ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Clarification efficacy of eggshell and aluminum base coagulant for the removal of total suspended solids (TSS) from cosmetics wastewater by coag-flocculation

Prosper E. Ovuoraye, Lawrence C. Okpala, Victor I. Ugonabo, and Gina F. Nwokocha

Department of Chemical Engineering, Nnamdi Azikiwe University, Awka, Nigeria

E-mail: pe.ovuoraye@gmail.com

Received: 20 February 2021  Accepted: 13 May 2021

Abstract:

This research compares two coagulants: Aluminum Base Coagulant (ABC) and Eggshell Coagulant (ESC) used for the coag-flocculation treatment of cosmetic wastewater to determine the efficacy of ESC at optimum conditions. The residual values of TSS particles in the wastewater were measured and recorded after the coag-flocculation treatment at 30 min settling time. The cubic models obtained following the Central Composite Design (CCD) were used to confirm the experimental determined optimum pH and dosage recorded as: 6 and 0.2 g/L for ESC, while pH 8 and 0.1 g/L were reported for ABC. The optimal point plots 85% and 97% TSS removal efficiency which corresponds to 38 mg/L and 7 mg/L of residual TSS recorded for ESC and ABC respectively. The results obtained show that; the ABC and ESC driven coag-flocculation satisfied the EPA standard for wastewater discharge at the optimal pH. The trend of the

figures obtained following second order coag-flocculation rate law shows that; rate constants \((k_{m} )\;{\text{ of}}\,\, 3 \times 10^{ - 4} {\text{L/mg}} \cdot \min\) and \(3.06 \times 10^{ - 4} {\text{L}}/{\text{mg}} \cdot {\text{min}}\) were obtained for ABC and ESC at pH 6, while \(5.83 \times 10^{ - 5} {\text{L}}/{\text{mg}} \cdot {\text{min}}\) and \({1}{\text{.93}} \times 10^{ - 3} {\text{L}}/{\text{mg}} \cdot {\text{min}}\) were recorded for ABC and ESC at pH 8. The values of \((k_{m} )\) recorded for ABC and ESC surpassed the value of the threshold rate constant \(\left( {k_{f} } \right) of\,\, 2.94 \times 10^{ - 4} {\text{L/mg}} \cdot {\text{min}}\) at optimum pH. ABC was more efficient than ESC at pH 8, while ESC was more effective than ABC at pH 6. The cost remediation results showed that; ESC maintained significantly lower operating cost for TSS clarification from cosmetics wastewater compared to ABC, hence it’s highly recommended as a coagulant/flocculants aid.

Keywords: Eggshell; Efficacy; Total suspended solids (TSS); Cosmetics wastewater; Coag-flocculation; Environmental protection agency (EPA); Central composite design

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-021-01703-x

Chemical Papers 75 (9) 4759–4777 (2021)