Cadmium concentration, sludge

Jung J., Logan T.J. Effects of sewage sludge cadmium concentration on chemical extractability and plant uptake. J Environ Qual 1992 21 73-81. 

Webber J.H., Beauchamp E.G. Cadmium concentration and distribution in com (Zea mays L) growing on a calcareous soil for three annual sludge applications. J. Environ Sc Health B 1979 14 459 174. 

As a result of the implementation of this program, there has been a discernable reduction of the cadmium entering the Hyperion system. This was also apparent in the reduced cadmium concentration in the sludge at Hyperion Treatment Plant. 

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... 

Due to the wide use of cadmium-based products, cadmium is widely distributed in the environment. The cadmium content in soil and water has been increasing as a result of disposal of cadmium-contaminated waste and the use of cadmium-containing fertilizers (particularly on cereal crops). Commercial sludge, contaminated with cadmium, has been used to fertilize agricultural fields. Cadmium concentrations in urban air are quite low, because of regulation of industrial air emissions. Lead and zinc smelters and waste incineration account for the majority of cadmium present in ambient air. 

Neal, R. H., and Sposito. G. (1986). Effects of soluble organic matter and sewage sludge amendments on cadmium adsorption by soils at low cadmium concentrations. Soil Sci. 142, 164-172. 

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. 

Copper smelting Copper concentrate, siliceous flux Sulfur dioxide, particulate matter containing arsenic, antimony, cadmium, lead, mercury, and zinc Acid plant blowdown slurry/sludge, slag containing iron sulfides, silica... 

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

The latest projects to eliminate the production of waste treatment sludges were undertaken in the wet process metal plating production area. The projects, completed in March 1989, involved the installation of separate cadmium, chrome, copper and nickel recovery systems. All of the recovery systems utilized redundant conventional ion exchange columns for initial metal waste recovery and concentration. 

The impact to health has been mostly dependent on the concentration of the candidate metal. Some metals (e.g., mercury, lead, arsenic, cadmium, iron, copper) ultimately find their way into human systems via soil, minerals, and water. Studies have shown the presence of many metals in daily consumable products (e.g., food, fruits, milk, fabric materials, drinking water). Further, heavy metals associated with particle material can be accumulated in areas suitable for sedimentation or particle concentration (e.g., upstream from sills or dams, in estuary sludge clog, etc.). These accumulation areas are creating possible pollution sources, as particles pooled could be resuspended during punctual hydrologic periods (floods, drains). Bioavailability, and therefore toxicity of heavy metals, is strongly bound to the current chemical form. 

Cadmium is found in low concentrations in most soils and waters. It is produced as a by-product of zinc and lead mining and smeltering. Industrial use of cadmium has led to a dramatic increase in environmental problems caused by this element. Cadmium is used in semiconductors, nickel-cadmium batteries, electroplating, polyvinyl chloride (PVC) manufacturing, and control rods for nuclear reactors. The most important sources for aquatic contamination are active and inactive lead-zinc mines, land application of sewage sludge, zinc-cadmium smelters, effluents from plastic and steel production, and wastewaters from the production of nickel-cadmium batteries and electroplating (Zuiderveen, 1994). 

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