Treatment of complex multi-sourced industrial wastewater — New opportunities for nanofiltration membranes

Fouling behavior of BTEX in petrochemical wastewater treated by nanofiltration (NF)

Membrane fouling generated by small molecular-weight aromatic compounds with poor biodegradability is a major barrier to advanced petrochemical wastewater treatment using nanofiltration (NF) technology. In this study, the fouling behavior of ten BTEX with different substituent existing in petrochemical wastewater on the NF membrane was systematically investigated. By examining the effect of the number, position, and type of substituents on the permeability of NF membranes and membrane resistance analysis, combined with XDLVO theory and correlation analysis, we found that stronger dipole-dipole interactions of BTEX with higher polarity and hydrogen bonding effects between substituents and the membrane surface were verified to be the main forces driving the attachment to the surface of membranes. Furthermore, by analyzing the effect of common inorganic ions in petrochemical wastewater on membrane fouling, it was found that electron-donating substituents (-CH3, -C2H5, and -NH2) enhanced the electron cloud density of the benzene ring, a process that exacerbated membrane fouling by strengthening electrostatic interactions between the benzene ring and Ca2+ ions. The fouling potential of electron-withdrawing substituted (-NO2, -OH) BTEX exhibited the opposite trend. Overall, this study provides a theoretical basis for developing effective membrane fouling control strategies in NF advanced treatment of petrochemical wastewater. ENVIRONMENTAL IMPLICATION: Aromatic chemicals in petrochemical effluent are difficult to degrade, and their accumulation will cause significant harm to humans and ecological systems. Determine the composition of small molecule BTEX in petrochemical wastewater, gain an in-depth comprehension of the membrane fouling behavior of nanofiltration membrane filtration, identify the primary forces causing irreversible membrane surface fouling using experimental data and model fitting, and propose viable anti-fouling membrane modification strategies. Establish a technical foundation for membrane fouling management in the long-term operation of petrochemical wastewater membrane treatment.

Evaluation of enhanced nanofiltration membranes for improving magnesium recovery schemes from seawater/brine: Integrating experimental performing data with a techno-economic assessment

The global demand for valuable metals and minerals necessitates the exploration of alternative, sustainable approaches to mineral recovery. Seawater mining has emerged as a promising option, offering a vast reserve of minerals and an environmentally friendly alternative to land-based mining. Among the various techniques, Nanofiltration (NF) has gained significant attention as a preliminary treatment step in Minimum Liquid Discharge (MLD) and Zero Liquid Discharge (ZLD) schemes. This study focused on the potential of two underexplored commercial polyamide based NF membranes, Synder NFX and Vontron VNF1, with enhanced divalent over monovalent separation factors, in optimizing the extraction of magnesium hydroxide (Mg(OH)2) from seawater and seawater reverse osmosis (SWRO) brines. The research encompassed a thorough characterization of the membranes utilizing advanced physic-chemical analytical techniques, followed by rigorous experimental assessments using synthetic seawater and SWRO brine in concentration configuration. The findings highlighted the superior selectivity of NFX for magnesium recovery from SWRO brine and the promising concentration factors of VNF1 for seawater treatment. Cross-validation of experimental data with a mathematical model demonstrated the model's reliability as a process design tool in predicting membrane performance. A comprehensive techno-economic evaluation demonstrates the potential of NFX, operating optimally at 23 bar pressure and 70% permeate recovery rate, to yield an estimated annual revenue of 5.683 M€/yr through Mg(OH)2 production from SWRO brine for a plant with a nominal capacity of 0.8 Mm3/y. This research shed light on the promising role of NF membranes in enhancing mineral recovery taking benefit of their separation factors and emphasizes the economic viability of leveraging NF technology for maximizing magnesium recovery from seawater and SWRO brines.

Physicochemical methods for process wastewater treatment: powerful tools for circular economy in the chemical industry

In the chemical industry, a typical problem is the appropriate treatment of the process wastewaters. The biological treatment cannot be usually applied because of the high content of organochemical compounds. However, phsycicochemical methods can significantly contribute to the proper treatment of the process wastewater and usually also allows the recovery of the polluting materials. This phenomenon opens the application area of physicochemical methods for the treatment of process wastewater and can contribute not only to the aims of the circular economy but also to the zero liquid discharge. Besides literature studies, authors’ own results and innovations have been also presented. The treatment strategy for pharmaceutical process wastewater is reviewed in detail, which also serves to point out that hybrid methods can be usually efficient to solve the primary goal–maximum recovery and reuse of polluting materials.

Impact of Polymer Membrane Properties on the Removal of Pharmaceuticals

The influence of various factors on the removal efficiency of selected pharmaceuticals by membrane filtration was investigated. Several commercial polymer membranes were used for nanofiltration (NF) from various manufacturers. The studies were conducted for ibuprofen (IBF), amoxicillin (AMX), diclofenac (DCF), tetracycline (TRC), salicylic acid (SA) and acetylsalicylic acid (ASA). The influence of the structure and properties of the tested compounds on the retention coefficient and filtration rate was investigated. The influence of pH on the filtration parameters was also checked. The properties of selected membranes influencing the retention of pharmaceuticals and filtrate flux were analysed. An extensive analysis of the retention coefficients dependence on the contact angle and surface free energy was performed. It was found that there is a correlation between the hydrophilicity of the membrane and the effectiveness and efficiency of the membrane. As the contact angle of membrane increased, the flow rate of the filtrate stream increased, while the retention coefficient decreased. The studies showed that the best separation efficiency was achieved for compounds with a molecular weight (MW) greater than 300 g/mol. During the filtration of pharmaceuticals with MW ranging from 300 to 450 g/mol, the type of membrane used practically did not affect the filtration efficiency and a high degree of retention was achieved. In the case of low MW molecules (SA and ASA), a significant decrease in the separation efficiency during the process was noted.