Application of Ultrafiltration in a Paper Mill: Process Water Reuse and Membrane Fouling Analysis

Abstract

High water consumption is a major environmental problem that the pulp and paper industry is facing. Ultrafiltration (UF) can be used to remove the dissolved and colloidal substances (DCS) concentrated during the recycling of white water (the process water) to facilitate the reuse of white water and reduce fresh water consumption. However, membrane fouling limits the application of UF in this industry. In this study, superclear filtrate obtained from a fine paper mill was purified with a polyethersulfone (PES) ultrafiltration membrane to evaluate the reuse performance of the ultrafiltrate. The membrane foulants were characterized by scanning electron microscopy, energy-dispersive spectrophotometry, attenuated total reflection-fourier transform infrared spectroscopy, and gas chromatography-mass spectrometry. The results indicate that the retention rate of stock and the strength properties of paper increased when the ultrafiltrate was reused in the papermaking process compared to when super-clear filtrate was used. The reversible membrane foulants during ultrafiltration accounted for 85.52% of the total foulants and primarily originated from retention aids, drainage aids, and wet strength resins, while the irreversible adsorptive foulants accounted for 14.48% and mostly came from sizing agents, coating chemicals, and others. Moreover, the presence of dissolved multivalent metal ions, especially Ca 2+ , accelerated membrane fouling.

Metallo-Terpyridine-Modified Cellulose Nanofiber Membranes for Papermaking Wastewater Purification

“…Most of water used in papermaking during sheet formation is recycled but finally huge amounts of water containing highly suspended particles of sub-micron size remain and should be treated to remove these particles to allow re-use of the wastewater. Ultrafiltration and nanofiltration are among the technologies that can be used to do this step [10,11]. Development of a cheap filter that can effectively remove these particles at reasonable flux is a challenge.…”

Identification of Foulants on Polyethersulfone Membranes Used to Remove Colloids and Dissolved Matter from Paper Mill Treated Effluent

“…In addition, it was easy to see the presence of most metal elements (sodium, calcium, magnesium, and silicate) on the fouled membranes, especially calcium, due to inorganic foulants [63]. It is worth mentioning that, as described by Chen et al (2015) [7], the interaction between the multivalent metal ions (electrolytes), such as Ca 2+ and Mg 2+ , can alter the thermodynamic and the kinetic stability of DCS via a Ca-and Mg-DCS complex and aggregate formation [64,65]. This consequently contributes to pore blocking and cake formation on the membrane surface during UF caused by the complexing of rejected colloids and metal ions in the PMTE, which was confirmed through EDS analysis of Cl − , K + , and Ca 2+ on washed membrane while Mg and Si were not detected.…”

“…These FOCs can be differentiated with high sensitivity due to their respective fluorescence properties in the ultraviolet and visible range [19]. Due to these limitations in achieving adequate water quality, membrane separation technology has attracted increasing attention as a tertiary treatment for these treated effluents from paper mills, particularly as it facilitates subsequent effluent recycling [7][8][9]. However, membrane fouling continues to be one of the main limitations and challenges to the wider scale application of membrane technology in paper mill effluent treatment.…”

Operating Conditions Optimization via the Taguchi Method to Remove Colloidal Substances from Recycled Paper and Cardboard Production Wastewater

“…Ultrafiltration is an attractive process for paper mill wastewater treatment and it can be used as an advanced tertiary treatment to remove suspended solids and dissolved and colloidal substances (DCS) during the treatment of paper industry effluent in order to facilitate the reuse of the treated wastewater and reduce fresh water consumption [ 19 , 20 ]. What makes it so attractive is that most of the pollutants consist of high-molecular-weight compounds and these are easily removed by UF [ 10 , 21 ].…”