Characterization of natural Yemeni zeolites as powder sorbents for ammonium valorization from domestic waste water streams using high rate activated sludge processes

BACKGROUND In this study three natural Yemeni zeolites (NZ1, NZ2 and NZ3) having major minerals such as clinoptilolite and mordenite, were evaluated as low cost sorbents for the removal and recovery of ammonium ions. RESULTS The zeolite samples, with pHPZC =¿9.1¿±¿0.2, 7.9¿±¿0.2 and 7.4¿±¿0.2 for NZ1, NZ2 and NZ3, respectively, showed high ammonium sorption capacities. At pH¿8, for treated waste waters: (i) with low NH4+ levels (from 25 to 100 mgNH4/L); and (ii) for concentrated NH4+ side streams generated from the anaerobic digestion of sewage sludge (from 400 up to 1500¿mg L-1), maximum loading capacities of 27 to 51 mgNH4 g-1 were measured for the studied zeolites. Measured sorption isotherms, in the concentration range 0.05 to 5¿g L-1, were well described by the Langmuir isotherm. The ammonium sorption kinetics was controlled by particle diffusion and was well described by both the homogeneous diffusion (HPDM) and shell progressive (SPM) models. CONCLUSION Comparison of the equilibrium data with results for natural and synthetic zeolites demonstrate the higher performance of the studied zeolites providing low residual ammonium values <1 mgNH4 g-1 and <10 mgNH4 g-1 when treating both diluted and concentrated-NH4+ streams, respectively.Preprin

Detrimental effects of magnesium (II) on hydroxyapatite precipitation from synthetic industrial brines

The influence of Mg(II) on phosphorous recovery as hydroxyapatite (Hap) from alkaline phosphate concentrates using desalinated industrial brines as the calcium source in a batch reactor was evaluated. Two synthetic brines with Mg/Ca molar ratios of 2.2 and 3.3 were continuously fed to reach a Ca/P molar ratio of ~1.67 to promote Hap formation under different constant pH values (8, 9.5, 10.5, 11.5 and 12). For both brines, inhibition of Hap precipitation and formation of the amorphous mineral phases of Ca-, Mg- and Ca/Mg-phosphates were observed at pH > 9.5. Mg(II) severely inhibited phosphate precipitation, allowing the formation of amorphous calcium phosphate from meta-stable clusters due to Mg(II) incorporation into Ca-phosphate. For the Mg/Ca (3.3) brine, a more soluble Mg-phosphate mineral (cattiite) was formed at pH 11.5. Thermal treatment of the amorphous solids to increase crystallinity confirmed the presence of Hap and chlorapatite as Ca-phosphate, stanfieldite as Ca–Mg-phosphate and farringtonite as Mg-phosphate. In the experiments at pH 8, the formation of stable nanometer-sized pre-nucleation clusters promoted nucleation inhibition, even in supersaturated solutions, and no solids were recovered after filtration. Although sulfate was involved in some of the precipitation reactions, its role in the inhibition of Hap formation is not clearly elucidatedPostprint (author's final draft

Phosphate recovery from aqueous solution by K-zeolite synthesized from fly ash for subsequent valorisation as slow release fertilizer

The sorption of phosphate by K-zeolites synthesized from fly ash (FA) by hydrothermal conversion is investigated in this study. The aim is the synthesis of Ca bearing K-zeolites to recover phosphate from urban and industrial wastewater effluents. The loaded zeolites are considered as a by-products rich in essential nutrients such K and P (KP1) with a potential use as slow release fertilizer. A number of synthesis conditions (temperature, KOH-solution/FA ratio, KOH concentration, and activation time) were applied on two FA samples (FA-TE and FA-LB) with similar glass content but different content of crystalline phases, to optimize the synthesis of a zeolitic sorbent suitable for the subsequent phosphate uptake. Merlinoite and W rich zeolitic products synthesized from FA-LB and FA-TE were found to have sorption properties for phosphate removal. A maximum phosphate sorption capacity of 250 mgP-PO4/g and 142 mgP-PO4/g for the zeolitic products selected (KP1-LB and KP1-TE, respectively) was achieved. The dominant phosphate sorption mechanism, in the pH range (6–9) of treated wastewater effluents, indicated that sorption proceeds via a diffusion-controlled process involving phosphate ions coupled with calcium supply dissolution from K-zeolitic products and subsequent formation of brushite (CaHPO4 2H2O(s)). The phosphate loaded sorbent containing a relatively soluble phosphate mineral is appropriate for its use as a synthetic slow release fertilizer. The simultaneous valorisation of fly ash waste and the P recovery from treated wastewaters effluents, (a nutrient with scarce natural resources and low supply) by obtaining a product with high potential for land restoration and agriculture will contribute to develop one example of circularityPeer ReviewedPostprint (author's final draft

Recovery of rare Earth elements from acidic mine waters by integration of a selective chelating ion-exchanger and a solvent impregnated resin

A polymeric ion-exchange resin, incorporating methyl-amino-phosphonic (TP260) functionalities, and a solvent impregnated resin (SIR) incorporating tri-methylpentylphosphinic acid (TP272), were evaluated for the selective separation of Rare Earth Elements (REE) from Transition (TE), post -Transition (PTE), and Alkaline Earth (AE) Elements in acidic mine waters (AMW). The influence of the functional groups nature and the acidity dependence were studied and their effects on efficiencies for REE removal and separation from TE/PTE were analysed Both resins provided good separation factors of REE from TE/PTE by acidity control of the treated effluent once Fe(III), the major component in AMW, had been removed by precipitation. The TP272 resin, containing tri-methylpentylphosphinic acid (Cyanex 272) onto the polymeric network, showed higher affinity towards Heavy REE (HRRE) than for Light REE (LRRE) by acidity control (pH > 4). Higher pre-concentration factors were achieved for TP272 impregnated resin (e.g., 20–30) in comparison with the TP260 phosphonic resin (2-5), as the pH extraction window is in the moderate pH region (1-5). The integration in series of both resins could be used to separate and recover HREE and LREE from TE/PTE from AMW generated concentrates could be used to recover REE as secondary resources for the clean energy technology industry.Peer ReviewedObjectius de Desenvolupament Sostenible::9 - Indústria, Innovació i InfraestructuraObjectius de Desenvolupament Sostenible::13 - Acció per al ClimaPostprint (author's final draft

Recovery of rare earth elements from acidic mine waters: An unknown secondary resource

Acidic mine Drainage (AMD) is still considered one of the greatest mining sustainability challenges due to the large volumes of wastes generated and the high associated treatment cost. New regulation initiatives on sustainable development, circular economy and the need for strategic elements as Rare Earth Elements (REE) may overcome the traditional research initiatives directed to developing low cost treatment options and to develop research initiatives to identify the potential benefit of considering such AMD as a potential secondary resource. As an example, this study develops the integration of a three-stage process where REE are selectively separated from base metals (e.g. Fe, Al, Mn, Ca, Mg, Cd, Pb) and then concentrate to produce a rich REE by-product recovered as REE-phosphates. Selective separation of Fe (>99%) was achieved by total oxidation to Fe(III) and subsequent precipitation as schwertmannite at pH 3,6 ± 0.2. REE were then extracted from AMD using a sulfonic ion-exchange resin to produce concentrated REE sulfuric solutions up to 0.25 gREE/L. In a final stage selective separation of REE from Al(III), Ca(II) and Mg(II) and transitions elements (Cu, Zn, Ni) was achieved by precipitation with phosphate solutions under optimized pH control and total phosphate concentration. XRD analysis identified low-crystalline minerals. By using a thermal treatment the presence of PrPO4(s) and Cheralite (CePO4(s)) where Ce is substituted by La and Ca and Xenotime (YPO4(s)) were found as main minerals AlPO4(s) Ca,MgYPO4(s) were also identified.Peer ReviewedObjectius de Desenvolupament Sostenible::13 - Acció per al ClimaObjectius de Desenvolupament Sostenible::9 - Indústria, Innovació i InfraestructuraPostprint (published version

Simultaneous ammonium and phosphate recovery and stabilization from urban sewage sludge anaerobic digestates using reactive sorbents

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 15 gZ/L) to 90 ± 3% (for 50 gZ/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 0.7–1 g NH4+/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.Peer ReviewedPostprint (author's final draft

Impact of functional group types in ion exchange resins on rare earth element recovery from treated acid mine waters

Ion-exchange (IX) resins incorporating single functional groups (sulfonic or amino-phosphonic) and two functional groups (sulfonic and phosphonic) were evaluated for selective recovery of Rare Earth Elements (REEs) from acidic mine waters (AMW). The composition of AMW solution, complexing properties of the functional group, and acidity were investigated as key parameters for concentration and separation of REEs from transition elements (TEs). Fe has to be removed from AMW to enable REE recovery and here the AMW was treated with NaOH solutions to reach pH 3.9 where Fe(III) was selectively removed (=99%) by precipitation of schwertmannite. Single functional IX resin containing a sulfonic group displayed a higher REE recovery efficiency and separation ratio than observed for the bi-functional resin (sulfonic/phosphonic). Concentration factors for REEs between 30 and 40 were achieved using regeneration cycles with H2SO4. The performance of the aminophosphonic resin showed lower separation factors for REEs from TEs than the two resins containing sulfonic groups. IX resins performance was improved by tuning the acidity to match the functional group reactivity, where pH adjustment to the range of 0.5–2.0 provided the highest REE/TE separation factor for the single sulfonic resin followed by the bifunctional resin. The integration of an elution cycle using Na2-EDTA/NH4Cl mixtures strongly increases the concentration factors of REE and Light REE (LREE) concentration factors of up to 260 were achieved for the single functional sulfonic resin.Peer ReviewedPostprint (published version

Effects of elastic band based plyometric exercise on explosive muscular performance and change of direction abilities of male team handball players

publishedVersio

Integration of selectrodialysis and ion-exchange for copper and zinc recovery from metallurgical process streams containing arsenic

Postprint (author's final draft

Simultaneous ammonium and phosphate recovery and stabilization from urban sewage sludge anaerobic digestates using reactive sorbents

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