Waste water definition

Many site-specific characteristics have an impact on vitrification technologies. One critical aspect of any thermal technology is the water content of the waste. Water dilutes feed material, requires energy to drive off, and physically limits the feed rate of waste. Feed preparation is another variable, which differs with the technology and with site-specific characteristics. Many estimates do not take into account site preparation and waste disposal costs. Only complete treatment life-cycle assessments can provide reliable comparison data, and such studies are, by definition, highly site and waste specific (D18248T, p. 55). 

As shown in this table, a zero discharge of process waste-water pollutants is required by EPA for all facets of the timber products industry except wet storage of legs, wet-process fiber products manufacture, and one segment of the wood preserving industry. This requirement, by definition, holds that a zero discharge is "the best practicable technology currently available" by which the affected industries can control pollution. 

The keyword in the definition of wastewater is used or spent. That is, the water has been used or spent and now it has become a waste water. On the other hand, to become a sewage, it is enough that water becomes polluted whether or not it had been used. When one uses the word wastewater, however, the meaning of the two words is blended such that they now often mean the same thing. Wastewater equals sewage. 

An important decision parameter for the definition of the remediation technology is the MTBE threshold value that needs to be achieved for the treated water. This depends on the kind of discharge (waste water channel, rain water channel, re-injection into the groundwater) and the general site situation. At present, for discharge into sewers MTBE concentrations of about 50 pg are commonly specified... 

It should also be noted that large-scale processes involving biological systems (such as waste water treatment and production of protein) fit the definition as well as traditional chemical processes such as the production of fertilisers and pharmaceuticals. 

Despite of some misunderstandings in the discussion about a proper definition of photocatalysis, photocatalytic reactions have captured the interest of chemists for a long time. Furtheron, photocatalysis has preserved its fascination as a method that not only provides a real alternative of usual chemical synthetic pathways [37]. Other promising fields of application of photocatalysis are the conversion of solar energy into chemical energy [38], information recording [39], and environmental problems like waste water decontamination [40]. 

In contrast to the cleaning of natural water by ozonation, which is experimentally confirmed as the most appropriate, the purification of waste water by ozone is still an area of intensive future research. This could be explained by the great diversity of pollutants in the used water and the necessity of specific approach for each definite case. 

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