Project Scope

Design, Engineering, Manufacturing, Supply, and Commissioning of an MCC Panel, PLC Panel, and SCADA System for a Membrane Bioreactor (MBR) Wastewater Treatment Plant.

Background

Membrane Bioreactor (MBR) technology combines membrane filtration and biological treatment for innovative wastewater processing. To automate the entire sewage treatment plant, including MBR transfer pumps and mixers, a comprehensive control system was required. The plant’s major units—Pre-treatment, Dewatering, and Aeration—needed to be controlled, involving several valves and flow meters. The customer sought a PLC and SCADA-based control system to automate the plant’s operations.

System Description:

The plant’s operations start with collecting wastewater in raw storage tanks. After pre-treatment, the water undergoes various processes like Anoxic, Aeration, and MBR treatments. The treated water is then subjected to sludge removal, chlorination, and polymerization before storage in treated water tanks.

Each MBR process has specific flow rates, time durations, and flow directions. Desired flow rates in the MBR system are achieved through PID control of permeate pumps and associated valves. Flow direction and stream control are managed using electro-pneumatic valves.

Each MBR cycle involves deaeration, backwash, and ventilation sequences until the desired cycle is reached. The water is then filtered, chemically dosed, and fed into storage tanks.

The PLC and SCADA-based control system automates and monitors the entire plant. Key components include:

• PLC: Mitsubishi Electric IQR Series
• SCADA: Genesis64 SCADA
• Motor Starters: Direct-On-Line (DoL) and Star-Delta Starters from Schneider Electric
• VFDs: F800 Series Variable Frequency Drives (VFDs) from Mitsubishi Electric
• Modular Enclosure: Housed in a Modular Enclosure System from Phoenix Contact

Implementation Approach

A centralized MCC panel was implemented to manage pump and mixer operations efficiently. The control system for the entire plant included PLCs, I/O modules, and other components, facilitating cumulative flow calculations for each stream.

Key Features:

• Visual Alarms: The system generates visual alarms, prioritizing visibility based on criticality.
• Parameter Monitoring: Captures critical parameters such as pump status, overload status, and power parameters (voltage, current, energy consumption).
• Automated Control: Includes solutions for unattended trip changeover, duration-based changeover, and other configurations for blowers and mixers.
• Tank Level Interlocks: Motor interlocks based on tank levels, configurable from SCADA with different access levels for security.

Project Outcomes

The SCADA system allows operators to monitor all operation sequences in a single window, with settings conveniently located nearby for ease of use. The customer now has a reliable and stable control system, with possibilities for future expansion and adaptation.