The concept of “Loop Cycle” in landfill management (Case study at Piyungan landfill, Yogyakarta, Indonesia)Hijrah Purnama Putra, Enri Damanhuri and Akhmad MarzukoMATEC Web Conf., 154 (2018) 02003DOI: https://doi.org/10.1051/matecconf/201815402003