Binding TiO2 nanoparticles to forward osmosis membranes via MEMO–PMMA–Br monomer chains for enhanced filtration and antifouling performance

Direct Contact Membrane Distillation for Treatment of Mixed Wastewater of Humic Acid and Reactive Dye: Membrane Flux Decline and Fouling Analysis

The main waste stream from the textile industry is its wastewater with high color, organic matters, and other contaminants. This study aims to investigate the effect of humic acid in mixed wastewater of humic acid and reactive dye on the treatment performance and permeate flux of a direct contact membrane distillation (DCMD) system. In this research, feed temperature and humic acid concentration were the main input parameters for the analysis of DCMD system operation. The fouling resistances significantly increased with higher humic acid concentrations in the mixed wastewater. As compared with the DI water test, 23% of flux decline occurred when the humic concentration in the wastewater was increased up to 20 mg/L. After the DCMD treatment, the 25 ADMI residual color was detected in the permeate when the mixed wastewater contained 20 mg/L humic acid. The mathematical model, based on the Antione equation, was proposed to predict the membrane flux decline of the DCMD system. The reduced pore size of the cake layer by a dimensionless constant β from the Kelvin equation was also considered for the fouling calculation to describe the transport mechanism.

Behaviour of Aquaporin Forward Osmosis Flat Sheet Membranes during the Concentration of Calcium-Containing Liquids

This study aims to examine the scaling and performance of flat sheet aquaporin FO membranes in the presence of calcium salts. Experiments showed that the application of calcium sulphate (CaSO4) resulted in an 8%-78% decline in the water flux. An increase in the cross-flow velocity from 3 to 12 cm/s reduced the decline in the flux by 16%. The deposition of salt crystals on the membrane surface led to the alteration in the membrane's intrinsic properties. Microscopy, attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, and X-Ray fluorescence (XRF) analyses confirmed measurements of the zeta potential and contact angle. The use of a three-salt mixture yielded severe scaling as compared with the application of calcium sulphate dehydrate (CaSO4 × 2H2O), i.e., a result of two different crystallisation mechanisms. We found that the amount of sodium chloride (NaCl), saturation index, cross-flow velocity, and flow regime all play an important role in the scaling of aquaporin FO flat sheet membranes.

New insights into the organic fouling mechanism of an in situ Ca2+ modified thin film composite forward osmosis membrane

In this study, the effect of organic substances on the fouling behavior of a thin film composite (TFC) membrane with in situ Ca²⁺ addition (TFC-Ca membrane) was evaluated. Bovine serum albumin (BSA), humic acid (HA) and sodium alginate (SA) were used as surrogate foulants for protein, natural organic substances and polysaccharides, respectively, thus enabling the analysis of foulant–membrane interaction in the membrane fouling process. Fouling experiments were carried out and the fouling mechanism was investigated by extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) theory. SEM-EDX, ICP-OES and TOC analysis were applied to characterize the fouled TFC-Ca membrane. Results suggested that the interfacial free energies obtained from advanced contact angle measurements were correlated strongly with the rates of membrane fouling. In situ Ca²⁺ addition in the TFC membrane resulted in the decrease of the interfacial adhesion free energy (i.e., foulant–membrane interaction) and thus the mitigation of membrane fouling. The permeate flux of TFC-Ca FO membrane after organic fouling could be fully restored by simple physical cleaning. The antifouling mechanism of Ca²⁺ pre-binding carboxyl groups in the TFC-Ca FO membrane was demonstrated, which provides new insights into the development of antifouling TFC membranes in the future.

In this study, the effect of organic substances on the fouling behavior of a thin film composite (TFC) membrane with in situ Ca²⁺ addition (TFC-Ca membrane) was evaluated.

Water reclamation and reuse

Literature published in 2018 pertinent to water reclamation and reuse has been classified into five topics: safe reuse, treatment technologies, management, assessment, and case studies. Researches have been conducted to develop new technologies and improve conventional treatments for achieving sustainable wastewater reclamation, and increasing efforts have been made to facilitate safe water reuse. PRACTITIONER POINTS: The way of publicity greatly influences people's acceptance of water reuse and willingness to purchase produce irrigated with recycled water. Integrated process is the most commonly used treatment technology to reclaim water. There is a lack of local or regional regulatory and policy for sustainable water management.