Water pollution has become a global concern, with rapid urbanization and industrialization affecting ground and surface water quality, and at this juncture, the review article  by Trivedi et al. is worth reading. They report that researchers are turning to biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More, a carbon-rich material made through the pyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More of organic waste like agricultural residues, fruit peels, poultry manure, and sewage sludge. This sustainable material has shown immense promise in treating wastewater by effectively removing pollutants such as heavy metals, nitrates, fluoride, and phosphorus. Have a great read!

What sets biochar apart is its versatility. Modified biochar, treated with chemicals like zinc chloride (ZnCl₂) and potassium hydroxide (KOH), has proven to be even more effective than its unmodified counterpart. These modifications enhance its adsorption capacity, enabling it to capture and immobilize harmful contaminants like lead, arsenic, and cadmium more efficiently. Still, unmodified biochar offers a more cost-effective solution, particularly in regions with financial constraints. The magic behind biochar’s performance lies in its mechanisms, including ion exchange, surface complexation, and physical adsorption. Functional groups such as carbonyl, carboxyl, and hydroxyl play a vital role in trapping pollutants. However, some challenges persist. For example, removing nitrates is particularly tricky due to their high solubility and stability in water. Additionally, the pHpH is a measure of how acidic or alkaline a substance is. A pH of 7 is neutral, while lower pH values indicate acidity and higher values indicate alkalinity. Biochars are normally alkaline and can influence soil pH, often increasing it, which can be beneficial More of the water significantly impacts how well biochar can remove heavy metals.

Biochar’s effectiveness depends on various factors, such as the feedstockFeedstock refers to the raw organic material used to produce biochar. This can include a wide range of materials, such as wood chips, agricultural residues, and animal manure. More used, pyrolysis conditionsThe conditions under which pyrolysis takes place, such as temperature, heating rate, and residence time, can significantly affect the properties of the biochar produced.   More like temperature and residence timeResidence time refers to the duration that the biomass is heated during the pyrolysis process. The residence time can influence the properties of the biochar produced.   More, and its chemical composition. Research also highlights the potential of engineered biochar, which can be tailored to address specific pollutants and wastewater challenges. Despite its potential, the biochar market, particularly in India, faces hurdles like limited market awareness and financial constraints.

However, with continued research and innovation, biochar could become a cornerstone in global wastewater treatment efforts. This sustainable and cost-effective material offers a win-win for the environment and society, paving the way for cleaner water and a healthier planet.

SOURCE: Trivedi, Yashasvi, et al. (2025) Biochar potential for pollutant removal during wastewater treatment: A comprehensive review of separation mechanisms, technological integration, and process analysis. Desalination. https://doi.org/10.1016/j.desal.2024.118509