Nonlinear PI Control with Adaptive Interaction Algorithm for Multivariable Wastewater Treatment Process

S I Samsudin,M F Rahmat,Norhaliza Abdul Wahab

doi:10.1155/2014/475053

S I Samsudin, M F Rahmat + Show 1 more

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https://doi.org/10.1155/2014/475053

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Abstract

The wastewater treatment plant (WWTP) is highly known with the nonlinearity of the control parameters, thus it is difficult to be controlled. In this paper, the enhancement of nonlinear PI controller (ENon-PI) to compensate the nonlinearity of the activated sludge WWTP is proposed. The ENon-PI controller is designed by cascading a sector-bounded nonlinear gain to linear PI controller. The rate variation of the nonlinear gainknis automatically updated based on adaptive interaction algorithm. Initiative to simplify the ENon-PI control structure by adaptingknhas been proved by significant improvement under various dynamic influents. More than 30% of integral square error and 14% of integral absolute error are reduced compared to benchmark PI for DO control and nitrate in nitrogen removal control. Better average effluent qualities, less number of effluent violations, and lower aeration energy consumption resulted.

Highlights

The wastewater treatment plant (WWTP) is naturally aimed to remove the suspended substances, organic material, and phosphate from the water before releasing it to the recipient
Two case studies are considered in the simulation, DO345 control and nitrogen removal process control
The effectiveness of the proposed enhanced nonlinear PI (ENon-PI) controller is investigated in two-level assessment, the performance of the controller and the performance of activated sludge process compared to benchmark PI

Summary

Introduction

The wastewater treatment plant (WWTP) is naturally aimed to remove the suspended substances, organic material, and phosphate from the water before releasing it to the recipient. The best technology available was used to control the discharge of pollutants emphasized in biological process, namely, as activated sludge process (ASP). In ASP, the organic materials are oxidized by microorganisms. The organic material is transformed into carbon dioxide and some incorporate into new cell mass. The new cell mass forms sludge that contains both living and dead microorganisms and, contains organic material, phosphorous, and nitrogen [1]. Referring to [2], the common problems in WWTP are caused by maintenance issues and poor effluent quality which are due to poor control approaches

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