As a consequence of the growing awareness of the need to protect the e
nvironment, a study was undertaken to investigate the impact of the us
e of recycled waste oils as an industrial fuel in relatively small ind
ustrial units. Combustion tests were carried out in a 230 kW experimen
tal furnace with oils that had been subjected to pretreatment involvin
g centrifugal separation of solids present. However, the analysis of t
he combustion gases demonstrated that the levels of principal contamin
ants such as lead and other heavy metals were still too high to meet t
he emission levels required by the European Union. This suggests that
physical processes are inadequate to remove the contaminants present i
n waste oils. (C) 1996 Elsevier Science Ltd.