Efficiency evaluation of textile basic dye removal from water by nanofiltration
Industrialization and urbanization have resulted in rapid deterioration of water quality. The scientific evidences prove that the effluents released from different industries e.g. textile, leather, paint etc. comprise of different hazardous and toxic compounds, some of which are known carcinogens and others probable carcinogens. The emergence of industrial centers without a corresponding growth in civic amenities and pollution control mechanisms results in a gradual decay of water quality. Textile industries, particularly those involved in finishing processes are major water consumers and the source of considerable pollution. The environmental challenge for the textile industry is associated with liquid waste, which tends to dominate over air emissions and solid wastes in terms of the severity of environmental impacts. A typical textile unit generates various types of wastewater differing in magnitude and quality. The wastewater from printing and dyeing units in a textile plant are often rich in color, containing residual of reactive dyes and chemicals, and needs proper treatment before releasing into the environment. The membrane process that can meet the necessary standards is nanofiltration, because nanofiltration membranes can retain ions as well as relatively small organic molecules from an aqueous solution (Rautenbach and Gröschl, 1990; Van der Bruggen et al., 1999). However, it is not well understood what mechanisms of retention and flux decline are involved in this process and it is generally accepted that membrane technology offers solutions for the wastewater problem in the textile industry, with the possibility of water recycling (Ciardelli et al., 2001; Vedavyasan, 2000). Nanofiltration (NF), in particular, is often suggested as a good candidate (Sungpet et al., 2004; Marcucci et al., 2001) and has been tested in a pilot scale (Marcucci et al., 2002; Koyuncu et al., 2001).