Assessment of organically bound iron removal from water using crushed eucalyptus tree bark as a Biosorbent

Abstract

The presence of Iron coexisting with natural organic matter (NOM) in surface water sources presents significant public health concerns, affecting potability and treatment processes. Conventional treatment methods, while effective, can be costly and generate chemical sludge. This study investigates the efficacy of crushed Eucalyptus grandis and Eucalyptus camaldulensis tree bark, both abundant and low-cost agricultural wastes, as biosorbents for the removal of organically bound iron from water. The research aims to provide a sustainable and environmentally friendly alternative for water treatment, particularly relevant in resource-limited settings. Raw water samples were collected from the National Water and Sewerage Corporation (NWSC) Masaka Treatment Plant along River Nabajjuzi, a source potentially impacted by organic matter that can bind with iron. The Eucalyptus grandis and Eucalyptus camaldulensis barks were collected, processed through oven drying and sieving, and treated with a calcium chloride solution to enhance its biosorption capacity. Batch experiments were conducted under varying conditions for example biosorbent dosage, contact time and biosorbent age to determine the optimal parameters for iron removal. Iron concentrations in the water samples before and after treatment were measured. The findings of this study evaluate the potential of Eucalyptus grandis and Eucalyptus camaldulensis bark as cost-effective and sustainable biosorbents for the removal of organically bound iron from water. The findings confirmed the suitability of eucalyptus bark for metal adsorption. Biosorption tests demonstrated that the best iron removal (97.12%) and highest adsorption capacity (405.34 mg/g) were achieved using 0.5 g of young Eucalyptus camaldulensis bark at a contact time of 72 hours. The pseudo-second-order kinetic model provided the best fit for the data, confirming that the process is governed by chemisorption. Comparative analysis across bark types and ages showed that younger barks outperformed other ones. This highlights the critical role of bark maturity and chemical structure in optimizing biosorption. The study ultimately reveals that crushed bark from young Eucalyptus camaldulensis offers a low-cost, locally available, and environmentally friendly solution for removing organically-bound iron from water. Iron concentrations below the WHO guideline limit of 0.3 mg/l were achieved, making this method highly relevant for decentralized water treatment in rural and resource-constrained settings.