Minimum Detection Limits for Toxic Pollutants

Toxic Pollutant

Organic pollutants Pesticides Metals Antimony Arsenic Asbestos Beryllium Cadmium Chromium Copper Cyanide Lead Mercury Nickel Selenium Silver Thallium Zinc

Concentration (|J.g/L)

10 5

100 10

1 x 107 fibers/L 10 2 5 9 100 20 0.1 5 10 20 100 50

Source: U.S. EPA, Development Document for Effluent Limitations Guidelines and Standards for the Aluminum Forming Point Source Category, Vols. 1 & 2, U.S. EPA, Washington, DC, 1984; U.S. EPA, Aluminum Forming Point Source Category, 2008.

on the pollutant removal efficiency at Plant A are summarized in Table 5.13. No production or water usage data are available for this plant.

5.4.2 Plant B: Case History

No plant-specific identification number was available for this facility. The wastewater from Plant B contains pollutants from both metals processing and finishing operations. It is treated by precipitation-settling followed by filtration with a rapid sand filter. A clarifier is used to remove much of the solids load. Table 5.14 summarizes the data on pollutant removal efficiency at Plant B.

5.4.3 U.S. EPA Data on Full-Scale Treatment of Aluminum Forming Wastewaters

U.S. EPA has documented case histories of full-scale treatment of aluminum forming wastewaters, which are included in Appendixes A, B, C, and D of this chapter for reference. The detailed theories and principles of the full-scale treatment processes can be found in the literature.8-10

Appendix A presents the actual data on a full-scale treatment of aluminum forming wastewater by emulsion breaking and oil-water separation. Either chemical emulsion breaking (CEB) or thermal emulsion breaking (TEB) can be used for breaking the emulsified oil in wastewater. Once the emulsified oil is freed as oil drops, it can be easily removed by an API oil-water separator (Figure 5.1), a parallel plate separator (Figure 5.2), an ultrafiltration unit, or a dissolved air flotation clarifier.8-10 It is very encouraging to note that over 94% of TSS, COD, TOC, O&G (oil and grease), cadmium, chromium, copper, lead, nickel, zinc, acenaphthene, phenol, bis-(2-ethylhexyl)-phthalate, bi-n-butyl phthalate, anthracene, fluorine, phenanthrene, pyrene, endrin-aldehyde, and PCB can be successfully removed by these preliminary treatment processes.

Appendix B presents the U.S. EPA data on a full-scale treatment of aluminum forming wastewater by emulsion breaking and ultrafiltration. After emulsion breaking, various oil-water separation

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