Excess nutrients such as nitrogen and phosphorus are among the leading causes of water pollution worldwide, fueling harmful algal blooms and degrading aquatic ecosystems. Now, researchers have developed a sustainable solution by transforming agricultural waste into an advanced biochar material capable of removing these pollutants from wastewater.
The new study introduces a calcium hydroxide modified biochar produced from discarded shells of Camellia oleifera, an oil producing tree widely cultivated in China. The research demonstrates that this low cost material can effectively remove ammonium and phosphate from water, two major drivers of eutrophication and ecosystem imbalance.
Camellia oleifera shell waste is generated in large quantities during oil production and is often difficult to dispose of safely. The research team recognized that these shells contain high carbon and lignin content, making them an ideal raw material for producing functional carbon materials. By converting the waste into biochar through pyrolysis and chemical modification, the scientists created a porous adsorbent capable of capturing nutrient pollutants while promoting circular resource use.
"Transforming agricultural waste into high performance environmental materials represents a promising path toward sustainable pollution control," said the study's corresponding author. "Our work shows that materials derived from biomass can provide both environmental protection and resource recycling benefits."
Laboratory tests showed that the modified biochar exhibited strong adsorption performance for both ammonium and phosphate. The material demonstrated maximum adsorption capacities of 15.44 milligrams per gram for ammonium and 172.04 milligrams per gram for phosphate. These results indicate that the new biochar can capture significant amounts of nutrient contaminants from water systems.
The researchers also investigated how environmental factors influence performance. They found that alkaline conditions enhanced ammonium removal, while acidic conditions improved phosphate removal. Detailed mechanistic analysis revealed that ammonium removal mainly occurred through ion exchange reactions, while phosphate removal was primarily driven by chemical precipitation with calcium, forming stable mineral compounds.
Importantly, the material maintained strong performance in real world wastewater tests. When applied to swine wastewater samples containing multiple contaminants, the biochar achieved phosphate removal efficiencies approaching 98 percent, demonstrating its potential for practical agricultural and industrial wastewater treatment.
In addition to its effectiveness, the biochar showed good reusability. After multiple adsorption and regeneration cycles, the material retained substantial pollutant removal capability, highlighting its feasibility for long term environmental applications.
The researchers believe their work provides a valuable strategy for addressing two environmental challenges simultaneously. By converting agroforestry waste into functional materials, the technology not only reduces waste disposal pressure but also supports nutrient recovery from wastewater. Nutrients captured by the biochar may potentially be reused as soil fertilizers, contributing to sustainable agriculture.
"This study highlights how waste materials can be redesigned into environmentally beneficial products," the research team noted. "Such technologies could help mitigate water pollution while advancing circular economy approaches."
As global concerns about water quality and nutrient pollution continue to grow, innovations that combine waste valorization with water treatment are gaining increasing attention. The newly developed modified biochar offers a promising example of how sustainable materials science can support cleaner water systems and improved environmental management.
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Journal reference: Chen M, Wu X, Wang Y, Wang J, Li C, et al. 2026. Ca(OH)2-modified Camellia oleifera shell biochar: preparation, characterization, and adsorption of NH4+ and PO43−. Biochar X 2: e005 doi: 10.48130/bchax-0026-0002
https://www.maxapress.com/article/doi/10.48130/bchax-0026-0002
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About the Journal:
Biochar X (e-ISSN: 3070-1686) is an open access, online-only journal aims to transcend traditional disciplinary boundaries by providing a multidisciplinary platform for the exchange of cutting-edge research in both fundamental and applied aspects of biochar. The journal is dedicated to supporting the global biochar research community by offering an innovative, efficient, and professional outlet for sharing new findings and perspectives. Its core focus lies in the discovery of novel insights and the development of emerging applications in the rapidly growing field of biochar science.
