Digital Signals

Abstract: The degree and importance of automation at municipal wastewater treatment plants (WWTPs) have increased with the development of technology and tightening of treatment requirements. The objective of this paper is to assess and document the current status of process automation at WWTPs in Finland to determine successful practices and the needs of plant operators. Renewing ammonia or organic content removal processes to total nitrogen removal processes has also increased the need of Instrumentation, Control and Automation (ICA). The survey has quantified that the reliability and accuracy of the on-line sensor measurement has improved recently, which makes the use of on-line measurements in control more applicable. The use of nutrient sensors in control is apparently still rare at Finnish WWTPs even though their use for monitoring purposes is common.

Introduction: The City of Winnipeg has initiated a program to perform upgrades to the wastewater treatment systems at the NEWPCC, SEWPCC, and WEWPCC facilities. As part of these upgrades, automation systems are required for process control and monitoring. These automation systems must be installed to provide effective monitoring and control of the wastewater treatment processes. There are many methods of implementing an automation system, and the purpose of this document is to provide an overall strategy for automation installations that are consistent with the City’s needs. It is expected that this document will form the basis for future design work.

. Introduction This chapter introduces the fundamental concepts of DCS systems. The terms Supervisory Control and Data Acquisition (SCADA), Distributed Control System (DCS), Programmable Logic Controller (PLC), and Smart Instrument are defined and placed in the context used in this manual. The chapter is split into the following sections:  Definitions of the terms SCADA, DCS, PLC and smart instrument  Remote terminal unit (RTU) structure  PLCs used as RTUs  System reliability and availability  Communication architectures and philosophies  Typical considerations in configuration of a master station