Refuse disposal in metropolitan areas is becoming increasingly difficult and expensive as ever-greater volumes of waste need to be transported to increasingly remote landfill sites. Acid hydrolysis offers an attractive alternative means of disposal, by aiming to convert the cellulose in the waste to glucose, for fermentation to ethanol. Recent research into the hydrolysis of cellulose at elevated temperatures and short reaction times has shown that high yields of glucose may be obtained: but experimental work with refuse has been lacking.
This work describes the development of a continuous reactor for carrying out the hydrolysis of refuse under the conditions required for the determination of reaction rate data. An existing rig was modified through a series of preliminary experiments: after this, detailed testwork was carried out with filter paper, newsprint and air-classified lights of municipal refuse as cellulosic substrates, as well as pure glucose, to investigate the decomposition reaction. High yields of glucose were obtained from experiments with newsprint and refuse, and the kinetic parameters derived were compared with those of previous researchers.
The data obtained from the hydrolysis of the refuse sample was used-to draw up a preliminary design of a 500 tonne/day plant to treat the air- classified light fraction of municipal refuse. The initial capital investment was estimated to be f8.1 million, and under present market conditions, it was shown to be advantageous to convert the cellulosic fraction of refuse into ethanol rather than RDF pellets. A rough estimate of a complete process to produce ethanol from untreated refuse indicated that considerable savings in overall disposal costs could be made, compared with disposing of the waste in the usual way, by landfilling after shredding or pulverisation
