Małgorzata Kabsch-Korbutowicz

Analysis of membrane fouling in the treatment of water solutions containing humic acids and mineral salts

The separation of humic substances from aqueous solution by ultrafiltration was investigated with flat Intersep Nadir membranes. Special consideration was given to the decrease of membrane permeability in the course of the ultrafiltration process. The decrease of membrane permeability was related to the increase of pH and calcium ion concentration in the solution. Transport properties were found to be strongly dependent on the hydrophilicity of the membranes. The membrane made of regenerated cellulose, the most hydrophilic of the membranes tested, displayed the highest permeability with respect to both water and humic substance containing solutions, and the lowest proneness to fouling by organic colloids. Analysis of the relationship between the properties of the solution and the course of the separation process revealed that the rise of pH from 4.6 to 7.0 reduced membrane fouling. The presence of mineral salts in the solution deteriorated the separation and transport properties of the membranes and intensified the fouling process.

Separation of anionic surfactants on ultrafiltration membranes

Abstract The objective of this study was to investigate the influence of MWCO, pressure, SDS concentration, salt amount and temperature on surfactant removal and permeate flux. Intersep Nadir membranes made from polyethersulphone (PES) and polysulphone (PS) were used. With the addition of a mineral salt to the SDS solution, a dramatic decrease in retention of SDS was observed. There was no discernible effect on the retention coefficient of the membranes with the increase in the amount of the mineral salt added to the SDS solution. The volume flux was slightly dependent on the ionic concentration in the feed solution: high ion concentration caused a small decrease of the water flux. The effect of pressure on the separation efficiency for the PES and PS membranes was evaluated; it produced only a small reduction in the retention as the pressure was increased. With the increase of temperature of SDS solutions, a decrease in the retention of SDS was observed. The permeate flux increased with temperature due to the solution viscosity decrease.

Salt effect on the dye separation by hydrophilic membranes

Abstract The preliminary studies were initiated to determine the influence of salt concentration and electrolyte type on the efficiency of dye ultrafiltration. On the variety of commercial UF membranes the Intersep Nadir membranes (PES, C, CA, PS and PA series) have been chosen. They are characterized by different MWCO and various surface hydrophilicity. Transport and separation properties of the membranes were tested with respect to three organic dyes of anionic nature (methyl orange, helion grey, direct meta black) and having various molecular weights (327, 617 and 781.2 daltons, respectively). The permeation measurements were carried out with distilled water, aqueous solutions of dyes, and aqueous solutions of dyes and salts (NaCl or CaCl2). Dye concentration in the aqueous solution was equal to 100 g/m3. Salt concentration amounted to 1, 10 and 25 kg/m3. An Amicon stirred cell was used in this experiments. The ultrafiltration process involved a pressure of 0.2 MPa. The results showed that increasing the salt concentration generally worsens the efficiency of dye ultrafiltration. This relationship becomes particularly pronounced for low-molecular-weight dyes and for CaCl2. The greatest decrement of transport properties was found to occur at the lowest salt concentration applied. The effect of salt on the rejection coefficient depended on the membrane type and dye particles applied.

SEPARATION OF HUMIC SUBSTANCES BY POROUS ION-EXCHANGE MEMBRANES FROM SULFONATED POLYSULFONE

Abstract Ultrafiltration involving sulfonated polysulfone membranes provides high efficiency for humic matter removal from water. The increase in ion-exchange capacity of the polymer matrix from 0.24 to 0.96 mmol SO3H groups per 1 g of dry membrane increases the membrane pore diameter and its hydrophilicity, and thus the permeate flux from 0.05 to 3.69 m3/m2·d. In order to decrease the manufacturing cost, membranes from polysulfone and sulfonated polysulfone blends were investigated. It was shown that a one-to-one blend resulted in a membrane having similar antifouling properties to pure sulfonated polysulfone. Both membranes reject humic matter in the 91–98% range and show a flux decline of 5–30% as a result of surface fouling.

The influence of organic carbon concentration on atrazine removal by UF membranes

Abstract The primary objective of the study described in the present paper was to investigate the problem of how the concentration of organic matter (expressed as dissolved organic carbon, DOC) contributes to the efficiency of separating atrazine form aqueous solutions by ultrafiltration. Another objective was to examine how the type of organic matter (humic substances HS, tannic acid TA) may affect the efficiency of atrazine separation. A series of experiments was carried out with model solutions containing atrazine (1000 mg/m 3 ), humic substances (10, 20, 50 g/m 3 ) or tannic acid (5, 10, 15, 20 g/m 3 ) at a neutral pH. The ultrafiltration process involved a DS-GE polysulfone/polyamide membrane (Osmonics) and a transmembrane pressure of 0.1 and 0.3 MPa. The highest atrazine rejection coefficient (80%) was achieved at the organic matter concentration, DOC = 8.1 g C/m 3 .

Effects of natural organic matter on atrazine rejection by pressure driven membrane processes

Abstract The objective of the study described in the present paper was to investigate transport and separation properties of ultrafiltration membranes for atrazine solutions in the presence of natural complexing agents (humic and tannic acids). Two ultrafiltration membranes made of various polymer materials were used in the tests. Atrazine concentrations in tested solutions amounted to 1000 mg/m 3 . The influence of pH of atrazine solutions as well as the dose of humic and tannic acids on the process efficiency was investigated. The highest efficiency of separation (80%) was achieved for DS-GE membrane at the concentration of humic substances equal to 20 g/m 3 .

The effect of gas bubble flow on ultrafiltration efficiency

We assessed the potentiality of reducing concentration polarization and enhancing ultrafiltration of macromolecules via gas sparging (gas bubbles supplied to the UF system with the feed solution). Consideration was given to the problem of how the quantity of the gas sparged and the duration of the process affect the transport and separation properties of hollow-fibre UF modules. Ultrafiltration tests were carried out with model solutions containing macroparticles either organic (dye) or mineral (kaolin). Gas sparging was found to increase the permeability of the module by approximately 25%, but there was a slight deterioration of selectivity. The rate of gas flow seems to be of negligible importance.

Influence of operating conditions on performance of ceramic membrane used for water treatment

The removal of natural organic matter (NOM) is a critical aspect of potable water treatment because NOM compounds are precursors of harmful disinfection by-products, hence should be removed from water intended for human consumption. Ultrafiltration using ceramic membranes can be a suitable process for removal of natural substances. Previously reported experiments were dedicated to evaluating the suitability of ultrafiltration through ceramic membrane for water treatment with a focus on the separation of natural organic matter. The effects of the membrane operating time and linear flow velocity on transport and separation properties were also examined. The experiments, using a 7-channel 300 kDa MWCO ceramic membrane, were carried out with model solutions and surface water at trans-membrane pressure of 0.2–0.5 MPa. The results revealed that a loose UF ceramic membrane can successfully eliminate natural organic matter from water. The permeability of the membrane was strongly affected by the composition of the feed stream, i.e. the permeate flux decreased with an increase in the NOM concentration. The permeate flux also decreased over the period of the operation, while this parameter did not influence the effectiveness of separation, i.e. the removal of NOM. It was observed that the increased cross-flow velocity resulted in the decrease in the membrane-fouling intensity and slightly improved the retention of contaminants.

The properties of NOM particles removed from water in ultrafiltration, ion exchange and integrated processes

AbstractNatural organic matter (NOM) is a complex mixture of organic compounds consisting of various elemental compositions and chemical structures. The different NOM fractions exhibit different properties in terms of treatability. This research focused on identification of NOM fractions removed from water in ion exchange, ultrafiltration and ion exchange/ultrafiltration integrated processes. Analysis based on fractionation with the use of XAD resins and membrane techniques as well as elemental analysis of organic matter was performed. Obtained results showed that the application of integrated processes allowed for a joint effect of low molecular weight compound removal by ion exchange processes with high molecular weight particle separation by ultrafiltration. Fractional analysis demonstrated a poor separation of hydrophilic fractions and effective removal of hydrophobic compounds by ultrafiltration and ion exchange, while integrated processes effectively removed both hydrophobic and charged hydrophilic ...