The Wastewater Treatment Plant: A Complex Facility Subject to Regulatory Oversight
A wastewater treatment plant (WWTP) is a complex industrial facility designed to treat domestic and industrial wastewater before it is discharged into the natural environment. Its operation involves dozens of electromechanical devices (pumps, blowers, agitators, screw conveyors, presses) and delicate biological processes that require constant monitoring.
A failure at a wastewater treatment plant has direct consequences for the environment (pollution of the receiving water body), on public health (bacteriological contamination), and on the operator’s legal liability (performance obligation established by the ICPE authorization order). Remote monitoring has become an essential tool for managing these risks.
Flowchart of a Wastewater Treatment Plant and Measurement Points
[[Sewage System]
Influent Flow (Electromagnetic Flowmeter)
↓
[[Preprocessing]
Screening — Sand Removal — Degreasing
↓
[Biological tank (activated sludge)]
Dissolved oxygen (DO sensors)
pH and temperature
Potentiel redox
Blower Flow Rates and Power Consumption
↓
[Clarificateur secondaire]
Sludge Level (US Probe)
Sludge recirculation flow rate
↓
[Traitement tertiaire (optionnel)]
Filtration, UV, Phosphate Removal
↓
[Rejet milieu naturel]
Effluent flow rate (flow meter)
Turbidity, Online Suspended Solids
Online NH4 and NO3 monitoring (at large wastewater treatment plants)
Monitored Electromechanical Equipment
Pumping Stations
- Status of each pump (on/off/fault)
- Suction tank level
- Motor current and hour meter
- Automatic switching between pumps
Ventilation Fans
- Discharge pressure (bar)
- Air flow rate (m³/h)
- Discharge air temperature
- Current and power consumption
- Operating hours
Sludge Treatment
- Extraction and recirculation pumps
- Screw press or centrifuge (flow rate, current)
- Polymer dosing (flow rate, meter)
- Liquid sludge tank levels
Alerts and Compliance Management
Monitoring a wastewater treatment plant generates several levels of alerts:
| Level | Example Trigger | Action |
|---|---|---|
| Warning | OD < 2 mg/L for 30 min | Automatic increase in aeration |
| Operational Alert | Lift pump failure | Operator notification + emergency pump activation |
| Critical Alarm | Bypass active, bypass flow > 0 | Notify operator + water authority |
| Environmental Alarm | Effluent TSS > VLR for 1 hour | Notify DREAL, trigger ICPE procedure |
The platform logs each alarm, including the timestamp, duration, and corrective action, to compile the regulatory self-monitoring record.
Energy Optimization: Ventilation Control
Aeration of biological treatment tanks accounts for 50 to 70 percent of a wastewater treatment plant’s electricity consumption. Automatic control based on continuous measurement of dissolved oxygen makes it possible to:
- Adjust the blower power to match the actual biological load (lower at night and on weekends).
- Avoid unnecessary over-aeration (OD > 4 mg/L).
- Control the alternating cycles between aerated and anoxic zones (denitrification).
At a wastewater treatment plant with a capacity of 50,000 PE, energy savings achieved through demand-based control typically amount to 25 to 40% of the aeration costs, or €30,000 to €60,000 per year.
VERSEAU Self-Monitoring and Compliance Reports
Automatic monitoring generates regulatory self-monitoring reports:
- Daily report: flow rates, loads, treatment performance, incidents.
- Monthly summary: treatment efficiency by parameter (COD, BOD5, TSS, NTK, PT).
- Annual report: comprehensive report for the DREAL/OFB.
- Incident report: description, timestamp, duration, and corrective actions for any significant event.
This data is automatically transmitted to the VERSEAU platform in the SandreEDL format, eliminating the need for manual entry and reducing the risk of errors or delays in reporting.