Improving capacity for phytoremediation of Vetiver grass and Indian mustard in heavy metal (Al and Mn) contaminated water through the application of clay minerals

Abstract

One of the consequences of mining is the release of heavy metals into the environment, especially water bodies. Phytoremediation of areas contaminated by heavy metals using Vetiver grass and Indian mustard is cost-effective and environmentally friendly. This study aimed at enhancing remediation of heavy metal contaminated water through the simultaneous hybrid application of clay minerals (attapulgite and bentonite) and Vetiver grass or Indian mustard. A 21-day greenhouse experiment was carried out to investigate the effectiveness of the clay minerals to improve heavy metal phytoremediation. The highest accumulation of aluminium (Al) by Vetiver grass was 371.8 mg/kg in the BT2.5VT treatment, while for Mn, the highest accumulation of 34.71 mg/kg was observed in the AT1VT treatment. However, Indian mustard showed no significant uptake of heavy metals, but suffered heavy metal toxicity despite the addition of clay minerals. From this study, it was evident that bentonite added at 2.5% (w/v) could improve the phytoremediation capacity of Vetiver grass for Al and Mn polluted water. The current laboratory-scale findings provided a basis for field trials earmarked for remediation in a post-mining coal environment in South Africa. This remediation approach can also be adopted in other places.

A mesocosm study on the use of clay minerals to improve heavy metal phytoremediation capacity of vetiver grass (Chrysopogon zizanioides L. Roberty)

“…In this study, we aimed to examine the efficiency of an optimised hybrid application of vetiver grass and clay minerals for remediation of soil and water contaminated with heavy metals (Al and Mn in water; and Co, Cr, Cu, Ni and Zn in soil) in a mesocosm setting as informed by success in previous greenhouse studies. 16,17 There is little documentation of mesocosm studies concerning assisted phytoremediation of soil and water [27][28][29] ; therefore, this study contributes to the repository of available studies of phytoremediation in mesocosms, further encouraging its application.…”

“…14,15 In particular, heavy metals including Co, Cr, Cu, Ni, and Zn have been detected in the soil, while Al and Mn have been detected in water bodies surrounding a former coal mining environment located in Sasolburg in the Free State Province of South Africa. 14,16,17 Considering the negative effects of heavy metals on the environment, several technologies have been identified for managing heavy metal polluted sites. Of these technologies, phytoremediation is a cost-effective and environmentally friendly option 18 , and there is growing interest in the application and optimisation of phytoremediation 19,20 .…”

“…Major examples of clay minerals include attapulgite, bentonite, montmorillonite, zeolite and kaolinite. 13 Previous studies by Otunola et al 16,17 showed that attapulgite administered at 2.5% (w/w) was most effective to improve the phytoremediation capacity of vetiver grass in metals polluted soil, while bentonite administered at 2.5% (w/v) was best for water remediation.…”

Influence of biochar amendment on removal of heavy metal from soils using phytoremediation by C. roseus and Chrysopogon zizanioides

“…Biochar is a solid carbon-rich organic material with high porosity, low density and high speci c surface area with high metal immobilisation capacity (Pandey et al, 2022;Otunola et al, 2023;Patwa et al, 2023;Sun et al, 2023). It is derived from the thermochemical decomposition of waste biomass in a closed container with low to no oxygen content (Patwa et al, 2022).…”

Chitosan Hydrogels for Water Purification Applications

“…Among them, adsorption treatment is an approach that attracts the attention of scientific research for water remediation due to several attractive properties such as simple operation, low cost, high adsorption capacity, a wide spectrum of pollutants, and favorable effects. Adsorbates such as alumina [ 33 ], clays [ 34 , 35 ], activated carbon [ 36 , 37 , 38 , 39 , 40 ], or biomass conversion [ 41 ] are currently used in adsorption treatment. In addition, by applying appropriate adsorption–desorption methods as well as suitable adsorbents, some pollutants, such as heavy metal ions, or critical materials (e.g., rare earth elements and lithium) can be recovered [ 42 ].…”