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SHIPBOARD POLLUTION CONTROL: U.S. Navy Compliance With MARPOL Annex V
pounds per day. ARPA has recently announced a program aimed at achieving a full-scale demonstration of a relatively compact land-based SCWO system for eventual shipboard deployment. This unit is designed to destroy hazardous waste. The 8 ft × 9 ft × 10 ft unit is expected to weigh less than 4 tons, and it is designed to destroy 100 lb of hazardous waste per hour. Assuming success of the ARPA program, it can be calculated that a facility to handle the shipboard waste of an aircraft carrier might require 1,200 to 3,200 ft2 of deck space. SCWO should be effective in destroying Annex V waste. Food waste, black water sludge, and other non-Annex V materials are well matched to the destructive capabilities of SCWO.
The relatively large high-pressure reactor may or may not be acceptable on Navy ships.
Other Oxidation Methods
Ambient temperature partial oxidation of dissolved organics can be accomplished through the addition of ozone or hydrogen peroxide and ultraviolet (UV) light. This method has been used to treat lightly contaminated water in the United States, and ozonation is used in Europe as an alternative to chlorination for drinking water. The committee sees no application of this technology to Annex V waste streams. Wet air oxidation is another technology that is useful in special situations but shows no promise for Annex V waste.
Molten Salt Oxidation
Oxidation with air can be carried out in molten sodium carbonate above 900ºC. Acidic products react to form salts which dissolve in the molten bath. It can be applied to combustible solids, organic liquids, solutions, and slurries. The gaseous products may contain unoxidized waste that has passed through the bath, and an afterburner may be needed. The method has been employed on a small scale for over 40 years for destruction of military waste materials. The relatively low temperature of operation, as compared with incineration, minimizes the formation of nitrogen oxides. Application to Annex V waste has not been investigated. Disposal of the spent salt bath is a problem.
It is important to recognize the many impediments that must be overcome if a practice is to be adopted by the U.S. Navy. It is unlikely that any other area of marine service makes comparable demands on candidate technologies. Table 4.2 summarizes the committee's assessment of shipboard compatibility attributes for the long-range waste disposal technologies discussed in this chapter. The attributes may be described as follows:
Status of Technology: The developmental status of the technology: Has it been demonstrated? Laboratory, full scale, or production? If further development is required, has it been funded?
Process Versatility: Identification of which shipboard wastes can be processed with this technology. Preprocessing requirements must also be considered.
Process Density: Lb/h/ft2—waste-processing rate in pounds per hour normalized by the projected footprint of machinery required to apply the technology.
Ship System Demands: Support system requirements for the machinery required to apply the technology, i.e., ventilation, cooling water, special containments, noise and vibration isolation, electromagnetic sensitivity or emissions, and external supply requirements.
Installation Flexibility: Based on constraints on noise and vibration, electromagnetic emissions, space, weight, system demands, or other attributes noted, determination of which Navy ship classes the machinery required to apply the technology can reasonably be installed on?
Ship Motion Effects: Equipment installed on naval ships is expected to operate with platform motion up to and including 45º roll and 10º pitch and permanent list of 15º in accordance with General