Anchan, S.S.Sankar Rao, C.S.2026-02-042022Chemical Engineering and Technology, 2022, 45, 3, pp. 467-4789307516https://doi.org/10.1002/ceat.202100409https://idr.nitk.ac.in/handle/123456789/22636The design of a centralized proportional integral controller for a single-tank activated sludge process is presented. The relative normalized gain array (RNGA) and dynamic relative gain array (dRGA) were adopted for enhancing the closed-loop performance of a multivariable system. The dRGA method gave superior and acceptable responses compared to the RNGA method. The designated error indices decreased significantly for the dRGA method compared with the RNGA method. The dRGA method is simple and effective, since it considers the process dynamics to provide an accurate interaction assessment. The designed centralized controller overcomes the limitations of the decoupler for stability challenges when compared with decentralized controllers. © 2022 Wiley-VCH GmbH.Activated sludge processDecentralized controlMultivariable systemsProcess controlTwo term control systemsActivated-sludge processCentralisedClosed-loop performanceController designsDynamic relative gainsError indexMulti-variables systemNormalized gainsProportional integral controllersRelative gain arrayControllers