Treatment Technology

The Department evaluated Information on treatment technologies collected from the literature, a survey of treatment technology vendors, site visits to selected treatment facilities in California, and an industry survey. There are two major groups of demonstrated technologies for aqueous wastes with metals chemical precipitation, and chemical or electrochemical reduction. 

Chemical precipitation refers to both the primary steps of forming the insoluble metal precipitates from dissolved metal ions by the precipitant(s), and follow-up operations that separate the solid precipitates from the liquid. 

There are two treatability groups of dissolved metals for chemical precipitation, complexed and non-complexed metals. Non-complexed metals can be removed by a direct precipitation with such a chemical as lime (Ca(OH) ), caustic (NaOH), sodium sulfide (Na2S), ferrous sulfide (FeS), or sodium carbonate (NajCOj). Complexed metals require coprecipitation with ferrous sulfate (FeS04), ferrous chloride (FeClj), or sodium dimethyl dithiocarbamate (DTC) in addition to a regular precipitant such as caustic or lime. Electrochemically generated ferrous ion is also effective in removing a wide variety of heavy metals, including hexavalent chromium. 

The Army has a number of options available for the treatment of NSCWM. They include the use of facilities designed to treat both non-stockpile and stockpile CWM, the use of mobile systems that can be incorporated into a facility or transported to the site of a find, and individual treatment technologies. Like mobile systems, individual treatment technologies may be incorporated into a larger entity such as a facility or mobile system or transported to the site of a find. This chapter examines these options, or tools, and, where appropriate, presents the committee s findings and recommendations related to their use. Each facility, mobile system, and individual technology is examined from the standpoint of its current status, as well as technical, RAP, and public involvement issues. An overview of the options for treating NSCWM considered in this chapter appears in Table 2-1. 

The discussion in this chapter is based on information the committee was able to gather on available test results or operational plans for use of the tools as presented by the Army. However, equipment does not always function as designed, and unexpected events—even catastrophic failures—may occur. The Army has conducted preliminary accident risk assessments of treatment systems (see, for example, U.S. Army, 2001a, Appendix D, Summary of Accident Risk Assessment ) but does not appear to have conducted an integrated site-specific risk assessment of its systems, including the risks of catastrophic failures. 

As discussed in Chapter 1, non-stockpile sites span a considerable range—from sites at which large numbers of nonstockpile munitions are buried or stored, to sites containing only a few chemical agent identification set (CAIS) vials or 

Some treatment options, such as the use of stockpile incinerators, would destroy the non-stockpile item directly. Others, especially those involving chemical neutralization, generate liquid secondary waste streams that require further treatment before disposal. This secondary waste treatment could take place in a commercial treatment, storage, and disposal facility (TSDF) or could employ one or more of the individual alternative technologies, such as chemical oxidation, either at the site where chemical neutralization takes place or at an off-site location. If secondary waste is defined as hazardous waste, such treatment would need to be conducted at a commercial TSDF permitted or approved by the appropriate regulatory authority under the Resource Conservation and Recovery Act (RCRA). 

The Army has at its disposition four principle types of facilities for treating non-stockpile chemical materiel nonstockpile facilities, designed to destroy large quantities of dissimilar CWM stockpile facilities, constructed to destroy large quantities of similar CWM research and development facilities and commercial treatment, storage, and disposal facilities (TSDFs). 

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S. Palmer and co-workers, MetaljCyanide Containing Wastes Treatment Technologies, Pollution Technology Review No. 158, Noyes Data Corp., Park Ridge, N.J., 1988, pp. 373-377. 

Table 1. Summary of Hazardous Waste Treatment Technologies...

E. J. Bouwer and G. D. Cobb, In Situ Groundwater Treatment Technology EsingBiodegradation, U.S. Army Toxic and Hazardous Materials Agency, Report AMXTH-TE-CR-88023, Washington, D.C., 1987. 

Fig. 1. Alternative wastewater treatment technologies, where GAC = granular activated carbon, PAC = powdered activated carbon, POTW = publicly owned treatment works, and RBC = rotating biological contactor (— ), wastewater return flows (—— ), sludge.

J. W. Patterson, Industrial Wasteirater Treatment Technology, Butterworth, Boston, 1985. 

Treatment Technology Background Document, United States Environmental Protection Agency (EPA), 1989. 

Optimized modern dry scrubbing systems for incinerator gas cleaning are much more effective (and expensive) than their counterparts used so far for utility boiler flue gas cleaning. Brinckman and Maresca [ASME Med. Waste Symp. (1992)] describe the use of dry hydrated lime or sodium bicarbonate injection followed by membrane filtration as preferred treatment technology for control of acid gas and particulate matter emissions from modular medical waste incinerators, which have especially high dioxin emissions. 

Implementation of cleaner production processes and pollution prevention measures can yield both economic and environmental benefits. The primary treatment technologies afforded to this manufacturing include the following ... 

It should be emphasized, however, that pollution prevention techniques are, nevertheless, often more cost-effective than pollution reduction through end-of-pipe treatment technologies. A case study based on the Amoco/EPA joint study claimed that the same pollution reduction currently realized through end-of-pipe regulatory requirements at the Amoco facility could be achieved at 15% of the current costs using pollution prevention techniques. 

Table 8 provides a list of pollution prevention practices for reducing air emissions in mini steel mills. Standard treatment technologies for air emissions are as follows. Dust emission control technologies include cyclones, baghouses, and ESPs. Scrubbers are used to control acid mists. 

Make no mistake about it - air pollution abatement, especially based upon end-of-pipe treatment technologies is expensive. Not too long ago the prevailing attitude among industry stakeholders was that air pollution control was simply a part of the cost of doing business, and that add-on costs associated with compliance simply had to be passed on to the consumer s purchase price for products. With the intensity of international competition in the chemical and allied industries, this philosophy simply does not cut it anymore. 

Although it is generally thought of as typical end-of-pipe treatment technology, the maimer in which it can be applied enables it to be used in pollution prevention applications. Figure 9 shows an installation in a steel mill operation. 

This brings us to some very basic principles of cost accounting. These concepts were covered in the first volume of this series Handbook of Water and Wastewater Treatment Technologies), but we will repeat a portion of them here because of their particular relevance to plarming air pollution control projects. The... 

RCRA Facility Investigation (RFI) - site characterization and pre-investigation identification of possible containment/treatment technologies ... 

Bench- or pilot-scale studies are necessary to demonstrate the ability of a technology to effectively treat a specific waste. Waste characteristics vary from site to site and because of this, the effect of a treatment technology with that particular waste may not be known, given the site-specific factors and conditions. Also, the proposed treatment technology may be new or unproven. 

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