Liquid purification or separation – Processes – Making an insoluble substance or accreting suspended...
Patent
1988-10-26
1991-03-19
Hruskoci, Peter
Liquid purification or separation
Processes
Making an insoluble substance or accreting suspended...
210715, 210720, 210724, 210726, 210748, 210913, 423 55, C02F 152, C02F 170
Patent
active
050008595
DESCRIPTION:
DESCRIPTION
DETAILED DESCRIPTION OF THE INVENTION
While the invention will be described primarily as related to processing waste streams from an electroplating facility, it will be appreciated that the process is useful for any waste stream containing appreciable amounts of heavy metal in order to minimize sludge generation. The reduction of hexavalent chromium (Cr.sup.+6) to trivalent chromium (Cr.sup.+3), while important in treating waste water comprising electroplating effluent, is not by itself the primary point of invention herein. The thrust of the invention is the treatment of metal bearing waste water in a novel process wherein significantly lower quantities of sludge are produced than is possible using conventional waste water treating processes.
Environmental Protection Agency (EPA) imposed limits for heavy metal concentrations in effluent from waste treatment plants at the Air Logistics Centers (ALCs) are set forth in TABLE I.
TABLE I ______________________________________
Concentration
Constituent (mg/L)
______________________________________
Cadmium, Total 0.03
Chromium, Total 1.0
Chromium, Hexavalent
0.1
Copper, Total 0.1
Lead, Total 0.1
Nickel, Total 1.0
Zinc, Total 1.0
______________________________________
Since 1980, the EPA has classified sludges bearing concentrations of such metals above permit limits as hazardous wastes and have required disposal in hazardous waste landfills, typically at a cost greater than $168 per ton. While certain processes, such as sludge dewatering, have been implemented to reduce the amount of sludge produced, no processes to date have been effective to reduce appreciably the amounts of generated sludge.
The commercially available Sulfex.TM. process is intended for precipitation of heavy metals, (not Cr.sup.+6 reduction) and produces a greater quantity of sludge than the conventional acid/SO.sub.2 /lime process. The process described in U.S. Pat. No. 4,705,639 referred to above is directed to a waste treatment scheme similar to that described herein; that prior process assumes 90-100% efficiency in transfer of electrons from a donor source to a selective recipient in a waste water stream containing many different and competitive ions. Such a process efficiency is not practical, and substantial excesses over stoichiometric quantities of treatment constituents may be required to effectively precipitate most heavy metal.
The invention can be illustrated by the following examples performed in demonstration of the invention and in definition of the process parameters thereof.
EXAMPLE I
Analyses were made of Cr.sup.+6 reduction and heavy metal removal in distilled water and electroplating wastes. Jar tests were conducted using Phipps and Bird six-paddle stirrer with an illuminated base. Beakers were filled with 800 ml of distilled water and 10 ml of a 2,000 milligrams per liter (mg/L) Cr.sup.+6 solution. The pH of each solution was adjusted with either caustic or lime. Appropriate volumes of 1,000 mg/L S.sup.-2 solution (Na.sub.2 S/9H.sub.2 O) was added to each beaker. The solutions were stirred at 100 rpm while the pH of each was adjusted as desired. After six minutes of stirring, the appropriate volume of a 1,000 mg/L ferrous solution (as FeSO.sub.4 /7H.sub.2 O) was added. It may be noted here that in the practice of the invention described herein the ferrous ion may be added in the form either as sulfate or chloride. The volume was brought to 1,000 ml with distilled water and pH adjusted again while the solutions were stirred at 100 rpm. After six minutes. mixing was slowed to 20 rpm for two minutes, during which period final pH adjustments were made. Stirring was stopped and the solutions were allowed to stand for two minutes. If required, the solution was filtered using a funnel with a cotton plug.
Cr.sup.+6 was determined using the 1,5-diphenyl carbohydrazide method and standard Hach Chemical Company procedures. Ferrous concentration was determined using the Hach procedures for the 1,10-phenanthroline method. Sulfide was determined using the Hach procedu
REFERENCES:
patent: 1932531 (1933-10-01), Parker
patent: 2110187 (1938-03-01), Williams
patent: 2346320 (1944-04-01), Moran et al.
patent: 2977202 (1961-03-01), Bueltman et al.
patent: 3023089 (1962-02-01), Graves et al.
patent: 3027321 (1962-03-01), Selm et al.
patent: 3218252 (1965-11-01), Glover et al.
patent: 3294680 (1966-12-01), Lancy
patent: 3575853 (1971-04-01), Gaughan et al.
patent: 3740331 (1973-06-01), Anderson et al.
patent: 4102784 (1978-07-01), Schlauch
patent: 4362629 (1982-12-01), Senda et al.
patent: 4705639 (1987-11-01), Aldrich
"Rate Studies on the Primary Step of the Reduction of Chromium (VI) by Iron (II)", James H. Espenson, J Am Chem Soc 92:7 (Apr. 8, 1970).
"Sulfide Process Removes Metals, Produces Disposable Sludge", M. C. Scott, Industrial Wastes (Jul./Aug. 1979).
"Potential Transformations of Chrominum in Natural Waters", David C. Schroeder and G. Fred Lee, Water, Air, and Soil Pollution 4:3/4 (Jul./Aug. 1975).
"Treatment of Metal Finishing Wastes by Sulfide Precipitation", Richard M. Schlauch and Arthur C. Epstein, Rept No EPA600/2-77-049 (Feb. 1977).
"Sulfide vs Hydroxide Precipitation of Heavy Metals From Industrial Wastewater", A. K. Robinson, 1st Annual Conference on Advanced Pollution Control for the Metal Finishing Industry, Jan. 1978, Rept No EPA-600/8-78-010, pp. 59-65 (May 1978).
"An EPA Demonstration Plant for Heavy Metals Removal by Sulfide Precipitation", Murray C. Scott, Second Conference on Advanced Pollution Control for the Metal Finishing Industry, Rept No EPA-600/8-79-014, pp. 106-113 (Jun. 1979).
"Summary Report-Control and Treatment Technology for the Metal Finishing Industry-Sulfide Precipitation", Rept No. EPA-625/8-80 -003 (Apr. 1980).
"Treatment of Plating Wastewaters by Ferrous Reduction, Sulfide Precipitation, Coagulation and Upflow Filtration", Thomas E. Higgins, Arizona State Univ. Rept. No. ERC-R-81014 (May 1981).
"Alkaline Chromium (VI) Reduction by Ferrous Iron and Sulfide", Thomas E. Higgins et al., Arizona State University Rept. No. ERC-R-81028 (Oct. 1981).
"Combined Removal of Cr, Cd and Ni by Alkaline Reduction, Precipitation and Upflow Filtration", Thomas E. Higgins et al., Arizona State University, Rept. No. CR-R-83015 (Mar. 1983).
"Treatment of Electroplating Wastewaters by Alkaline Ferrous Reduction of Chromium & Sulfide Precipitation", Thomas E. Higgins et al., Rept. No. ESL-TR-83-21 (Jun. 1983).
"Sludge Generation from Ferrous/Sulfide Chromium Treatment", J. R. Aldrich, Rept. No. ESL-TR-84-27 (Aug. 1984).
"Ferrous and Sulfide Treatment of Industrial Wastewater at OC-ALC", CENTEC Applied Technologies (Oct. 15, 1985).
"Final Report-Ferrous and Sulfide Treatment of Industrial Wastewater at OC-ALC", CENTEC Corporation (Dec. 16, 1985).
"Final Report, Research and Development Design and Evaluation Report, Ferrous andd Sulfide Treatment of Hexavalent Chromium", CENTEC Corporation (Jan. 1986).
"Sodium Sulfide/Ferrous Sulfate Treatment of Hexavalent Chromium and Other Heavy Metals at Tinker AFB", P. M. Wikoff et al., Rept. No. ESL-TR-87-39 (Mar. 1988).
"Pilot Field Verification Studies of the Sodium Sulfide/Ferrous Sulfate Treatment Pr
Beller John M.
Carpenter Charles J.
Suciu Dan F.
Wikoff Penny M.
Hruskoci Peter
The United States of America as represented by the Secretary of
LandOfFree
Process for sodium sulfide/ferrous sulfate treatment of hexavale does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for sodium sulfide/ferrous sulfate treatment of hexavale, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for sodium sulfide/ferrous sulfate treatment of hexavale will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2008297