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Chapter 7 Comparison of Land-Based and Ocean Incineration Technologies Contents Page Composition of Incineration Products . .. ....119 Plume Gases . ...119 Residual Parent Compounds and Products of Incomplete Combustion (PICs) . ........119 Metals and Particulate. .1’20 Solid Residues . ............121 Comparison of ’Technical and Regulatory Requirements. ........122 Waste Analysis and Waste Limitations. ..122 Performance Standards . , . .......123 Operating Conditions . , . 125 Air Pollution Control Technology . ..............127 Sampling and Monitoring Requirements and Procedures . .. ...128 .Additional Provisions Not Required of Land-Based Incineration . ..129 Chapter 7 References . ..129 Table Table No. Page 12. Performance Standards Applicable to Land-Based and Ocean Incineration. .124 Chapter 7 Comparison of Land-Based and Ocean Incineration Technologies Although liquid organic wastes are currently This chapter describes the nature of the combus- managed in various ways, ocean incineration’s pri- tion products arising from both land-based and mary competition and closest analog is land-based ocean incineration and compares and contrasts their incineration. Therefore, it is important to compare respective technical and regulatory requirements. and contrast their technical features, the nature and extent of their regulation, and their relative risks of environmental release and adverse impacts. COMPOSITION OF INCINERATION PRODUCTS The products resulting from incineration of haz- waste incineration may contribute significantly to ardous waste, whether on land or at sea, can re- the risks posed by hazardous air pollutants. sult from complete or partial thermal oxidation of waste components. The products can be grouped Residual Parent Compounds and Products as follows: plume gases, residual parent com- pounds, products of incomplete combustion (PICs), of Incomplete Combustion (PICs) metals and particulate, and solid residues. A brief Parent compounds refer to those present in the description of each category is provided below. original waste, a small fraction of which pass through the incinerator intact. PICs include both Plume Gases partially destroyed compounds and new chemical Total combustion of simple, nonhalogenated compounds not originally present in the wastes. PICs, which all types of combustion processes gen- chemicals generates carbon dioxide and water as erate to some degree, include a wide range of com- end products. If combustion is incomplete, carbon pounds that are apparently synthesized during or monoxide is also formed, and its level in emissions immediately after combustion through chemical re- indicates the degree of incomplete combustion. In- actions or the recombining of molecular fragments. cineration of halogenated compounds generates acid gases (e. g., hydrogen chloride) and much smaller PICs often bear little or no resemblance to the amounts of chlorine gas, in addition to carbon di- parent compounds from which they were derived; oxide and water. The incineration of liquid wastes nor does the presence of a particular PIC neces- containing sulfur or nitrogen can produce a vari- sarily correlate with the presence of a particular ety of sulfur oxides and nitrogen oxides. waste component. Very little is understood about how PICs are formed. They have been detected in Except for acid-forming emissions (dominated the emissions from burning a wide range of mate- by hydrogen chloride), the Environmental Protec- rials, both hazardous and nonhazardous (e. g., mu- tion Agency (EPA) has not promulgated or pro- nicipal garbage, wood). The generation of PIGs posed regulations limiting emissions of stack gases might be correlated with the level of oxygen present from hazardous waste incinerators. Relative to during incineration and with the completeness of larger combustion sources like powerplants, the in- combustion. cinerators probably are a relatively minor source for most of these pollutants. For certain wastes or Both dioxin and dibenzofuran compounds, in certain geographic settings, however, hazardous known to be highly toxic to humans and in the envi- 119 120 ● Ocean Incineration: /ts Role in Managing Hazardous Waste ronment, have been identified among PICs pro- pending further study, but EPA is considering two duced from incinerating various materials, includ- approaches to their possible future regulation (see ing municipal garbage. Our understanding of the ch. 2, and proposed Ocean Incineration Regula- public health significance of these emissions, or even tion, 50 FR 8247, Feb. 28, 1985). their major sources, is far from complete. The quantities of both residual parent com- Metals and Particulate pounds and PICs present in incinerator emissions vary with operating conditions, such as residence These incineration products are the largely non- time, turbulence, and temperature. An EPA study combustible, inorganic (mineral) remainder from of land-based hazardous waste incinerators (13) the combustion of waste. In addition, substantial found that the concentrations of PICs in the stack amounts of particulate matter are sometimes de- gases were typically as high as the concentrations rived from the refractory firebrick lining of the com- of parent compounds, but that both were rarely bustion chamber, itself. How much of these prod- above 0.01 percent of the concentration of the par- ucts are generated depends on the type of waste ent compounds in the original waste. EPA’s Sci- incinerated; for example, the quantity of particu- ence Advisory Board’s analysis of available studies late from incineration of liquid wastes is gener- characterizing emissions from land-based inciner- ally significantly less than from incineration of solid ators, however, led the Board to conclude that: wastes. It is apparent that even with the uncertainties Because metals are not destroyed by incinera- related to sampling efficiencies and inadequate tion, those present in the waste feed are either de- chemical analyses, as much as 1 percent of the posited in ash residues or are emitted from the com- mass of the waste feed could exit an incinerator bustion chamber. Metals can be emitted in either as compounds other than carbon dioxide, carbon a particulate (solid) or a volatilized (gaseous) state. monoxide, water, and hydrochloric acid. (16) Control strategies and environmental behavior vary Under such conditions, a total destruction effi- considerably for these two forms and from metal ciency (DE) of only 99 percent would be achieved, to metal. I even though a much higher DE would probably be Incineration can alter the form and properties I measured under EPA’s current definition (see dis- of metals in several important respects, which are cussion of DE in ch. 2). discussed below. With respect to ocean incineration, EPA was un- able to detect any dioxins or dibenzofurans in stack Volatilization emissions from the Vulcanus ships burning poly - The high temperatures typically employed in chlorinated biphenyls (PCBs) or the defoliant Agent hazardous waste incinerators can volatilize heavy Orange. Questions have arisen, however, about the metals that are present in the waste; the degree of adequacy of sampling and analytic methodology volatilization varies with the incinerator’s operat- employed during those monitoring efforts (see refs. ing conditions, and from metal to metal. Mercury, 3, 16; also see discussion of past U.S. burns in cadmium, and lead are generally considered most ch. 11). problematic because they are easily volatilized and EPA is currently devoting considerable effort to are harmful if inhaled by humans. Although few characterizing the PICs that result from hazard- data are available for hazardous waste incineration, ous waste incineration, and the Agency considers one study examined the release of metals from in- it a research priority. PICs are currently unregu- cineration of sewage sludge at 1,6000 F in a facil- lated, although EPA proposed regulations under ity possessing air pollution control equipment (6). the Resource Conservation and Recovery Act At least 20 percent of the lead and cadmium, and (RCRA) in 1981 (46 FR 7684, Jan. 23, 1981). The essentially all of the mercury, were emitted because proposed Ocean Incineration Regulation would not of the scrubber’s low efficiency at removing volati- include any specific limits on the emissions of PICs, lized metals. Ch. 7—Comparison of Land-Based and Ocean Incineration Technologies . 121 Volubility Solid Residues Incineration can also alter the chemical form and These products include ash left behind in the volubility of metals found in wastes, thereby alter- combustion chamber and wastes generated when ing the metals’ potential availability and routes of air pollution control equipment (e. g., scrubber exposure to organisms or humans. For example, sludges) is used. incineration might change a water-insoluble form of cadmium in an organic wastestream to a more Ash soluble form; when the resultant ash is disposed of in a landfill, the cadmium would be more likely to The quantity and composition of ash resulting leach into nearby groundwater. Incineration in- from incineration varies widely and primarily de- creases the water volubility of cadmium and cop- pends on the waste itself. For example, incinera- per and decreases the water volubility of chromium, tion generates substantially greater amounts of ash nickel, and lead (4). from solid wastes than from liquid wastes. Oper- ating conditions can also influence the quantities Bioavailability 1 of residuals.

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