**1. Introduction**

To begin with, freshwater is a prerequisite for human beings as well as animals. In addition, availability of clean water for maintaining a healthy life is a critical factor. However, different water sources have become polluted with increased global water demand [1]. Furthermore, researchers have found that the impacts of climate change, such as rise in temperature and water cycle changes, also aggravate the water issues, which potentially result in floods, severe droughts, and contamination of water bodies with various pollutants and toxic heavy metals [2–4]. The contaminated water

sources can be harmful and perilous to humans as well as wildlife, also the aquatic life is negatively affected [4]. However, in developing countries, human health is mainly affected by the direct consumption of contaminated water because they are destitute in the efficient technologies for remediation of water sources, resulting in increased water pollution.

The World Health Organization (WHO) estimates that nearly 844 million population lack primary drinking water sources out of which approximately 230 million people spend more than 30 min/d for collecting water from an improved water source, which includes piped water, protected wells and springs, boreholes, rainwater and stored water [5, 6]. The lacking of efficient water sources and its accessibility in developing countries increases waterborne ailments. According to WHO, approximately 1.6 million people succumb to curable waterborne diseases, of which 90% of deaths are of children under 5 years of age [7].

Landfilling and mining sites have become the main reason for the introduction of heavy metals into freshwater bodies, eventually leading to water pollution. Due to their toxic nature, these heavy metals can bioaccumulate in living cells [8]. There are many conventional methods and technologies for removing heavy metals from an aqueous environment to protect human beings, wildlife, and aquatic life. However, their utilization for remediation is confronted with high costs, waste disposal issues, and effectiveness in removal. However, adsorption is a unique and promising technique and has been found as one of the most suitable methods for the removal and recovery of heavy metals from water economically and efficiently [9].

Groundnut shell is a cheaper agricultural waste and occupies an important position in agricultural waste and biomass because it is produced in larger quantities worldwide. Groundnut shell and groundnut shell-derived biochar play a crucial role in eliminating heavy metals from water sources [10, 11]. This chapter highlights the results of several scientific studies illustrating the efficacy of groundnut shells for the removal of heavy metals from wastewater. Furthermore, the chapter also discusses the characteristics of groundnut shell-derived biochar.
