Alex Kwong Jun Kiu, Ngie Hing Wong, Hong Kiat Huang, Yali Li, Fuping Li, Diah Agustina Puspitasari, Yong Wang, Jaka Sunarso
Septic tanks require periodic desludging and further treatment at the Septic Sludge Treatment Plant (SSTP). However, the relationship between desludging frequency (DF), which is influenced by the sludge accumulation rate (SAR) in the sludge accumulation rate (SAR) inside different types of septic tanks, and the sludge generation rate (SGR) at the SSTP remains unclear. This work presents a systematic analytical approach for predicting and validating DF by simultaneously investigating the SAR and SGR from septic tanks and the SSTP, respectively. Seventy-eight (78) septic tanks, i.e., fiberglass (FG, 10), plastic (PL, 44), and reinforced concrete (RC, 24), were evaluated for their SAR based on serving population equivalent (PE) and sludge depth profiles over the years. No significant difference in SAR was found across these tanks, with an average SAR of 0.043 m3 PE-1 yr-1. To verify this, the SGR was found to range from 1.251 to 1.933 metric tons d-1 for the coarse (cs), fine (fs), and rotary drum screenings (rds) at the SSTP, resulting in a similar average SAR (0.044 m3 PE-1 yr-1). Consequently, a standardized DF of every three years is recommended for 6-PE septic tanks. This work provides insight into SAR (septic tanks) and SGR (SSTP), offering a more realistic estimate of DF to enhance their design and operational guidelines. Copyright © 2026. Published by Elsevier Ltd.
Research Centre for Sustainable Technologies, Faculty of Engineering, Computing and Science, Swinburne University of Technology, Jalan Simpang Tiga, Sarawak, Kuching, 93350, Malaysia; Centre of Smart Infrastructure and Digital Construction, Department of Civil and Construction Engineering, Swinburne University of Technology, 3122, VIC, Australia; International Joint Research Center for Biomass Materials, Southwest Forestry University, Yunnan, Kunming, 650051, China; Department of Chemical Engineering, Faculty of Engineering, Brawijaya University, MT Haryono 167, Malang, 65145, Indonesia; School of Pharmaceutical and Chemical Engineering, Taizhou University, Taizhou, 318000, China
