COMPARISON OF PROPORTIONAL-INTEGRAL-DERIVATIVE AND LADDER LOGIC CONTROLLER APPLICATION FOR AN INDUSTRIAL WASTEWATER TREATMENT PLANT

Conventional wastewater treatment processes applied for highly loaded industrial effluents lead to reduced efficiencies and to the need for processes improvement. The study is focused on a wastewater treatment plant that processes the effluent of textile industry. From the technological process (cotton fibers processing and dyeing) high pollutants concentrations result in the wastewater and chemical pretreatment is necessary. Following that, a biological stage with activate sludge treats the chemical stage effluent. Due to the high values of the concentration the effluent doesn't meet the national legislation requirements and several solutions were evaluate in order to reduce the effluent organic loading. The study is focused on two different control strategies for the biological stage: proportional-integral-derivative and ladder logic controllers. Based on the data from the wastewater treatment plant a simulation study was developed in order to compare the two cases results and to evaluate the proper solution for the industrial wastewater treatment plant.