What an Online Urban Sewage Monitoring System Can Measure

Online monitoring systems for municipal wastewater treatment plants continuously track key parameters to ensure compliance with discharge standards and optimize process control. Typical measurements include:

1. Physical Parameters

• Flow rate (influent and effluent): using electromagnetic or ultrasonic flowmeters.

• Temperature: affects biological activity and chemical reactions.

• Suspended Solids (SS) : measured by turbidity or optical sensors.

2. Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD)

• COD: rapid UV absorption or chemical oxidation sensors.

• BOD: estimated via online respirometers or correlation models.

3. Nutrients

• Ammonia‑nitrogen (NH₃‑N) : ion‑selective electrodes or colorimetric analyzers.

• Total phosphorus (TP) and Total nitrogen (TN) : digestion + photometry.

• Nitrate (NO₃‑N) : UV absorbance.

4. pH and ORP

• pH: glass electrode.

• ORP (Oxidation‑Reduction Potential): indicates disinfection or nitrification status.

5. Dissolved Oxygen (DO)
Optical or electrochemical sensors in aeration tanks to control blowers.

6. Sludge Parameters
Mixed liquor suspended solids (MLSS) and sludge volume index (SVI) via online sensors.

Modern systems often integrate data loggers and SCADA for real‑time alarms, remote reporting, and predictive maintenance. By monitoring these parameters, operators can quickly detect upsets, reduce energy consumption, and protect receiving waters.