Waste electrochemical treatment

The electrochemical generator is designed for both small (0.136-4.5 kg C102/day) and larger scale (0.5-27 kg/h range and more) chlorine dioxide production rates. The chlorine dioxide solution from this system is suitable for sanitizing and disinfection applications as well as waste water treatment. 

Endyus kin PN, Selezenkin SV, Dyumaev KM (1983) Electrochemical treatment of waste-water from organic dye manufacturing plants, Zh Prikl Khim, 56(5) 1167 Chem Abstr 99 (1983) 76176b... 

Electrochemical iron generation is a site-specific technology that is pH dependent. Process pH should be from 6 to 9. Optimal removal efficiencies require electrochemical treatment in combination with an ideal precipitation pH for the metals being removed. Nearly all fuU-scale systems include a pH control system. Andco performs lab and pilot-scale testing to evaluate the ability of the process to treat a particular waste stream. If flow rates or contaminant loads fluctuate, control equipment is required to compensate for changes in influent. 

The process can be used to treat dissolved metals and is commonly used in groundwater treatment for the reduction and precipitation of hexavalent chromium, as well as in the oxidation of cyanide wastes (at concentrations up to 10%). Other potential applications of electrochemical treatment include remediation of arsenic, cadmium, molybdenum, aluminum, zinc,... 

In electrochemical treatment of extracted groundwater, the operating costs for electrode consumption, power, and acid for the electrochemical unit are estimated at approximately 10 cents per 1000 gal of groundwater treated. At an anticipated flow rate of 20 gal/min (gpm), the operating costs are approximately 1000 annually. Labor and waste disposal costs for the electrochemical treatment process are estimated to be approximately 50 per day (D168869, p. 7-14). 

Geer, R.D. 1978. Predicting the anaerobic degradation of organic chemical pollutants in waste water treatment plants from their electrochemical reduction behavior. In Montana University Joint Water Resources Research Center, Bozeman, MT, Completion Report No. 96... 

Several investigations [56,57] have been devoted to the electrochemical treatment of human wastes in an attempt to make possible its electrochemical combustion. Tennakoon et al. [57] degraded artificial feces/urine mixtures at 90°C in a U tube cell, further scaling up the process to a parallel plate cell... 

Comninellis C. Electrocatalysis in the electrochemical conversion/combustion of organic pollutants for waste water treatment. Proceedings of the Symposium on Water Purification by Photocatalytic, Photoelectrochemical and Electrochemical Processes. Vol. 94-19. Pennington, NJ The Electrochemical Society, 1994 75-86. 

Comninellis C, Plattner E. Electrochemical waste water treatment. Chimia 1988 42 250-252. 

Comninellis C, Pulgarin C. Anodic oxidation of phenol for waste water treatment. J Appl Electrochem 1991 21 703-708. 

Kotz R, Stucki S, Career B. Electrochemical waste water treatment using high overvoltage anodes Part I. Physical and electrochemical properties of Sn02 anodes. J Appl Electrochem 1991 21 14—20. 

Tennakoon CLK, Bhardwaj RC, Bockris JO M. Electrochemical treatment of human wastes in a packed bed reactor. J Appl Electrochem 1996 26 18-29. 

Hobbs DT. Electrochemical treatment of liquid nuclear wastes. Abstract of the 8th International Forum on Electrolysis in the Chemical Industry. Lake Buena Vista, FL The Electrosynthesis Co., 1994... 

Farmer JC, Wang FT, Hawley-Fedder RA, Lewis PR, Summers LJ, Foiles L. Electrochemical treatment of mixed and hazardous wastes oxidation of ethylene glycol and benzene by silver. J Electrochem Soc 1992 139 654-662. 

Chung YH, Park SM. Electrochemical treatment of organic wastes by mediated electrochemical oxidation. Proc Electrochem Soc (Honolulu, HI) 1999 99(39) 67-74. 

The following section describes a few examples of the electrochemical treatment of wastes. 

The experimentally determined dependence of the concentration of the various entities as a function of time is shown in Fig. 15.26. The catholyte and anolyte concentrate NaOH and HN03, respectively, using a membrane separator. A plan for the electrochemical treatment of low-level nuclear wastes is shown in Fig. 15.27. The considerable electricity costs of such processes could be compensated by the sale of HN03 and NaOH. The Ru might be commercially valuable for some purposes, but its use may be compromised by residual radioactivity. 

Fig. 15.27. A schematic of a possible plant for the electrochemical treatment of low-level nuclear waste. (Reprinted from J. O M. Bockris and J. Kim, J. Appl. Electrochem. 27 626, copyright 1997.)...

D. T. Hobbs, Technical Report on the Electrochemical Treatment of Alkaline Nuclear Wastes. DOE Report WSRC-TR 94-0287 (1994). Review. 

Since the extreme oxidizing power of the oxyl spin centers is successfully employed in waste water treatment, an application of these intermediates seems to be self-contradictory in terms of synthetic use. However, alkoxylation of hydrocarbons is a very important technical field since it allows the installation of functionalities without using the detour via halogenations. The selective introduction of functional groups on a completely nonactivated hydrocarbon has not yet been realized by BDD technology. In contrast, the direct anodic methoxylations of activated carbons exhibiting benzylic or allylic moieties can be performed at BDD anodes. The results obtained with BDD electrodes are quite similar to those when graphite serves as anode [57]. The anodic synthesis of benzaldehyde dimethyl ketals is industrially relevant and performed on the scale of several thousand tons. A detailed study of the anodic methoxylation of 4-tert-butyltoluene (10) at BDD was performed [58]. Usually, the first methoxylation product 11 and the twofold functionalized derivative 12 are found upon electrochemical treatment (Scheme 5). 

Since boron-doped diamond electrodes are commercially available, most of these suppliers offer a wide variety of electrolysis cells. Modular electrochemical cells equipped with BDD electrodes have been reported in detail [122]. However, most of these cells were designed for waste water treatment and were not suitable for electrosynthesis in organic media. Electrolysis cells for synthetic purposes designed for a small volume made of organic-compatible materials are required. Additionally, any contact of the support with the organic electrolyte has to be strictly eliminated in order to avoid the corrosion. Most BDD electrodes are on a silicon support which causes eventual loss of the BDD electrode by the brittle nature of crystalline silicon. Consequently, the material used for sealing has to be inert but soft enough to avoid friction of the silicon support. The available BDD... 

Canizares, P., Saez, C., Lobato, J. and Rodrigo, M. A. (2004b) Electrochemical treatment of 2,4-dinitrophenol aqueous wastes using boron-doped diamond anodes. Electrochim. Acta 49, 4641 1650. 

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