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<br /> Comprehensive Review of <br /> S olid W aste Collection and Disposal Options <br /> <br /> <br />v2.1 164 10/22/12 <br />Modular combustion units offer a lower capital cost and simplicity than the larger field-erected <br />mass-burning systems for communities considering WTE systems. These systems are generally <br />reliable and are backed by many years of successful operating experience. The newer batch <br />oxidation systems (BOS) appear to offer substantially lower costs of operations and <br />maintenance. For example, the manpower required to operate these systems is generally <br />minimal with one worker required to load the primary chamber and discharge the ash stream <br />within an hour. Many suppliers claim nearly complete burn out between energy recovery and <br />recycling. The ash remaining is reported to be about 3 to 8% of the original volume (depending <br />on waste composition). Lastly, these systems are modular and can be easily increased or <br />decreased in size. <br /> Based on our experience with similar modular plants, SCS would anticipate that an experienced <br />staff of six (6) to nine (9) people, spread over three shifts per day, is required to continuously <br />operate a plant of the size potentially applicable to the Town or region. <br /> <br />12.3.4 Refuse -Derived Fuel Systems <br />Several American corporations have developed technologies that pre-process solid waste to <br />varying degrees to separate the non-combustibles from the waste stream. By undergoing <br />processing steps of hammering, shredding, or hydropulping, the combustible fraction of the <br />waste is transformed into a fuel, which can then be fired in a boiler unit specifically dedicated for <br />this type of refuse-derived fuel (RDF), or co-fired with another fuel, such as coal, shredded tires, <br />or wood chips. The fuel produced can thus be utilized in equipment that can have higher <br />efficiencies than mass-fired units resulting in greater electricity or steam output. However, the <br />front-end processing of the solid waste into a fuel has been one of the problem areas of this type <br />of refuse disposal technology. <br />Since the early 1970's, there have been several dozen facilities which have been constructed in <br />the United States to process solid waste into a RDF through the use of dry processing systems. <br />Such dry processing systems are classified according to the type of products that can be <br />produced: fluff RDF, densified RDF, and powdered RDF. A cross-section of a typical RDF <br />system is illustrated in Exhibit 12-5. <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br />