Effect of iron sulphate on the phosphorus speciation from agro-industrial sludge based and sewage sludge based compost
- Department of Agricultural Sciences, Alma Mater Studiorum, University of Bologna, Viale G. Fanin, 44, 40127 Bologna (Italy)
- Department of Chemistry “Giacomo Ciamician”, Alma Mater Studiorum, University of Bologna, Via F. Selmi 2, 40126 Bologna (Italy)
Highlights: • Composting of agro-industrial and waste water sewage sludge promoted organic P mineralization. • Mineralized P is mainly adsorbed/precipitated on calcium. • FeSO{sub 4} reduced organic P mineralization and its further adsorption/precipitation on calcium. - Abstract: Composting is considered a suitable process for organic waste management, providing stable products that can be safely utilized as fertilizers, but little is still known about the variation of phosphorous (P) extractability during the stabilization process. In this work, sequential chemical extraction (SCE) with increasing strength extractants (H{sub 2}O; 0.5 M NaHCO{sub 3} pH 8.5; 0.1 M NaOH, 1 M HCl) was applied for P speciation over 56 days of composting of either agro-industrial or urban wastewater sludge with green waste treated (AIC{sub Fe+}; SSC{sub Fe+}) or not (AIC{sub Fe−}; SSC{sub Fe−}) with FeSO{sub 4} (2% v/v). Composting strongly reduced the H{sub 2}O-P, promoting the organic-P (P{sub o}) mineralization from the labile fraction (H{sub 2}O + NaHCO{sub 3} 40%), in addition to the increases of NaHCO{sub 3}- and HCl-extractable inorganic-P (P{sub i}) in both AIC{sub Fe−} and SSC{sub Fe−} (+20% on average). The FeSO{sub 4} treatment did not negatively affect the process, reducing the P{sub o} mineralization during composting by increasing the NaOH-P, also protecting this fraction from fixation in the sparingly soluble fraction. The final P fractionation (%) was in AIC{sub Fe−}: NaOH (41) = NaHCO{sub 3} (38) > HCl (18) > H{sub 2}O (3); in AIC{sub Fe+}: NaOH (53) > NaHCO{sub 3} (24) = HCl (22) > H{sub 2}O (2); in SSC{sub Fe−}: NaOH (46) > NaHCO{sub 3} (29) > HCl (21) > H{sub 2}O (4) and in SSC{sub Fe+}: NaOH (66) > NaHCO{sub 3} (13) > HCl (20) > H{sub 2}O (1). Composting reduced the more easily leachable fraction (labile-P{sub o}), reducing the risk of P loss by increasing the long-term available P fraction (NaOH-P). This was enhanced by the FeSO{sub 4} addition. Further investigation into soil behaviour and plant availability of P from this source is needed.
- OSTI ID:
- 22742177
- Journal Information:
- Waste Management, Vol. 69; Other Information: Copyright (c) 2017 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0956-053X
- Country of Publication:
- United States
- Language:
- English
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