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Hermassi M, Dosta J, Valderrama C, Licon E, Moreno N, Querol X, Batis NH, Cortina JL. Simultaneous ammonium and phosphate recovery and stabilization from urban sewage sludge anaerobic digestates using reactive sorbents. Sci Total Environ 2018; 630:781-789. [PMID: 29499536 DOI: 10.1016/j.scitotenv.2018.02.243] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 02/19/2018] [Accepted: 02/19/2018] [Indexed: 06/08/2023]
Abstract
The use of low-cost inorganic sorbents as a new sustainable strategy to enhance the valorization of nutrients (N-P-K), from the urban water cycle (e.g., side streams from sewage sludge anaerobic digestion), in agriculture applications is presented. The simultaneous recovery and stabilization of ammonium and phosphate by using a mixture of two reactive sorbents (Na and K zeolites and magnesium oxide) was evaluated. The nutrients stabilization process, favoured at alkaline pH values, is carried out by a) the precipitation of phosphate ions with magnesium and/or ammonium ions and b) the sorption of ammonium by Na- and K-zeolites. MgO(s) promoted the stabilization of phosphate as bobierrite (Mg3(PO4)2(s)) or struvite (MgNH4PO4(s)) depending on the applied dose. Doses with the stoichiometric molar ratio of Mg/P promote the formation of bobierrite, while molar ratios higher than 3 favour the formation of struvite. Na zeolites (NaP1-NA, NaP1-IQE) demonstrated efficiency on ammonium stabilization between 60±2 (for 15gZ/L) to 90±3% (for 50gZ/L). The ammonium recovery efficiency is limited by the zeolite sorption capacity. If the target of the fertilizing criteria should include K, then the use of a K-zeolite (e.g., 5AH-IQE) provides a good solution. The optimum pH for the precipitation of struvite and bobierrite is 9.5 and the optimum pH for ammonium removal is between 4 and 8.5. N is present in higher concentrations (up 0.7-1gNH4+/L) when pH is ranged between 8.2 and 8.6. The ammonium recovery ratios were better than those previously reported using only magnesium oxide or even a more expensive reagent as newberrite (MgHPO4(s)). The recovery mechanisms described generate low-solubility stabilized nutrients forms that potentially can be applied as slow-release fertilizers in agriculture. Thus, the use in agriculture of blends of digested sludge with low-solubility stabilized nutrients forms will improve soils quality properties in terms of organic matter and nutrients availability.
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Affiliation(s)
- M Hermassi
- Chemical Engineering Department, Barcelona TECH-UPC, Barcelona, Spain; Department of Biological and Chemical Engineering, National Institute of Applied Sciences and Technology (INSAT), University of Carthage, Tunisia; Barcelona Multiscale Science and Engineering Research Center, Barcelona, Spain
| | - J Dosta
- Department of Chemical Engineering and Analytical Chemistry, Universitat de Barcelona (UB), Spain
| | - C Valderrama
- Chemical Engineering Department, Barcelona TECH-UPC, Barcelona, Spain; Barcelona Multiscale Science and Engineering Research Center, Barcelona, Spain.
| | - E Licon
- Chemical Engineering Department, Barcelona TECH-UPC, Barcelona, Spain
| | - N Moreno
- Institute of Environmental Assessment and Water Research IDAEA, Consejo Superior de Investigaciones Científicas, Barcelona, Spain
| | - X Querol
- Institute of Environmental Assessment and Water Research IDAEA, Consejo Superior de Investigaciones Científicas, Barcelona, Spain
| | - N H Batis
- Department of Biological and Chemical Engineering, National Institute of Applied Sciences and Technology (INSAT), University of Carthage, Tunisia
| | - J L Cortina
- Chemical Engineering Department, Barcelona TECH-UPC, Barcelona, Spain; Barcelona Multiscale Science and Engineering Research Center, Barcelona, Spain; Water Technology Center, CETaqua, Cornellà de Llobregat, Spain
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