Sustainable Aluminium Ion Removal Using Agro-Waste-Derived Activated Carbon for River Preservation: From Lab-Scale Towards Upscaling Study

Abstract

High heavy metal content in river water has been a threat to the ecosystem due to bioaccumulation and biomagnification. The Miri River was deemed unsuitable for recreational use with body contact. It requires conventional treatment if used for water supply, primarily due to its high aluminium (Al) content. This is due to the anthropogenic influences of the industrial areas upstream of the river. The Al could flow into the river due to surface runoff or wastewater discharge. This study synthesised an effective adsorbent from recycled agro-waste, specifically coconut shells (CS), obtained from local areas, for Al removal. The CS was continuously produced in association with a large amount of coconut production. The current study aims to address the local water pollution issue with locally available sources to maximise environmental benefits. Under optimal conditions, the adsorbent is able to remove up to 99.84% of Al from synthetic water on a laboratory scale, reducing the concentration from 58.81 mg/L to 0.10 mg/L. A larger-scale application was examined by implementing a floating prototype with an adsorbent pack placed on it, where a residual Al content of approximately 0.06 mg/L was obtained. Moreover, the thermodynamic study validated that the Al adsorption is not limited by temperature. The efficiency remains above 99.84% with a temperature range from 25oC to 60oC . The current study demonstrates the technical feasibility of Al removal on a larger-scale application by an adsorbent derived from recycled waste. These findings determined that the local agro-waste CS is an efficient adsorbent source for heavy metals remediation, particularly for the Miri River. A future study is required to focus on the installation of the system at other contaminated rivers.