Waste solutions, characteristics

The risk assessment has also concluded that a level of 200 mg/kg for lead in the soil will be a protective level for expected site exposures along with an excess cancer risk level for TCE-contaminated soil (56 pg/L). Based on investigations of activities at the site, the TCE-contaminated soil has not been determined to be a listed RCRA hazardous waste, as the cleaning solution records indicate the solution contained less than 10% TCE. However, the lead-contaminated soil is an RCRA hazardous waste by characteristic in this instance due to extraction procedure (EP) toxicity. None of the waste is believed to have been disposed at the site after November 19, 1980 (the effective date for most of the RCRA treatment, storage, and disposal requirements). 

According to the vendor, a key advantage of the SpinTek system is that the membranes are less likely to foul compared to static membrane systems. This feature results in less downtime for the system. The system also allows continuous operation during changes in influent waste stream characteristics, eliminating downtime for flux recovery. In addition, SpinTek requires a relatively small area for operations. The vendor states that the system is ideal for operation in hostile environments, including high temperature, pH, radioactive waste, chemical solutions, and solvent solutions. 

Ho et al. [141-143,146,151] published a series of papers on removal/recovery of several metals from waste solutions by pertraction through B LM E in H F contactors as shown in Table 23.4. For some metals, such as zinc and copper, scale-up of this system to pilot plant with a HF module with a surface area of fibers of 19 m2 (with diameter 10.2 and length 71.1 cm) was done and mass-transfer characteristics have been estimated [142]. Separation of phases in the dispersion from the stripping was satisfactory. 

Electrosorption technique, which may use the electrical potential as the 3" driving force to the traditional adsorption and ion exchange mechanism, has reversible characteristics of purifying waste solution by adsorption and concentrating contaminants by desorption. Carbon materials satisfy the basic requirements for an efficient electrode material, and have good radiation and chemical-stability. Especially activated carbon fiber (ACF), which can be easily made into a variety of types (textures or sheet), has a high specific surfece area and electrical conductivity. 

Design is specific to the solute being recovered and the waste stream characteristics. The major design parameters are the choice of solvent, distribution coefficient, and solvent flow rate (relative to the feed flow rate). 

Finding RAP options associated with treatment of EDS neutralents, rinsates, and cleaning solutions depend on whether the waste is regulated as hazardous within the state where it is generated and, if it is, whether it is a listed hazardous waste, a characteristic hazardous waste, or both. 

As a result of its highly polar character, silica gel is particularly useful in the separation of polarizable materials such as the aromatic hydrocarbons and polynuclear aromatics. It is also useful in the separation of weakly polar solute mixtures such as ethers, esters and in some cases, ketones. The mobile phases that are commonly employed with silica gel are the n-paraffins and mixtures of the n-paraffins with methylene dichloride or chloroform. It should be borne in mind that chloroform is opaque to UV light at 254 nm and thus, if a fixed wavelength UV detector is being used, methylene dichloride might be a better choice. Furthermore, chloroform is considered toxic and requires special methods of waste disposal. Silica gel is strongly deactivated with water and thus, to ensure stable retentive characteristics, the solvent used for the mobile phase should either be completely dry or have a controlled amount of water present. The level of water in the solvent that will have significant effect on solute retention is extremely small. The solubility of water in n-heptane is... 

The reversibility of reactions is another important characteristic in assessing the fate of deep-well-injected wastes. Depending on environmental conditions, reversible reactions readily proceed in either or both directions. Most acid-base reactions exemplify reversible processes. In aqueous solutions, relatively minor changes in such factors as pH or concentration can change the direction of these reactions. Irreversible reactions, typified by hydrolysis, have a strong tendency to go in one direction only. 

The concentration of a compound in water is controlled by its equilibrium solubility or solubility constant (the maximum amount of a compound that will dissolve in a solution at a specified temperature and pressure). Equilibrium solubility will change with environmental parameters such as temperature, pressure, and pH for example, the solubility of most organic compounds triples when temperature rises from 0°C to 30°C. Each type of waste has a specific equilibrium solubility at a given temperature and pressure. The solubility of toxic organic compounds is generally much lower than that of inorganic salts. This characteristic is particularly true of nonpolar compounds because of their hydrophobic character. 

The majority of systems studied have been aqueous solutions of either aromatic compounds or halogenated hydrocarbons. Such materials represent models for the major classes of organic pollutants in waste and ground water. The primary products resulting from the sonochemical treatment of phenol at 541 kHz (27 °C with bubbled air) are hydroquinone and catechol [22]. These compounds are easy to monitor and are clearly seen to be intermediates which disappear as the reaction progresses (Fig. 4.1). Similarly the sonolysis of aqueous 4-chlorophenol leads to products mainly characteristic of oxidation by OH radical e. g. 4-chlorocatechol but in both cases the final organic products are CO, CO2 and HCOOH (Scheme 4.2) [22-25]. 

The unique characteristic of the HAZCON process is the use of the proprietary ingredient Chloranan. The wastes most effectively solidified by the process are aqueous solutions, suspensions, or solids containing appreciable amounts of heavy metals and inorganic salts. The claimed characteristic of the Chloranan to inhibit the effects of organics on the crystallization of the cement is unique to the HAZCON process. 

A special cleaning procedure was developed which virtually eliminated the characteristic decomposition of dilute metal-ammonia solutions. The optical cell was evacuated with a diffusion pump for several hours, about 50 ml. of anhydrous ammonia condensed onto the walls of the apparatus, and this wash ammonia was forced into a waste flask containing sodium and cooled with dry-ice. The optical cell was rinsed a total of four times. Approximately 500 ml. of anhydrous ammonia was condensed into the cell, about 5 mg. of potassium was introduced into the cell with the winch assembly (Figure 3a), and the solution was allowed to remain in the cell for at least 48 hours. The metal-ammonia solution was then forced from the cell into the waste flask the cell was rinsed four times with anhydrous ammonia and evacuated before introducing ND8. 

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