Optimization of Domestic Wastewater Treatment Using Ferric Chloride Coagulant: Physicochemical Analysis and Impedance Spectroscopy Studies

The study investigates the effectiveness of Ferric Chloride as a coagulant for removing pollutants from domestic wastewater in El Jadida, Morocco. It analyzes various parameters, including Total Suspended Solids (TSS), Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD), pH levels, and heavy metals. The study combines conventional methods with impedance spectroscopy to monitor the process, and an equivalent circuit model is developed to correlate theoretical factors with empirical data. The study reveals that a concentration of 1000 mg/L of Ferric Chloride is optimal for effective treatment, significantly reducing TSS, BOD, and COD levels. However, higher concentrations show diminishing returns. The study also highlights the presence of heavy metals exceeding Moroccan standards in the wastewater, emphasizing the need for proper treatment. The impedance analysis elucidates the relaxation processes associated with the coagulation reaction and the migration/agglomeration of flocs. The analysis suggests that below 1000 mg/L, more Ferric Chloride is required for effective coagulation, while above 1000 mg/L, overcoagulation may occur. Complex conductivity analysis confirms the presence of two distinct relaxation processes in the samples. The equivalent circuit model accurately describes the electrical spectra.