Drinking water, dissolved organic matter

DISSOLVED ORGANIC MATTER (DOM) IN NATURAL ENVIRONMENTS 10.6.2. Drinking Water... 

Eor water-treatment processes such as drinking water or potable water production, reverse osmosis (desalination), nanofiltration, and ultrafiltration are mainly used. In these processes often a microfiltration stage is implemented as the first cleaning stage for the removal of dissolved organic matter, colloids and particles from the source. 

Water-treatment plants commonly use chlorination to destroy bacteria. A by-product is chloroform (CHCI3), a suspected carcinogen, produced when HOCl, formed by reaction of CL and water, reacts with dissolved organic matter. The United States, Canada, and the World Health Organization have set a limit of 100. ppb of CHCI3 in drinking water. Convert this concentration into molarity, molality, mole fraction, and mass percent. 

Rosario-Ortiz, F.L., Snyder, S.A., and Suffet, 1. H. (2007). Characterization of dissolved organic matter in drinking water sources impacted by multiple tributaries. Water Res., 41,4115 128. 

Because trihalomethane compounds were identified in chlorinated water from drinking water-treatment plants [37], multiple research studies have addressed their efforts to identify the nature of dissolved natural organic matter and the action of oxidants to yield by-products, usually called disinfection by-products. As for natural organic matter (NOM), after the... 

On the other hand, pressure is applied in reverse osmosis to drive the solvent (water) out of the high-concentration side into the low-concentration side this facilitates de-watering insoluble species for their removal. This process produces high-quality water and concentrated refuse. It separates and removes dissolved solids, organics, pyrogens, colloidal matter, viruses, and bacteria from water in the particle range 10 4—10—2 pm. Reverse osmosis can remove up to 95%-99% of the total dissolved solids (TDS) and 99% of all bacteria. It is used for the ob-tention of drinking water from seawater and for the production of ultra pure water in various industries. 

Water treatment by granular activated carbon (GAC) filters is an effective technology for removing dissolved organic compounds. GAC filters are therefore applied for drinking water purification as well as decontamination of polluted water, as for example in pump and treat procedures. Unfortunately, removal capacity towards micropollutants is often reduced by natural organic matter (NOM) in water due to competitive interaction on GAC adsorption sites. 

Activated carbon, in powdered (PAC) or granular (GAC) form, has many applications in drinking water treatment. It can be used for removing taste and odor (T O) compoimds, synthetic organic chemicals (SOCs), and dissolved natural ot] nic matter (DOM) from water. PAC typically has a diameter less than 0.15 mm, and can be applied at various locations in a treatment system (Fig. 1). GAC, with diameters ranging from 0.5 to 2.5 mm, is employed in fixed-bed adsorbers such as granular media filters or post filters. Despite difference in particle size, the adsorption properties of PAC and GAC are fundamentally the same because the characteristics of activated carbon (pore size distribution, internal surface area and smface chemistry) controlling the equilibrium aspects of adsorption are independent of particle size. However, particle size impacts adsorption kinetics. 

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