Abstract: An apparatus (1) and method for treating contaminated waste water (2). The apparatus comprises a heater (30), a feed apparatus (11, 12, 13, 14), for supplying contaminated waste water (2) to the heater (30) and a centrifuge (50, 60) downstream of the heater (30). A heat exchanger (20) is also provided which has a first channel (22) and a second channel (24). The first channel (22) is connected in a flow path extending between the feed apparatus (11, 12, 13, 14) and the centrifuge (50, 60); and a waste water outlet (9) from the main centrifuge (60) is fluidly coupled to an inlet of the second channel (24) of the heat exchanger (20).