Enhancing dissolved inorganic phosphorous capture by gypsum‐incorporated biochar: Synergic performance and mechanisms

Abstract

Excess nutrients such as phosphorus (P) in watersheds jeopardize water quality and trigger harmful algal blooms. Using phosphorus sorption material (PSM) to capture P from wastewater and agricultural runoff can help recover nutrients and prevent their water pollution. In this study, a novel designer biochar was generated by pyrolyzing woody biomass pretreated with a flue gas desulfurization gypsum. The removal of dissolved inorganic phosphorus (DIP) by the gypsum‐incorporated designer biochar was more efficient than the gypsum, suggesting the pretreatment of biomass with the gypsum results in a synergic effect on enhancing DIP capture. The maximum P adsorption capacity of the designer biochar was more than 200 mg g−1, which is one order of magnitude greater than that of the gypsum. This result clearly showed that the designer biochar is a better PSM to capture DIP from nutrient‐contaminated water compared to the gypsum. Post‐sorption characterization indicated that the sorption of DIP by the gypsum‐incorporated biochar involves multiple mechanisms. The precipitation reactions of Ca cations and P anions to form CaHPO4 and Ca3(PO4)2 precipitates on the highly alkaline surface of the designer biochar were identified as a main mechanism. By contrast, CaHPO4·2H2O is the only precipitated product for DIP sorption by the gypsum. In addition, the initial solution pH and the coexisting bicarbonate had less effects on the DIP removal by the designer biochar in comparison with the gypsum, which further confirms the former is an excellent PSM to capture DIP from a variety of aquatic media.This article is protected by copyright. All rights reserved

Modified Biochars Reduce Leaching while Maintaining Bioavailability of Phosphate to Dragoon Lettuce (Lactuca sativa) in Potting Tests

“…A growing body of literature reveals that specific, thoughtful, and tailored biochar modification can benefit nutrient recapture and agricultural systems. For example, biochar modification via enrichment of Ca, Mg, Mn, and Fe has been shown to enhance nitrate and phosphate sorption. − A recent paper provides an overview of phosphate retention by Ca-, Mg-, and Fe-rich biochars …”