Irrigation with Unsafe Industrial Wastewater and Associated Health Risks: An Emerging Technology for Heavy Metals Removal

Abstract

The scarcity of freshwater resources, being currently experienced in water-stressed countries has prompted millions of smaller farming communities to depend on wastewater for crop irrigation, drinking, bathing and fishing. However, in this context, the treatment of wastewater from textile and tannery industries is the subject of interest, this paper aim to address. The rule of thumb suggests, wastewater to constitute beneficial nutrients recycling due to rich organic matter content. Inherently, the same kind of wastewater has been investigated and analysed by several researchers and found to contain micro-pollutants such as inorganics (heavy metals, salts) and organics (dyestuff, starch). Regrettably, the presence of these pollutants in wastewater used for irrigation is of concern particularly as it relates human health. Although, several conventional wastewater treatment technologies exist; their applications are now hamstrung by high procurement, operation and maintenance costs. Recent studies on cheap and readily available biomass wastes have confirmed their high sorption potential and can therefore, be used as adsorbents for micro-pollutants removal from industrial wastewater. In this study, chicken eggshell, coconut peat, coconut shell, rice husk and lemon peel were all used for the wastewater treatment. Hydrothermal carbonisation (HTC), was used to change the surface functional characteristics of the adsorbents for enhanced adsorption. To achieve this, batch experiments using raw biomass were carried out in triplicates at 3 different contact times and pH values. After 2 hr of contact time at pH9, the coco-peat was proven to have Cr removal efficiency of 91.6% against 73.2% using a bonechar; and 95.0% for Pb (II) against 91.2% for the bonechar. The outcome of this study suggests that coconut-peat and eggshell even without been carbonised can provide a cost-effective means for metal removal from industrial wastewaters.