Water-technological consideration

Some Water-Technological Considerations in Coagulation and Flotation... 

SOME WATER-TECHNOLOGICAL CONSIDERATIONS IN COAGULATION, FILTRATION, AND FLOTATION... 

Robbins, C. J. (Elf Atochem North America). Condensate Line Control/ Humidification Considerations. Presented to Association of Water Technologies, Franklin Plaza, Philadelphia, Pennsylvania, USA, April 1994. 

The paper deals with electrolysis side-stream desalting which offers an alternative solution to the problem of water and salt management in electric power generating plants where blowdown disposal is needed, and where the value of recovered water is considerable. An advanced electrodialysis technology is described. 4 refs, cited. 

The SMR-HMM technology considerably simplifies the industrial process since it does not require oxygen production, is implemented at much lower temperatures (at HMM production - up to 700°C), does not require energy-intensive and cost-intensive water electrolysis and is based on process solutions, modes and catalysts tested in heavy-tonnage chemical industry. 

Recarbonation will transform the 15.0 mg/L as CaC03 of carbonate ions from the limit of technology to 15.0 mg/L as CaC03 of bicarbonate ions. From the order of removal, these carbonate ions will be coming solely from the removal of the raw calcium bicarbonate. The carbonate ions coming from the use of soda ash to form calcium carbonate will not be accounted for in this limit of technology consideration, since by the time they are formed, the water is already saturated with the carbonate coming from the removal of the raw calcium bicarbonate. 

Non-volatile compounds are not removed from water by air stripping. Air stripping may be used in conjunction with another treatment method, such as GAC, flocculation, or chlorination, to achieve treatment levels at an operating cost below that possible by the use of a single technology. Consideration of the factors herein presented allows an accurate assessment of the effectiveness of air stripping for specific water treatment objectives. 

Technology has developed for time to stabilize soil at a considerable depth (20). The U.S. method is called time slurry pressure injection, with time slurry being injected in situ to 3—6.6 m depth through lances on a grid-pattern but there is no mixing of time and soil. Both Japan and Sweden have developed techniques using specially constmcted machines to inject dry quicklime and then mixing the time, soil, and water to depths of 11 m or more under critical hydraulic conditions. 

The use of supercritical and hot water as a solvent is still largely experimental. Because supercritical technology is well known in the power industry, this use of water is likely to increase in the future. Corrosion control may be an important limiting consideration. General process economics are the second potential limit (see SUPERCRITICAL FLUIDS). 

D. M. McKnight, S. W. Chrishohn, F. M. M. Morel, INCRA Project No. 252, Copper Sulfate Treatment of Takes and Reservoirs Chemical and Biological Considerations, Ralph M. Parsons Lab, Division of Water Resources Hydrodynamics, Massachusetts Institute of Technology, Cambridge, Mass., 1981. 

Maximum Contaminant Level (MCL) - The highest level of a contaminant that is allowed in drinking water. MCLs are set as close to MCLGs as feasible using the best available treatment technology and taking cost into consideration. MCLs are enforceable standards. 

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