Conditioning of waste

Soil burial is widely used as the method of testing susceptibility to degradation. It closely mimics the conditions of waste disposal used for plastics but it is often difficult to reproduce results obtained because of absence of control over either the climate at the test site or the variety of micro-organisms involved in the degradation. Soil burial is thus used to provide qualitative indications of biodegradability, with more controlled laboratory work with cultured micro-organisms being used to obtain more quantitative detail. 

Snider, E.H. and Alley, F.C. Kinetics of the chlorination of biphenyl under conditions of waste treatment processes. Environ. Sci TechnoL, 13(10) 1244-1248, 1979. 

Describe the conditions of waste disposal. Wastes in specified physical and chemical forms and having certain compositions or ranges of compositions of hazardous substances are assumed to be emplaced in certain ways in a disposal site having specified characteristics. The disposal site can be a real location or generic with hypothetical characteristics typical of real sites. The exposure assessment usually assumes that disposal operations have been completed and the site is closed, although the... 

Experiment Number Condition of Waste Form Backfill and Rock Apparatus and Experimental Condition Status (3/22/83)... 

Waste disposal and treatment facilities have their own requirements for acceptance of waste. For example, wastewater may be discharged into sanitary sewer if it meets the requirements of the POTW batch discharge permit. This permit will list the analytes, methods, and discharge limitation concentrations (action levels). Disposal facilities (e.g. landfills) have lists of analyses that must be performed as a condition of waste acceptance by the facility. 

Although soil burial testing affords a way to test samples for breakdown close to actual conditions of waste disposal, it lacks reproducibility because of the difficulties in controlling climatic factors and the populations of various biological systems that are involved. For more reproducible results, degradations by cultured fungi and bacteria as well as degradations by purified enzymes are used. 

Transmutation of long-lived nuclides (actinides and fission products) in the fuel cycle of fast reactors should proceed, at least, until the biologically equivalent activity of the waste to be buried declines to that of the natural uranium consumed (this condition is referred to as equivalence in terms of radiation and biological hazards). Notably, such equivalence may be attained both by the time of burial and within a historically short and reliably predicted period of, e.g., 200-1,000 years. This approach allows reasonably minimizing the mass and hazard of long-lived waste, while the specific conditions of waste disposal should meet the national regulatory requirements. 

Suzuki T, Ichihara Y, Dazai M, Misono T (1973b), Treatment conditions of waste water containing polyvinyl alcohol using activated sludge , JFerment Technol, 51, 692-698. 

There are many other sources of waste associated with process operations which can only be taken care of in the later stages of design or after the plant has been built and has become operational. For example, poor operating practice can mean that the process operates under conditions for which it was not designed, leading to waste. Such problems might be solved by an increased level of automation or better management of the process. These considerations are outside the scope of this text. 

Hydrothermal Synthesis Systems. Of the unit operations depicted in Figure 1, the pressurized sections from reactor inlet to pressure letdown ate key to hydrothermal process design. In consideration of scale-up of a hydrothermal process for high performance materials, several criteria must be considered. First, the mode of operation, which can be either continuous, semicontinuous, or batch, must be determined. Factors to consider ate the operating conditions, the manufacturing demand, the composition of the product mix (single or multiple products), the amount of waste that can be tolerated, and the materials of constmction requirements. Criteria for the selection of hydrothermal reactor design maybe summarized as... 

The processing of hides and skins into leather results in a large quantity of waste materials (9). The hide in the salt-cured condition contains salt in a crystalline form, water as salt solution, and as hide Hquid components, flesh, blood, manure, and surface dirt from the animal. 

Chlorination of Hydrocarbons or Chlorinated Hydrocarbons. Chlorination at pyrolytic temperatures is often referred to as chlorinolysis because it involves a simultaneous breakdown of the organics and chlorination of the molecular fragments. A number of processes have been described for the production of carbon tetrachloride by the chlorinolysis of various hydrocarbon or chlorinated hydrocarbon waste streams (22—24), but most hterature reports the use of methane as the primary feed. The quantity of carbon tetrachloride produced depends somewhat on the nature of the hydrocarbon starting material but more on the conditions of chlorination. The principal by-product is perchloroethylene with small amounts of hexachloroethane, hexachlorobutadiene, and hexachloroben2ene. In the Hbls process, a 5 1 mixture by volume of chlorine and methane reacts at 650°C the temperature is maintained by control of the gas flow rate. A heat exchanger cools the exit gas to 450°C, and more methane is added to the gas stream in a second reactor. The use of a fluidi2ed-bed-type reactor is known (25,26). Carbon can be chlorinated to carbon tetrachloride in a fluidi2ed bed (27). 

Waste category Container Auxiliary equipment and conditions of use... 

Haul distance Although minimum haul distances are desirable, other factors must also he considered. These include collection-route location, types of wastes to he hauled, local traffic patterns, and characteristics of the routes to and from the disposal site (condition of the routes, traffic patterns, and access conditions). 

Gas and Leachate Movement and Control Under ideal conditions, the gases generated from a landfill should be either vented to the atmosphere or, in larger landfills, collected for the production of energy. Landfills with >2.5 miUion cubic meters of waste or >50 Mg/y NMOC (nonmethane organic compounds) emissions may require landfill-gas collection and flare systems, per EPA support WWW, CFR 60 Regulations. The leachate should be either contained within the landfill or removed for treatment. 

Due to both carbonization and penetration of chloride ions, steel will pass from a passive to an active condition and (consequently) may corrode. If the mortar is completely surrounded by water, oxygen diffusion in wet mortar is extremely low so that the situation is corrosion resistant because the cathodic partial reaction according to Eq. (2-17) scarcely occurs. For this reason the mortar lining of waste pipes remains protective against corrosion even if it is completely carbonated or if it is penetrated by chloride ions. 

An extremely difficult task is the estimation of emissions from hazardous waste sites. Frequently, both the amounts of materials existing vithin the site and the compounds and mixtures that are represented are not known. Even if both of these pieces of information are reasonably well known, the conditions of the containers holding these chemicals are not initially known. 

In many cases, it is appropriate to compare the waste treatment costs under existing conditions with those associated with the waste-reduction option. The size of a treatment plant and the treatment processes required may be altered significantly by the implementation of waste-reduction options. This should be considered in an economic evaluation. 

---