What is the difference between suspended solids and turbidity?

In sewage treatment, we often see monitoring indicators of SS and turbidity, so what do these two indicators mean? What is the difference between them? First of all, the concepts of the two are completely different. SS is the abbreviation of suspended solids, which refers to solid matter that cannot pass through the filter(filter paper or filter membrane), including suspended solids and dissolved solids. The unit is mg/L. It mainly refers to insoluble solids such as soil, sand, and animal and plant residues. Impurity particles with a diameter of more than 10^-4mm. Turbidity refers to the suspended solids and colloids such as soil, silt, fine organic matter, and plankton contained in the water, which can make the water turbid and show a certain degree of turbidity. The degree of turbidity is called turbidity, and the scattering turbidity unit is NTU.

Secondly, suspended solids and turbidity are parameters that reflect the number of suspended particles in water. In the past, suspended solids were often measured by the mass difference before and after filtration using an analytical balance weighing filter paper. This method has a long test cycle and is difficult to monitor in real time. Nowadays, online suspended solids analyzers are commonly used. Daruifuno's DUC2-SS online Suspended Solids Controller is paired with the MLSS series suspend solids sensor. They can be used for the real-time monitoring of water suspended solids value. Turbidity is generally measured in laboratories using a turbidity meter, and the commonly used unit in water treatment is NTU. Turbidity reflects the turbidity of water through the ligh scattering effect of particulate matter in the water. The online turbidity analyzer DUC2-TU is paired with the OPTU series Turbidity Sensor to achieve continuous monitoring of water turbidity through the scatteri method.

Finally, whether to monitor turbidity or suspended solids in water quality depends on the water quality. When the value of suspended solids in the water is small, such as in natural water bodies, it is more accurate to use turbidity to reflect the amount of suspended solids. When there are many suspended solids in the water, such as the sludge concentration in an aerobic tank, it is more straightforward to use SS, which can clearly reflect the microbial quality per unit volume of water. Moreover, when the number of suspended solids in the water reaches a certain amount, the turbidity and suspended solid concentration are not linearly related, making it inconvenient for experimental analysis. In general, suspended solids contribute to the development of turbidity.

The above is an introduction to water quality turbidity and suspended solids. Delfino company focuses on the research and development and production of water quality analysis instruments. Our measurement parameters include pH, ORP, conductivity, TDS, salinity, dissolved oxygen, COD, ammonia nitrogen, turbidity, Chlorophyll, blue-green algae, residual chlorine, chlorine dioxide, etc. In addition to ORP sensors, our main products include pH ORP analyzer, conductivity analyzer, turbidity analyzer, COD analyzer, dissolved oxygen analyzer, ammonium analyzer, chlorine analyzer, etc.