Phsicochemical Treatment of Hazardous Wastes - Chapter 3 pptx

3 Physicochemical Treatment Processes 3.1 Introduction Treatment technologies can be classified many different ways. For example, for achieving cleanup standards, the Clear Water Act (CWA) classifies treatment technologies as follows: • Best practicable control technology (BPCT) applies to all pollutants. • Best conventional technology (BCT) applies to conventional pollutants. • Best available technology (BAT) applies to toxic and unconventional pollutants. • Best available demonstrated technology (BADT) is used for new dischargers. According to treatment mechanisms, however, treatment technologies are classified as biological, physicochemical, and thermal processes. In terms of the place where the actual treatment takes place, the issue of in situ vs. ex situ comes into play as far as selecting the most cost-effective remediation processes. For example, most bioremediation processes are in situ , while physicochemical processes may be implemented both in situ and ex situ , according to the following: • In situ physical/chemical treatment — The advantage of in situ treatment is that it allows soil to be treated without being excavated and transported; however, it generally requires longer time periods, and treatment uniformity is less certain because of the variability in soil and aquifer characteristics. Physical/chemical treatment processes destroy, separate, or contain pollutants by using physicochemical approaches. Physical/chemical technologies for volatile organic compounds (VOCs) include soil flushing, soil vapor extraction, and solidification/stabilization ( in situ vitrification). TX69272_C03.fm Page 55 Tuesday, November 11, 2003 11:39 AM © 2004 by CRC Press LLC 56 Physicochemical Treatment of Hazardous Wastes • Ex situ physical/chemical treatment — Ex situ treatment generally requires excavation of soil or pumping of groundwater — processes that may increase costs but which are less time consuming than in situ treatment. In addition, ex situ treatment is more reliable due to being able to homogenize the contaminants. The available ex situ physicochemical technologies for VOCs consist of soil washing, ultraviolet oxidation, air stripping, liquid-phase carbon adsorption, and dehalogenation. • In situ thermal treatment — In situ thermal treatment allows pollutants to be treated without being excavated and transported. Thermal treatment requires a shorter clean-up time; however, high costs are usually associated with the amount of energy and equipment required. For example, enhanced soil vapor extraction is usually an energy-intensive process. • Ex situ thermal treatment — Ex situ thermal treatment generally requires excavation of soil or pumping of groundwater, processes that may increase costs; however, much shorter time is required for ex situ than in situ treatment. Moreover, it can achieve the designed efficiency due to the controlled reaction environments. Thermal processes typically use heat to increase the volatility (separation), det- onate (destruction), or melt (immobilization). Innovative ex situ thermal treatment technologies for VOCs include thermal desorption (separation technology) and incineration (destruction technology). The history of physicochemical treatment processes is summarized in Table 3.1. 3.2 Treatment Technologies 3.2.1 Phase Transfer Technologies for Halogenated VOCs and Nonhalogenated VOCs 3.2.1.1 Air Stripping Air stripping can be used to separate a broad range of VOCs from water; however, it is effective only for contaminated water with VOC or semivolatile concentrations with a dimensionless Henry’s constant greater than 0.01. Henry’s law constant is used to determine whether air stripping will be effective. Generally, organic compounds with Henry’s constants greater than 0.01 atm-m 3 /mol, such as chloroethane, trichloroethylene (TCE), dichloro- ethylene (DCE), and perchloroethylene (PCE), are amenable to air stripping. Organic pollutants with low volatility at cold temperatures may require preheating of groundwater. Figure 3.1 shows the relative range of Henry’s TX69272_C03.fm Page 56 Tuesday, November 11, 2003 11:39 AM © 2004 by CRC Press LLC Physicochemical Treatment Processes 57 TABLE 3.1 Historical Aspects of Treatment Technologies for VOCS and SVOCS Time Technologies/Events Contaminant Organization 1874 First incinerator (Cheremisinoff, 1989) Hazardous wastes British government 1885 First U.S. incinerators (Cheremisinoff, 1989) Hazardous wastes U.S. government 1947– 1977 Hot spot: PCBs from two electric plants were discharged into the Hudson River PCBs U.S. government 1974 Vulcanus incinerator ship test in Gulf of Mexico Halogenated VOCs USEPA 1976– 1983 Love Canal, New York Dioxins, TCP, and hazardous wastes Hooker Chemical Company, New York 1982 Times Beach, Missouri Dioxins, and hazardous wastes U.S. government 1983 Vulcanus II in North Sea Halogenated VOCs USEPA 1983 Mobile rotary kiln with afterburn facility HCB, 1,2-4 trichlorobenzenes in toluene USEPA 1987 Terra Vac, vacuum extraction system (Cheremisinoff, 1989) VOCs and TCE Valleys Products Co., Ltd., Montana 1987 Organic extraction using solvents at the general refining Superfund site in Savannah, GA (Cheremisinoff, 1989) Oily sludges, hydrocarbon- contaminated soil, and triethylamine (TEA) Resources Conservation Company, Georgia 1988 Organic extraction using solvents at New Bedford Harbor, MA (Cheremisinoff, 1989) PCBs (sediments) CF Systems Corporation , Arvada, CO 1989 Debris washing system (Cheremisinoff, 1989) PCBs, pesticides, and metals IT Corporation / USEPA 1989 Soil washing system (water-based volume reduction) at MacGillis & Gibbs Superfund site in Minnesota (Cheremisinoff, 1989) PAHs, PCBs, and PCP BioTrol, Inc., Minnesota 1990 AquaDetox, integrated vapor extraction and stream vacuum stripping (Cheremisinoff, 1989) VOCs, PCE, and TCE Dow Chemical Co., Ltd. 1990s Detoxifier for in situ stream/air stripping (Cheremisinoff, 1989) VOCs, PCBs, and SVOCs Toxic Treatment (USA) Inc., California 1991 Membrane microfiltration at the Palmerton Zinc Superfund site in Pennsylvania VOCs (liquid), metals, and oily, inorganic, organic wastes E.I. DuPont de Nemours and Oberlin Filter Company 1990s Udell Technologies’ stream injection and vacuum extraction (Cheremisinoff, 1989) VOCs and SVOCs McClellan Air Force Base, California 1993 In situ stabilization/solidification proprietary binder (Cheremisinoff, 1989) SVOCs in soil S.M.W. Seiko, Inc., California TX69272_C03.fm Page 57 Tuesday, November 11, 2003 11:39 AM © 2004 by CRC Press LLC 58 Physicochemical Treatment of Hazardous Wastes FIGURE 3.1 Ranges and relative values. (From Thomas, R.G., Volatilization from soil, in Handbook of Chemical Property Estimation Methods , Lyman, W. J., Reed, W.F., and Rosenblatt, D.H., Eds., McGraw-Hill, New York, 1982, chap. 16. With permission.) TX69272_C03.fm Page 58 Tuesday, November 11, 2003 11:39 AM © 2004 by CRC Press LLC © 2004 by CRC Press LLC Physicochemical Treatment Processes 59 constants of organic pollutants and their volatility in terms of treatability using air-stripping technology. Typical design considerations include feed water flow rates, water and air temperatures, tower feed and discharge systems (gravity feed or type and location of pumps), and influent contaminant concentrations. In addition, requirements for effluent water contaminant concentrations and restrictions on air emission should be considered according to the various federal and state regulations. Air stripping involves the mass transfer of volatile contaminants from water to air. An air-stripping tower usually packs a number of trays in a very small chamber to maximize air–water contact while minimizing space. Because of the significant vertical and horizontal space savings, these units are increasingly being used for groundwater treatment. A major operating cost of air strippers is the amount of electricity required for the groundwater pump, the sump discharge pump, and the air blower. Fouling of packing may cause a reduction of the airflow rate, which is caused by the oxidation of minerals (such as iron and manganese) in the feed water, by precipitation of calcium, and by biological growth on the packing material. In-well stripping technology utilizes the application of VOCs for the treatment of contaminated groundwater. Typically, a blower introduces air or an inert gas (e.g., nitrogen) into the water column within an extraction well. Bubbles produced by the gas create enough pressure to suck the VOCs in the contaminated water into the bubbles by volatilization. Wells are usually equipped with two screened sections and a deflector plate. As the contaminated water encounters the deflector plate, the bubbles break and combine. Water then flows from the screen section, re-infiltrating the vadose zone until all the remediation goals are met. Peng et al. (1994) investigated the volatilization of benzene, toluene, trichloroethene, and tetrachloroethene from qui- escent water. The volatilization rate was found to be inversely proportional to the square of the water depth. 3.2.1.2 Soil Vapor Extraction (SVE) In situ soil vapor extraction (SVE) is a process for removing and venting VOCs from the unsaturated (vadose) zone of soil (Cheremisinoff, 1989). A vacuum is applied to the soil to induce a flow of clean air from the atmosphere into the subsurface. The process resembles continuous flushing of the soil with clean air and continues until volatilization and desorption of contaminants are complete. The gas that leaves the soil can be processed for VOC removal (e.g., via activated carbon adsorption) and then discharged to the atmosphere or injected into the subsurface. It can also be destroyed by combustion in existing boilers that are operating on a continuous basis, depending on local and state air discharge regulations. Vertical extraction vents are typically used at depths of 1.5 m, although they have been successfully applied to a depth of 91 m. Horizontal extraction vents can be used depending on the contaminant zone geometry, drill rig access, or other site-specific factors. TX69272_C03.fm Page 59 Tuesday, November 11, 2003 11:39 AM © 2004 by CRC Press LLC 60 Physicochemical Treatment of Hazardous Wastes Vapor extraction and air injection wells differ from conventional groundwater monitoring wells in that they are installed in the vadose zone with the screened sections extending above the water table surface. A geo- membrane is placed over the soil surface to prevent short circuiting and the loss of the injected air to the ground surface. In case of a high groundwater table or when the contamination is confined to shallow depths, perforated pipes buried in horizontal trenches would be used in lieu of wells. Compounds with a Henry’s law constant greater than 0.01 or that exhibit vapor pressure greater than 0.5 mmHg (0.02 in Hg) can be successfully treated by in situ SVE. For example, solvents such as perchloroethylene (PCE) and trichloroethylene (TCE) and most constituents in gasoline can be effectively removed by this technology. On the other hand, SVE will not remove heavy oils, metals, polychlorinated biphenyls (PCBs), or dioxins. The technical factors that must be considered include: (1) volatility of pollutants, (2) lateral and vertical concentration of VOCs, (3) soil types and properties (e.g., structure, texture, permeability, stratification, and moisture content), (4) emission control requirement, (5) schedule for cleanup, (6) position and length of screened interval, (7) blower type, and (8) site factors (e.g., depth and contaminated extension area, depth to water table). The cost of an SVE system varies with the size of the site, nature of the contaminants, and hydrological setting. Cost estimates for in situ SVE range from $10 to $50 per cubic meter of soil or from $10 to $40 per cubic yard (USEPA, 1989). The advantages of the SVE system are (1) relatively low cost, (2) low maintenance and operating costs, (3) treatment of VOC-contaminated soil in the vadose zone, (4) effective source control, and (5) no further release of contaminants to groundwater. Therefore, it is ideal to use at sites in highly developed areas and/or where contamination has spread to adjacent properties, or underneath buildings. The volatility of pollutants, type of soil, and groundwater hydrology will affect the treatment efficiency of the process; thus, SVE does have some disadvantages. For example, it is limited to volatile compounds, low groundwater table, and loose sandy formations. It is not recommended for low-hydraulic-conductivity soils (required conductivity exceeding 0.001 to 0.01 cm/sec). Soil that has a high percentage of fines and a high degree of saturation will require higher vacuums (increasing costs). As a result, the technology is not effective in saturated zones. Also, channeling treatments may result from nonhomogeneity of the subsurface; therefore, good knowl- edge of subsurface characteristics is required for the proper location and design of wells. Finally, soil of high organic content or that is extremely dry and has a high sorption capacity of VOCs may result in reduced removal rates. TX69272_C03.fm Page 60 Tuesday, November 11, 2003 11:39 AM © 2004 by CRC Press LLC Physicochemical Treatment Processes 61 3.2.2 Phase Transfer Technologies for Halogenated SVOCs, Nonhalogenated SVOCs, and Non-VOCs 3.2.2.1 Activated Carbon Adsorption Groundwater is pumped through a series of canisters or columns containing activated carbon to which dissolved organic contaminants adsorb. Hydrocarbons, semivolatile organic compounds (SVOCs), nonvolatile organic compounds (non-VOCs), and explosives are all easily removed by GAC; however, because it is a phase transfer technology organic pollutants are not destroyed. All of the used carbon eventually needs to be properly discarded. Periodic replacement or regeneration of saturated carbon is required. Type, pore size, quality of the carbon, and operating temperature will impact performance of the process. Streams with high suspended solids (>50 mg/L), oil, and grease (>10 mg/L) may cause fouling of the carbon and may require frequent treatment. Water-soluble compounds and small molecules are not adsorbed well. When the concentration of contaminants in the effluent from the bed exceeds a certain level, the carbon can be regenerated at the site. The two most common reactor configurations for carbon adsorption systems are fixed beds or moving beds. The fixed-bed configuration is the most commonly used for the adsorption of non-VOCs from contaminated waters. Liquid-phase carbon adsorption is effective for removing contaminants at low concentrations (<10 mg/L) from water at nearly any flow rate. It is also effective for removing higher concentrations of contaminants from water at low flow rates (typically 2 to 4 L/min or 0.5 to 1 ppm). The removal of suspended solids from contaminated water is critical for effective treatment. The major design variables for liquid-phase carbon applications are empty-bed contact time (EBCT), flow rate, and system configuration, all of which will have an impact on carbon usage. Particle size and hydraulic loading are often chosen to minimize pressure drop and reduce or eliminate backwashing. For a single adsorbent, the EBCT is normally chosen to be large enough to minimize the carbon usage rate. Alternatively, multiple beds in series may be used to decrease carbon usage rate. The theory and engineering aspects of the technology are well documented by performance data. Carbon adsorption is a relatively nonspecific adsorbent and is effective for removing many organic, explosive, and some inorganic contaminants from liquid and gaseous streams. Costs will depend on waste flow rate, type of contaminant, concentration of contaminant, mass loading, required effluent concentration, and site and timing requirements. Costs are lower at lower concentration levels of a contaminant. Costs are also lower at higher flow rates. At flow rates of 0.4 million L/day (0.1 million gal/day), costs increase from $0.32 to $1.70 per 1000 liters treated water ($1.20 to $6.30 per 1000 gallons treated water). 3.2.2.2 Soil Washing Contaminants are flushed out from soil by using suitable reagents such as surfactants. The contaminants are dissolved in washing solution or TX69272_C03.fm Page 61 Tuesday, November 11, 2003 11:39 AM © 2004 by CRC Press LLC 62 Physicochemical Treatment of Hazardous Wastes concentrated in a smaller volume of soil through size separation and attrition scrubbing. Soil washing would probably find its greatest site remediation where the soil is contaminated with a single contaminant or a class of contaminants. While certain contaminants such as simple phenols can be readily extracted from both organic and inorganic soils, other contaminants such as PCBs or arsenic cling tenaciously to the soils and resist release into the washing fluids. SVOCs, non-VOCs, and fuels are usually removed through soil washing. Heavy metals can be washed away from soil by using ethyl- enediamine tetraacetic acid (EDTA), which is recycled in the process. Soil washing can clean a wide range of organic and inorganic contaminants from coarse-grained soil and can recover chemicals from accidental chemical spills; however, the process is not feasible when a mixture containing a range of contaminants with different solubilities is present. The recovered solutions can be very dilute and large in volume, hence costly to treat. Washing processes that separate the clay silt from the coarser particles can effectively separate and concentrate the contaminants into a smaller volume of soil for further treatment. Sequential washing or different washing solutions may be required for a mixture of contaminants. In designing a soil washing system, soil size distribution (0.24 to 2 mm) and the characteristics, nature, and concentration of contaminants should be evaluated using a bench-scale treatability study. The average cost of $170 per ton depends on the target contaminant. 3.2.3 Thermal Treatment Processes 3.2.3.1 Thermal Desorption Thermal desorption is a physical separation process. Waste is heated to volatilize water and organic contaminants. A carrier gas or vacuum system transports volatilized water and organics to the gas treatment system. The bed temperatures and residence times designed for these systems will volatilize selected contaminants without oxidation. Three types of thermal desorption are available: 1. Direct fired process — Fire is applied directly to the surface of contaminated media. The main purpose of the fire is to desorb contaminants from the soil though some contaminants that may be thermally oxidized. 2. Indirect fired process — A direct-fired rotary dryer heats an air stream, which, by direct contact, desorbs water and organic contaminants from the soil. 3. Indirectly heated process — An externally fired rotary dryer volatilizes the water and organics from the contaminated media into an inert carrier gas stream. The carrier gas is later treated to remove or recover the contaminants. TX69272_C03.fm Page 62 Tuesday, November 11, 2003 11:39 AM © 2004 by CRC Press LLC Physicochemical Treatment Processes 63 Two common thermal desorption designs are the rotary dryer and thermal screw. Rotary dryers are horizontal cylinders that can be directly or indirectly fired. The dryer is normally inclined and rotated. For the thermal screw units, screw conveyors or hollow augers are used to transport the medium through an enclosed trough. Hot oil or steam circulates through the auger to indirectly heat the medium. All thermal desorption systems require the treatment of the off-gas to remove particulates and contaminants. Conventional particu- late removal equipment, such as wet scrubbers, remove particulates or fabric filters. Contaminants are removed through condensation followed by carbon adsorption, or they are destroyed in a secondary combustion chamber or a catalytic oxidizer. Most of these units are transportable. Based on the operating temperature of the desorbent, thermal desorption processes can be categorized into two types. The first is high-temperature thermal desorption (HTTD), in which waste is heated to temperatures from 320 to 560˚C (600 to 1000˚F). This process is frequently used in combination with incineration, solidification/stabilization, or dechlorination of SVOCs, PAHs, PCBs, and pesticides. The second type is low-temperature thermal desorption (LTTD), in which waste is heated to temperatures from 90 to 320˚C (200 to 600˚F). Nonhalogenated VOCs, SVOCs, and fuels can be effectively treated by LTTD. All ex situ soil thermal treatment systems employ similar feed systems consisting of a screening device to separate and remove materials, a belt conveyor to move the screened soil from the screen to the first thermal treatment chamber, and a weight belt to measure soil mass. The size reduction equipment can be incorporated into the feed system, but its installation is usually avoided to minimize shutdown as a result of equipment failure. Soil storage piles and feed equipment are generally covered to protect them from rain to minimize soil moisture content and material handling prob- lems. Soils and sediments with water contents greater than 20 to 25% may require the installation of a dryer. Some volatilization of contaminants occurs in the dryer, and the gases are routed to a thermal treatment chamber. The cost for this process ranges from $45 to $330 per metric ton ($40 to $300 per ton) of soil. The advantage of thermal desorption is that it is effective for the full spectrum of organic contaminants; however, dewatering may be necessary to achieve acceptable soil moisture content levels. Highly abrasive feed can potentially damage the processor unit, and heavy metals in the feed may produce a treated solid residue that requires stabilization. Clay, silty-type soil, and soil with a high humic content may increase reaction time because of the strong binding of contaminants between pollutants and soils. Maxymillian Technologies (1994) presented a full-scale test conducted by Clean Berkshires, Inc. They demonstrated that the thermal desorption system could treat soil contaminated with VOCs and PAHs and achieve 99.99% removal. TX69272_C03.fm Page 63 Tuesday, November 11, 2003 11:39 AM © 2004 by CRC Press LLC 64 Physicochemical Treatment of Hazardous Wastes 3.2.3.2 Dehalogenation at High Temperature Dehalogenation occurs by either the replacement of halogen molecules or the destruction of the contaminant. Soil and sediment that are contaminated with chlorinated organic compounds, especially PCBs, dioxins, and furans, can be remediated through dehalogenation. The contaminated soil is screened, processed with a crusher and pug mill, and mixed with sodium bicarbonate. The mixture is heated to above 330˚C (630˚F) in a reactor to partially decompose and volatilize the contaminants. The volatilized contaminants are captured, condensed, and treated separately. Treatability tests should be conducted to identify parameters such as water, alkaline metals, humus contents in the soils, the presence of multiple phases, and total organic halides that could affect processing time and costs. This technology uses standard equipment. The reaction vessel must be equipped to mix and heat the soil and reagents. The cost for the operation of a full- scale facility is estimated to range from $220 to $550 per metric ton ($200 to $500 per ton). The cost does not include excavation, refilling, residue disposal, or analytical costs. Factors such as high clay or moisture content may slightly increase the treatment cost. As opposed to air stripping or activated carbon adsorption, the contaminant is partially degraded rather than being transferred to another medium. The target contaminant groups for dehalogenation treatment are halogenated SVOCs, PCBs, and pesticides; however, high clay and moisture content will increase costs. Concentrations of chlorinated organics greater than 5% may require large volumes of chemical reagents. The dehalogenation process has been approved by the EPA’s Office of Toxic Substances for PCB treatment and has been experimentally implemented for the cleanup of PCB-contaminated soil at the following three Superfund sites: Wide Beach in Erie County, New York (1985); Re-Solve in Massachusetts (1987); and Sol Lynn in Texas (1988). The glycolate process has been used to successfully treat contaminant concentrations of PCBs from less than 2 ppm to reportedly as high as 45,000 ppm. Using this technology, Helland et al. (1995) investigated reductive dechlorination of carbon tetrachloride with elemental iron and found that the rate of dechlorination to chloroform and methylene chloride was a fast first-order process. 3.2.3.3 Incineration Incineration is required to have a destruction and removal efficiency (DRE) for hazardous wastes of greater than 99.99%. High temperatures ranging from 1600 to 2200˚F are used to combust halogenated and other refractory organics. Common types of incinerations are liquid injection incineration, rotary kiln incineration, infrared combustion, fluid-bed incineration, bub- bling fluid-bed incineration, and circulating fluid-bed incineration. Under extremely high temperatures, organic pollutants are completely oxidized to carbon dioxide and water. Design factors are threshold temperature, pressure, residence time, mixing intensity, air supply, and materials of construc- TX69272_C03.fm Page 64 Tuesday, November 11, 2003 11:39 AM © 2004 by CRC Press LLC [...]... aq Pb3+ aq Cu3(OH )32 –Pb (CO2 )3 CuCO3 AgSH CdOH– CoOH– Zn(OH)– Ag3S3H3 2- Organic Complexes, Chelates 10 Å Me-SR Me-OOCR C= O CH2 NH2 O Metal Species Bound to High-MolecularMetal Species in the Weight Organic Form of Highly Material Dispersed Colloids 100 Å Me-lipids Me-humic-acid polymers “Lakes” “Gelhstoffe” Me-polysaccharides FeOOH Fe(OH )3 Mn(IV) oxides Mn2O 13 ◊ 5H2O Na2Mn14O31Ag3S Metal Species Sorbed... Stabilization/solidification (soil) 3. 3.4.2 Remedial Cost The DOD estimates that the cost of completing the remaining work at all DOD sites will be over $28.6 billion © 2004 by CRC Press LLC TX69272_C 03. fm Page 70 Tuesday, November 11, 20 03 11 :39 AM 70 3. 3.5 Physicochemical Treatment of Hazardous Wastes Department of Energy 3. 3.5.1 Remedial Technology The Department of Energy recognized that much of the remediation... enhances the biodegradability of the chemicals The results of Adams et al show an initial decrease in the rate of biodegradation of EO/PO, but this decrease was followed by an © 2004 by CRC Press LLC TX69272_C 03. fm Page 76 Tuesday, November 11, 20 03 11 :39 AM 76 Physicochemical Treatment of Hazardous Wastes BOD5/COD 0.6 0.5 26mgO3/L/m 0.4 19.5mgO3/L/m 0 .3 13mgO3/L/m 0.2 6.5mgO3/L/m 0.1 0 0 2000 4000 Ozone... Sci., 33 1 33 3(A), 138 –142, 1995 © 2004 by CRC Press LLC TX69272_C 03. fm Page 81 Tuesday, November 11, 20 03 11 :39 AM Physicochemical Treatment Processes 81 Hewitt, A.D., Comparison of sample preparation methods for the analysis of volatile organic compounds in soil samples: solvent extraction vs vapor partitioning, J Environ Sci Technol., 32 (1), 1 43 149, 1998 Horst, G and Dieter, H., Analysis of vapor... Biotechnol., 74(5), 39 0 39 8, 1999 Rowe, D and Lloyd, W., The catalytic purification of CO-rich air, J AWMA, 49 (3) , 30 8 30 9, 1999 Sasaoka, E., Sada, N., Hara, K., and Sakata, Y., Catalytic activity of lime for N2O decomposition under coal combustion conditions, Indust Eng Res., 38 (4), 133 5– 134 0, 1999 Shin, H.S and Lim, J.L., Environ Sci Health, 31 (5), 1009–1024, 1996 Stefan, M and Bolton, J., Mechanism of the degradation... trickle-bed reactor, Indust Eng Chem Res., 131 0– 131 5, 38 (4), 1999 Biswas, P and Zachariah, M.R., In situ immobilization of lead species in combustion environments by injection of gas phase silica sorbent precursors, J Environ Sci Technol., 31 (9), 2455–24 63, 1997 Carberry, J.B and Benzing, T.M., Peroxide pre-oxidation of recalcitrant toxic waste to enhance biodegradation, Water Sci Technol., 23, 36 7 37 6,... A.W., Ed., Hazardous Waste Management, McGraw-Hill, New York, 1989 Cheremisinoff, P.C., Ed., Encyclopedia of Environmental Control Technology, Vol 1: Thermal Treatment of Hazardous Waste, Gulf Publishing, Houston, TX, 1989 Cheremisinoff, P.C., Ed., Encyclopedia of Environmental Control Technology, Vol 4: Hazardous Waste Containment and Treatment, Gulf Publishing, Houston, TX, 1990a Cheremisinoff, P.C.,... as off-site disposal and incineration The innovative technology most often selected has been SVE 3. 3.2.2 Remedial Cost According to an estimate derived from the Regulatory Impact Analysis (RIA), the RCRA will cost $38 .8 billion in 1996 dollars to implement PRPs will incur most of the cost (about 89%), with the remaining 11% being incurred by federal facilities 3. 3 .3 Underground Storage Tank Sites 3. 3 .3. 1... (From Norris, R.D et al., Handbook of Bioremediation, Lewis Publishers, Boca Raton, FL, 19 93 With permission.) © 2004 by CRC Press LLC TX69272_C 03. fm Page 74 Tuesday, November 11, 20 03 11 :39 AM 74 Physicochemical Treatment of Hazardous Wastes Extensive investigations have shown that molecular structure quantitatively affects the biodegradability of a compound Table 3. 3 summarizes quantitative structure–activity... Ion Pairs, Inorganic Complexes TX69272_C 03. fm Page 72 Tuesday, November 11, 20 03 11 :39 AM 72 TABLE 3. 2 TX69272_C 03. fm Page 73 Tuesday, November 11, 20 03 11 :39 AM Physicochemical Treatment Processes 73 • When particle size is between 100 and 1000 mm, the metal is membrane filterable These particles include metal species bound to highmolecular-weight organic materials • When particle size is . Cu 3 aq Fe 3+ aq Pb 3+ aq Cu 3 (OH) 3 2– Pb (CO 2 ) 3 CuCO 3 AgSH CdOH – CoOH – Zn(OH) – Ag 3 S 3 H 3 2- Me-SR Me-OOCR Me-lipids Me-humic-acid. billion. TX69272_C 03. fm Page 69 Tuesday, November 11, 20 03 11 :39 AM © 2004 by CRC Press LLC 70 Physicochemical Treatment of Hazardous Wastes 3. 3.5 Department of Energy 3. 3.5.1 Remedial Technology . (on-site or off-site) or treatment (in- site and off-site), similar to DOE or DOD as the predominant technologies 3. 3.7.2 Remedial Cost The EPA estimates that it will take an average of 30