PID Control of Reverse Osmosis Based Desalination Process

Acess to clean water has become a global concern due to the growth in population and consequently their industrial and agricultural needs. Seawater desalination by reverse osmosis (RO) has become the main source of fresh water in many regions that have freshwater scarcity. Due to its sensitivity to quality of the feed and plant operating conditions, RO desalination process needs an efficient and accurate control system to maintain operation at optimum conditions that ensures the least energy utilization and prevent scaling and fouling.In this work, a rigorous mathematical model of RO process is developed for Hollow Fibre B-10 Permasep Permeator based on solution diffusion model to describe the RO performance and takes into account concentration polarization through film theory approach. A first order transfer function is built to represent the model and a PID controller is designed and used to control the rigorous model which is assumed to represent a real process. Optimal PID design based on the minimization of the integral of the squared error (ISE) performance index was used to tune the controller.