Feasibility of Rice Husks Adsorption for Removal of Lead and Zinc from Contaminated Wastewater

Abstract

Tanzania, like other parts of the world faces a challenge of environmental contamination from heavy metals due to untreated or partially treated industrial wastewater. Although previous studies have demonstrated the effectiveness of agricultural wastes in heavy metals removal from wastewater, but still there remains a limited understanding on the use of rice husks. This study aimed to determine the optimum conditions in removing lead and zinc from wastewater using rice husks. A series of batch experiments were conducted, varying pH, particle size, and adsorbent dose. Agitation at 210 rpm for 24 hours was employed to enhance adsorption. Lead and zinc ions were measured by Atomic Absorption Spectrophotometer. Analysis was done by One-way ANOVA. The results showed that the highest removal efficiencies were at pH of 6.4, particle size of 0.8 mm and adsorbent dosage of 10 g, achieving 96% Pb and 95% removals. Adsorption capacities were 0.12 mg g⁻¹ for Pb and 0.19 mg g⁻¹ for Zn. However, ANOVA results indicated no statistically significant differences in removal efficiencies among the tested parameters (p > 0.05). Rice husks demonstrated potential as effective and low-cost adsorbents for removing both lead and zinc from contaminated wastewater, highlighting their potential for wastewater treatment applications.

Key words: Adsorption; Agro-wastes; Heavy metals, Wastewater Treatment