Expanding wastewater treatment capacity with Siemens PCS7 Automation
The existing wastewater treatment plant (WWTP) of Cargill needed greater capacity, improved reliability and a future-proof control architecture. To support ongoing production growth and sustainability goals, they were willing to invest in both an expansion of its anaerobic treatment capacity and a complete upgrade of its biogas handling installation.
Agidens, as preferred automation partner, took care of the software engineering, testing and commissioning.
Project objectives
Increase WWTP throughput capacity
By installing and commissioning a fourth anaerobic reactor and optimizing feed, degassing and sludge handling, the site could significantly increase biological treatment performance.
Improve biogas system stability and reliability
The existing biogas train was replaced and expanded with a new biogas buffer balloon, blowers, desulphurization units and revamped biogas compression and distribution controls.
Agidens scope
A key focus was the development of a unified process start-up sequence. Where operators previously had to intervene manually to manage tank levels and pump ramp-up during start-up, this is now handled automatically and in a controlled sequence. The result is a more reliable, safer start-up with less dependency on operator experience.
New overview screens were also designed, which operators experience as clearer and more intuitive than the previous interface.
Sofware engineering (PLC & SCADA)
Development of control logic, interlocks, sequences and operator interfaces for:
- Anaerobic reactor 4 (full operation: feed control, degassing, sampling, sludge discharge)
- Flexible reactor selection logic, allowing operators to easily configure which reactors are active (with a maximum of two reactors running simultaneously)
- Biogas buffering and transport systems
- Desulphurization lines, conditioning units, blowers and safety systems
Functional Design Support
Beyond software delivery, Agidens took an active role in refining the functional design together with Cargill. Through a series of collaborative working sessions, the scope was progressively detailed and aligned, defining overarching process functionality that allows the installation to be started up as one integrated whole rather than as separate modules.
FAT, SAT & Commissioning in 4 phases
To guarantee production continuity, commissioning was sequenced in four controlled steps. Each phase included separate FAT and SAT testing moments to ensure safe and validated go-lives.
- Connect anaerobic reactor 4, biogas balloon, blowers and stripper 4, and disconnect anaerobic reactor 3
- Reconnect anaerobic reactor 3, and disconnect anaerobic reactor 2 and old gasholder
- Switch to the new biogas train
- Connect all anaerobic reactors to the new biogas balloon
Documentation & as-built dossier
A full PCS7 software as-built package was delivered, ensuring long-term supportability.
Project management & coordination
Agidens supported on-site coordination and quality assurance (ISO 9001 procedures) as part of a multi-contractor project, working within the overall planning framework managed by the client.
Results
- The upgraded installation gives the WWTP the ability to handle higher loads with greater stability and flexibility. The new and optimized anaerobic reactors add significant capacity, while the renewed biogas system offers more reliable buffering and safer, more consistent operation.
- Operators benefit from a more automated and intuitive system, reducing reliance on manual intervention during critical process steps and lowering the threshold for day-to-day operation.
- The modernized WWTP is a resilient and efficient installation that is well equipped to support long-term operational growth and sustainability ambitions.