Livestock and poultry farming effluents (LPFE) are a major source of water pollution, rich in nitrogen (N) and phosphorus (P). Traditional wastewater treatment methods often fall short, and the increasing demand for meat and dairy products intensifies this environmental challenge. A study published in PLOS One by Yu Jin, Haifeng Wu, and their co-authors offers a promising solution: using inexpensive, magnesium-modified materials to recover these pollutants. The research focuses on corncob 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 (CCBC) and natural zeolite (NZ), comparing their effectiveness and recovery mechanisms before and after modification. The findings provide a theoretical foundation for developing cost-effective, self-alkaline carrier materials that can simultaneously recover N and P from LPFE.

The study’s most significant finding is the dramatic increase in recovery performance after the materials were modified with magnesium (Mg2+). Adsorption capacity for N and P saw a remarkable boost, with corncob biochar modified with magnesium (CCBC-Mg) demonstrating the best phosphorus (P) recovery, and magnesium-modified natural zeolite (NZ-Mg) showing the best ammonia nitrogen (AN) recovery. Specifically, the maximum adsorption capacity for P reached 116.99 mg/g with CCBC-Mg, while AN recovery reached 47.50 mg/g with NZ-Mg. This is a substantial improvement over the unmodified materials, which showed very low P adsorption capacity, underscoring the critical role of magnesium in the process.

The enhanced performance of the modified materials is rooted in the formation of struvite on their surfaces. Struvite is a crystalline mineral with the molecular formula MgNH4​PO4​⋅6H2​O, and it’s considered an ideal slow-release fertilizer. The study found that the Mg2+ modification increased the solution’s 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, which created a favorable alkaline environment and provided the necessary conditions for struvite precipitation. This struvite precipitation became the primary mechanism for N and P recovery for the modified materials, surpassing the less efficient ion exchange and electrostatic attraction mechanisms of the unmodified materials.

Kinetic and isotherm modeling further clarified the adsorption process. The experimental data for all materials fit well with the pseudo-second-order kinetic model and the Langmuir isotherm. This indicates that the main mechanism of adsorption is a monolayer adsorption process governed by chemical interactions, rather than simple physical attachment. The research also found that the modified materials, particularly CCBC-Mg, developed a honeycomb-like porous structure that provided abundant sites for N and P enrichment.

Beyond wastewater treatment, these modified materials hold great promise as sustainable soil conditioners. The final products, enriched with N and P in the form of struvite, can be used as slow-release fertilizers, reducing the need for traditional fertilizer inputs and mitigating nutrient leachingLeaching is the process where nutrients are dissolved and carried away from the soil by water. This can lead to nutrient depletion and environmental pollution. Biochar can help reduce leaching by improving nutrient retention in the soil.   More. The study notes that CCBC-Mg and NZ-Mg have good application potential because they are cost-effective to produce and their end-use is environmentally beneficial. While the N in the zeolite is immediately available, requiring the use of nitrification inhibitors, the N and P in the biochar remain trapped within its matrix, allowing for a gradual release. This makes them valuable resources for sustainable agriculture.

Source : Jin, Y., Wu, H., Huo, S., Chen, S., Shen, L., Di, H., Du, L., & Li, P. (2025). Mg²-modified corncob biochar and natural zeolite significantly enhanced simultaneous N and P recovery from livestock wastewater. PLOS One, 20(8), e0331575.