Emission control sludge

Many different chemical treatment systems have been developed to reduce the leachability of lead and cadmium compounds in flue dust. These systems usually rely on stabilization/solidification, adsorption, chemical reduction, or pH control. Chemical reduction employing the use of metallic iron has been successful in reducing the leachability of lead to below EP-Toxicity levels. Adding a 5 percent by weight dose of iron filings to cupola furnace emissions control sludge, for instance, reduced lead leaching from 28.6 mg/1 to less than 0.1 mg/1 (Stephens 1984). 

FIGURE 7 LEAD AND CADMIUM LEACHATE CONCENTRATIONS FROM CUPOLA EMISSION CONTROL SLUDGE TREATED WITH METALLIC IRON... 

Use of some biomass feedstocks can increase potential environmental risks. Municipal solid waste can contain toxic materials that can produce dioxins and other poisons in the flue gas, and these should not be burned without special emission controls. Demolition wood can contain lead from paint, other heavy metals, creosote, and halides used in presen a-tive treatments. Sewage sludge has a high amount of sulfur, and sulfur dioxide emission can increase if sewage sludge is used as a feedstock. 

The primary leachable hazardous constituents of EAF emission control dust/sludge are lead, cadmium, and hexavalent chromium. Generally, 20 to 40 lb of EAF dust per ton of steel are generated, depending on the mill s specific operating practices, with an average of about 35 lb/t of steel melted.1 Table 2.11 shows the typical ranges of concentration of each of these elements in EAF dust. 

Pollutants and sludges extracted from CAA air emission control devices are subject to RCRA hazardous waste regulations if hazardous... 

If an incinerator burns a listed hazardous waste, the ash is also considered a listed waste. The derived-from rule states that any solid waste generated from the treatment, storage, or disposal of a listed hazardous waste, including any sludge, spill residue, ash, emission control dust, or leachate, remains a hazardous waste unless and until it is delisted. The owner/operator must also determine whether the ash exhibits any of the characteristics of a hazardous waste. 

Both air emission control and sludge disposal are extremely important in a steel acid pickling plant.18-20... 

The capital cost includes covered tank, carhon feed system. O M costs cited are for groundwater treatment, air emissions control/treatment, sludge dewatering/disposal, and analytical. 

The vendor claims that Mixflo is an economical option for capacity expansion and emission control at wastewater treatment plants. According to the vendor, upgrading air-based activated sludge treatment systems with Mixflo can reduce energy costs by greater than one third (D22912J,... 

Stephens, W.A., Stolzenburg, T.R., Stanforth R.R., and Etzel, J.E. May 1984. "Use of Iron to Render Sludge from Ferrous Foundry Melting Furnace Emission Control Waste Nonhazardous." Presented at the 39th Annual Purdue Industrial Waste Conference. West Lafayette, Indiana. 

In a study (Boyle, et al., 1981) conducted by the American Foundrymen s Society (AFS) in conjunction with the University of Wisconsin and the USEPA, leaching tests were conducted on cupola emission control dusts and sludges from 21 different foundries. This study concluded that 9 out of the 21 foundries generated emission control residuals which would be considered as a hazardous waste on the basis of EP Toxicity for lead. Two other foundries generated emission control residuals which would be classified as hazardous on the basis of EP Toxicity for cadmium. Concentrations in the EP Toxicity Test for the 21 foundries ranged from less than 0.6 mg/1 to 130 mg/1. The mean lead... 

Electric arc furnace dust is a listed hazardous chemical waste. This material is deemed hazardous because it contains relatively high concentrations of heavy metals. The waste consists of the emission control dust or sludge collected from electric arc furnaces during the manufacture of iron and steel. The principle chemicals of concern and their concentrations are listed in Table 7.5 (EPA, 1988). 

However, emission control dust or sludge from ferrochromium and ferrochromium-silicon production is listed as hazardous waste by EPA (1988b). The processed wastes from several chromium chemical industries are designated as hazardous wastes as well (EPA 1981), and disposal of process wastes is regulated by the EPA. Land filling appears to be the most important method for the disposal of chromium wastes generated by chemical industries. Of the total chromium released in the environment by chemical industries, 82.3% is released on land. An equally large amount of chromium waste is transferred off-site (see Section 5.2). It is anticipated that most of this off-site waste will be disposed of in landfills after proper treatment. It is important to convert chromium wastes into forms of chromium... 

FIGURE 5.1 I Multiple hearth combustion unit with emission controls, for the disposal of sludges and combustible solid wastes. Rakes around air preheat tube at center of multiple hearth unit rotate slowly around tube to move initial sludges or solids across each tray and down, eventually to exit as ash from the base of the unit. (Adapted from Sebastian and Cardinal [74]. Excerpted by special permission from Chemical Engineering [Oct. 1998]. Copyright 1968, by McGraw-Hill, Inc., New York, NY 10020.)... 

K061. . Emission control dust/sludge from the primary production of steel in electric furnaces... 

KlOO. . Waste leaching solution from acid leaching of emission control dust/sludge from secondary lead smelting... 

The Control of Industrial Pollution Water Quality and Health Aspects of the Chemistry and Analysis of Substances of Concern in the Water Cycle The Role of Wastewater Treatment Processes in the Removal of Toxic Pollutants Sewage and Sewage Sludge Treatment The Chemistry of Metal Pollutants in Water Effects of Pollutants on the Aquatic Environment Important Air Pollutants and Their Chemical Analysis Pollutant Pathways and Modelling of Air Pollution Legislation and the Control of Air Pollution Catalyst Systems for Emission Control from Motor Vehicles Evaluating Pollution Effects on Plant Productivity A Cautionary Tale Epidemics of Non-infectious Disease Systems Methods in the Evaluation of Environmental Pollution Problems Organometallic Compounds in the Environment. 

While the emphasis here has been on the reduction of the amount of waste sludges, it is also equally important to address the problem of regulating the effluents and emissions. In this context, special mention may be made of ammonia which must be carefully regulated. The procedure for processing ammonium fluoride or ammonium sulfate containing solutions begins with lime treatment. The filtrates are fed continuously into a column and stripped with live steam and upgraded. In this way it is possible (with improved equipment and carefully controlled operation) to attain ammonia contents of less than 50 ppm in the effluent. 

Extraction of pollutants from air emissions using CAA controls (e.g., scrubbers) can create hazardous wastes or sludges containing such wastes. Disposal of these materials must comply with RCRA. 

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