Water Purification Using Nanotechnology an Emerging Opportunities

Aluminium in drinking water comes from natural sources and the alum used as coagulant in the water treatment process. Exposure to aluminium has been implicated in dialysis dementia, Parkinson and Alzheimer’s disease. Drinking water containing aluminium was considered to be one of the main sources of Al intake into human body. For this reason, the removal of aluminium from drinking water is vital to our health. In this study, removal of aluminium was carried out by using a chelating resin.

The 2006 version of the Pa. DEP Inorganic Contaminant Removal module has detailed advanced treatment information on this topic and can be obtained by e-mailing the Pa. DEP Safe Drinking Water Training Section at DEPWSTechtrain@pa.gov to request a copy. This advanced module has additional information on the removal of various inorganic contaminants as well as on oxidation, ion exchange, activated alumina and sequestration. The 2006 document also includes more detailed information on the inorganic contaminant treatments of GAC (granular activated carbon), coagulation/filtration, membranes, and lime softening. It includes the following information:

• Inorganic contaminant treatment selection considerations
• Advanced inorganic contaminant removal chemistry terminology
• Advanced inorganic contaminant removal chemistry explanations
• Conventional filtration and how it relates to inorganic removal
• Detailed information on treatments for iron and manganese removal
• Detailed information on treatments for hardness removal
• Detailed information on inorganic contaminant monitoring protocols
• Detailed tables on the following topics:
• Sources of 26 inorganic contaminants
• Common secondary standards with effects, inorganic contributors and indications
• Various treatment technology options to consider for 24 inorganic contaminants
• Potential forms of iron and manganese
• Iron and manganese sampling procedures
• Iron and manganese oxidant selection criteria
• Iron and manganese theoretical (initial) dosing criteria
• Potential treatments for less common inorganics
• Potential treatments for miscellaneous trace metals

Introduction: Desalination using seawater reverse osmosis (SWRO) technology is an important option available to water-scarce coastal regions. Worldwide sea water desalination is a very effective and economical way of producing potable water for drinking and industries. Reverse osmosis plants to convert sea water to potable drinking water and for other usages have been prevalent throughout the world for more than 4 decades. Design and operation of seawater reverse osmosis plants strongly depend on the raw seawater quality to be treated. The performance of desalination reverse osmosis (RO) systems relies upon the production of high quality pre treated water, and the selection of the best pre treatment technology depends on the raw seawater quality and its variations. Number of full-scale experiences has shown that pre treatment is the key for this application of reverse osmosis technology. It is why during these last years, an import effort has been done to identify and to characterise the diverse organic and mineral components present in the seawater in a view to optimise the seawater pre-treatment and to develop advanced analytical methods for feed water characterization, appropriate fouling indicators and prediction tools. This Chapter describes firstly a comprehensive approach to characterize raw seawater samples through analytical tools which allow the knowledge of the characterization of seawater from many aspects: (a) inorganic content, (b) natural organic matter, (c) enumeration of micro-organisms and phytoplankton. Secondly, this Chapter describes the effect of each of these parameters on the fouling of the reverse osmosis membrane. Finally, this chapter describes the different possible pre treatments available to reduce or remove the elements or substances up-stream reverse osmosis stage.

All over the world the presence of arsenic in water sources for human consumption has been raising great concern in terms of public health since many epidemiologic studies confirm the potential carcinogenic effect of arsenic. Because arsenic removal is the most frequent option for safe drinking water, the development of more efficient and sustainable technologies is extremely important. Membrane separation processes are suitable for water treatment because they can provide an absolute barrier for bacteria and viruses, besides removing turbidity and colour. Their application is a promising technology in arsenic removal since it does not require the addition of chemical reagents nor the preliminary oxidation of arsenite required in conventional treatment options. However, since membrane technologies such as reverse osmosis can be a very expensive and unsustainable treatment option for small water supply systems, it becomes crucial that alternative methods are developed. This work presents a few conclusions based on a laboratorial study performed to evaluate the efficiency of arsenic removal using ultrafiltration, microfiltration and solar oxidation processes under different experimental conditions for relevant parameters. The results showed removal efficiencies higher than 90%. Key-words: safe drinking water, arsenic removal, membranes, public health.