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Abstract

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.
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Abstract

The objective of this study was to determine the suitability of the nanofi ltration (NF) process to recover the regenerating agent (NaOH) from spent solutions contaminated with organic compounds. NaOH recovery from 2 spent regenerant solutions after cleaning ultrafiltration (UF) membranes (polymeric 30 kDa, ceramic 300 kDa) fouled with natural humic water was carried out using 2 types of NF membranes: NP010P (Na2SO4 rejection: 35–75%) and NP030P (Na2SO4 rejection: 80–95%). It has been shown that the use of the NP030P membrane allows for very high separation effi ciency of organic compounds (up to 97% of color intensity reduction) from the tested solutions. It was also observed that the effectiveness of the process, in addition to the type of membrane used, also depends on the time of NF process – along with the elapsed time of the process, the hydraulic and separation properties of the tested membranes deteriorated. The obtained results showed that the use of both tested NF membranes allows for the recovery of NaOH to a degree that allows its re-use.
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Abstract

The paper describes the effectiveness of mycoestrogen removal in an integrated ozonation - nanofiltration system for water treatment. The results were compared to those obtained for ozonation and nanofiltration carried out as single processes. It has been found that the effectiveness of mycoestrogen removal in the integrated system was higher than that observed for single ozonation. During ozonation, the removal of micropollutants was affected by the dose of an oxidizing agent and type of treated water. As far as nanofiltration is concerned, its effectiveness both in the integrated system and as a single process was similar. Nevertheless, it is advisable to precede nanofiltration with ozonation because of membrane efficiency.
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Abstract

There is often a need to improve the taste of mineral water by reducing the sulphate ion content. It was found that for such an effect, nanofiltration (NF) process can be used. In the case, the proposed formula was assumed obtaining a mineral water with reduction of H2S and SO42- content through the following processes: stripping - UF/MF or rapid fi ltration - nanofiltration - mixing with raw water or filtration through calcium bed. The paper shows the results of the tests, with use of mineral waters and nanofiltration. Commercial nanofiltration membranes NF-270 Dow Filmtec and NF-DK GE Infrastructure Water&Process Technologies were applied. NF was carried out for mixed water from both water intakes (1 and 2), recovery of 50%, at transmembrane pressure of 0.8-1.2 MPa in the dead-end fi ltration mode. In addition, the permeate obtained in NF was filtered through a column fi lled with 1.0-3.0 mm limestone rock, in order to improve the composition of mineral water. The tested mineral water is the sulphate-chloride-sodium-calcium-magnesium in nature and contains 991 mg/L of SO42- and 2398 mg/L of TDS, while the permeate after NF showed the chloride - sodium hydrogeochemical type (TDS: 780-1470 mg/L, sulfate 10-202.7 mg/L, calcium 23-39.7 mg/L, magnesium 11-28 mg/L). As a result of water treatment in the NF process, high reduction of SO42- ions was obtained (79-98.7%), while the TDS was reduced in 51-64%. Because the process of NF allows for relatively high reduction of bivalent ions, a significant reduction in calcium ion content (84-88%) and magnesium (84-89%) has been also obtained. Monovalent ions were reduced to a lesser extent, i.e. sodium in 46% and bicarbonates in 39-64.1%. Despite obtaining the positive effect of the sulphate ions content reduction, the NF process significantly changed the mineralogy composition of water. The permeate filtration (DK-NF membrane) on the CaCO3 deposit led to a correction of the hydrogeochemical type of water from chloridesodium to chloride-bicarbonate-sodium. The concentration of calcium ions was increased by 60.5% and was 28.2 mg/L, and bicarbonate ions by 7.78% (increased to 195 mg/L). Based on a morphological assessment of the deposits in the SEM image and their chemical composition, the presence of gypsum crystals was detected on the surface of the NF-270 membrane. The deposits formed on the NF-DK membrane were of a completely different character as aggregations of iron and aluminium oxides/hydroxides were found. Such significant mineralogical differences between the secondary deposits crystallising on the surface of the membranes point to the impact of several factors, including membrane characteristics, concentration polarisation, mass transport mechanisms, etc.
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Abstract

A number of inorganic compounds, including anions such as nitrate(V), chlorate(VII), bromate (V), arsenate(III) and (V), borate and fluoride as well as metals forming anions under certain conditions, have been found in potentially harmful concentrations in numerous water sources. The maximum allowed levels of these compounds in drinking water set by the WHO and a number of countries are very low (in the range of µg/l to a few mg/l), thus the majority of them can be referred to as charged micropollutants. Several common treatment technologies which are nowadays used for removal of inorganic contaminants from natural water supplies, represent serious exploitation problems. Membrane processes such as reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF) and microfiltration (MF) in hybrid systems, Donnan dialysis (DD) and electrodialysis (ED) as well as membrane bioreactors (MBR), if properly selected, offer the advantage of producing high quality drinking water without inorganic anions. I
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