Adsorptive behavior of phosphorus onto recycled waste biosolids after being acid leached from wastewater sludge

•Loaded sludgechar had the highest P content but all biomaterials performed well.•Adsorption capacity reached ranges of 300-500 mg/g depending on the conditions.•Positive cooperative adsorption occurred due to presence of multiple species.•Examined biosolids show promise as sustainable solution as slow-release fertilizer.