Chemical treatment technologies

Various treatment technologies are used at the iron and steel plant for recycle system water treatment prior to recycle and reuse, or end-of-pipe wastewater treatment prior to discharge to surface water or a POTW. The physical/chemical treatment technologies extensively used include equalization, tar removal, free and fixed ammonia stripping, cooling technologies, cyanide treatment technologies,... 

Ground-Water Remediation Technologies Analysis Center, In Situ Chemical Treatment, Technology Evaluation Report TE-99-01, Prepared by Y. Yin and H.E. Allen, July 1999. Available at www.gwrtac. org/pdf/inchem.pdf, 2009. 

Pyrodigestion is an ex situ thermal and chemical treatment technology. This technology uses a molten alloy of metals (principally aluminum) in an anaerobic atmosphere to destroy virtually any organic contaminant and to absorb most metal contaminants into the metal bath. Contaminated materials are added to the liquid metal bath where they are broken down into elemental components, nonhazardous compounds, and simple salts. 

The estimated price range for the chemical treatment technology is from 150 to 500 per ton of waste treated (DIOIOIF, p. 9). 

Continued research into both fundamentals and applications of chemical treatment technologies will hopefully provide solutions to many current pollution treatment problems, both for waste streams and for contaminated sites. Only through cooperation among scientists, engineers, industry, government, and consumers can we maintain a healthy and productive environment for the future. 

Various chemical treatment technologies have been applied to remove these ions from drinking water sources, including ion exchange, metal oxide based adsorption and coagulation. However, these methods alone are insufficient to remove the contaminants below the Maximum Contaminant Limit (MCL) and therefore are better to be used as a pretreatment step (Favre-Reguitlon et al., 2005 Mondal et al, 2013). 

A wide range and a number of purification steps are required to make available hydrogen/synthesis gas having the desired purity that depends on use. Technology is available in many forms and combinations for specific hydrogen purification requirements. Methods include physical and chemical treatments (solvent scmbbing) low temperature (cryogenic) systems adsorption on soHds, such as active carbon, metal oxides, and molecular sieves, and various membrane systems. Composition of the raw gas and the amount of impurities that can be tolerated in the product determine the selection of the most suitable process. 

M. G. Noack and S. A. lacovieUo, "The Chemistry of Chlorine Dioxide in Industrial and Wastewater Treatment AppHcations," 2nd International Symposium on Chemical Oxidation Technologies Tor the 90 s, Vanderbilt University, NashviUe, Term., Feb. 19—21,1992. 

Make no mistake about it - air pollution abatement, especially based upon end-of-pipe treatment technologies is expensive. Not too long ago the prevailing attitude among industry stakeholders was that air pollution control was simply a part of the cost of doing business, and that add-on costs associated with compliance simply had to be passed on to the consumer s purchase price for products. With the intensity of international competition in the chemical and allied industries, this philosophy simply does not cut it anymore. 

Chemical treatment is a class of processes in which specific chemicals are added to wastes or to contaminated media in order to achieve detoxification. Depending on the nature of the contaminants, the chemical processes required will include pH adjustment, lysis, oxidation, reduction or a combination of these. Thus, chemical treatment is used to effect a chemical transformation of the waste to an innocuous or less toxic form. In addition, chemical treatment is often used to prepare for or facilitate the treatment of wastes by other technologies. Figure 12 identifies specific treatment processes which perform these functions. 

Technology Description In-situ chemical treatment uses the same principles employed for above-ground chemical processes. Materials are added to neutralize, oxidize or remove contaminants in groundwater or soils in order to avoid digging or pumping of the contaminated waste above ground for... 

Solidification/Stabilization technologies are techniques designed to be used as final waste treatment. A major role of these processes is posttreatment of residuals produced by other processes such as incineration or chemical treatment. In some cases, solidification/ stabilization processes can serve as the principal treatment of hazardous wastes for which other detoxification techniques are not appropriate. High volume, low toxicity wastes (such as contaminated soils) are an example of this application. 

Physical devices (catalytic devices) for the nonchemical treatment of water and, more specifically, devices for scale prevention that employ magnetic fields have been part of the water treatment marketplace around the world since its earliest days. These devices include electronic, catalytic, electrostatic, and magnetic water treatments. There are also various other types of more recent alternative technologies (to chemical treatments) now available in the marketplace. These are being promoted for use in treating all types of MU water, FW, and BW. 

---