The aim of this study was to investigate the usefulness of a membrane hybrid process for the treatment of real textile wastewater (TWW) and its potential reuse in the dyeing of cotton knitted fabric ...(DCF) process. To determine a suitable pretreatment, sand filtration, coagulation, and UF hollow fiber (UF–HF) were compared on a laboratory scale in terms of turbidity, color, and total organic carbon (TOC). Here, UF-HF provided the best removal results of 93.6%, 99.0%, and 29.0%, respectively. The second stage involves the study of UF flat sheet membranes (5, 10, 20, and 50 kDa). The 5 kDa membrane provided the best permeate quality according to the chemical oxygen demand (COD), turbidity, TOC, conductivity, and color by 54.5%, 83.9%, 94.2%, and 45.7–83.3%, respectively. The final step was treatment with nanofiltration (NF) and reverse osmosis (RO) and these effluents were reused for dyeing. Finally, the effluents from UF-HF/5 kDa UF/RO (Scenario 1) and UF-HF/5 kDa UF/NF (Scenario 2) were analyzed for turbidity, COD, TOC, biological oxygen demand, conductivity, hardness, anions and cations, and color. Both scenarios provided high removal results of 76.3–83.5%, 94.6–97.7%, 88.5–99%, 95.4–98.0%, 59.2–99.0%, 88.7–98.7%, 60.7–99.1%, and 80.0–100%, respectively. They also satisfied the DCF tests compared to the standard DCF samples. The innovative aspect of this research is as follows: 1) the complete analysis of hybrid membrane separation processes for the purpose of reuse of treated textile wastewater and 2) the proposal of a new criterion for reuse for DCF.
Display omitted
•Usefulness of hybrid membrane process for reuse in textile dyeing was established.•ZW-1/5 kDa UF/NF–RO showed removal efficiencies of monitored parameters of 59–100%.•High color fastness of dyed textile with ZW-1/5 kDa UF/NF permeate was achieved.•New reuse criteria for dyeing cotton knitted fabric were proposed.•Treatment ZW-1/5 kDa UF/NF shows the better economic efficiency of 395.656,00 €.
The textile industry is a massive consumer and polluter of our fresh water. This paper focuses on wastewater produced by the textile industry with the aim of treating and reusing it for certain wet ...processes in the textile industry, i.e., washing dyed knitted cotton fabric. Accordingly, UF membranes (GH, GK, PT, PU, PW, MW) with different molecular weight cut-offs (MWCO) ranging from 2 to 50 kDa were used. Wastewater treatment studies were performed on a lab scale and all samples were subjected to the following tests: chemical oxygen demand (COD), biochemical oxygen demand (BOD5), total bound nitrogen (TNb), turbidity, conductivity, color, and concentration of SO42−, Na+, Ca2+, K+. The permeate flux was also monitored and investigated in the process due to possible fouling and its effect on membrane performances. Based on the conducted tests, results for the membrane with the lowest MWCO (GH), were 79.8% COD, 56.0% BOD5, 82.4% TOC, 81.0% TNb, > 99.3% turbidity, 79.2% conductivity, 93.1% SO42−, 79.3% Na+, 98.6%, Ca2+, and 53.3% K+ removal which is the highest value of all investigated membranes. For this reason, the same permeate was tested for its suitable use in the process of washing dyed knitted cotton fabric. The results showed a high reuse potential of textile wastewater due to the same quality of dyed knitted cotton fabric washed with the UF permeate and with water used in the factory. The innovative aspect of this research is as follows: 1) direct use of UF membranes (without pre- and post-treatments) for the purpose of reusing treated wastewater in the textile industry in processes as yet not investigated and 2) identifying reuse criteria for washing dyed knitted cotton fabric.
Display omitted
•Direct UF treatment was used to treat real textile wastewater.•Washing experiment on dyed knitted fabric with treated wastewater was investigated.•Design criteria and capital costs for direct UF treatment were performed.•Water consumption can be reduced by 80% after UF implementation.•First wastewater reuse criteria for washing dyed knitted fabric was proposed.
Pharmaceuticals are present in various waters and can be almost completely rejected by membrane separation processes, i.e., nanofiltration (NF) and reverse osmosis (RO). Nevertheless, the adsorption ...of pharmaceuticals can decrease their rejection, so adsorption can be considered a very important removal mechanism. In order to increase the lifetime of the membranes, the adsorbed pharmaceuticals must be cleaned from the membrane. The used pharmaceutical (albendazole), the most common anthelmintic for threatening worms, has been shown to adsorb to the membrane (solute-membrane adsorption). In this paper, which is a novelty, commercially available cleaning reagents, NaOH/EDTA solution, and methanol (20%, 50%, and ≥99.6%) were used for pharmaceutical cleaning (desorption) of the NF/RO membranes used. The effectiveness of the cleaning was verified by Fourier-transform infrared spectra of the membranes. Of all the chemical cleaning reagents used, pure methanol was the only cleaning reagent that removed albendazole from the membranes.
The aim of this study was to investigate the best pretreatment of textile wastewater (TWW) for membrane separation processes and the previously unexplored reuse of treated TWW for washing dyeing ...machines. Sand filtration (SF), coagulation, coagulation/flocculation, and ultrafiltration (UF) with hollow fiber membrane (ZW1) were used for pretreatment. Pretreatment selection was based on turbidity, total organic carbon (TOC), and color. SF and ZW1 were found to be the best pretreatments. In addition, the SF and ZW1 effluents were subjected to the 5 (PT) and 50 (MW) kDa UF flat sheet membranes to test removal efficiency. ZW1-PT was better in terms of removal results and fouling. To reduce the use of drinking water for washing dyeing machines, the characteristics of ZW1-PT effluent were compared with drinking water from a textile factory. TWW treated with this hybrid process fulfils the purpose of reuse for washing dyeing machines and can be used in Galeb d.d., Croatia, or in any other textile factory, saving up to 26,000 m
of drinking water per year. This contributes to both sustainable production and the conservation of water resources.
The influence of textile wastewater (TWW) secondary effluent on ultrafiltration (UF) membrane characteristics was investigated. TWW treated with a membrane bioreactor was subjected to four commercial ...UF membranes (2, 3, 5, and 10 kDa). Both the pristine membranes and the membranes after TWW secondary effluent treatment were characterized. Surface roughness, microscopic analysis of the membrane surface and cross-section, zeta potential, contact angle, membrane composition, and membrane flux were compared. After treatment of secondary effluent, the zeta potential decreased for 5 and 10 kDa membranes, while the contact angle and surface roughness increased for all investigated membranes. In addition, a fouling layer formed on all membranes, and new interactions with pollutants and membranes were confirmed. Membranes with larger pores (5 and 10 kDa) showed a greater decrease in permeate flux during treatment. Detailed analysis showed variations in membrane characteristics after TWW secondary effluent treatment, indicating the stability of the membranes used.
Otpadne vode tekstilne industrije pripadaju kategoriji najjače onečišćenih industrijskih otpadnih voda te su posebna opasnost za vodeni okoliš. Cilj ovog istraživanja bio je ispitati membransku ...učinkovitost zadržavanja bojila iz tekstilne otpadne vode (TOV) s komercijalnim ultrafiltracijskim (UF) membranama (GH, GK, PT, PU, PW, MW) širokog područja graničnih molekulskih masa (MWCO), od 2 do 50 kDa. Testirane UF membrane rezultirale su smanjenjem obojenja i intenziteta obojenja od 56,35 % do 97,93 %. Membrane nižih MWCO vrijednosti (ispod 3 kDa) mogu se smatrati prikladnim za uklanjanje bojila iz realnog uzorka TOV-a.
Wastewater from the textile industry belongs to the category of the most polluted industrial wastewaters and poses a special danger to the aquatic environment. The aim of this study was to examine the membrane retention efficiency of textile wastewater (TOV) with commercial ultrafiltration (UF) membranes (GH, GK, PT, PU, PW, MW) with a wide range of molecular weight cut-off (MWCO), 2–50 kDa. The tested UF membranes resulted in a reduction in colour and colour intensity from 56.35 % to 97.93 %. Membrane of lower MWCO values (below 3 kDa) may be suitable for removing dyes from the real TOV sample.
The acquisition of negation in the second language has been investigated in numerous studies (Cancino et al., 1975; Meisel, 1997;Fuentes, 2008), however, there are no systematic studies of the ...acquisition of the English negation by speakers of the Croatian language. The aim of this paper is to gain a better insight into the types and frequency of errors in a relatively free production of negation in English as a second language. The analysis is based on the hypotheses that errors in sentences where the so called dummy do has to be inserted in the negative sentence, omissions of auxiliary verbs, and double marking errors are expected. The analysis is based on a questionnaire consisting of one task of positive to negative sentence transformations. The answers were grouped according to the error type. Errors classified as “other” were the most frequent (37 %), followed by double marking and congruency errors (14 %), omissions (12 %), and additions (9 %). The results corroborate the frequency hypothesis of errors in sentences where the so called dummy do had to be inserted in the negative sentence, which may be attributed to negative interference from Croatian as the first language.
Iako je ovladavanje negacijom u inome jeziku temom brojnih istraživanja (Cancino i dr., 1975, Meisel, 1997, Fuentes, 2008), sustavne analize o tome kako govornici hrvatskoga jezika ovladavaju ...negacijom u engleskome jeziku izostaju. Stoga je cilj rada dobiti bolji uvid u vrstu i učestalost odstupanja pri relativno slobodnoj produkciji negacije u engleskome kao inome jeziku. Istraživanje se temeljilo na pretpostavkama da će najučestalija odstupanja biti kada je pri tvorbi rečenične negacije nužno dodavanje pomoćnoga glagola do (do staviti u kurziv), zatim izostavljanje pomoćnoga glagola kao i dvostruko označavanje. Istraživanje se temelji na upitniku sa zadatkom preoblike potvrdnih rečenica u niječne. Odgovori su zatim svrstani u skupine sukladno vrsti odstupanja. Pokazalo se da se najučestalija odstupanja mogu svrstati u kategoriju ostala odstupanja (37 %), slijede dvostruko obilježavanje i sročnost (14 %), ispuštanje (12 %) te dodavanje (9 %). Rezultati potvrđuju pretpostavku o učestalosti odstupanja u rečenicama u kojima je bilo nužno dodati pomoćni glagol do pri tvorbi negacije, što je moguće tumačiti nepovoljnim prijenosom iz materinskoga hrvatskog jezika.
Komunalna otpadna voda obrađena je hibridnim procesom koji se sastojao od membranskog bioreaktora (MBR), nanofiltracije (NF) i reverzne osmoze (RO) te je procijenjena primjena RO/NF permeata za ...navodnjavanje poljoprivrednih površina. Električna provodnost, mutnoća, koncentracija suspendiranih čestica i kemijska potrošnja kisika smanjeni su s MBR-om za prosječno 19,1 %, 99,8 %, 100,0 % i 96,7 %. Dodatnom obradom MBR permeata s RO/NF membranama sniženi su svi parametri gdje je reverzno osmotska XLE membrana pokazala najveće smanjenje praćenih parametara, a nanofiltracijska NF270 najmanje. RO/NF permeati zadovoljavaju upute Svjetske zdravstvene organizacije uz prilagodbu
električne provodnosti i natrijevog adsorpcijskog indeksa dodavanjem kalcijevih soli ili miješanjem MBR efluenta s permeatom NF270 membrane u omjeru 50:50. Prema uputama Europske unije RO/NF permeati spadaju u Klasu A kvalitete oporabljene vode.
PDF
