Monitoring the Coagulation/Flocculation Mechanism and Process During Wastewater Treatment: Impedance Spectroscopy

The coagulation-flocculation process is an important step and operation, most often used as a pretreatment before separation processes of the liquid and solid phases. The fundamental mechanisms of this process have been the subject of several studies in recent years. However, it is still difficult to predict the required amounts of the coagulants as well as the flocculants to achieve these processes properly. Indeed, these amounts are can be considered as a crucial parameter because any execs can lead to generate a secondary pollution in addition to the cost of these products. In this context, a new approach was carried out to investigate the complex impedance Z*(ω) measurements as well as others dielectric/electrical characteristics including the complex permittivity ε*(ω), complex modulus M*(ω) and complex conductivity σ*(ω) were explored. It is revealed from our study that the analysis of the dielectric and electric properties could be very useful to address these criteria for estimating the optimal amount the coagulants and flocculants. This approach was employed to investigate these properties in the case for effluents from the textile industry. Calcium oxide and aluminum sulfate were used as coagulants, while a cationic polymer was used as a flocculants. For coagulation process: The analysis and modeling of the electrical dielectric properties of the samples exhibited a significant change the evolution of conductivity by decreasing and reaching a minimum value at (3%) of calcium oxide then started to increases. Moreover, the relaxation time and dielectric strength increased in the first phase up to (3%), indicating the formation of more compact aggregations during the coagulation process, and decreased in the second phase above (3%). These results were supported and revealed a good agreement by a complementary analysis of the rheological properties. The evolution of the viscosity exhibited a similar behavior to the evolution of conductivity by decreasing and reaching a minimum value at (3%).