Chromium is a heavy metal used in tanneries, leather industries, electroplating, and metallurgical operations, but improper disposal of waste from these industries leads to environmental contamination. Chromium exists primarily in trivalent and hexavalent forms, with hexavalent chromium (Cr (VI)) being highly toxic. Cr (VI) is carcinogenic, damages fish gills, and negatively impacts crops. Considering these negative impacts of Cr (VI), several physical, chemical, and biological remediation methods have been implemented at contaminated sites, but in most instances, these methods could be uneconomical, highly labor-intensive, and not sustainable. Therefore, a crucial goal is to implement an effective and sustainable remediation technique with consideration of actual site conditions. The aim is to develop a sustainable remediation strategy for a hexavalent chromiumcontaminated site in Ranipet, Tamil Nadu. The comprehensive risk assessment for the site has depicted hazard quotients greater than 1 for both onsite and offsite conditions, indicating the necessity of remediation. To address this, it is suggested to build permeable reactive filters (PRFs) packed with scrap iron filings to reduce Cr (VI) to Cr (III), and succeeding filters with locally produced waste coconut shell biochar to aid in adsorption. The use of waste here aims to eliminate the need to procure any commercially available materials for remediation, completely cutting down the environmental impact of raw material extraction or processing. A continuous chambered set-up packed with contaminated soil and PRFs with biochar and iron filings aided in the decrease of the peak concentration of Cr (VI) by 61 % as compared to a set-up without intervention. Moreover, the outlet concentration after 7 days reduced to 0.08 mg/L, which was 97.6 % less than that in the set-up without intervention.

The need to build a long-term or even permanent base is now a significant concern with the development of the exploration of extraterrestrial celestial bodies. Sulfur concrete was first proposed as a new building material in the 20th century. Recently, sulfur concrete has attracted much interest, as sulfur is considered one of the most accessible resources on the Moon and Mars, thanks to the in-situ resource utilization methodology. In addition, sulfur concrete is one of the most promising building materials for improving terrestrial sustainability or extraterrestrial exploration. So far, reviews have only focused on developing sulfur concrete and extraterrestrial building materials. This review paper summarizes the history of sulfur concrete development and different modified sulfur concretes. Previous research on extraterrestrial building materials is also reviewed. The unique advantage of sulfur concrete as an extraterrestrial material is justified, as no water is used during mixing. Lunar and Martian soil simulants are also examined as possible aggregate types. Finally, further improvements are proposed to broaden the application of sulfur concrete and the corresponding treatments. The possibility of recyclability and circularity is discussed from a sustainable development point of view. This review article provides readers with a detailed overview of sulfur concrete and its history, why it is more promising and accessible as an (extra)terrestrial building material, the challenges of its future application, and corresponding treatments to overcome the obstacles.