Utilization of pulverized fuel ash in Malta Josette Camilleri a , Michael Sammut b , Franco E. Montesin a, * a Department of Building and Civil Engineering, Faculty of Architecture and Civil Engineering, University of Malta, Msida, Malta b Department of Pathology, St. Luke’s Hospital, G’Mangia, Malta Accepted 29 November 2005 Available online 24 January 2006 Abstract In Malta all of the waste produced is mixed and deposited at various sites around the island. None of these sites were purpose built, and all of the waste is above groundwater level. The landfills are not engineered and do not contain any measures to collect leachate and gases emanating from the disposal sites. Another waste, which is disposed of in landfills, is pulverized fuel ash (PFA), which is a by-prod- uct of coal combustion by the power station. This has been disposed of in landfill, because its use has been precluded due to the radio- activity of the ashes. The aim of this study was to analyze the chemical composition of the pulverized fuel ash and to attempt to utilize it as a cement replacement in normal concrete mixes in the construction industry. The levels of radiation emitted from the ashes were measured by gamma spectrometry. The results of this study revealed that although at early ages cement replacement by PFA resulted in a reduction in compressive strength (P = 0), when compared to the reference concrete at later ages the strengths measured on concrete cores were comparable to the reference concrete (P > 0.05). The utilization of PFA up to 20% cement replacement in concrete did not raise the radioactivity of the concrete. In conclusion, utilization of PFA in the construction industry would be a better way of disposing of the ashes rather than controlling the leachate and any radioactivity emitted by the landfilled ashes. Ó 2006 Elsevier Ltd. All rights reserved. 1. Introduction Landfill has been the most frequently if not the only method used for waste disposal in Malta. There are several landfill sites all over the island, which have been filled to capacity. None of these sites were purpose built, and the level of waste is above the surface. More recently a site in the northern part of Malta, Maghtab, was being used. Over the years Maghtab has risen above ground level (Fig. 1). It measures 100 ha and has been in use since 1977. Accession of Malta to the European Union has necessitated the clo- sure of this landfill. Maghtab is not an engineered landfill and receives all forms of waste including municipal waste and construction and demolition waste. This waste is mixed; thus it is totally unusable. The disposal of waste is a serious problem in densely populated countries like Malta. In 1989 the Maltese domestic solid waste produc- tion was estimated at 97,200 tonnes, and is estimated to increase to around 127,000 tonnes in 2010 according to the forecast in the Review Report by RH & H Consult (1993). The total amount of industrial waste in 1992 was estimated at approximately 90,000 tonnes; the estimate for 2010 is 100,000 tonnes. In Malta the main power station utilized coal until 1992 when it was relocated to the south of the island and started using diesel as the main supply of fuel. In 1991 the Marsa power station used 250,000 tonnes of coal, producing circa 50,000 tonnes of pulverized fuel ash (PFA). The PFA pro- duced as a by-product of coal combustion was dumped in two unused quarries in southern Malta with no protective measures or leachate collection systems. The quarries are overlooking the sea and cover a very wide span of land. Dumping of PFA is problematic as the material is poten- tially toxic and cannot be landfilled within the aquifer pro- tection zone (Vella, 1999). Caruana and Gambin (1991) have shown that several heavy metals are leached out of PFA when it is exposed to a marine environment. Manage- 0956-053X/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.wasman.2005.11.022 * Corresponding author. Tel.: +356 2340 2869; fax: +356 21 330 190. E-mail address: franco.montesin@um.edu.mt (F.E. Montesin). www.elsevier.com/locate/wasman Waste Management 26 (2006) 853–860