Skip to main content

Synergetic effects of mixing parameters, settling characteristics and process kinetics on coagulation treatment of tannery industry wastewater


The coagulation treatment for the removal of turbidity from tannery industry wastewater using the coagulant protein in Moringa oleifera seeds was investigated in this research work. The natural coagulant was prepared from the seed powder using NaCl and KCl salt solutions each having a concentration of 0.25 M. The effect of coagulant dosage and initial pH on % turbidity removal was investigated for both coagulants. A higher turbidity removal efficiency of 74.11% was achieved with NaCl extracted coagulant at an optimum coagulant dosage of 30 mL and initial pH 9, whereas the coagulant prepared by KCl salt solution exhibited a lower treatment efficiency of 68.52%. The maximum and minimum velocity gradients attained was 1098.8 s−1 at 31 °C and 257 s−1 at 25 °C, respectively. The least residual turbidity was achieved at 440 rpm impeller speed. The relationship between power function and Reynolds number (Re) for unbaffled tank shows that transition zone develops between 30,500 < Re < 56,000. The residual turbidity concentration decreases with increase in settling velocity for different coagulant dosages. The turbidity removal process follows the second-order kinetics model with a rate constant of 0.000158 (mg/500 mL)−1 min−1. The variation of coagulation rate constant with temperature was supported by Arrhenius law (R2 = 0.9645) rather than Transition state theory (R2 = 0.96) and Collision theory (R2 = 0.9624). The exponential decay of concentration ratio with time indicates that Smoluchowski rate equation explains the growth of floc particles governed by fluid motion. This study reveals the successive and optimistic influence of coagulant dose, pH, mixing dynamics, settling mechanism and coagulation rate on turbidity removal from tannery wastewater.

Graphical abstract

This is a preview of subscription content, access via your institution.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9
Fig. 10
Fig. 11
Fig. 12
Fig. 13
Fig. 14

Data availability

All data generated or analyzed during this study are included in this published article.


Download references


No funding was obtained from any organization. So, it is not applicable.

Author information

Authors and Affiliations



MKM has designed and developed experimental protocols, prepared the results in graphical form and table, analyzed and interpreted the data’s, written the full manuscript. HPN has conducted all the experiments and involved with collection of data’s, and assisted in writing the manuscript and interpretation of results. Authors’ information (optional) was already provided during the registration process.

Corresponding author

Correspondence to Magesh Kumar Marichamy.

Ethics declarations

Conflict of interest

All the authors declare that they have no competing interests.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Marichamy, M.K., Narayan, H.P. Synergetic effects of mixing parameters, settling characteristics and process kinetics on coagulation treatment of tannery industry wastewater. Chem. Pap. 76, 4169–4188 (2022).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:


  • Green coagulant
  • Kinetic models
  • Power number
  • Arrhenius law
  • Smoluchowski equation