Southern Interior BC WWTP: Hazardous-Area Centrifuge Case Study
A HAUS DDE 3042 decanter and an Archer control system laid out for a Class I, Division 2 dewatering room replace the ageing centrifuge at a municipal wastewater plant in the Southern Interior of BC.
The application
A village in the Southern Interior of BC dewaters waste activated sludge at its wastewater treatment plant. The old centrifuge and its control system were reaching the end of their life, so Archer proposed a staged replacement: new controls first, then a new centrifuge working with the plant’s existing cake conveyor.
The village ordered the controls in October 2025 and the centrifuge in March 2026. Both were delivered together in July 2026, and the new unit was started up in October 2026, with operator training on site.
The centrifuge room is a Class I, Division 2 hazardous location; only the area where the control panel stands is general purpose. Air from the centrifuge casing may carry hydrogen sulphide, so the foul-air outlet is vented or taken to odour control.
Designed for the hazardous area
Archer kept the control panel, with its PLC and drives, in the general-purpose area, and specified everything inside the classified room for that rating.
- Class I, Division 2 motors on the centrifuge main drive and back-drive, the sludge feed pump and the cake conveyor, with a dV/dt filter on every drive output
- A Beckhoff 15-inch multi-touch operator panel rated for Zone 2 at the machine, linked to the PLC over a single CP-Link 4 cable
- Intrinsically safe circuits for the bearing temperatures and field sensors, through zener barriers and Ex i EtherCAT I/O terminals; the panel is cUL certified, including intrinsic safety
- Low-power, intrinsically safe flush valves for the centrifuge and conveyor
What Archer supplied
- One HAUS DDE 3042-H decanter centrifuge: duplex stainless steel bowl, tungsten carbide wear protection, 15 kW main drive and 4 kW back-drive, automatic bearing lubrication, special tools and spare parts
- NEMA 12 free-standing control panel, designed by Archer and built in BC: Beckhoff CX5130 PLC programmed in TwinCAT 3, Altivar VFDs for the bowl, scroll and feed pump, reversing starter for the conveyor, safety relay with Safe Torque Off
- Centrifuge junction box with EtherCAT I/O for speed, vibration and bearing temperatures
- Sydex BK 045 progressive cavity sludge feed pump with a Class I, Division 2 motor, and a Class I, Division 2 motor for the existing cake conveyor
- Stainless steel centrate chute designed by Archer
- Seismic anchorage design for the centrifuge plinths, remote monitoring of the running machine, start-up and operator training
Engineered in-house: electrical schematics in EPLAN, the centrate chute modelled in SolidWorks, and the seismic anchorage of the centrifuge on its plinths checked to NBC 2020 with finite element and response-spectrum analysis in code_aster.
Design basis
| Feed | Waste activated sludge, 0.7–2.0 % TS, about 75 % volatile solids |
|---|---|
| Design sludge flow | 4–6.5 m³/h |
| Operation | 6–8 h/day, 5 days/week |
| Polymer | 6–12 kg active/t DS |
| Guarantee | 16 % ± 2 % cake solids and ≥ 95 % capture at 5.5 m³/h and 0.9–1.5 % TSS feed |
| Drives | 15 kW main, 4 kW back-drive, 2.2 kW feed pump; 600 V, 3-phase, 60 Hz |
| Area classification | Class I, Division 2 around the centrifuge; control panel in a general-purpose area |
Design and guarantee figures from Archer proposal 25082901 (September 2025); drives and area classification from the project drawings.
Related
- Control Panels: PLC control panels designed by Archer and built in BC, including panels for hazardous areas.
- Decanter Centrifuges: HAUS decanters for sludge dewatering and process separation.
- Municipal Water and Wastewater: equipment for municipal treatment plants.
- Remote Monitoring: IIoT monitoring and remote support.
- All case studies: more Archer projects in the field.