Semi-solid sludge

Hazardous waste could be solid, semi-solid (sludge), liquid and gaseous and possesses variable characteristic properties such as toxicity, reactivity, flammability, explosivity, corrosivity and radioactivity. 

Solid, Semi-solids, Sludge Samples—Weigh accurately 3.0 g of sample into a 40 mL vial fitted with a TFE-fiuo ocarbon-lined cap. Spike this sample with 100 uL of decachlorobiphenyl surrogate working standard. Add 30 mL of acetone/hexane to the vial for a 1 10 dilution. Vortex for at least 30 s. 

Incineration of mycelium and excess biological sludge. Incineration system may also receive pathogenic wastes, unrecoverable solvents, fermentation broths or syrups, semi-solid and solid wastes, and so on. The system can be further integrated with the burning of odorous air streams. 

Sludge a semi-solid to solid product that results from the storage instability and/ or the thermal instability of petroleum and petroleum products. 

Sludge is here defined as that solid or semi-solid biologically active material used in wastewater treatment plants to break down organic matter. The material to be sampled may be obtained from relatively stationary points within the plant, from a pumpable slurry return line, or from the dewatered filter cake. 

Particles, single as well as granulated or agglomerated forms, may be produced in one step from a thin, pumpable slurry or solution, a semi-solid paste or sludge, or a particulate (wet) solid. A bewildering assortment of dryers is available to produce such dry solid particles (the word dry here implies a solid with a moisture content in equilibrium with the ambient storage conditions for the product). Depending on the specified physical or chemical characteristics of the final product different dryers operated at different thermal conditions may be needed even if the feed material is the same. Often different dryers yield similar product at comparable costs. 

Usually, the typology of batch reactors also includes the semi-batch gas-liquid reactors, in which a gaseous phase is fed continuously in order to provide one of the reactants. A typical example is given by the reactors used both in different oxidative industrial processes and in the active sludge processes for the treatment of wastewater. It is possible to distinguish between the bubble columns (Fig. 7.1(c)), in which the gas rises undisturbed in the liquid phase, and the bubble stirred reactor, in which a mechanical mixer is added. Finally, the slurry reactors can be considered, in which the liquid phase contains a finely dispersed solid phase as well, which can act as a reactant or as a heterogeneous catalyst these reactors assume in general the features of Fig. 7.1(d). 

Soxhlet extraction Semi-volatile and non-volatile organics from soils, relatively dry sludges and solid wastes Considered a rugged extraction method because it has very few variables that can adversely affect extraction recovery... 

Automated Soxhlet extraction Polychlorinated biphenyls, organochlorine pesticides and semi-volatiles from soils, relatively dry sludges and solid wastes Allows equivalent extraction efficiency to Soxhlet extraction in 2 h... 

Supercritical fluid extraction Semi-volatile petroleum hydrocarbons from soils, relatively dry sludges and solid wastes Normally uses pressurized C02 with additional small volumes of organic solvent. Limited applicability. Relatively rapid extractions... 

In the field of environmental analysis, thermal extraction is proposed by an EPA method for the quantitative analysis of semi-volatile compounds from solid sample materials. The US EPA method 8275 is a thermal extraction capillary GC-MS procedure for the rapid and quantitative determination of targeted PCBs and PAHs (polynuclear aromatic hydrocarbons) in soils, sludges and solid wastes. This method requires extraction temperatures of 340 C for 3 min for the quantitative desorption of the PCBs (EPA, 1996). 

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