Wastewater Treatment and Control Zeta Potential

Wastewater contains different kinds of pollutants (dissolved substances, suspended particles), and is treated in suitable plants before the processed water is released. 

Wastewater contains both soluble and insoluble substances that need to be removed. These substances that (solutes) are in either molecular (such as benzene, etc.) or ionic (such as Na+, Cl-, Mg++, K+, Fe++, etc.) form. The concentrations are given in various units  

The specific unit used depends on the amounts present. The unit used for a trace amount of a solute, such as benzene, is given in ppm or ppb. The hardness of drinking water (mostly Na, Ca-Mg) concentration is given as mg L 1. The typical values as found are in the range of less than 10 mg L-1 (soft water) or over 20 mg L-1 (hard water). 

The presence of a net charge at the particle surface produces an asymmetric distribution of ions in the surrounding region. This means that the concentration of counterions close to the surface are higher than the ions with the same charge as the particle. Thus, an electrical double layer is measured around such a particle placed in water. 

The magnitude of the zeta potential, Q, is obtained from the following relation  

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