Reuse of textile wastewater for dyeing cotton knitted fabric with hybrid treatment: Coagulation/sand filtration/UF/NF-RO.

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.

Effect of water matrices on removal of veterinary pharmaceuticals by nanofiltration and reverse osmosis membranes.

This study explored the removal of five veterinary pharmaceuticals (VPs) (sulfamethoxazole (SMETOX), trimethoprim (TMP), ciprofloxacin (CIPRO), dexamethasone (DEXA) and febantel (FEBA)) from different water matrices (Milli-Q water, model water, tap water and real pharmaceutical wastewater using four types of nanofiltration (NF) membranes (NF90, NF270, NF and HL) and two reverse osmosis (RO) membranes (LFC-1 and XLE). All VPs were added to different water matrices at a concentration of 10 mg/L. Rejections of VPs and water flux were measured. The rejection increased with increase of molecular weight. The highest rejections were obtained with RO membranes (LFC-1, XLE) and tight NF (NF90) membrane. In general, the rejection of VPs was higher in model water and tap water than in Milli-Q water, but the water flux was lower. This was mainly explained by ion adsorption inside the membranes pores. Narrower pore size counteracted the effect of presence of low concentration of natural organic matter (NOM) in tap water. The NOM was assumed to enhance the adsorption of VPs onto membrane surface, increased the size exclusion and electrostatic repulsion also appeared during the transport. Investigated water matrices had influence on water flux decline due to their complexity.

Optimization of coagulation with ferric chloride as a pretreatment for fouling reduction during nanofiltration of rendering plant secondary effluent.

The treatment and reuse of rendering plant wastewater with membrane processes is a poorly investigated area that could result in substantial water savings. Membrane fouling is still the main obstacle when treating secondary effluents (SEs) with high content of effluent organic matter (EfOM). Thus, the optimization of coagulation with ferric(III) chloride (FeCl3) as a pretreatment for nanofiltration was performed to reduce membrane fouling and achieve higher permeate quality. Coagulation was modeled (total carbon, inorganic carbon, dissolved organic carbon (DOC), turbidity, conductivity, and resulting pH) and optimized with response surface methodology (RSM) to remove DOC and turbidity with a pH close to neutral. The effluent after coagulation at optimal conditions (5.58 pH and 26.38 mg L-1 of Fe3+) and sand filtration (SF) was subjected to nanofiltration (NF270, NF, and NF90 membranes). The fouling was compared to evaluate the efficiency of each pretreatment. Coagulation with FeCl3 reduced the flux decline of nanofiltration membranes 4.2 to 19.3 times while SF barely reduced the fouling. Coagulation increased the flux recovery and chemical cleanliness after the membrane washing. In addition to fouling reduction, higher permeate quality was achieved.

Removal of emerging contaminants from municipal wastewater with an integrated membrane system, MBR-RO.

The presence of emerging contaminants in the aquatic environment and their potential effects on living organisms has become an issue of growing concern. Among emerging contaminants, pharmaceuticals may enter the aquatic environment due to their high consumption and their incomplete removal in conventional municipal wastewater treatment plants (WWTPs). The main goal of this study was the assessment of the removal efficiency of pharmaceuticals found in municipal wastewater of a coastal WWTP (Castell-Platja d'Aro, Spain) using an integrated pilot scale membrane system (MBR-RO). Twenty multiple-class pharmaceuticals (including psychiatric drugs, macrolide antibiotics, ß-blockers, sulfonamide and fluoroquinolone antibiotics, histamine H2 receptor antagonists, anti-inflammatories, nitroimidazole, ß-agonist and antiplatelet agent) were measured in real influent with the lowest average concentration for psychiatric drugs (0.017 µg L(-1)) to the highest for macrolide antibiotics (2.02 µg L(-1)). Although some contaminants were in relatively high concentrations (even up to 2.90 µg L(-1) in the case of ofloxacin). The combination of MBR and RO treatment showed excellent overall removal of target emerging contaminants with removal rates above 99% for all of them. For some compounds (metronidazole, hydrocodone, codein, ranitidine) MBR provided high removal efficiency (up to 95%). Additionally RO membrane showed removal rates always higher than 99%.