Application of advanced control techniques in water treatment and supply systems (2005)

Funded by: Water Research Commission

Partner organisations: Partners in Development, eThekwini Water and Sanitation

Project description
The rapid increase in pressure on natural resources brought about by human economic activity has led to a growing realisation of the need to manage such resources on an integrated basis. In the water field, the growing importance of disciplines such as Integrated Catchment Management, Demand Management, Life Cycle Analysis and Pinch Analysis are evidence of this trend. The use of these and other, strategic tools which attempt to ensure that resources are consumed with the maximum benefit and minimum environmental degradation, inevitably leads to technological systems with many complex interactions and constraints. To realise the benefits of integrated planning and design, it is vitally necessary to be able to control these systems effectively. This basic problem is common to many issues beside water management, and process control technology continues to develop rapidly to provide the required capabilities. It is these capabilities which need to be assimilated by the water and wastewater industry if the benefits of integrated planning are to be fully realised.

This project aimed to build capacity within the industry by demonstrating and apply advanced control techniques to water treatment processes. Target levels were senior managers (an appreciation of the potential), middle managers (project identification and management) and engineers (implementers of the advanced control systems). The application of advanced process control techniques should reveal that opportunities exist for enhanced management and operation of water systems.

Following the recent replacement of analogue control systems in the industry with digital systems (SCADA and DCS), there has been little advantage taken of the ability of digital computers to work quite differently from the old analogue control loops. Instrument technicians have been inclined to
translate the old loops one-by-one into the equivalent digital controllers. This ignores the ability of the computer systems to take many input variables into account in an algorithm, possibly manipulate many outputs simultaneously, and indeed to do far more complex calculations in the control algorithm itself.

The identification of suitable demonstration applications was considered best achieved in discussion with the key water industries, in this case the Umgeni Wiggins Water Works and the Ethekwini Municipality Water Services.

Project Objectives
  1. To demonstrate the use of advanced process control for integrated management of water and wastewater systems in the South African Water Industry.
  2. To develop advanced control systems for managing selected water and/or wastewater treatment systems.
  3. To develop advanced process control as a tool which will enhance the capacity of the South African Water Industry to achieve greater integration of the management of water and wastewater.