The field of water treatment encompasses a wide variety of unit processes that can be analyzed using tools developed for the field of Chemical Engineering. The disinfection of water, for example, can be modeled using the same tools used for the design, analysis, and troubleshooting of chemical reactors. Using the principle of residence time distributions, contact tanks can be designed to produce effective microorganism disinfection while minimizing the production of disinfection byproducts.
Multiphase reactors can also be used for a variety of water treatment processes. Multiphase systems (liquid-solid, gas-solid) can be used for the development of efficient fluid-particle contacting systems such as those used in catalytic reactions. Recent advances in photocatalysis provide a basis for the development of water purification systems that mineralize organic compounds and their halogenated derivatives. Novel fluid-particle contacting systems provide an efficient, flexible recycle loop for catalyst regeneration. This design satisfies the need for ready water-catalyst separation while providing large surface areas for the contaminant degradation reaction. Large-scale systems can be designed and constructed for the treatment of municipal sized flow rates of water. Development of these processes will provide a means of improving water quality, removing chemical contaminants with no significant waste stream, and allowing some communities to use ground and surface waters that have become contaminated by natural or other means.