The emission of hydrochloric acid can be controlled by scrubbing, and suitable equipment is available from vendors of commercial incinerators. The apparatus is sizable, however, and it is not clear that it is justified in the space-sensitive circumstances characteristic of Navy ships. Where it is determined that HCl emissions are deemed to be a problem, the emissions might be best controlled by regulating the chlorine content of the waste streams.
Incineration of shipboard wastes will give rise to gaseous emissions, most of which will be vented up a stack along with engine exhaust, but operators may be exposed to emissions that escape directly into the incinerator room. Navy personnel on board should be considered from the standpoint of health effects of these emissions, and incinerator operators should be protected in the occupational health sense. It is incumbent upon the Navy, as it continues to operate large numbers of shipboard incinerators, to measure actual emissions of vessels at sea and in harbors, both in the incinerator room and at appropriate sites on the ship. Screening of equipment through land-based measurement should also continue.
The measured substances should be those of concern to operators of land-based incinerators. For example, U.S. Environmental Protection Agency (EPA) guidelines (U.S. EPA, 1994) place limits on the following materials: particulates, cadmium, lead, mercury, sulfur dioxide, hydrogen chloride, and ash. To this list, we may add dioxins, furans, and other known or suspected human health hazards. There are no public health or occupational health standards for shipboard incinerator emissions, although the EPA is rumored to be near the point of releasing relevant information. It should be kept in mind that the individual substance exposure may not impose the greatest danger to exposed individuals. The totality of exposure should be studied as well. With measurement results in hand, and with the Navy's controlled population and excellent record keeping practice on health matters, an exemplary program of personnel protection can be established.
In certain circumstances, burning 3 or 4 tons per day of paper products and, possibly, plastics may affect air quality in coastal areas or in surrounding vessels. Such effects will depend on the distances involved and the local meteorological conditions. The importance of these factors can be estimated using appropriate meteorological models. In some cases, additional experimental and field studies may be required to extend existing models. Refer to Appendix C for additional discussion.
Incineration has met resistance by some environmental groups. Some of this opposition has grown out of some poor combustion practices in the past, but modern incinerators have greatly reduced the emissions that led to the poor image. Also, perceptions that have no basis in science or engineering have contributed to the opposition. Nevertheless, the image persists, and the Navy should be prepared to demonstrate that environmental issues have been considered and overcome. Incineration as a waste management tool has been supported by academic and industrial researchers.
It should be further noted that amendments to MARPOL have been proposed, including the statement: “Subject to the provisions of paragraph 5 of this regulation, incineration shall not take place (a) within the Antarctic area as defined in regulation 10(g) of Annex I, of the present convention, (b) inside ports, harbors, and estuaries. ” These potential constraints on the use of incineration should be kept in mind as consideration of Navy incineration systems progresses.
This section presents a possible scenario for implementing incineration as a short-term approach to the Navy's solid waste disposal problem. According to information supplied by the Navy (U.S. Navy,