Phosphorus recovery as struvite from hydrothermal carbonization liquor of chemically produced dairy sludge by extraction and precipitation

Phosphorus (P) recovery from dairy wastewater involves its accumulation into phosphorus-rich sludge using a physico-chemical or biological process. The high iron content in chemical decreases usability agricultural activities. hydrothermal carbonization (HTC) is an option used to treat the obtain hydrochar for various applications, including use as energy source and carbon-dense material. HTC process leaves bigger volume of nutrient-rich liquor, which phosphorus purification was subject this work. By direct precipitation, product 17.96%, value higher than accepted limits phosphate fertilizers. Thus, P extraction followed by struvite precipitation studied. oxalic acid extracted 86.7% while 86.6% removed. conditions pH 9, salt dosage 1.73:1.14:1 Mg:NH4+:P mole ratio were obtained with 99.96%, effluent concentration below 2 mg∙L−1. quality products fertilizers tested both in-vitro in-vivo assays. High demonstrated negative effect on plant germination, whilst extract advantage macro micronutrient availability. method useful two separate respectively.