The purpose of this study is to optimize a hybrid sludge drying system using a primary cold flush drying system and a secondary microwave drying system filled with a heating material. The system also includes an odor reduction facility to remove the complex odors generated from sludge drying. Through operating the system, the final dry sludge moisture content was reduced to an average of 15.8%. The energy consumption was 711.6 kcal kg(-1). The advantage of this system is that it can achieve high efficiency sludge drying with low energy consumption, and it can apply a complex heating technology to each drying section, depending on the physical properties and operating conditions of the target material to be dried. Therefore, this system is expected to achieve a high drying efficiency while simultaneously reducing the energy and processing costs in future sludge drying processes. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.