THERMAL DRYING OF SEWAGE SLUDGE - HSE'S ROLE IN PROMOTING SAFER PLANT

摘要

UK waste water treatment companies, driven by the need to stop dumping of sewage sludge at sea and the uncertainty of the future of sludge disposal to land, have invested heavily in thermal drying equipment for sewage treatment. The dried sludge products are typically granular, are easy to handle and have a range of potential uses. The product can however give rise to a dust explosion hazard and under certain conditions may smoulder and self-ignite. There has been a rapid growth in the number of thermal drying plants in the UK over the last 3 years, bringing to the waste water treatment companies large-scale chemical engineering challenges outside their previous experience. Several of these, using different technologies, have suffered dust explosions, which, fortunately, despite causing significant damage to equipment, have not resulted in any injuries. This paper describes some of the incidents, which have occurred, highlights common features and outlines HSE's approach to risk reduction in terms of encouraging cooperation with manufacturers and users and producing appropriate guidance. It also describes areas where new work has been needed to establish safe operating conditions.