Hazardous waste particulate matter

Temperature. The temperature for combustion processes must be balanced between the minimum temperature required to combust the original contaminants and any intermediate by-products completely and the maximum temperature at which the ash becomes molten. Typical operating temperatures for thermal processes are incineration (750—1650°C), catalytic incineration (315—550°C), pyrolysis (475—815°C), and wet air oxidation (150—260°C at 10,350 kPa) (15). Pyrolysis is thermal decomposition in the absence of oxygen or with less than the stoichiometric amount of oxygen required. Because exhaust gases from pyrolytic operations are somewhat "dirty" with particulate matter and organics, pyrolysis is not often used for hazardous wastes. 

The management or disposal of metals and ash, other by-products of the combustion process, also causes concern. Ash is an inert solid material composed primarily of carbon, salts, and metals. During combustion, most ash collects at the bottom of the combustion chamber (bottom ash). When this ash is removed from the combustion chamber, it may be considered hazardous waste via the derived-from rule or because it exhibits a characteristic. Small particles of ash (particulate matter that may also have metals attached), however, may be carried up the stack with the gases (fly ash). These particles and associated metals are also regulated by the combustion regulations, as they may carry hazardous constituents out of the unit and into the atmosphere. Since combustion will not destroy inorganic compounds present in hazardous waste, such as metals, it is possible that such... 

Emissions from hazardous waste combustors are regulated under two statutory authorities RCRA and the CAA. The MACT standards set emission limitations for dioxins, furans, metals, particulate matter, total chlorine, hydrocarbons/carbon monoxide, and destruction and removal efficiency (DRE) for organics. Once a facility has demonstrated compliance with the MACT standards by conducting its comprehensive performance test (CPT) and submitting its notification of compliance (NOC), it is no longer subject to the RCRA emission requirements with a few exceptions. RCRA-permitted facilities, however, must continue to comply with their permitted emissions requirements until they obtain modifications to remove any duplicative emissions conditions from their RCRA... 

The goal of setting operating requirements for hazardous waste combustion units is to ensure that the unit will operate in a way that meets the performance standards for organics, chlorine, particulate matter, and metal pollutants. The unit s permit will specify the operating conditions that have been shown to meet the performance standards for organics, chlorine gas, particulate matter, and metals. 

To control the emission of organics, these units must comply with similar DRE requirements to the other hazardous waste combustion units. Owners or operators of MACT combustion units must select POHCs and demonstrate a DRE of 99.99% for each POHC in the hazardous wastestream. Sources that bum hazardous waste have a required DRE of 99.9999% for each POHC designated. Additionally, for dioxins and furans, U.S. EPA promulgated more stringent standards under MACT. For example, MACT incinerators and cement kilns that bum waste with dioxins and furans must not exceed an emission limitation of either 0.2 ng of toxicity equivalence per dry standard cubic meter (TEQ/m3) or 0.4 ng TEQ/m3 at the inlet to the dry particulate matter control device. This unit of measure is based on a method for assessing risks associated with exposures to dioxins and furans. 

Particulate matter emissions in relation to hazardous waste combustion standards. 

Significant dispersion of hexachlorobutadiene has been confirmed by the detection of hexachlorobutadiene at areas which are far removed from release sources (Class and Ballschmiter 1987). A high partition coefficient (log Ko=) value of 3.67 (Montgomery and Welkom 1990) for hexachlorobutadiene indicates that adsorption to soils with high organic carbon content can occur. Wind erosion of contaminated surface soils can then lead to airborne hexachlorobutadiene-containing particulate matter. Levels of hexachlorobutadiene have been detected in fly ash from the incineration of hexachlorobutadiene-containing hazardous waste (Junk... 

US Studies. In 1994 the US EPA published the results of an extended study of PCDD/F and particulate emissions from a variety of combustors fed with hazardous waste, in a report entitled Combustion Emissions Technical Resource Document (CETRED).6 According to the report, US EPA is evaluating [particulate] emissions because controlling [particulate emissions] will control emissions of most toxic metals and toxic organic compounds absorbed into the [particulate matter] . 

Incineration is a well-known process that involves the conversion of toxic and hazardous waste into a less or nontoxic waste by heating at a very high temperature to convert them into gaseous and particulate matter. Incineration is considered an attractive option after source reduction, and recycling. This method is sometimes preferred over the other treatment methods because it destroys permanently the hazardous components in the waste material. 

The exhaust gases from the rotary furnace are usually ducted to a baghouse which removes any particulate matter. In some cases, this filter dust may also be classified as hazardous waste, which again increases the disposal costs. 

An incinerator burning hazardous waste must not emit particulate matter in excess of 180 mg per dry standard cubic meter (0.08 grain per dry standard cubic foot) when corrected to the amount of oxygen in the stack gas according to the formula... 

The CAA establishes national primary and secondary air quality standards for sulfur oxides, particulate matter, carbon monoxide, ozone, nitrogen dioxide, and lead. It also limits the emission of 189 listed hazardous waste pollutants such as vinyl chloride, arsenic, asbestos, and benzene (CAA, 1977). States are responsible for enforcement of the CAA. To assist in this effort. Air Quality Control Regions (AQCRs) were established. Allowable emission limits are determined by the AQCR or its subunit, the Air Quality Management District. These emission limits are based on whether or not the region is currently within attainment of National Air Quality Standards. 

Exposures to xenobiotics have been associated with the onset of several autoimmune diseases. Lupus [systemic lupus erythematosus (SLE)], scleroderma (systemic sclerosis), rheumatoid arthritis, and other maladies have been strongly associated with exposures to single chemicals and mixtures of chemicals. The single chemicals include sihca dust, VC, mercuric chloride, trichloroethylene, HCB, hydrazine, and tartrazine. Mixtures include epoxy resins, hair dyes, paint thinners and other (unspecified) organic solvent mixtures, industrial emissions, airborne particulate matter, and hazardous waste-site emissions [27-32],... 

For the incineration of hazardous waste, three performance standards have been set Organic wastes must be destroyed with an efficiency of 99.99 percent gaseous hydrogen chloride (e.g., from the incineration of PVC scrap) must be reduced 99 percent or to less than 4 lbs per hour, and particulate matter emissions may not exceed ISOmg per dry cubic meter of stack gas. The EPA requires test bums on all incinerators to ensure that these conditions are met, a major expense costing companies up to 100,000 for each unit. 

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