Designated POHC

The DRE performance standard implicitly requires a sampling and analysis to measure the amoimts of the designated POHC(s) in both the waste stream and the stack effluent gas during a trial bum. 

SW-846, is used to measure emissions of semivolatile principal organic constituents. Method 0010 is designed to determine destruction and removal efficiency (DRE) of POHCs from incineration systems. The method involves a modification of the EPA Method 5 sampling train and may be used to determine particulate emission rates from stationary sources. The method is applied to semivolatile compounds, including polychlorinated biphenyls (PCBs), chlorinated dibenzodioxins and dibenzofurans, polycyclic organic matter, and other semivolatile organic compounds. 

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. 

RCRA performance standards require a minimum DRE of 99.99% for POHCs designated in the permit and a minimum DRE of 99.9999% for dioxin-bearing wastes. 

First, the incinerator must achieve a destruction and removal efficiency (DRE) of at least 99.99% for each of the designated Appendix VIII chemicals present in the waste feed. In other words, 0.01% of the respective compound in the waste feed can be emitted in the incinerator stack gases. The specific Appendix VIII chemicals evaluated are selected by EPA from those found in the hazardous waste at reasonable concentrations and are termed principal organic hazardous constituents (POHCs). 

The routine monitoring of each hazardous constituent of a waste stream and all products of incomplete combustion in the effluent gases of operating incinerators is not presently possible, particularly since the quantities of the suspect materials are relatively small in the feedstock and very small in the effluent gases. EPA has established procedures for characterizing incinerator performance in terms of selected components of the anticipated waste stream. These compounds, labeled principal organic hazardous components (POHCs), are presently designated on the basis of the estimated difficulty of incineration and the concentration in the anticipated waste stream. 

The second condition is a high-temperature test (HTT) using the same POHCs designated for the low-temperature test, plus ethylene glycol and 21 metal oxides to determine metal emissions. The third condition is an HTT using the pollution abatement system filtration system (PFS). Both HTT conditions use the same surrogates and additives, but additional metal oxides are fed in this third condition test to determine the metal removal efficiency of the PFS. 

The application process requires basic information to demonstrate that the design and operation of the incinerator will result (see previous problem) in the destruction of principal organic hazardous constituents (POHCs) by 99.99% a hydrogen chloride scrubbing efficiency of 99% or, as described in the previous problem, <41b/h maximum HCl emissions and particulate emissions <0.08gr/dscf corrected to 50% excess air (EA). These may be written in equation form as ... 

A trial bum is conducted with the waste composition in the preceding table. The designated principal organic hazardous constituents (POHCs) for the trial bum are methyl alcohol, polyvinyl chloride, and xylene. The results of the trial bum are ... 

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