20.500.12556/DiRROS-23664 Design and implementation of the SRT control at the Ljubljana WWTP he solid retention time (SRT) is one of the most important parameters for the operation of a wastewater treatment plant (WWTP). Maintaining the SRT at the prescribed set-point is necessary to achieve an appropriate food-to-microorganism (F/M) ratio. This article describes the design and implementation of SRT control at the Ljubljana WWTP. The designed SRT control wastes a defined proportion of the mixed liquor suspended solid (MLSS) mass in the aerobic reactors. The sludge wasted from the secondary settlers is determined based on measurements of the MLSS concentration, waste sludge concentration, and waste sludge flow rate. The SRT control is simple and does not require an SRT estimation or an SRT feedback controller. It includes a constraining controller that keeps the MLSS in the aerobic reactors within the prescribed minimum and maximum values. Validation of the designed SRT control on a mathematical model of the Ljubljana WWTP shows better set-point tracking than the proportional integral (PI) SRT control, as well as reduced SRT variations and lower ammonia nitrogen concentrations compared to the initial MLSS control. The testing of the designed SRT control at the Ljubljana WWTP confirmed the set-point tracking and reduced SRT variations despite large influent variations and operational disturbances. waste sludge control solid retention time odpadno blato nadzor true false true IWA Publishing Združeno kraljestvo Angleški jezik Slovenski jezik Ljubljana (Slovenija); © 2025 The Authors Neznano 2025-09-23 13:22:47 2025-09-23 13:22:47 2025-10-24 03:54:47 0000-00-00 00:00:00 2025 0 0 Nasl. z nasl. zaslona; Opis vira z dne 18. 9. 2025; str. 720-731 iss. 5 Vol. 92 Sep. 2025 0000-00-00 Zaloznikova Objavljeno apc 2025-02-07 2025-08-09 2025-08-20 628.3 1996-9732 10.2166/wst.2025.126 249466115 https://iwaponline.com/wst/article/92/5/720/109236/Design-and-implementation-of-the-SRT-control-at 1 a31958c6-986f-11f0-9bb7-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=35037 RAZ_Vrecko_Darko_2025.pdf RAZ_Vrecko_Darko_2025.pdf 1 1DDBAB6704FCF7E3E736ED27E045B483 e03048c9683617f999e3f788bd7cea2c3c57c1e124cec0e0eaacbe0d0c06d385 b1fbae80-9870-11f0-9bb7-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=35038 Institut Jožef Stefan 0 0 0