Surface waters organics removal

Hormones are the main active ingredients in contraceptive pills. In particular, removal of EE2 (17-alpha-ethynylestradiol) from waste water is often nowhere near complete, as has been demonstrated by the findings of Lamoree et al. There is evidence that environmentally relevant concentrations of estrogens in surface waters can affect wild fish populations. Recently, an aquatic predicted no-effect concentration (PNEC) of 0.35 ng for EE2 in order to adequately protect organisms in surface waters was recommended by Caldwell et al. EE2, 17-beta-estradiol (a naturally occurring hormone) and the pain killer diclofenac were included in the watch list of the EU water framework directive in 2013 in order to be included in routine surface water monitoring. ... 

Removing small amounts of suspended inorganic or organic particles from surface water prior to its use as drinking water or industrial process water. 

Water and Waste Water Treatment. PAG products are used in water treatment for removal of suspended soHds (turbidity) and other contaminants such as natural organic matter from surface waters. Microorganisms and colloidal particles of silt and clay are stabilized by surface electrostatic charges preventing the particles from coalescing. Historically, alum (aluminum sulfate hydrate) was used to neutralize these charges by surface adsorption of Al cations formed upon hydrolysis of the alum. Since 1983 PAG has been sold as an alum replacement in the treatment of natural water for U.S. municipal and industrial use. 

As the water evaporates into steam and passes on to the superheater, soHd matter can concentrate in a boHer s steam dmm, particularly on the water s surface, and cause foaming and unwanted moisture carryover from the steam dmm. It is therefore necessary either continuously or intermittently to blow down the steam dmm. Blowdown refers to the controHed removal of surface water and entrained contaminants through an internal skimmer line in the steam dmm. FHtration and coagulation of raw makeup feedwater may also be used to remove coarse suspended soHds, particularly organic matter. 

Makeup. Makeup treatment depends extensively on the source water. Some steam systems use municipal water as a source. These systems may require dechlorination followed by reverse osmosis (qv) and ion exchange. Other systems use weUwater. In hard water areas, these systems include softening before further purification. Surface waters may require removal of suspended soHds by sedimentation (qv), coagulation, flocculation, and filtration. Calcium may be reduced by precipitation softening or lime softening. Organic contaminants can be removed by absorption on activated carbon. Details of makeup water treatment may be found in many handbooks (22—24) as well as in technical Hterature from water treatment chemical suppHers. 

Adsorption — An important physico-chemical phenomenon used in treatment of hazardous wastes or in predicting the behavior of hazardous materials in natural systems is adsorption. Adsorption is the concentration or accumulation of substances at a surface or interface between media. Hazardous materials are often removed from water or air by adsorption onto activated carbon. Adsorption of organic hazardous materials onto soils or sediments is an important factor affecting their mobility in the environment. Adsorption may be predicted by use of a number of equations most commonly relating the concentration of a chemical at the surface or interface to the concentration in air or in solution, at equilibrium. These equations may be solved graphically using laboratory data to plot "isotherms." The most common application of adsorption is for the removal of organic compounds from water by activated carbon. 

For organic contaminant removal from surface water packed-tower aeration, granular activated carbon (GAC), powdered activated carbon (PAC), diffused aeration, advanced oxidation processes, and reverse osmosis (RO). 

A final are we should discuss is color removal. This is perhaps the most difficult impurity to remove from waters. In surface waters color is associated with dissolved or colloidal suspensions of decayed vegetation and other colloidal suspensions. The composition of this material is largely tannins and lignins, the components that hold together the cellulose cells in vegetation. In addition to their undesirable appearance in drinking water, these organics can cause serious problems in downstream water purification processes. For examples ... 

Under some circumstances transport processes other than fluid motion and molecular diffusion are important. One important example is sedimentation due to gravity acting on particulate matter submerged in a fluid, e.g., removal of dissolved sulfur from the atmosphere by precipitation scavenging, or transport of organic carbon from the surface waters to the deep... 

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