화학공학소재연구정보센터
Separation Science and Technology, Vol.50, No.14, 2155-2163, 2015
An Investigation of pH Mediated Extraction and Precipitation of Phosphorus from Sludge Using Microfiltration: Processing and Costs
Membrane filtration of wastewater sludge is a feasible technology for the recovery of sustainable nutrients in bacteria and particle-free solutions. Diafiltration and acidification strategies were investigated for the recovery of phosphorus (P) from trout farm sludge. Extraction costs were determined using a pilot-scale unit. pH of 2.7 was found to maximize the extraction of P (and metals) and highest concentrations were achieved by acidic leaching of the sludge sediment. Levels of P, Ca, Fe, Mg, and K recovered in soluble fractions were 418 mg/L, 6730 mg/L, 66.8 mg/L, 29 mg/L, and 34.1 mg/L, respectively. Operational costs associated with acidification and power consumption were estimated to be 0.018 kWh/L permeate or 0.037 kWh/g P obtained. The extraction of P by membrane filtration was mainly dependent on pH and cost was considerably lower than that for P-based fertilizers. Owing to the high concentration of Ca and P in the permeate fractions, 99% of the soluble P was precipitated from solution at pH 8. Elemental analysis and FTIR of the precipitate obtained indicated to be carbonated calcium-deficient hydroxyapatite.