Wastewater nanofiltration

With a growing scarcity of freshwater available for irrigation, other sources of lower quality like brackish water, saline water, and treated wastewater become more important as additional or substituting inputs for the agricultural sector. At the same time, it is clear that a sophisticated treatment like desalination or nanofiltration under current conditions is still far too expensive to be a major solution to future irrigation water needs. Hence adaptation of farming and irrigation practices to the particular water qualities constitutes a more viable approach. 

Pazdzior K, Klepacz-Smolka A, Ledakowicz S, Sojka-Ledakowicz J, Mrozinska Z, Zylla R (2009) Integration of nanofiltration and biological degradation of textile wastewater containing azo dye. Chemosphere 75 250-255... 

Filtration, 11 321-397 75 824—825. See also Filter cycles Filter performance Filters Microfiltration Nanofiltration membranes Ultrafiltration as advanced wastewater treatment, 25 908-909... 

In the recent years, many researchers have devoted attention to the development of membrane science and technology. Different important types of membranes, such as these for nanofiltration, ultrafiltration, microfiltration, separation of gases and inorganic membranes, facilitated or liquid membranes, catalytic and conducting membranes, and their applications and processes, such as wastewater purification and bio-processing have been developed [303], In fact, almost 40 % of the sales from membrane production market are for purifying wastewaters. 

Beier S, Koster S, Veltmann K, Schroder HFr, Pinnekamp J (2010) Treatment of hospital wastewater effluent by nanofiltration and reverse osmosis. Water Sci Technol 61 1691-1698... 

WHEY DEMINERALIZATION USING AN IE OR ED UNIT WITH AN OVERALL CAPACITY OF 45 m3/DAY OF NANOFILTRATED WHEY COMPARISON OF WASTEWATER FORMATION AND... 

Ivnitsky, H., Katz, I., Minz, D., Shimoni, E., Chen, Y Tarchitzky, J., Semiat, R. and Dosoretz, C.G. (2005) Characterization of membrane biofouling in nanofiltration processes of wastewater treatment. Desalination, 185, 255—268. 

Microfiltration, ultrafiltration, and nanofiltration are becoming standard in feed pretreatment for water desalination, wastewater treatment and fruit-juice concentration. 

Another already mentioned application of membrane filtration is for the recovery of ionic liquids from wastewaters. Here the challenge is to find appropriate membranes, since rejection values that have been reported to date [136] are too low for industrial application. However, for similar ionic liquids we found a membrane that shows rejection rates above 99% throughout at considerably high permeate flow rates above 50 L m 2 h 1 in cross flow filtration. Such numbers make washing in combination with nanofiltration an interesting option. 

It should be stated here that on a technical scale washing requires a concept for water reuse and recovery of ionic liquid from the wastewater. As already discussed, nanofiltration is likely be a successful approach for the recovery task. 

Before discharge of the wastewater dissolved amounts of ionic liquid need to be recovered for environmental and economical reasons, e.g. by nanofiltration. 

Hoffman D. (1993) Use of Potassium and Nanofiltration Plants for Reducing the Salinity of Urban Wastewater. Adam Technical and Economic Services, Agriculture Ministry of Israel, Water Department 084/91. 

Membrane technology may become essential if zero-discharge mills become a requirement or legislation on water use becomes very restrictive. The type of membrane fractionation required varies according to the use that is to be made of the treated water. This issue is addressed in Chapter 35, which describes the apphcation of membrane processes in the pulp and paper industry for treatment of the effluent generated. Chapter 36 focuses on the apphcation of membrane bioreactors in wastewater treatment. Chapter 37 describes the apphcations of hollow fiber contactors in membrane-assisted solvent extraction for the recovery of metallic pollutants. The apphcations of membrane contactors in the treatment of gaseous waste streams are presented in Chapter 38. Chapter 39 deals with an important development in the strip dispersion technique for actinide recovery/metal separation. Chapter 40 focuses on electrically enhanced membrane separation and catalysis. Chapter 41 contains important case studies on the treatment of effluent in the leather industry. The case studies cover the work carried out at pilot plant level with membrane bioreactors and reverse osmosis. Development in nanofiltration and a case study on the recovery of impurity-free sodium thiocyanate in the acrylic industry are described in Chapter 42. 

Hwang, Eui-Deog et al.. Effect of precipitation and complexation on nanofiltration of strontium-containing nuclear wastewater. Desalination, 147, 289, 2002. 

Tang, A. and Chen, V., Nanofiltration of textile wastewater for water reuse. Desalination, 143, 11, 2002. 

Membrane processes are widely used in oil water separation. In general, a membrane is classified into two groups pressure-driven membrane and electrical membrane, known as electrodialysis. The most applicable process for oily wastewater removal is the former type. The pressure-driven membrane applications include microfiltration (MF), ultrafil-tration (UF), nanofiltration (NF), and reverse osmosis (RO). All of them are categorized by the molecular weight or particle size cut-off of the membrane as shown in Table 5. 

Conventional methods for treating wastewater containing dyes, aromatic compounds, or heavy metals are coagulation, flocculation, reverse osmosis, nanofiltration and pervaporation (Paul and Ohlrogge, 1998), and activated carbon adsorption, the latter of which is combined with membrane processes like nanofiltration (Eilers and Melin, 1999) or ultrafiltra-tion (Lenggenhager and Lyndon, 1997). 

Membrane technology used in water reclamation includes five major membrane types reverse osmosis, nanofiltration, ultrafiltration, microfiltration, and liquid membranes. These five types of membranes are discussed briefly, and examples of their applications in municipal and industrial wastewater reclamation is also described. 

Membrane-based pretreatment, before reverse osmosis (RO), employing poly electrolytes, is used on wastewater, brackish water, and sea water plants [109-114]. It includes ultrafiltration or nanofiltration membrane units with feed pressure from 1-1.5 to 2.5-4 MPa. RO units need much higher feed pressure, 6-8 up to 10 MPa. It makes the RO technology economically expensive. Decreasing the high feed pressure in RO plants is the main direction for designers efforts. 

The introduction of nanofiltration under pressure has led to a reduction in the organic content of the wastewater of up to 95 %, so that the filtrate has a COD of only... 

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