Hazardous waste separation

Thorium, uranium, and plutonium are well known for their role as the basic fuels (or sources of fuel) for the release of nuclear energy (5). The importance of the remainder of the actinide group Hes at present, for the most part, in the realm of pure research, but a number of practical appHcations are also known (6). The actinides present a storage-life problem in nuclear waste disposal and consideration is being given to separation methods for their recovery prior to disposal (see Waste treati nt, hazardous waste Nuclear reactors, waste managet nt). 

Dissolved Air Flotation. Dissolved air flotation (DAF) is used to separate suspended soflds and oil and grease from aqueous streams and to concentrate or thicken sludges. Air bubbles carry or float these materials to the surface where they can be removed. The air bubbles are formed by pressurizing either the influent wastewater or a portion of the effluent in the presence of air. When the pressurized stream enters the flotation tank which is at atmospheric pressure, the dissolved air comes out of solution as tiny, microscopic bubbles. Dissolved air flotation is used in many wastewater treatment systems, but in the United States it is perhaps best known with respect to hazardous waste because it is associated with the Hsted waste, K048, DAF flotation soflds from petroleum refining wastewaters. Of course, the process itself is not what is hazardous, but the materials it helps to remove from refining wastewaters. 

LandtiUing of Solid Wastes Landfilling involves the controlled disposal of solid wastes on or in the upper layer of the earth s mantle. Important aspects in the implementation of sanitary landfills include (1) site selection, (2) landfimng methods and operations, (3) occurrence of gases and leachate in landfills, (4) movement and control of landfill gases and leachate, and (5) landfill design. The landfilling of hazardous wastes is considered separately. 

LandtiUing of Hazardous Wastes In many states, the only disposal option available for most hazardous wastes is landfilling. The basis for the management of hazardous-wastes landfills is set forth in the Resource Conservation and Recovery Act of 1976. In general, disposal sites for hazardous wastes shoiild be separate from sites for municipal solid wastes. If separate sites are not possible, great care must be taken to ensure that separate disposal operations are maintained. 

Table 28-1 indicates the four main types of hazardous material, with examples of substances of each type. Not presented in Table 28-1 are radioactive materials, which are considered as a separate type of hazardous waste (5). 

Now you can reconsider the material balance equations by adding those additional factors identified in the previous step. If necessary, estimates of unaccountable losses will have to be calculated. Note that, in the case of a relatively simple manufacturing plant, preparation of a preliminary material-balance system and its refinement (Steps 14 and 15) can usefully be combined. For more-complex P2 assessments, however, two separate steps are likely to be more appropriate. An important rule to remember is that the inputs should ideally equal the outputs - but in practice this will rarely be the case. Some judgment will be required to determine what level of accuracy is acceptable, and we should have an idea as to what the unlikely sources of errors are (e.g., evaporative losses from outside holding ponds may be a materials loss we cannot accurately account for). In the case of high concentrations of hazardous wastes, accurate measurements are needed to develop cost-effective waste-reduction options. It is possible that the material balance for a number of unit operations will need to be repeated. Again, continue to review, refine, and, where necessary, expand your database. The compilation of accurate and comprehensive data is essential for a successful P2 audit and subsequent waste-reduction action plan. Remember - you can t reduce what you don t know is therel... 

For PM applications, wet scrubbers generate waste in the form of a slurry or wet sludge. This creates the need for both wastewater treatment and solid waste disposal. Initially, the slurry is treated to separate the solid waste from the water. The treated water can then be reused or discharged. Once the water is removed, the remaining waste will be in the form of a solid or sludge. If the solid waste is inert and nontoxic, it can generally be landfilled. Hazardous wastes will have more stringent procedures for disposal. In some cases, the solid waste may have value and can be sold or recycled. 

Interim measures may be separate from the comprehensive Corrective Action plan but should be consistent with, and integrated with, any longer-term Corrective Action (e.g., corrective measure through an order, an op erating permit, a post-closure permit or interim status closure requirements). To the extent possible, interim measures should not seriously complicate the ultimate physical management of hazardous wastes or constituents, nor should they present or exacerbate a health or environmental threat. Interim measures may add additional costs or work to the comprehensive Corrective Action. Such added costs or work do not preclude implementation of an interim measure. 

Normal work elothes are appropriate for the support zone. PPE worn for the hazardous waste work should remain in the CRZ/C. At some point, this PPE will be deeontaminated or paekaged for transport and disposal or deeontamination. Separate support zone faeilities may not be needed where site faeilities are readily available and near to the worksite, and if elose eommunieation is maintained. Eor multiple hazardous waste operations eondueted in elose proximity, it is possible to design one support zone to serve several operations. This will depend on the logisties of the projeet. 

Particle size distribution relating to gas cleaning is well understood in the industry. This section deals with general rules of thumb. Certain important issues not included in this section are flue gas desulfurization, flue gas denitrification, hazardous waste gas cleaning, waste incineration gas cleaning, and removal of CO2 from flue gas. All these topics have special requirements, which must be considered separately in the design process. 

A new scheme for location management has developed whereby wastes are diverted to separate holding facilities according to the hazard imposed by the waste. Separate pits are created to hold rig washing and precipitation wastes, solid wastes and drilling fluids [225]. The waste is then reused, disposed on site, or hauled away for offsite treatment. The system reduces contamination of less hazardous materials with the more hazardous materials, thereby reducing disposal costs. 

Likewise, fly ash from power plant combustors often contains small amounts of metals or their oxides, which require costly disposal in the ever-shrinking number of approved hazardous waste landfills. Thus, there are economic incentives to recover the metal values as well as to reduce the costs of ultimate disposal. Here, too, the metal content is low, and research is needed to develop economical separation processes. In principle, advances in this area could be translated into recovery of metal values from mine tailings. 

A large fraction of the hazardous waste generated in industry is in the form of dilute aqueous solutions. The special challenges of separation in highly dilute solutions may be met by the development of new, possibly liquid-filled, membranes by processes involving selective concentration of toxic chemicals on the surfaces of particles or by the use of reversed micelles. 

Agarwal et al. 1978), the quantification of these specific enzymes may indicate that exposure to endosulfan has occurred. Blood tests, such as decay curves for aminopyrine in plasma, which are semiquantitative indices of liver enzyme induction, have been used successfully in the past to demonstrate enzyme induction in pesticide-exposed workers. Because numerous chemicals found at hazardous waste sites also induce these hepatic enzymes, these measurements are not specific for endosulfan exposure. However, measurements of enzyme activity, together with the detection of the parent compound or its metabolites in tissue or excreta, can be useful indicators of exposure. All of these potential biomarkers require further verification in epidemiological studies. Further studies with focus on the development of methods to separate and measure the estrogenicity of endosulfan in in vitro assays would be valuable since these assays are more sensitive and discriminative than other conventional biomarkers. Preliminary results have been presented by Sonnenschein et al. (1995). 

RCRA was passed to manage nonhazardous and hazardous wastes and underground storage tanks, with an emphasis placed on the recovery of reusable materials as an alternative to their disposal. This act introduced the concept of the separate management of hazardous and nonhazardous wastes, and defined procedures to identify whether a waste is hazardous or nonhazardous. A waste exhibits the characteristic of toxicity, classified as a hazardous material, if the concentration of any of 39 selected analytes in the Toxicity Characteristic Leaching Procedure (TCLP) extract exceed regulatory action levels. 

Nonhazardous coating solids and water should be segregated from hazardous solvents and thinners, and containers labeled to prevent mixing. Separation of the materials reduces the amount of hazardous waste that is produced. Coating material solids can be dried and treated as a solid waste allowing for disposal in a landfill. 

Transporter regulations apply only to the off-site transport of hazardous waste. They do not apply to the on-site transportation of hazardous waste within a facility s property or boundary. On-site refers to geographically contiguous properties, even if the properties are separated by a public road. Consequently, a facility may ship wastes between two properties without becoming subject to the hazardous waste transporter regulations, provided that the properties are contiguous. 

Lab packs Laboratories commonly generate small volumes of many different listed hazardous wastes. Rather than manage all these wastes separately, labs often consolidate these small containers into lab packs. Trying to meet the individual treatment standards for every waste contained in a lab pack would be impractical. To ease the compliance burden, U.S. EPA established an ATS for lab packs that allows the whole lab pack to be incinerated, followed by treatment for any metal in the residues. Treatment using this alternative standard satisfies the LDR requirements for all individual wastes in the lab pack. 

There are two major areas of overlap between MPRSA and RCRA. MPRSA prevents waste from an RCRA generator or TSDF from being deposited into the ocean, except in accordance with a separate MPRSA permit. In addition, dredged materials subject to the requirement of an MPRSA permit are not considered as hazardous wastes under RCRA.2... 

Filter layers, frost penetration, and cap-liner connections are other factors to consider in designing the closure system for a hazardous waste landfill. Before using geotextiles for filter layers in closures, one should conduct pressure tests and clogging tests on the material. Freeze-thaw cycles probably have little effect on membranes, but their impact on clay is still not known. Because of this lack of knowledge, membrane and clay layers should be placed below the frost penetration layer. Finally, a cap membrane should not be welded to the primary FML. Differential settlement in the cap can put tension on the cap membrane. In such a situation, the seam could separate and increase the potential for integration of the surface water collection system into the LDS. 

The use of nanoscale materials in the dean-up of hazardous waste sites is termed nanoremediation. Remediation of soil contaminated with pentachloro phenol using NZVI was studied [198]. In a separate study, soils contaminated with polychlorinated biphenyls was treated using iron nanopartides [194], NZVI and iron oxide have been suggested to be used as a colloidal reactive barrier for in situ groundwater remediation due to its strong and spedfic interactions with Pb and As compounds [199]. 

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