Phosphorus recovery and reuse in water bodies with simple ball-milled Ca-loaded biochar

The demand to control eutrophication in water bodies and the risk of phosphorus scarcity have prompted the search for treatment technologies for phosphorus recovery. In this study, ball-milled Ca-loaded biochar (BMCa@BC) compos-ites were prepared with CaO and corn stover biochar as raw materials by a new ball-milling method to recover phos-phorus from water bodies. Experimental results demonstrated that BMCa@BC could efficiently adsorb phosphorus in water bodies with an excellent sorption capacity of 329 mg P/g. Hydrogen bonding, electrostatic attraction, complex-ation, and surface precipitation were involved in adsorption process. In addition, phosphorus recovered by BMCa@BC had high bioavailability (86.7 % of TP) and low loss (3.3 % of TP) and was a potential slow-release fertilizer. P-laden BMCa@BC significantly enhanced seed germination and growth in planting experiments, proving that it could be used as a substitute for P-based fertilizer. After five cycles of regeneration, BMCa@BC still showed good adsorption recovery and the P-enriched desorption solution could be recovered as Ca-P products with the fertilizer value. Overall, BMCa@ BC has good cost-effectiveness and practical applicability in phosphorus recovery. This provides a new way to recover and reuse phosphorus effectively.

Automated summary

In this study, ball-milled Ca-loaded biochar (BMCa@BC) composites were successfully prepared for phosphorus recovery from water bodies. BMCa@BC exhibited a high adsorption capacity of 329 mg P/g and involved various mechanisms such as hydrogen bonding, electrostatic attraction, complexation, and surface precipitation. The phosphorus recovered by BMCa@BC had high bioavailability and low loss, and showed potential as a slow-release fertilizer. After regeneration cycles, BMCa@BC still maintained good adsorption recovery, and the P-enriched desorption solution could be recovered as Ca-P products with fertilizer value. Overall, BMCa@BC showed good cost-effectiveness and practical applicability in phosphorus recovery.