Dielectric Measurements Of Fouling Of Nanofiltration Membranes By Sparingly Soluble Salts

 Introduction Industrial wastewater treatment, such as those used for tannery wastewater, is complex due to the variety of chemicals added at different stages of processing of hides and skins. Major problems in tanneries are due to wastewater containing heavy metals, toxic chemicals, chloride, lime with high dissolved and suspended salts and other pollutants (Uberoi, 2003). The tanning process and the effluents generated have already been reported in literature (Wiegant et al., 1999, Sreeram and Ramasami, 2003, Stoop, 2003). Many conventional processes were carried out to treat wastewater such as biological process (Ahn et al., 1996, Vijayaraghavan and Murthy, 1997, Wiemann et al., 1998, Di Iaconi et al., 2003, Farabegoli et al., 2004), oxidation process (Sekaran et al., 1996, Dogruel et al., 2004, Sacco et al., 2012, de Caprariis et al., 2012) and chemical process (Di Iaconi et al., 2001, Orhon et al., 1998, Song et al., 2004) etc. Among these, physical and chemical methods are considered very expensive in terms of energy and reagents consumption (Churchley, 1994, Stern et al., 2003), and generation of excessive sludge (Chu, 2001). To reduce the production of sludge by the treatment of this wastewater combined or alternative systems must be explored. In particular, in this work, two spiral wound membrane modules were used: nanofiltration (NF) and reverse osmosis (RO). The goal of this approach is to insert membranes into the cycle of wastewater treatment in order to remove the entire chain of biological treatment and the resulting post physico[1]chemical residue with a significant reduction of sludge up to 95%. A modified version of the traditional method used to measure critical fluxes of membranes, that is the pressure cycling method, was applied to measure both the critical and the threshold flux on the nanofiltration membrane in order to optimize the operating conditions. Once obtained the critical and threshold flux values, this data was used as input for a batch membrane process optimization method developed previously by Stoller at al. (Stoller and Chianese, 2006, Stoller and Bravi, 2010, Stoller, 2009, Iaquinta et al., 2009, Stoller, 2008, Stoller, 2011). The output of the method indicates the optimal permeate feed flow rate which should be used during the batch in order to inhibit membrane fouling. Finally, the obtained results were compared from an economical point of view with a conventional biological process to validate the membrane plant as possible alternative to conventional process.

Abstract: Water is life, and without water, there would be no civilizations and a vacant Earth. Water is considered an abundant natural resource on the earth. Water covers 3/4 of the surface. However, 97% of the available water on the earth is salty oceanic water, and only a tiny fraction (3%) is freshwater. This small portion of the available water supplies the needs of humans and animals. However, freshwater exists in underground, rivers, and lakes and is insufficient to cover all the world’s water demands. Thus, water saving, water reuse, rainwater harvesting, stormwater utilization, and desalination are critical for maintaining water supplies for the future of humanity. Desalination has a long history spanning centuries from ancient times to the present. In the last two decades, desalination has been rapidly expanding to meet water needs in stressed water regions of the world. Yet, there are still some problems with its implementation in several areas of the world. This review provides a comprehensive assessment of the history of desalination for wiser and smarter water extraction and uses to sustain and support the water needs of the earth’s inhabitants.

Water is one of the world’s most abundant resources, but less than 1% of the global supply of water is available and safe for human consumption [1]. According to the World Health Organization, over 760 million people were without adequate drinking water supply in 2011 [2]. Where it is available, the cost of potable water is rising due to increasing energy costs, growing populations, and climatic or other environmental issues [1,3]. In addition, an increasing number of drinking water sources are showing evidence of contamination, especially by emerging pollutants like pharmaceuticals and personal care products [4,5]. Many traditional water and wastewater treatment methods do not effectively remove these emerging contaminants, and/or are not capable of removing enough to meet increasingly stringent water quality standards [5,6]. Contamination of surface waters also constitutes a risk to water supplies because pollutants may penetrate into aquifers, where they can be transported to drinking water sources.

ABSTRACT Drinking water is unfortunately becoming a rare luxury on our planet.On the other hand, with a trend of population growth, need for water which is essential to life,is becomingbigger every day.Practical application of nanotechnology in saving water worldwide is in using nanoparticles in detection of water pollution and water purification. This knowledge has importance in medicine and public health, so as in environment safety.Possible application areas of nanotechnology in field of purification and treatment of water are in filtration, catalytic and separation processes, ion exchanging, sensitive pollutant detection,etc.Nanotechnology could be the main solution in future fortreatment of surface water,groundwater, and waste water contaminated by toxic metal ions, organic and inorganic solutes, and microorganisms.

Abstract Industrialization and excessive use of pesticides for boosting agricultural production have adversely affected the ecosystem, polluting natural water reserves. Remediation of contaminated water has been an area of concern with numerous techniques being applied to improve the quality of naturally available water to the level suitable for human consumption. Most of these methods, however, generate by-products that are sometimes toxic. Heterogenous photocatalysis using metal oxide nanostructures for water purification is an attractive option because no harmful by-products are created. A discussion on possible methods to engineer metal oxides for visible light photocatalysis is included to highlight the use of solar energy for water purification. Multifunctional photocatalytic membranes are considered advantageous over freely suspended nanoparticles due to the ease of its removal from the purified water. An overview of water remediation techniques is presented, highlighting innovations through nanotechnology for possible addressing of problems associated with current techniques.