Biological Treatment of Heavy Metal in Aquatic Environment: A Review of Wetland Phytoremediation and Plant-Based Biosorption Methods

Abstract

Aquatic bodies such as the lagoons, rivers and seas are known to be environmental sinks for heavy metal trapped within the soil matrix (from anthropogenic activities) as they are leached and wash-off via water percolation into the soil, erosion and floods. Thus designing treatment method under such condition (aquatic) becomes imperative. The use of chemical and physical method of treatments are established methods which are often times expensive to operate. The use of more sustainable method often referred to as biological method has put the use of techniques such as wetland phytoremediation and plant-based bioadsoptionas a more promising method of treatment.Both biological methods are cheaper, more sustainable and greener in approach compared to the physical and chemical method.

Wetland phytoremediation through the use of macrophyte are capable of metal uptake, precipitation, translocating and storage of metal toxins in thousands of ppm. These hyperaccumulators are highly vascularized plants and can be found in waterlogged areas or underground in water. Different wetland plants generally have dissimilar affinity for heavy metal absorption and thus specific macrophytes have been identified for a wide range of metal pollutant and used by water authorities around the world. On the other hand, plant-based biosorption function with the use of agricultural waste materials which are pretreated to improve their surface functionality and hence affinity for these pollutants. Unlike wetland phytoremediation, aqueous condition such as water pH, mineral solubility affects its effectiveness.

Wetland phytoremediation through the use of macrophyte are capable of metal uptake, precipitation, translocating and storage of metal toxins in thousands of ppm. These hyperaccumulators are highly vascularized plants and can be found in waterlogged areas or underground in water. Different wetland plants generally have dissimilar affinity for heavy metal absorption and thus specific macrophytes have been identified for a wide range of metal pollutant and used by water authorities around the world. On the other hand, plant-based biosorption function with the use of agricultural waste materials which are pretreated to improve their surface functionality and hence affinity for these pollutants. Unlike wetland phytoremediation, aqueous condition such as water pH, mineral solubility affects its effectiveness.