Streams self-purification

Many of the contaminants are highly stabilized organic compounds that are not destroyed by biological or chemical treatment of wastes, and they often survive the self-purification that normally occurs in moving streams. One synthetic chemical in waste, orthonitrochloro-benzene, was detectable in the Mississippi River for a distance of over 900 miles from the point of origin.70... 

Chemical deterioration of water quality is caused by admixtures of soUd, Uquid or gaseous phases which are water-soluble. These particularly include free acids, nitrates, chlorides, sulphates, salts of heavy metals, cyanides and phenols, and gaseous substances. Such substances can entirely destroy biological revival and the self-purification capability of the stream as a consequence of exhaustion of dissolved oxygen from water [12-16]. 

In water streams, spontaneous self-purification processes take place with an active participation of microorganisms. By the metabolic activities of these,... 

The biochemical activities of bacteria constitute the most important phase of self-purification of polluted streams. It was essential, therefore, to study the biodegradability of Sevin, 1-naphthol, baygon, pyrolan, and dimetilan. 

Spellman, F.R. (1996a). Stream Ecology and Self-Purification An Introduction for Wastewater and Water Specialists. Technomic, Lancaster, PA. 

The oxidative degradation of organic pollutants in water and air streams is considered as one of the so-called advanced oxidation processes. Photocatalytic decomposition of organics found widespread industrial interest for air purification (e.g., decomposition of aldehydes, removal of NO , ), deodorization, sterilization, and disinfection. Domestic applications based on Ti02 photocatalysts such as window self-cleaning, bathroom paints that work under illumination with room light, or filters for air conditioners operating under UV lamp illumination have already been commercialized. Literature-based information on the multidisciplinary field of photocatalytic anti-pollutant systems can be found in a number of publications, such as Bahnemann s [237, 238] (and references therein). 

NASA has designed and contracted a water testing, purification, and retest (certification) system that is a self-contained unit about the size of a small automobile. Human involvement is restricted to putting hose A into a puddle, polluted stream, saltwater bay, or almost any other liquid source, and to drinking pure water from liose B. The fully automated laboratory (and processing) system is intended for an eventual Mars base. It is currently used on navy ships and some desert warfare army units. 

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