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Heavy Metal Remediation/Removal Heavy metal contamination is a problem in domestic and process water systems, in large measure because the potentially pernicious health consequences of heavy metals are becoming better understood by health scientists. (Heavy metals have probably always been present in the water. It has only recently become possible to detect them in the trace concentrations at which they can occur, however. Therefore, because they have only recently become detectable, government regulators have only recently turned attention to them.) For example, small levels of lead, mercury, cadmium, thallium, arsenic, selenium, etc. have been linked to disorders of the central nervous system, respiration, renal system, blood, cardiovascular system, birth defects, and many more afflictions in humans and in animals. Increasingly, medical and bioscientists are coming to believe that deleterious heath consequences are a direct, proportional function of the concentration of the pernicious ions no matter how small such concentrations might be. For example, many believe that twice as much concentration, no matter how small, has twice as much consequence. Four times has four time as much, etc. Perhaps more importantly to the regulator, half as much concentration has half as much health consequence. A quarter as much concentration has a quarter as much consequence, etc. This means that even vanishingly small concentrations are believed to have deleterious health consequences, albeit proportionately lower than high concentrations. Findings about dilute concentrations have increasingly motivated state and federal environmental regulators to initiate immediate remedial actions to eliminate such ions no matter how small the concentration. Typically such regulatory motivation takes the form of a very immediate and very binding regulation with imminent conditional threat of plant shutdown and legal-economic-personal liability for noncompliance (and perhaps even criminality). Such draconian measures increasingly motivate immediate action, and they catalyze either shutdown or consideration of quite expensive and inefficient removal technology. Reticle Carbon has the potential to help people stave off such consequences. Until Reticle, the only way to remove offending heavy metals is to utilize expensive precipitation techniques, often following rather expensive preconcentration and constantly searching for ways to increase the efficiency of precipitation. In particular, the pernicious ions must be preconcentrated to a substantial degree by processes such as an ion exchange resin. Preconcentration then allows precipitation and other standard techniques, which themselves have proven very expensive (in addition to the ion exchange resins themselves, which are known to be very expensive). Preconcentration and precipitation have proven uneconomic in practice, and Reticle Carbon CDI allows those uneconomic techniques to be avoided. All of the various offending heavy metals are directly and easily removable from water using Reticle Carbon CDI technology because they all occur in dissolved, ionic (metal salt) form. To wit, they are charged particles. Reticle Carbon CDI arrests ions within an inbound water stream and allows the water to flow through after leaving the ions behind adhered to the surfaces of the electrodes. That is, Reticle Carbon CDI removes all ions, heavy and light, from the inbound water stream and creates a clean water stream. The ability to remove all ions dissolved in an inbound water stream is a huge advantage for Reticle Carbon, which is specifically directed toward removing ions from an incoming aqueous solution. Using Reticle Carbon CDI, very large-scale plants can be engineered to rid water of dissolved metal ions right at their source. In addition, small scale, home-size, faucet-mounted units can be made to remove heavy metals right under the residential sink, right at the point of use. To wit, Reticle Carbon CDI units can be designed and implemented at the level of large, central station units, and they can be designed and implemented at the level of small, point of use units. The options for implementation are quite broad. Yet in all cases, they remove all the dissolved ions from the inbound water stream. A primary advantage of Reticle Carbon CDI for removal of heavy metal ions is its low capital cost and its low operating and maintenance cost. During operation, the Reticle Carbon CDI cell will create a clean water stream and will simultaneously create a high concentration waste stream, a stream comprised of the adsorbed, offending ions from the electrode regeneration process. When arrayed in single or multiple passes, Reticle Carbon CDI is capable of achieving quite high levels of concentration of the pernicious ions in a wastewater stream and thereby to clean up and in effect "liberate" a large proportion of the inbound water. At lower levels of concentration (which require less intensive processing because there are fewer dissolved ions), the regeneration solution is probably amenable to disposal via deep injection or evaporation ponding. At higher levels of concentration (which require more serial passes through Reticle Carbon cells to achieve), the regeneration solution might actually have significant commercial value. The offending heavy metal ions oftentimes have commercial value as concentrates or sludges in processes specifically designed to treat them and extract the metals. In particular, heavy metal removal applications may offer additional and significant fair market value derivable from the sale of the solid coproducts that emerge from the Reticle Carbon process. For example, xerographic copiers use copying drums made from light-sensitive selenium metal. (Selenium metal is the "secret sauce" in xerography.) Mercury vapor lights are quite economical when measured in terms of illumination per unit of power consumption, and arsenic remains a viable, inexpensive pesticide used in products such as D-Con and other commercially available pesticides. Effluent streams containing such products are likely to have independent economic value and might generate a secondary revenue stream for Reticle. Removal of pernicious heavy metals is not limited to centralized, utility owned water systems. Quite the contrary, the mandate to remove such metals from water at the point of final consumption is becoming increasingly strict. Other sections discuss decentralized, private water purification by Reticle Carbon. |
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