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.
Department of Chemical Engineering and Analytical Chemistry, Universitat de Barcelona (UB), Spain.
Sci Total Environ. 2018 Jul 15;630:781-789. doi: 10.1016/j.scitotenv.2018.02.243. Epub 2018 Feb 27.
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 (Mg(PO)(s)) or struvite (MgNHPO(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 0.7-1gNH/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 (MgHPO(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.
本文提出了一种利用低成本无机吸附剂作为一种新的可持续策略，以提高城市水循环（例如，污泥厌氧消化的侧流）中的营养物质（N-P-K）的利用价值，并将其应用于农业领域。评估了使用两种反应性吸附剂（Na 和 K 沸石和氧化镁）混合物同时回收和稳定铵和磷酸盐的方法。在碱性 pH 值下，通过以下方式进行营养物质的稳定化过程：a）磷酸根离子与镁和/或铵离子形成沉淀，b）Na 和 K 沸石吸附铵。MgO(s)可促进磷酸盐以鸟粪石（Mg(PO)(s)）或磷酸铵镁（MgNHPO(s)）的形式稳定化，具体取决于施加的剂量。具有 Mg/P 化学计量摩尔比的剂量促进鸟粪石的形成，而摩尔比高于 3 则有利于形成磷酸铵镁。Na 沸石（NaP1-NA、NaP1-IQE）在 60±2（15gZ/L）至 90±3%（50gZ/L）之间表现出对铵稳定化的效率。铵的回收效率受沸石吸附容量的限制。如果施肥标准的目标应包括 K，则使用 K 沸石（例如 5AH-IQE）是一个很好的解决方案。形成鸟粪石和磷酸铵镁的最佳 pH 值为 9.5，铵去除的最佳 pH 值在 4 和 8.5 之间。当 pH 值在 8.2 和 8.6 之间时，N 的浓度较高（高达 0.7-1gNH/L）。铵的回收率优于以前仅使用氧化镁或甚至更昂贵的试剂作为新伯利石（MgHPO(s)）报道的回收率。所描述的回收机制产生了低溶解度的稳定化营养物质形式，这些形式可能被用作农业中的缓释肥料。因此，在农业中使用消化污泥与低溶解度稳定化营养物质形式的混合物将改善土壤的有机质和营养物质供应方面的质量特性。
