In a review published in the journal Frontiers in Water and Environment, authors Nurain Azman and Nur Hafizah Ab Hamid evaluate the evolving landscape of domestic wastewater treatment, focusing specifically on the removal of phosphorus-based compounds. Phosphorus is a critical yet finite resource essential for global food security, but its presence in domestic wastewater—stemming from human waste, food residues, and detergents—poses a severe threat to aquatic ecosystems. When excess phosphorus enters water bodies, it triggers eutrophication, a process where rapid algae growth depletes oxygen levels and destroys aquatic life. While various biological and physical treatment methods exist, they often require large footprints or expensive maintenance. The authors highlight that adsorption using activated carbon derived from biomassBiomass is a complex biological organic or non-organic solid product derived from living or recently living organism and available naturally. Various types of wastes such as animal manure, waste paper, sludge and many industrial wastes are also treated as biomass because like natural biomass these More has emerged as a superior alternative due to its operational simplicity and high efficiency. By shifting away from non-renewable coal-based carbon toward sustainable biomass precursors like agricultural waste, the industry can align water treatment with circular economy principles.

The research findings emphasize that the performance of biomass-derived activated carbon is not uniform but is instead heavily dictated by the specific type of precursor and the method of activation used during production. The study notes that agricultural residues such as corn stalks, peanut shells, and coconut shells provide excellent frameworks for creating highly porous materials. One of the most significant quantitative insights from the review is the dramatic increase in adsorption capacity when these carbon materials are modified with metal species. For instance, activated carbon derived from corn stalks and impregnated with magnesium demonstrated a remarkable adsorption capacity of 221.89 milligrams per gram. This is a substantial improvement over unmodified or simply salt-activated carbons, which often see capacities ranging much lower, sometimes between 30 and 40 milligrams per gram. These metal ions, such as calcium, magnesium, and iron, act as bridges that attract and bind phosphate molecules more effectively than the carbon surface alone.

Physical characteristics like surface area and pore structure also play a decisive role in how much phosphorus a material can remove from a liquid stream. The review explains that a high surface area, often ranging between 500 and 3,000 square meters per gram, provides the necessary landscape for chemical interactions to occur. However, the researchers clarify that a large surface area is only beneficial if the pore structure is well-developed. They categorize these pores into three sizes: micropores, mesopores, and macropores. The most effective materials possess a combination of mesopores and micropores. The larger mesopores facilitate the rapid movement of phosphate ions into the deeper, smaller micropores where they are eventually trapped. When activation temperatures are optimized, typically between 600 and 1000 degrees Celsius, the carbonization process removes volatile matterVolatile matter refers to the organic compounds that are released as gases during the pyrolysis process. These compounds can include methane, hydrogen, and carbon monoxide, which can be captured and used as fuel or further processed into other valuable products.   More and moisture to leave behind this intricate, sponge-like architecture that is essential for high-performance filtration.

The study further explores how activation methods, specifically the choice between physical and chemical processes, influence the final product. Physical activation using steam or carbon dioxide at high temperatures is a common industry standard, but chemical activation using acids or alkalis is often preferred for specific applications because it can create a more diverse array of surface functional groups. Recent advancements in microwave-assisted activation have also shown promise, as this method heats the material more rapidly and evenly than traditional furnaces. This leads to better-developed pore networks in a shorter amount of time, which can save significant energy and reduce production costs. For example, bamboo-derived carbon processed via microwave heating achieved a surface area more than three times higher than that produced through conventional furnace heating, showcasing the potential for technological innovation to drive down the costs of sustainable water treatment.

The chemistry of the wastewater itself, particularly its acidity or alkalinity, is a final critical factor identified by the researchers. The point of zero charge for the activated carbon determines the specific environment in which the material will be most effective. Many metal-modified biochars perform best at a neutral to slightly basic 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, where the surface charge and the form of the phosphorus molecules are most compatible for binding. While the study confirms the effectiveness of these materials in laboratory settings, the authors recommend that future research focus on the selective removal of phosphorus in real-world domestic wastewater, which often contains competing salts and organic matter. By refining these “designer” carbons to target phosphorus specifically, the wastewater treatment industry can move closer to a model where phosphorus is not just a pollutant to be removed, but a resource to be recovered and returned to the soil as a sustainable biofertilizer.

Source: Azman, N., & Ab Hamid, N. H. (2026). A short review: Phosphorus-based compounds removal using biomass-derived activated carbon in domestic wastewater treatment. Frontiers in Water and Environment, 10(1), 13-32.