Mariola Rajca

Removal of halogenated by-products precursors in photocatalysis process enhanced with membrane filtration

AbstractIn the article, the results of the research on removal of halogenated by-products precursors in a photocatalysis (PC) process enhanced with membrane filtration have been presented. In the research, the following by-products were analyzed as follows: trihalomethanes (trichloromethane, bromodichloromethane, dibromochloromethane, tribromomethane), haloacetic acids (monochloroacetic acid, monobromoacetic acid, dichloroacetic acid, bromochloroacetic acid, dibromoacetic acid, trichloroacetic acid), haloacetonitriles (bromochloroacetonitrile, dibromoacetonitrile, dichloroacetonitrile, trichloroacetonitrile), haloketones (1,1-dichloro-2-propanone, 1,1,1-trichloro-2-propanone), chloropicrin, and chloral hydrate. The analyses were conducted on the model solutions of humic and fulvic acids and also on the samples of surface water taken from the Goczalkowice Reservoir. These water samples were treated in a sequence of PC and membrane filtration. The PC process was conducted using TiO2 and low-pressure monochr...

Photocatalytic oxidation of natural organic matter enhanced with microfiltration and nanofiltration

In the article, the results of the study on the effectiveness of removal of natural organic matter from simulated water containing fulvic (FA) and humic (HA) acids as well as natural water contaminated with a mixture of organic compounds are presented. The treatment process comprises a photocatalytic microfiltration reactor (PhMFR), the operation of which was supported with nanofiltration (NF). The photocatalysis process was performed with the use of TiO2 P25 catalyst and immersed UV low-pressure lamps. Microfiltration was carried out with the use of a capillary membrane module—MICROZA, while NF with a flat-sheet composite membrane. It was found that such a configuration of the water treatment process, which resulted in a highly effective removal of natural organic compounds, could be successfully applied in practice.

Nanofiltration renovation of mineral water

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.