Journal of Hazardous Materials 145 (2007) 195–202 Process engineering design of pathological waste incinerator with an integrated combustion gases treatment unit A.F. Shaaban ∗ Department of Chemical Engineering and Pilot Plant, National Research Centre, 33 El-Behoos Street, PZN 12622, Dokki, Cairo, Egypt Received 23 March 2006; received in revised form 7 November 2006; accepted 9 November 2006 Available online 15 November 2006 Abstract Management of medical wastes generated at different hospitals in Egypt is considered a highly serious problem. The sources and quantities of regulated medical wastes have been thoroughly surveyed and estimated (75t/day from governmental hospitals in Cairo). From the collected data it was concluded that the most appropriate incinerator capacity is 150 kg/h. The objective of this work is to develop the process engineering design of an integrated unit, which is technically and economically capable for incinerating medical wastes and treatment of combustion gases. Such unit consists of (i) an incineration unit (INC-1) having an operating temperature of 1100 ◦ C at 300% excess air, (ii) combustion-gases cooler (HE-1) generating 35 m 3 /h hot water at 75 ◦ C, (iii) dust filter (DF-1) capable of reducing particulates to 10–20 mg/Nm 3 , (iv) gas scrubbers (GS-1,2) for removing acidic gases, (v) a multi-tube fixed bed catalytic converter (CC-1) to maintain the level of dioxins and furans below 0.1 ng/Nm 3 , and (vi) an induced-draft suction fan system (SF-1) that can handle 6500 Nm 3 /h at 250 ◦ C. The residence time of combustion gases in the ignition, mixing and combustion chambers was found to be 2 s, 0.25 s and 0.75s, respectively. This will ensure both thorough homogenization of combustion gases and complete destruction of harmful constituents of the refuse. The adequate engineering design of individual process equipment results in competitive fixed and operating investments. The incineration unit has proved its high operating efficiency through the measurements of different pollutant-levels vented to the open atmosphere, which was found to be in conformity with the maximum allowable limits as specified in the law number 4/1994 issued by the Egyptian Environmental Affairs Agency (EEAA) and the European standards. © 2006 Elsevier B.V. All rights reserved. Keywords: Medical wastes; Hazardous wastes; Wet scrubbing; Catalytic treatment; Incinerators 1. Introduction The principal available and potentially sound techniques for treating medical wastes are incineration, steam sterilization, gas sterilization, chemical disinfection with grinding, thermal inactivation, irradiation, microwave treatment, grinding and shredding, as well as compaction. Among those mentioned tech- niques, incineration of medical wastes has proved itself as the most technically and economically feasible technology particu- larly in developed countries. It is always advantageous to practice incinerators-technique as they can: (a) potentially destroy any material containing organic carbon including pathogens, (b) typically reduce the ∗ Tel.: +20 2 337 5626; fax: +20 2 337 0931. E-mail address: drahmedshaaban@yahoo.com. volume and mass of material that must be disposed off in land- fills by 80–95%, and (c) heat of combustion can be recovered and used to generate steam or hot water. The different medical-waste categories that can be handled by incinerators are: (a) cultures and stocks of infectious agents, (b) pathological wastes, (c) waste human blood, (d) hypodemic nee- dles, syringes, pasteur pipettes, broken glass and scalpel blades, (e) contaminated animal carcasses, body parts and animals bedding, (f) wastes from surgery or autopsy, (g) wastes from medical, pathological, pharmaceutical laboratories, (h) dialysis waste, (i) discarded medical equipment and parts in contact with infectious agents, and (j) biological waste and discarded mate- rials contaminated with blood, excretion, exudates or secretion from human being or animals. Thus the prime objective of this work is to develop an integrated treatment unit for the incineration of hazardous medical-wastes followed by a subsequent wet and catalytic 0304-3894/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.jhazmat.2006.11.013