Anaerobic water purification

For o-, p-, and m-cresol, as well as the mixed isomers, anaerobic degradation studies, analytical methods development, and transformation studies are all on-going (EPA 1989b). Additionally, for o-cresol, studies on water purification techniques are on-going, while for p- cresol, aerobic degradation and toxicity studies are on-going. 

This process, according to the manufacturer,54 has been developed in such a way that space requirements are kept to a minimum. A BIOPAQ IC reactor is used as the initial step in the treatment process. The name of this anaerobic reactor is derived from the gas-lift driven internal circulation that is generated within a tall, cylindrical vessel. These reactors have been operational in the paper industry since 1996. The second step in the purification process is a mechanically mixed and aerated tank. The aerating injectors can be cleaned in a simple way without the need to empty the aeration tank. Potential scaling materials are combined into removable fine particles. At the same time, the materials that may cause an odor nuisance are oxidized into odorless components. The process can be completed by a third and a fourth step. The third step focuses on suspended solids recovery and removal. The fourth step is an additional water-softening step with lamella separation and continuous sand filters in order to produce fresh water substitute. The benefits claimed by the manufacturer are as follows54 ... 

Boija, R., and Banks, C. J., Kinetics of an Anaerobic Fluidized Bed System Used for the Purification of Fruit Processing Waste-Water, Chem. Eng. J., 54 B25 (1994)... 

Surfactant concentrations in polluted natural water bodies interfere with the self-purification process in several ways. First, certain detergents such as ABS are refractory or difficult to biodegrade and even toxic or inhibitory to microorganisms, and influence the BOD exhibited by organic pollution in surface waters. On the other hand, readily biodegradable detergents could impose an extreme short-term burden on the self-purification capacity of a water course, possibly introducing anaerobic conditions. 

Cimningham JA-SG, Sedlak P, Caffrey J. Aerobic and anaerobic TiO -photocatalysed purifications of waters containing organic pollutants. Catal Today 1999 53 145-158. Penuela GAB, Damia. Photosensitized degradation of organic pollutants in water processes and analytical applications. Trends Anal Chem 1998 17 605-612. 

Solid or water soluble polymers likely to enter anaerobic digestion plants or landfill site Solid polymers likely to enter anaerobic digestion plants or landfill site Solid or water soluble polymers likely to enter purification plants (PVA, for example) Polymers destined for landfill (agricultural films, for example) Polymers whose end of life is in an industrial composting facility (packaging, for example)... 

Many problems in waste-water treatment - both in municipal and industrial plants - are caused by oxygen deficiency. The consequences include inadequate purification or even anaerobic decomposition processes, causing offensive odours. 

Cunningham J., Al-Sayyed G., Sedlak R, Caffrey J. Aerobic and anaerobic TiOj-photocatalysed purifications of waters containing organic pollutants. Catal. Today 1999 53 145-158 Damrauer N.H., Cerullo G., Yeh A., Boussie T., Shank C.V., McCusker J.K. Femtosecond dynamics of excited-state evolution in Ru(bpy)j. Science 1997 275 54-57 Das T.K., Khan L, Rousseau D.L., Friedman J.M. Preservation of the native structure in myoglobin at low pH by sol-gel encapsulation. J. Am. Chem. Soc. 1998 120 10268-10269 Desilvestro J., Pons S., Vrachnou E., Gratzel M. Electrochemical and FUR spectroscopic characterization of ferrocyanide-modified Ti02 electrodes designed for efficient photosensitization. J. Electroanal Chem. 1988 246 411-422... 

---