintronics, solar cells, light emitting diodes, and photonic crystals have been studied [10][11][12][13][14][15][16]. Most of these applications are related to the high structural regularity of NPAS, which exhibit almost ideal cylindrical pores with narrow pore radius distribution and without tortuosity, but their thermal and chemical resistance are also of great interest when used as nanofilters or membranes due to their stability under cleaning protocols commonly used to reduce fouling (adsorption/deposition of transported molecules or particles), which is the main problem in such applications [17,18]. The two-step anodization method creates samples with a wide range of pore radii (r p ranging between 10 nm and 200 nm) and interpore distances (D int , between 20 nm and 1000 nm) depending on the electrolyte solution, applied voltage, and temperature used during the first step, while pore length (l p ) and film thickness, which usually range between 10 µm and 100 µm, are basically associated to the second anodization step duration [2].…”

Membrane Fouling Characteristics of a Side-Stream Tubular Anaerobic Membrane Bioreactor (AnMBR) Treating Domestic Wastewater

“…Membrane permeate flushing was used in the cleaning process [22,23] but showed low efficiency for flux recovery [24], thus, chemical cleaning was addressed as an essential cleaning approach to control this fouling issue. Sodium hypochlorite (NaOCl) is a commonly used cleaning reagent in in situ and ex situ cleaning due to its chemical stability and good cleaning efficiency [14,25]. Mei et al found it effective at removing organic matter by NaOH cleaning on anaerobic ceramic membranes [26].…”

Online monitoring of N-nitrosodimethylamine rejection as a performance indicator of trace organic chemical removal by reverse osmosis

“…Chlorination to polyamide-based RO membranes typically lead to the deterioration in the rejection of salts and TOrCs including NDMA (Kwon and Leckie, 2006;Simon et al, 2009;Tin et al, 2017). In this study, the impact of chlorine treatment on TOrC rejection was more apparent at higher feedwater temperature.…”