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Biomimetic membranes for forward osmosis application in industrial wastewater treatment
Jasmina Korenak, 2018, doctoral dissertation

Abstract: The problem of wastewater is increasing as we face tighter regulations in limiting parameters for discharge into sewers or surface waters. At the same time, the challenge is also how to upgrade existing technology and identify new appropriate technologies for purification of industrial wastewater for re-use. The optimal solution, which can give the appropriate quality of purified water at acceptable operating costs also is not straightforward. However, increasing environmental legislative demands combined with increased fresh water consumption can facilitate implementation of emerging technologies which at the current state are not fully mature. Forward Osmosis (FO) is one such recent achievement which is considered as a promising membrane process and potentially a sustainable alternative to reverse osmosis (RO) process for wastewater reclamation and sea/brackish water desalination. However, there are many limiting parameters (e.g. membrane fouling, draw solutions) in FO process that needs to be studied and improved. To reduce the membrane fouling in FO, many improvements were attempted, e.g. synthesis of different membrane materials, fabrication of membrane modules, membrane coating etc. One of the novelties in membrane development research field is biomimetic membranes incorporate in separation processes. They employ natural proteins known as AQPs (aqpourins) to regulate the flow of water, providing increased permeability and near-perfect solute rejection. Membrane surface characteristics were measured on virgin, used and cleane membrane in order to confirm the resistance to different types of industrial wastewater and sewage.
Keywords: biomimetic membrane, forward osmosis, industrial wastewater, reverse osmosis, textile wastewater, ultrafiltration, wastewater reuse
Published: 25.07.2018; Views: 1005; Downloads: 78
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Forward osmosis in wastewater treatment processes
Jasmina Korenak, Subhankar Basu, Malini Balakrishnan, Claus Hélix-Nielsen, Irena Petrinić, 2017, original scientific article

Abstract: In recent years, membrane technology has been widely used in wastewater treatment and water purification. Membrane technology is simple to operate and produces very high quality water for human consumption and industrial purposes. One of the promising technologies for water and wastewater treatment is the application of forward osmosis. Essentially, forward osmosis is a process in which water is driven through a semipermeable membrane from a feed solution to a draw solution due to the osmotic pressure gradient across the membrane. The immediate advantage over existing pressure driven membrane technologies is that the forward osmosis process per se eliminates the need for operation with high hydraulic pressure and forward osmosis has low fouling tendency. Hence, it provides an opportunity for saving energy and membrane replacement cost. However, there are many limitations that still need to be addressed. Here we briefly review some of the applications within water purification and new developments in forward osmosis membrane fabrication.
Keywords: wastewater treatment, biomimetic membranes, desalination, draw solutions, forward osmosis
Published: 18.08.2017; Views: 721; Downloads: 304
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Multivariate analysis and chemometric characterisation of textile wastewater streams
Darja Kavšek, Tina Jerič, Alenka Majcen Le Marechal, Simona Vajnhandl, Adriána Bednárová, Darinka Brodnjak-Vončina, 2013, original scientific article

Abstract: The aim of this work was to design a quick and reliable method for the evaluation and classification of wastewater streams into treatable and non-treatable effluents for reuse/recycling. Different chemometric methods were used for this purpose handling the enormous amount of data, and additionally to find any hidden information, which would increase our knowledge and improve the classification. The data obtained from the processes description, together with the analytical results of measured parameters' characterising the wastewater of a particular process, enabled us to build a fast-decision model for separating different textile wastewater outlets. Altogether 49 wastewater samples from the textile finishing company were analysed, and 19 different physical chemical measurements were performed for each of them. The resulting classification model was aimed at an automated decision about the choice of treatment technologies or a prediction about the reusability of wastewaters within any textile finishing or other company having similar characteristics of wastewater streams.
Keywords: textile finishing wastewater, chemometrics, multivariate data analysis, wastewater treatment
Published: 10.07.2015; Views: 1244; Downloads: 40
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The applicability of an advanced oxidation process for textile finishing wastestreams & fate of persistent organic pollutants
Julija Volmajer Valh, Alenka Majcen Le Marechal, Boštjan Križanec, Simona Vajnhandl, 2012, original scientific article

Abstract: The trend of sustainable use of available water resources encourages textile finishing enterprises to implement efficient wastewater treatment technologies that enable water recycling, and not just itćs discharging into the local wastewater treatment plants (WWTP). This paper presents the results obtained from the H2O2/UV treatment of wastewater from Slovene textile finishing company. Laboratory scale decolouration experiments were performed on the most representative wastewater samples, collected in three months period. In general 80 % decolouration and 86 % total organic carbon (TOC) reduction was achieved. On the other hand, the use of ultraviolet (UV) radiation to degrade and destroy organic pollutants in textile wastewater could lead to the formation of toxic dioxins and dioxin-like compounds, groups of persistent organic pollutants, especially due to the presence of halogenated compounds in textile finishing processes. For these reasons, textile wastewater samples were analysed for any content of dioxins before and after the treatment with H2O2/UV.
Keywords: tekstilne odpadne vode, napredni oksidacijski procesi, H2O2/UV, dioksini, textile wastewater, advanced oxidation processes, H2O2/UV, ecological parameters, dioxins
Published: 10.07.2015; Views: 1098; Downloads: 35
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The removal of reactive dye printing compounds using nanofiltration
Irena Petrinić, Niels Peder Raj Andersen, Sonja Šostar-Turk, Alenka Majcen Le Marechal, 2007, original scientific article

Abstract: A synthetically prepared reactive dye print wastewater, mimicking real wastewater obtained from a local textile mill, was treated by nanofiltration using an NFT-50 membrane in a plate and frame module configuration at different cross-flow velocities (0.4, 0.6 and 0.8 m/s) and pressures (2-15 bar). The nanofiltration membrane was evaluated for membrane fouling, permeate flux and its suitability for removing colour, conductivity, Na+ ions and COD as a function of operating pressure and feed concentration. The permeate separation efficiency was monitored by measuring the removal efficiency of colour, conductivity, Na+ ions and COD retention. The membrane achieved high dye retention for each of the four dyes (from 99.4 to 99.9%) and electrolytes used (63-73%). The retention of organic substances varied between 20 and 50%, depending on the pressure used; higher retentions were achieved at higher pressure and by using higher cross-flow velocities.
Keywords: nanofiltration, nanofitration membranes, wastewater after reactive printing, reactive dye, concentration polarization
Published: 01.06.2012; Views: 1376; Downloads: 77
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Uncertainty of nitrate and sulphate measured by ion chromatography in wastewater samples
Brigita Tepuš, Marjana Simonič, 2007, original scientific article

Abstract: This paper presents an evaluation of measurement uncertainty regarding the results of anion (nitrate and sulphate) concentrations in wastewater. Anions were determined by ion chromatography (EN ISO 10304-2, 1996). The major sources of uncertainty regarding the measurement results were identified as contributions to linear least-square or weighted regression lines, precision, trueness, storage conditions, and sampling. Determination of anions in wastewater is very important for the purification procedure, especially the amount of nitrate in waste and potable waters. The determined expanded uncertainty was 6% for nitrate anions and 8.3% for sulphate anions. The difference between measurement uncertainties determined by the two methods, the weighted and linear least-square methods is negligible.
Keywords: wastewater, nitrates, sulphates, measurements, measuring uncertainty
Published: 01.06.2012; Views: 1404; Downloads: 291
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Residual dyebath purification using a system of constructed wetland
Alenka Ojstršek, Darinka Fakin, Danijel Vrhovšek, 2007, original scientific article

Abstract: A constructed wetland model, comprising two different substrate mixtures, was used to purify textile dyebath wastewater. Three laboratory prepared wastewaters containing three commercial dyes of different classes and chemicalconstitution (one vat and two reactive dyes), different chemicals (NaOH, NaCl) and auxiliaries (migration inhibitor, sequestering, defoaming andwetting agents) were employed. Purifying efficiency was verified by measuring pollution parameters, such as absorbance, pH, total organic carbon (TOC), chemical oxygen demand (COD) and electrical conductivity (EC). It was found that the constructed wetland model reduced dye concentration by up to 70%, lowered the TOC and COD values up to 88%, electrical conductivity up to 60% and pH from 12 to 7.6.
Keywords: textile dyeing, reactive dyes, vat dyes, wastewater treatment, constructed wetland model, biological treatment, purification
Published: 01.06.2012; Views: 1508; Downloads: 74
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Case study of the sonochemical decolouration of textile azo dye Reactive Black 5
Simona Vajnhandl, Alenka Majcen Le Marechal, 2007, original scientific article

Abstract: The decolouration and mineralization of reactive dye C.I. Reactive Black 5, a well-known representative of non-biodegradable azo dyes, by means of ultrasonic irradiation at 20, 279 and 817 kHz has been investigated with emphasis on the effect of various parameters on decolouration and degradation efficiency. Characterization of the used ultrasound systems was performed using calorimetric measurements and oxidative species monitoring using Fricke and iodine dosimeter. Experiments were carried out with low frequency probe type, and a high-frequency plate type transducer at 50, 100 and 150 W of acoustic power and within the 5-300 mgžL initial dye concentration range. Decolouration, as well as radical production, increased with increasing frequency, acoustic power, and irradiation time. Any increase in initial dye concentration results in decreased decolouration rates. Sonochemical decolouration was substantially depressed by the addition of 2-methyl-2-propanol as a radical scavenger, which suggests radical-induced reactions in the solution. Acute toxicity to marine bacteria Vibrio fischeri was tested before and after ultrasound irradiation. Under the conditions employed in this study, no toxic compounds were detected after 6 h of irradiation. Mineralization of the dye was followed by TOC measurements. Relatively low degradation efficiency (50% after 6 h of treatment) indicates that ultrasound is rather inefficient in overall degradation, when used alone.
Keywords: textile industry, wastewater treatment, textile dyeing, reactive dyes, azo dyes, decoloration, ultrasound, degradation, decoloration kinetics, oxidizing species
Published: 01.06.2012; Views: 1548; Downloads: 73
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The use of constructed wetland for dye-rich textile wastewater treatment
Tjaša Griessler Bulc, Alenka Ojstršek, 2008, original scientific article

Abstract: The objective of the present paper was to examine the treatment efficiency of constructed wetlands (CW) for the dye-rich textile wastewater with special focus on colour reduction. Preliminary, a series of dynamic experiments were performed in the CW model packed with gravel, sand, and zeolitic tuff on three synthetically-prepared wastewaters using chemically differ dyestuffs, auxiliaries and chemicals, in order to investigate the potential of low-cost materials as media for textile dye-bath wastewater treatment. The obtained results evidence that applied CW model reduces colour by up to 70%, and COD and TOC by up to 45%. Based on these results, the pilot CW with vertical (VF) and horizontal flow (HF) was constructed near textile factory mainly for cotton and cotton/PES processing with intention to treat real textile wastewater in-situ. It was designed for 1 m3/d, covering 80 m2, packed with sand and gravel, and planted with Phragmites australis. The average treatment efficiency of the CW for the selected pollution parameters were: COD 84%, BOD5 66%, TOC 89%, Ntotal 52%, Norganic 87%, NH4-N -331%, sulphate 88%, anion surfactant 80%, total suspended solids (TSS) 93%, and colour 90%, respectively. The results unequivocally proved that the CW could offer an optimal solution to meet the environmental legislation as well as requirements for effective and inexpensive textile wastewater treatment.
Keywords: coloured textile wastewater, constructed wetland, Phragmites australis
Published: 01.06.2012; Views: 1227; Downloads: 72
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Implementing sustainable laundering procedures for textiles in a commercial laundry and thus decreasing wastewater burden
Sabina Fijan, Rebeka Fijan, Sonja Šostar-Turk, 2008, original scientific article

Abstract: This paper presents a research on how to optimize a laundering program to reduce wastewater burden thus achieving a more sustainable laundering procedure. A green surgical textiles program was investigated and the first step of optimization was performed based on the results of measuring certain parameters in the water taken from individual chambers. The wastewater parameters were reduced after optimization of the program although effluent treatment plants for water reuse remain necessary. An experimental laundering procedure with a high dosage of sodium hypochlorite was also conducted in order to observe a correlation between measured values of active chlorine and conductivity. As an approximate correlation was found this could result in thepossibility of incorporating a sensor in the washing machine measuring online the conductivity with the possibility of regulating the dosage of sodium hypochlorite and thus preventing overdosing, which increases the damages of the laundered textiles and the burden of wastewater.
Keywords: laundry wastewater, optimization, textiles, sustainable laundering
Published: 01.06.2012; Views: 1389; Downloads: 77
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