The Application of Metakaolin in Nickel and Natural Organic Matter Removals from Anoxic Groundwater

Elevated concentrations of heavy metals in groundwater are one of the common water quality issues due to the anoxic and reductive conditions in groundwater. In addition, high NOM content in groundwater decreases the water aesthetic value and develops disinfection by-products when reacted with disinfectants. Such abstracted groundwater prior to any treatments is not suitable for consumption due to the elevated concentrations of contaminants that affect its acceptability and chemical aspects. This paper aims to assess the groundwater quality abstracted from a tubewell located in Universiti Sains Malaysia, Pulau Pinang. This study also evaluates the potential of metakaolin as an absorbent for nickel and NOM’s adsorption. In average, the selected groundwater samples contain high concentration of contaminants, namely iron (615.4 μg/L), manganese (444.0 μg/L), nickel (174.6 μg/L) and NOM (as measured in UV254: 1.23 cm−1). The anoxic and circumneural characteristics of the groundwater are known to be the governing factors for these contaminants’ concentrations. The removals of nickel and NOM were achieved at approximately 35% and 22%, respectively, with an optimum value of dosage of 14 g. The high ionic strength and competitive adsorption in a multi-solute system have been recognised as the limiting factors. The optimum contact time for these removals was 120 min.