Izarul Machdar was born in Banda Aceh, Indonesia. He graduated with a PhD from the Environmental System Engineering, Nagaoka University of Technology, Japan in 2001. He taught in the Chemical Engineering Department, Syiah Kuala University since 1991 with subjects of Wastewater Engineering, Chemical Process, Chemical Plant Design, Water Treatment and Plant Utility, Microbiology, Unit Operation of Chemical Engineering, and Synthesis Process. He and co-workers at the Nagaoka University of Technology developed the first unique design concept of aerobic wastewater treatment system published in 1998 known as the DHS (downflow hanging sponge) reactor. He published some books (in Indonesian) Dasar-dasar Sintesis Proses (978-979-8278-47-1), Ekologi dan Pencemaran Linkungan (ISBN: 978-602-8826-10-5), Q/A Pengendalian Pencemaran (ISBN: 978-979-17153-6-2), Dasar Sintesis Proses dan Prarancangan Pabrik Kimia (ISBN: 978-602-1270-33-2).