1. Monitoring scope: On-line monitoring of sewage treatment focuses on common water quality indicators, and the selection of monitoring equipment and sensors is based on monitoring efficiency, reliability and economy. The monitoring of heavy metal indexes needs more complicated equipment, sample processing and analysis process.
2. sewage treatment objectives: the main objectives of sewage treatment are to remove organic matter, inorganic matter and nutrients, reduce suspended solids and improve redox conditions of water bodies. Heavy metals are not one of the main pollutants, so they are not particularly emphasized in online monitoring.
3. Monitoring requirements: Monitoring heavy metals requires stricter monitoring measures and high-precision analytical methods, such as using more complex instruments and laboratory tests. Compared with this, online monitoring of sewage treatment pays more attention to real-time continuous monitoring and rapid feedback of treatment effect.