The partial solution for the growing contamination of the environment is the implementation of new technologies. The most of the currently operated systems for surface and groundwaters treatment as well as for wastewater treatment characterize with complex technological arrangements based on a number of unit operations. In water-wastewater management membrane processes are more often applied, especially those in which the difference of pressure at both membrane sites is used as a driving force. As an example of such application is the use of nanoﬁ ltration for groundwaters treatment at Water Treatment Plant Zawada near Dębica or the treatment of municipal landﬁ ll leachate and industrial wastewater at Eko Dolina Waste Utilization Plant in Łężyce near Gdynia (reverse osmosis unit capacity of 120 m /d). Municipal wastewater treatment based on membrane technologies has already been implemented at domestic wastewater treatment plant. It is especially proﬁ table, when the load of contaminant present in a wastewater varies within a year. In the case of membrane systems use, this issue can be neglected. As an example of membrane based system may serve WWTP in Rowy n/Ustka started up in 2013 and modernized in 2017. The latest trends and developments of selected suppliers of membrane systems are also presented.
To improve dye retention, there is a concurrent interest in the development and optimization of an alternative and promising method for the dye recovery in aqueous solutions. In this regard, considerable attention was paid to the polyoxometalates (POMs) assisted ultraﬁ ltration (POMAUF). The aim of the present study is to eliminate toluidine blue (TB) dye by ultraﬁ ltration membrane using keggin polyoxometalates (POMs) as complexing agents. In the ﬁ rst step, the keggin polyoxometalates K3[PW12O40]∙6H2O(PW12) and K7[PW) were prepared. Then, the obtained powders were characterized by X-ray diffraction and infrared spectroscopies. Afterwards, the removal of toluidine blue (TB) using polyoxometalates assisted ultraﬁ ltration (POMAUF) was studied. Factors affecting the retention of dye and permeate ﬂ ux such as transmembrane pressure, operating time, polyoxometalates concentration, ionic strength, surfactant and pH were investigated. All results of both compounds have been presented and discussed. The results reveal that the addition of POMs leads to an increase in dye retention from 11 to 95% for the PW 12 and to 98% for the PW . The results of this work have thus suggested the promising enhancement of ultraﬁ ltration membrane selectivity for the dye removal using new complexing agents such as POMs in place of polyelectrolytes and surfactants.
Linden honey ultrafiltration (15 kDa MWCO ceramic membrane) was performed as honey solution pre-treatment before spray drying. Feed and retentate solutions with the addition of maltodextrin as a carrier were spray dried. Drying yield and physical properties of powders were studied (after drying and after 12 weeks of storage). During ultrafiltration it was possible to remove some amount of sugars responsible for honey low glass transition temperature, while keeping protein compounds. Yet, it did not have a significant impact on the drying performance and improvement of powder physical properties immediately after drying and after storage. However, the possibility to remove sugars from honey solution by ultrafiltration can be an encouragement for further research.
This paper presents ultrafiltration results of model BSA (bovine serum albumin) and MB (myoglobin) solutions prepared with or without NaCl addition. The protein concentrations in the solutions were equal to 0.05 g#1;dm3 for MB and 0.5 g#1;dm3 for BSA. The ultrafiltration tests were performed using a laboratory scale unit equipped with 90 mm ceramic disc membranes with a filtration area of 5:6#2;103 m2 and cut-off of 50 or 150 kDa. The tests were run under constant process conditions, i.e. a cross flow volume (CFV) of 5 m#1;s1, transmembrane pressure (TMP) of 0.2 MPa, temperature of 20 ◦C and NaCl concentration of 0 or 10 wt%. The installation worked in a semi-open mode with a continuous permeate discharge and retentate recycle. The performance of the membranes was measured with the permeate volumetric flow rate, JV (m3m2s1) while their selectivity was determined by the protein rejection, R. The paper evaluates and discusses the protein rejection mechanisms as well as the influence of the membrane cut-off and sodium chloride concentration in the feed on the flux decline during the ultrafiltration of BSA and MB. Moreover, it provides an analysis of the first fouling phase by applying usual filtration laws.
The paper presents the results of studies on the changes in the PAHs concentration during pre-filtration and ultrafiltration (UF) processes. In the study, biologically treated wastewater (after denitrification and nitrification processes), discharged from the biological treatment plant and used in coke plant, was used. A gas chromatography-mass spectrometry (GC-MS) was used in order to qualify and quantify the PAHs. Sixteen PAHs listed by EPA were determined. The wastewater samples were collected three fold and initially characterized for the concentration of nitrate nitrogen, ammonium nitrogen, COD, TOC and pH. In the first step, wastewater was filtrated on the sand bed. Total concentration of 16 PAHs in the treated wastewater before initial filtration was in the range of 44.8‒53.5 mg/L. During the process the decrease in the concentration of the most studied hydrocarbons was observed. Concentration of PAHs after initial filtration ranged from 21.9 to 38.3 μg/L. After the initial filtration process the wastewater flew to the ultrafiltration module and then was separated on the membrane (type ZW-10). The total concentration of 16 PAHs in the process of ultrafiltration was in the range of 8.9‒19.3 mg/L. The efficiency of removal of PAHs from coke wastewater in the process of ultrafiltration equaled 66.6%. Taking into account the initial filtration, the total degree of removal of PAHs reached 85%. The obtained results indicate the possibility of using the ultrafiltration process with the initial filtration as additional process in the coke wastewater treatment.
This paper presents an experimental study on chicken egg white solution ultrafiltration, where membrane fouling has been the main point of concern. Separation process has been performed with a 150 kDa tubular ceramic TiO2/Al2O3 membrane. The operating parameters have been set as follows: transmembrane pressure 105–310 kPa, cross-flow velocity 2.73–4.55 m/s, pH 5 and constant temperature of 293 K. Resistance-in-series model has been used to calculate total resistance and its components. The experimental data have been described with four pore blocking models (complete blocking, intermediate blocking, standard blocking and cake filtration). The results obtained show that the dominant fouling mechanism is represented by cake filtration model.
In the study, particle size distribution of the MIEX® resin was presented. Such analyses enable to determinate whether presence of fine resin fraction may be the reason for unfavorable membrane blocking during water purification by the hybrid MIEX®DOC – microfiltration/ultrafiltration systems. Granulometric analysis of resin grains using the laser diffraction particle size analyzer (laser granulometer) was carried out as well as the microscopic analysis with scanning electron microscope. The following samples were analyzed: samples of fresh resin (a fresh resin – not used in water treatment processes) and samples of repeatedly used/regenerated resin that were collected to analysis during mixing and after sedimentation process. Particle size distribution was slightly different for fresh resin and for repeatedly used/regenerated resin. The grains sizes of fresh resin reached approximately 60 μm (d10), 120 μm (d50) and 220 μm (d90). Whereas the sizes of repeatedly used/regenerated resin were about 15 μm (d10), 40 μm (d50) and 115-130 μm (d90). The smallest resin grains sizes were in the range of 0.3-0.45 μm. This ensures that the ultrafiltration membranes retain all resin grains, even the smallest ones. Whereas the microfiltration membranes must be appropriately selected to guarantee full separation of the resin grains and at the same time to exclude a membrane pores blocking.
The post-processes coke wastewater treatment was carried out using flat ultrafiltration membranes with a variable polysulfone concentration in membrane solution (15 wt% - 17% wt.) and variable evaporation time of the solvent from the polymer film surface (0s, 2s, 5s). The ultrafiltration process was carried out with the transmembrane pressure of 0.4 MPa and the linear speed of water flow over the surface of the membrane at 2 m / s. For all the membranes transport characteristic of de-ionized water describing the dependence of the volumetric flow on the transmembrane pressure was done. Since none of the ultrafiltration membranes prepared had provided a sufficiently high degree of pollutants removal from wastewater, it was post-treated by RO method. The wastewater treated this way can be used as technical water for coke quenching. The calculations based on the assumptions of the hydraulic model of filtration resistance allowed to predict the efficiency of ultrafiltration membranes used in the process. To that end, for each of the membranes, the following parameters were determined experimentally: the alterations of effluent stream volume over the time of the low-pressure filtration, the total hydraulic resistance and the resistance constituents such as „new” membrane resistance, the resistance generated by polarization layer and the resistance caused by fouling - reversible and irreversible.