Water Boffins: Sewage Treatment Plant Control System
The Challenge
Water Boffins needed a comprehensive control and automation system for a 250 KLD sewage treatment plant that would integrate multiple treatment stages — from raw sewage screening through biological treatment, membrane filtration, disinfection, and sludge handling. The system had to monitor and control dozens of pumps, blowers, dosing systems, and instrumentation across MBBR, MBR, and chlorine contact zones while maintaining strict compliance with water quality standards and regulatory reporting requirements.
Our Approach
Deftec designed and engineered a complete control solution centred on an Allen Bradley ControlLogix PLC platform integrated with a 14” HMI panel housed in a custom Motor Control Centre (MCC). The system incorporates multiple variable frequency drives for optimal pump and blower control, precision level sensing across nine tank zones, flow measurement on critical process streams, and real-time water quality monitoring including pH, dissolved oxygen, turbidity, and chlorine residual. All field instrumentation — temperature sensors, pressure transmitters, flow meters, and level switches — connects through structured cable schedules and termination drawings with full SCADA integration. The design included comprehensive electrical architecture with 250A main protection, distribution across 48-way control boards, and localised isolation points for safe maintenance access.
The Outcome
The delivered system provides Water Boffins with continuous real-time visibility of all treatment processes, enabling operators to respond immediately to changing influent conditions and maintain consistent effluent quality. Data archival and trending through SCADA historian allows compliance reporting and performance optimisation, while integrated alarm management and E-stop safety controls ensure plant reliability and operator safety. The standardised equipment tagging and detailed termination documentation simplifies commissioning, maintenance, and future system updates.
Technologies and Capabilities
- Allen Bradley ControlLogix PLC with Panel View HMI
- Variable Frequency Drives (Schneider ATV630 series, 3-7.5 kW)
- Motor Control Centre with 250A main incomer and 100A distribution
- Magnetic flow meters and pressure transmitters (4-20 mA analogue)
- Multi-point level sensing and float switches
- Water quality instrumentation (pH, DO, MLSS, turbidity, chlorine analysers)
- Contactor and relay logic for pump/blower sequencing
- Earth leakage protection and emergency stop integration
- Real-time SCADA trending and data historian
- Comprehensive cable scheduling and field termination documentation