International Journal of Energy Science and Engineering Vol. 2, No. 5, 2016, pp. 28-32 http://www.aiscience.org/journal/ijese ISSN: 2381-7267 (Print); ISSN: 2381-7275 (Online) * Corresponding author E-mail address: emilian.narcis@gmail.com (Emilian-Narcis Riti-Mihoc), emil_riti@yahoo.com (E. Riti-Mihoc), Dan.Porcar@imadd.utcluj.ro (D. Porcar) Drying Sewage Sludge Using Microwave Technology - Modern Method and Energy Efficiency Emilian-Narcis Riti-Mihoc * , Emil Riti-Mihoc, Dan Porcar Faculty of Materials and Environmental Engineering, Department Environmental Engineering and Sustainable Development Entrepreneurship, Technical University of Cluj-Napoca, Cluj-Napoca, Romania Abstract This paper presents new experimental results regarding energy efficiency of the treatment in microwave field of the sludge from wastewater treatment plants. Research was based on comparing by drying in heat convection and drying by heating in the microwave field. Are presented the results of experiments, and the phenomena occurring in the two types of drying analyzed. The final results highlights the energy efficiency of drying in microwave field compared to convective drying. Keywords Sewage Sludge, Wastewater, Microwave Treatment, Energetic Efficiency, Drying Sludge Received: February 29, 2016 / Accepted: March 19, 2016 / Published online: December 27, 2016 @ 2016 The Authors. Published by American Institute of Science. This Open Access article is under the CC BY license. http://creativecommons.org/licenses/by/4.0/ 1. Introduction According to the study "Environmental, Economic and Social Impacts of use of sewage sludge on land" commanded by DG Environment of the European Commission, carried out by the company Milieu Ltd and WRC, resulting an average of sludge 25 kg dry solid / capita / year, in the European Union [11]. So in the whole European Union in 2018 production is estimated at 12.5 million t dry solid /year, the equivalent of over 13 billion m 3 wet sludge/year. These huge amounts of sludge raises big management problems and handling. Thus, there are several concerns at European and global level to reduce sludge quantities handled. The main method to reduce the volume of sludge is drying. But we find that this current production of sludge, drying methods, e.g. natural drying on sand is not effective and requires large spaces, and the thermal drying, classical, requires high energy. Therefore, a new drying technology that minimizes energy consumption, it must be developed [1] [2] [3] [5] [7]. The microwave drying was analyzed as an alternative to the convective drying, was analyzed in terms of process efficiency due to the different nature of the heating phenomena [6]. To determine the efficiency of drying of sludge in microwave field compared to conventional drying by heat input from an external source, the experiments ware made with two dimensions of samples, namely samples of mass 30 g respectively 40 g [7]. In the process of drying in microwave field we determined that drying to be at maximum 1000 W power and minimum power at 100 W. In the process of conventional drying, the enclosure was made in an oven with the temperature in the workspace set at 200±5°C. I used for determinations, sludge from the line of treatment from WWTP Cluj-Napoca, taken immediately after