Removal of arsenic from contaminated groundwater using biochar: a technical review

Groundwater is considered as the primary source of drinking water in many countries around the world. For maintaining resource sustainability, clean and safe groundwater is a priority for water authorities worldwide. Unfortunately, groundwater resources are susceptible to various types of pollution, with arsenic (As) being a major pollutant in certain areas due to natural or anthropogenic activities. Due to its adverse health effects, As, a class-1 carcinogen, has been a topic of intense research. The technical difficulty and high cost incurred by conventional treatment systems for As removal have led many researchers to work on developing efficient, eco-friendly, and cost-effective technologies for the treatment of groundwater sources. Biochar has been widely used as an adsorbent for the decontamination of groundwater. High As removal rates have been achieved following metal (Fe, Zn, Mn) impregnation and magnetic modification to biochar. Despite numerous researches on biochar for As removal, very limited efforts have been made for upscaling to a convenient treatment system. Thus, this review highlights key findings of previous studies required for pragmatic applications. Following up with future trends, an overview is given on real-time monitoring techniques that can be combined with biochar for evaluating adsorption studies. Furthermore, research opportunities that exist in biochar adsorption studies have also been identified. This technical review is aimed for scientists, scholars and researchers as a supplementary guide for understanding As decontamination processes, highlighting the role of biochar as an adsorbent and conceptualizing the prospects of integration of real-time monitoring techniques.