**Klaus Zimmermann**

Danube BioSolutions, Hauptstrasse 119/2/2, 3021 Pressbaum, Austria; klaus.zimmermann@live.at

Received: 6 July 2018; Accepted: 1 August 2018; Published: 2 August 2018

**Abstract:** Inappropriate treatment and disposal of waste containing biohazardous materials occurs especially in developing countries and can lead to adverse effects on public and occupational health and safety, as well as on the environment. For the treatment of biohazardous waste, microwave irradiation is an emerging tool. It is a misbelief that microwave devices cannot be used for inactivation of solid biohazardous waste; however, the inactivation process, and especially the moisture content, has to be strictly controlled, particularly if water is required to be added to the process. Appropriate control allows also inactivation of waste containing inhomogeneous compositions of material with low fluid/moisture content. Where appropriate, especially where control of transport of waste cannot be guaranteed, the waste should be inactivated directly at the place of generation, preferably with a closed waste collection system. In waste containing sufficient moisture, there are direct useful applications, for example the treatment of sewage sludge or human feces. A number of examples of microwave applications with impacts for developing countries are presented in this review. In respect to energy costs and environmental aspects, microwave devices have clear advantages in comparison to autoclaves.

**Keywords:** microwave; inactivation; disinfection; biohazardous waste; healthcare waste; sludge; carbon footprint; developing countries
