Zulkarnaini, Zulkarnaini, et al. “Nitrogen Removal in the Anammox Biofilm Reactor Using Palm Fiber As Carrier in Tropical Temperature Operation”. Jurnal Riset Teknologi Pencegahan Pencemaran Industri, vol. 10, no. 2, Dec. 2019, pp. 7-15, doi:10.21771/jrtppi.2019.v10.no2.p7-15.