Water treatment and environmental protection

The provision of water suitable for drinking is another essential to life. The quality of naturally available water varies greatly from site to site and in many places it may be necessary to remove bacteria, salts, heavy metal ions and organics desalination and chlorination are the most common processes. Moreover, it is again advantageous to monitor the water quality continuously or, at least, routinely. 

Stage BOD range (mg l i) Mechanical or biological processes Physical or chemical processes 

Primary 400 250 Communition, sedimentation, sludge digestion or incineration Flocculation by chemical additives, flotation 

Secondary 250 40 Percolation through activated sludge filters, biological oxidation, nitrification Flotation, coagulation by additives, precipitation (e.g. phosphate, fluoride, heavy metals), filtration 

Tertiary 40 20 Filtration, oxidation ponds, disinfection Treatment with CI2 or O3, adsorption on high-surface-area carbons, osmosis, UV sterilization 

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Water Treatment and Environmental Protection 283 11.1 METAL ION REMOVAL AND METAL RECOVERY... 

Cortec Corporation of White Bear Lake, MN, is a manufacturer of environmentally responsible packaging, metalworking, cleaning, water treatment and metal protection technologies. Cortec manufactures over 300 products in five plants located in Minnesota, Wisconsin. It is a global supplier of environmentally-friendly speciality chemicals, plastics and coated paper. 

The flows of wastewater originating from the water supply of a community and runoff from precipitation on urban surfaces are typically collected and conveyed for treatment and disposal. The system used for this purpose is called a sewer network or a collection system that consists of individual pipes (sewer lines) and a number of installations, such as inlet structures and pumps, to facilitate collection and transport. The efficient, safe and cost-effective collection and transport of wastewater and urban runoff have been identified as key criteria to be observed. In this context, the word safe means that public health, welfare and environmental protection have high priority. The demand for solutions toward more sustainable water management in the cities is a new challenge. 

New products are being developed to replace heavy metals in water-treatment and protective-coatings applications. The products have become available from suppliers of protective coatings under pressure from the U.S. EPA to remake paints and primers minus the solvents that contain volatile organic componnds. Mannfacturers have come np with a variety of formnlations that do not pose the environmental and health risks associated with chromium. These formulations are more expensive than chromium-based solutions, however, and are likely to remain so for the immediate fnture (Hairston, 1996b). 

In summary, the biocatalytic process reduces raw material costs by a factor of four and the percentage of process costs for environmental protection (incineration, waste water treatment and waste gas cleaning) is cut down considerably from 21% to 1%. Compared with the chemical process the environmental protection costs were reduced by about 90% per ton of 7-ACA. 

In chemical production processes wastewaters loaded with side products are often formed, and these must be cleaned in a wastewater-treatment plant before they are discharged into a body of water.The amount of wastewater can be reduced, for example, by recycling, recovery of ingredients, and by using low-water processes (integrated environmental protection) [Christ 1999]. In spite of these measures, more than 4 x 10 m a of wastewater is produced in Germany. 

Higher costs for energy, water treating chemicals, and environmental protection make it well worthwhile to recover as much condensate as practical. Capital expenditures will probably be required to upgrade return systems, segregate clean and contaminated streams, provide monitoring instrumentation, and provide a treatment system, but the economic justifications have risen tremendously. 

In considering risk, EPA considers factors including environmental effects, distribution, and fate of the chemical substance in the environment, disposal methods, waste water treatment, use of protective equipment and engineering controls, use patterns, and market potential of the chemical substance. 

Reference [7] gives a detailed description of the basic principles for the treatment of industrial waste waters and also discusses the legal aspects, problems regarding environmental protection, and the various technical processes. In addition to an overview on industrial waste waters, evaluation criteria, and the possibilities of reducing or avoiding waste water are also addressed. The chemical, physical, and biological processes for waste water treatment and the elimination of waste water contaminants are described in detail. 

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