Ecofriendly remediation technologies for wastewater contaminated with heavy metals with special focus on using water hyacinth and black tea wastes: a review

Abstract

Treatment of water contaminated with heavy metals is challenging. Heavy metals are non-degradable, persistent in the environment, have a high dispersion capacity by water, can bioaccumulate, and represent risks to human and environmental health. Conventional treatment methods have disadvantages; however, adsorption in biomass is a highly promising method with high efficiency and low cost that avoids many of the disadvantages of conventional methods. Black tea (BT) wastes and water hyacinth (WH) have attracted attention for their ability to remove heavy metals from wastewater. Utilizing these approaches can remove contaminants and effectively manage problematic invasive species and wastes. The conventional uses of BT and WH were efficient for removing heavy metals from wastewater. Due to the unique and distinct properties and advantages of biochar and nano-forms of biosorbents, the use of BT and WH in these forms is promising to achieve sustainable heavy metals removal from wastewater. However, more study is needed to confirm preliminary results.

Keywords: Biochar; Polluted wastewater; Wastes; Wastewater treatment.

Fig. 1

SEM micrographs of BT biochar a before and b after Cd adsorption (Pal & Maiti, 2019)

Fig. 2

SEM micrographs of WH biochar surfaces at several magnifications (Allam et al., 2020)

Fig. 3

TEM micrographs of biochar surfaces created with black tea wastes at 500 °C

Fig. 4

TEM micrographs of biochar surfaces created with water hyacinth wastes at 500 °C

Fig. 5

TEM micrographs of a black tea nano-biochar and b water hyacinth nano-biochar surfaces. Both biochars were created at 500 °C