International Journal of Academic Research in Education and Review

Vol. 12(2), pp. 86-91, May 2024

ISSN: 2360-7866

https://doi.org/10.14662/ijarer2024160

 

Full Length Research

 

 

Evaluation of the Efficiency of Local Clay in Mitigating Heavy Metal Pollution in Ballast Water: A Case Study of Calabar, Onne, and Warri Ports in the Niger Delta

 

1Boisa, N., 2Obunwo, C. C., 3Cookey, G. A and 4Akpobire, O

 

(1, 2, 3, 4Department of Chemistry Factory of Science, Rivers State University, Nkpolu-Oroworukwo Port Harcourt)

Corresponding author’s Email: honkome@yahoo.com  

Accepted 25 May 2024

Abstract

Abstract: This study investigates the concentrations and removal efficiencies of heavy metals in ballast water from the ports of Calabar, Onne, and Warri, Nigeria, using local clay as a treatment method. The research focused on major ports within the Niger Delta region, where ballast and surface seawater samples were collected. Samples were obtained using cleaned plastic containers. Transportation and storage adhered to the D-2 standard to maintain sample integrity. Heavy metal analysis was conducted using flame atomic absorption spectroscopy (FAAS), with high-purity reagents and rigorous calibration procedures. Initial analysis revealed significant contamination with lead (Pb), zinc (Zn), copper (Cu), and cadmium (Cd), exceeding the limits set by the National Environmental Standards and Regulations Enforcement Agency (NESREA) and, in some cases, the International Maritime Organization (IMO). Lead concentrations were 0.279 mg/L in Calabar, 0.294 mg/L in Onne, and 0.235 mg/L in Warri, all surpassing the NESREA limit of 0.001 mg/L and the IMO limit of 0.250 mg/L. Zinc levels reached 0.83 mg/L in Calabar, 1.08 mg/L in Onne, and 2.75 mg/L in Warri, significantly exceeding both the NESREA limit of 0.02 mg/L and the IMO limit of 0.200 mg/L. Copper and cadmium concentrations also notably exceeded NESREA guidelines. Post-treatment analysis showed reductions in heavy metal concentrations, with varying effectiveness across different elements and ports. Lead levels in Calabar, Onne, and Warri were reduced to 0.172 mg/L, 0.278 mg/L, and 0.242 mg/L, respectively, with Calabar meeting the IMO limit. Zinc concentrations were lowered to 0.214 mg/L in Calabar, 0.911 mg/L in Onne, and 1.114 mg/L in Warri, with Calabar meeting the IMO limit but all samples still exceeding NESREA guidelines. Cadmium levels were significantly reduced to 0.002 mg/L in Calabar and Onne, and 0.005 mg/L in Warri, yet remained above NESREA limits. The percentage removal efficiencies for heavy metals after treatment with local clay revealed a 38.35% reduction in lead in Calabar, 5.44% in Onne, and an unexpected increase of 2.98% in Warri. Zinc removal was highest in Calabar at 74.22%, moderate in Warri at 59.49%, and lowest in Onne at 15.65%. Cadmium removal was highly effective in Calabar and Warri, with reductions of 88.89% and 92.96%, respectively, but was ineffective in Onne (0.00%).The use of local clay demonstrated significant potential in reducing heavy metal concentrations in ballast water, particularly for elements like zinc and cadmium. However, further optimization of the treatment process is needed to achieve consistent and comprehensive removal across different ports and heavy metals, ensuring compliance with stringent environmental standards.

 

Key Words: Heavy metals, ballast water treatment, local clay, Niger Delta ports, flame atomic absorption spectroscopy (FAAS), environmental standards, removal efficiency.

Paper type: research