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In a recent study published in the Journal of Environmental Chemical Engineering, researchers explored an innovative method for recovering phosphate from sludge-incinerated ash (SIA) using modified biochar. This approach not only aims to extract valuable nutrients but also offers potential benefits as a soil conditioner and phosphorus (P) fertilizer.

The study focused on modifying biochar, a carbon-rich product derived from agricultural biomass, to improve its phosphate adsorption capabilities. Typically, biochar has a negatively charged surface, which hinders its ability to absorb phosphate, a nutrient that exists in anionic forms. To address this, the researchers used calcium (Ca2+) and magnesium (Mg2+) to modify the biochar, enhancing its capacity to adsorb phosphate from the acidic leachate of SIA.

The modified biochar demonstrated impressive results, achieving over 80% phosphate adsorption with capacities ranging from 56.20 to 93.76 mg P/g biochar. This high adsorption efficiency indicates that the modified biochar could be an effective tool for phosphate recovery.

Moreover, the study revealed that the phosphate-laden biochar could function as a slow-release P-fertilizer. Pot tests showed that this biochar significantly promoted lettuce growth, improved soil pH, and enhanced nutrient uptake by plants. These findings suggest that the modified biochar not only recovers phosphate efficiently but also has practical applications in agriculture.

This research highlights a promising pathway for recycling nutrients from waste products, contributing to sustainable agricultural practices and the circular economy.