Treatment of Electroplating Wastewater Using NF pH-Stable Membranes: Characterization and Application

Abstract

Industrial adoption of nanofiltration (NF) for treatment of low-pH wastewater is hindered by the limited membrane lifetime at strongly acidic conditions. In this study, the electroplating wastewater (EPWW) filtration performance of a novel pH-stable NF membrane is compared against a commercial NF membrane and a reverse osmosis (RO) membrane. The presented membrane is relatively hydrophobic and has its isoelectric point (IEP) at pH 4.1, with a high and positive zeta potential of +10 mV at pH 3. A novel method was developed to determine the molecular weight cut-off (MWCO) at a pH of 2, with a finding that the membrane maintains the same MWCO (~500 Da) as under neutral pH operating conditions, whereas the commercial membrane significantly increases it. In crossflow filtration experiments with simulated EPWW, rejections above 75% are observed for all heavy metals (compared to only 30% of the commercial membrane), while keeping the same pH in the feed and permeate. Despite the relatively lower permeance of the prepared membrane (~1 L/(m2·h·bar) versus ~4 L/(m2·h·bar) of the commercial membrane), its high heavy metals rejection coupled with a very low acid rejection makes it suitable for acid recovery applications.

Effect of Textile Wastewater Secondary Effluent on UF Membrane Characteristics

“…Moreover, these results showed that these membranes have high acidic properties. In the case of the PES membranes, this could be due to the negatively charged sulfonic acid group in the polymer structure [ 21 ].…”

Membrane Filtration Opportunities for the Treatment of Black Liquor in the Paper and Pulp Industry

“…Membrane A was coated by hand and has a MWCO between 600 and 800 Da, while Membrane B was coated by machine and had a MWCO around 500 Da. The MWCO of these membranes was determined using a protocol described in the previous work of Hegoburu et al, in which a mixture of probe PEG molecules at MW different fractions was used [19]. Membrane C was a commercial polyethersulfone membrane with a MWCO in the range of 500-600 Da, which can be used in the entire pH range of 0-14 [14,20].…”

Circular Economy Approach in Treatment of Galvanic Wastewater Employing Membrane Processes

“…Alternatively, or to supplement the methods listed above, membrane filtration techniques can also be used to treat galvanic wastewater [ 13 , 14 , 15 ]. Such techniques, in accordance with the concept of the Best Available Techniques (BAT), are among the primary elements of clean (i.e., zero waste) technologies, ensuring that up to 60% of the treated water is recirculated and heavy metals are removed from wastewater.…”