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Implementing nutrient recycling in wastewater treatment plants is essential for sustainable agriculture. In this study, we investigated a biphasic treatment system for anaerobic liquid digestate, which involved natural and K-enriched zeolite for NH4+ recovery (phase 1), followed by struvite crystallization under two conditions: NH4+ excess and Mg2+ excess (phase 2). The adsorption of NH4+ by natural zeolite enabled saving Mg and P reagents, used to achieve target Mg:NH4:PO4 ratios. The reagent use efficiency of struvite precipitation was highest with natural zeolite under NH4+ excess conditions (96%), whereas the other treatments exhibited lower yields. In this condition, the digestate enriched in Ca2+ released by zeolite; however, no P interferences occurred (Ca2+/Mg2+ < 0.5). Fractions of Ca2+ precipitated as CaCO3. Both the isomorphic NH4- and K-struvite occurred, distinguished by calibrating XRPD data (total struvite) with N contents (indicative of NH4+-struvite). The precipitates comprised NH4- and K-struvite at 60% and 30% (calcite at 9%) in the treatment that involved natural zeolite, 65% and 35% with the K-exchanged zeolite, due to higher presence of K+. Concerning the chemical evolution of the treated digestate, fewer alterations occurred for inorganic ions in the treatment that involved natural zeolite (phase 1) with NH4+ excess condition (phase 2), besides for unreacted SO42– derived from the Mg reagent. The recovered zeolite was enriched in N at 0.5%. Struvite precipitates met the EU regulations regarding permissible levels of organic C, P content, and heavy metal impurities, thereby potentially enabling its use as a fertilizer.Highlights: Zeolites allowed less reagents for reaching optimum struvite precipitation. N loads were reduced with zeolite–struvite treatment up to 86%. Struvite from digestate is usable in agriculture and complied with EU regulations. The precipitation of K-struvite limited the recovery of N from digestate. To discern (K) and (NH4)-struvite, XRD must be combined with chemical information. [ABSTRACT FROM AUTHOR]

Ancient Ardaxšīr Khwarrah, today known as Shahr-e Gur, situated near the modern town of Firuzabad in Fars, Iran, holds historical significance as the inaugural capital city of the Sasanian Empire. During archaeological excavations conducted in 2005 by an Iranian–German team directed by Mas'oud Azarnoush and Dietrich Huff, a mud-brick complex was uncovered, revealing a remarkably well-preserved stretch of wall painting and a polychrome painted floor. The discovery prompted the hypothesis of a potential funerary context dating back to the Sasanian period. Both the wall painting and painted floor have suffered extensive deterioration attributed to the environmental conditions of the archaeological site, which was inscribed on the UNESCO World Heritage List in 2020. To address the urgent need for preservation and further understanding of the site's artistic and structural elements, an emergency diagnostic project was initiated. Non-invasive investigations were carried out on the wall and floor by optical digital microscopy and portable energy-dispersive X-ray fluorescence. Additionally, representative minute samples underwent analysis through various techniques, including micro-X-ray fluorescence, polarised light microscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy, micro-Raman spectroscopy, micro-Fourier Transform Infrared Spectroscopy, gas chromatography-mass spectrometry and pyrolysis coupled with gas chromatography-mass spectrometry. The palette of the floor and mural paintings were identified to contain red and yellow ochres, lead-based pigments, carbon black and bone white. The unexpected presence of Egyptian blue mixed with green earth was recognised in the green hues of the wall painting. The detection of protein material in both the wall painting and polychrome floor indicates the use of "a secco" technique, thereby shedding light on the artistic practices employed in Ardaxšīr Khwarrah. [ABSTRACT FROM AUTHOR]

The study seeks to unravel the intricate operational sequence involved in preparing prehistoric pigments for rock art within the Puerto Roque rock art shelter. Sixteen pigment samples were meticulously collected from specific figurative representations. Additionally, three ochre samples were sourced from the shelter's soil. Employing a comprehensive multi-analytical approach, including Raman microspectroscopy, X-ray microfluorescence (EDxrf), Fourier-transform infrared spectroscopy (ATR-FTIR), and scanning electron microscopy (SEM-EDS), all nineteen samples underwent thorough analysis. Notably, darker pigments revealed a composition of hematite with the added presence of carbon. Meanwhile, one sample exhibited an orange hue primarily composed of goethite and bright red pigments predominantly characterised by hematite, as confirmed by Raman analysis. EDxrf analysis demonstrated an elemental composition akin to the three ochre pieces examined. Furthermore, ATR-FTIR spectroscopy suggested the potential influence of a heating process in enhancing red coloration, corroborated by spectral results from specific samples. This finding aligns with prior research, underscoring the technological sophistication embedded in early artistic endeavours. [ABSTRACT FROM AUTHOR]

This work is the first archaeometric investigation on copper and iron wastes from the Phoenician site of Motya (Sicily, Italy), dating back to the 8th to the 4th century BC. The samples were analyzed through micro‐Raman Spectroscopy (μ‐RS), Optical Microscopy (OM), Scanning Electron Microscope‐Energy‐Dispersive X‐ray Spectroscopy (SEM‐EDS), High‐Resolution Field Emission Scanning Electron Microscopy (HR‐FESEM), and Electron Micro‐Probe Analysis (EMPA). Micro‐Raman techinique permitted to identify both primary phases, for example, calchopyrite, and secondary products such as cuprite and copper thrihydroxychlorides in the Cu‐slags and goethite in the Fe‐slags. SEM and HR‐FESEM imaging showed the occurrence of inhomogeneous microstructures in the Cu‐ and Fe‐slags due to elements segregation, solidification, and corrosion. EMPA data revealed that the archaeometallurgical wastes from Motya can be differentiated on the basis of their chemical compositions. These preliminary results showed different typologies of by‐products, such as base metals speiss, copper slags from smelting sulfide ore with matte, and iron smelting and smithing slags, suggesting different stages of copper and iron productions. [ABSTRACT FROM AUTHOR]

This work is focused on the characterization of metallic finds that are part of an ancient war biga from the Tomba della Biga, using different approaches for the diagnostics and also the conservation of this important cultural heritage. The materials analyzed were brought to light in the necropolis of Canal Bianco (Adria, Italy). The samples were analyzed using Optical Reflected Light Microscopy (ORLM), Scanning Electron Microscopy (SEM) and micro-Raman Spectroscopy (µ-RS). The results highlighted the occurrence of two different alloys (Fe and Cu-Sn-bronze) showing important structural and textural variations. These results, along with µ-RS, gave details on the surface and subsurface morphology, as well as the microstructures and the chemical and mineralogical composition of the finds. In particular, µ-RS highlighted the presence of magnetite and goethite as the main mineralogical phases for Fe-samples and malachite, azurite and Cu-oxide for bronze samples. In addition, an attempt was made to trace the manufacturing process, the purity of the alloys and the degree of slagging. Results of analytical studies show corrosion products of the samples which could be evidence of metallurgical aspects. The good state of conservation due to favorable conditions in the burial environment preserved the metal finds from intense corrosion, supporting the hypothesis that the samples reached equilibrium with soil during their life in the burial environment. This proposed methodology based on the microstructure, chemistry and mineral microanalysis allows the diagnostic and evaluation of the state of conservation of metallic finds. [ABSTRACT FROM AUTHOR]

Featured Application: The results derived from this research paper contributes to the body of knowledge available from Bagan painting materials and techniques and also to a treatment proposal for the conservation and restoration of Bagan's temples. Pagán is an ancient city located in Myanmar that is renowned for the remains of about 4000 pagodas, stupas, temples and monasteries dating from the 11th to 13th centuries. Due to a magnitude 6.8 earthquake in 2016, more than 300 ancient buildings were seriously damaged. As a part of the post-earthquake emergency program, a diagnostic pilot project was carried out on Me-taw-ya temple wall paintings to acquire further information on the materials and on their state of conservation. This article presents our attempts at characterising the painting materials at Me-taw-ya temple using non-invasive portable energy dispersive X-ray fluorescence (ED-XRF), portable Raman spectroscopy and micro-invasive attenuated total reflectance—Fourier transform infrared spectroscopy (ATR-FTIR), micro-Raman spectroscopy (µ-Raman), gas chromatography-mass spectrometry (GC-MS), polarized light microscopy (PLM) and environmental scanning electron microscope—X-ray energy dispersive system (ESEM-EDS) investigations with the aim of identifying the composition of organic binders and pigments. The presence of a proteinaceous glue mixed with the lime-based plaster was ascertained and identified by GC-MS. In addition, this technique confirmed the occurrence of plant-derived gums as binders pointing to the a secco technique. Fe-based compounds, vermillion, carbon black and As-compounds were identified to have been incorporated in the palette of the murals. [ABSTRACT FROM AUTHOR]

The archeological site RS-TQ-141 is located in Rio Grande do Sul (Brazil) and belongs to the pre-colonial Guarani Tradition (between fifth and seventeenth century). The site extends to the bank of the Taquari River. About 200 small fragments of ceramic from the site present internal and/or external coating surfaces. Archaeometry analyses were applied in order to understand coating application mechanism. X-ray Fluorescence (XFR) analyses revealed that the main elements are iron, titanium, potassium, and calcium. Applying the micro Fourier Transform Interferometer (ATR-FTIR) method it was possible to differentiate white and red coatings produced with different types of (ocher) clays. ATR-FTIR was applied in order to try to distinguish the vessels use. The coatings were produced with the same groups of clays used for the manufacture of ceramics. The presence of at least two groups of clay is recorded: montmorillonite-like and kaolinite-like. The white coatings can be distinguished in the FTIR spectra by the presence of a carbonate peak. From this research, there does not seem to be any difference between internal and external coatings. Carbonyl materials were detected, both in the coating and in the production of the ceramics; the latter is probably related to pyrolysis. [ABSTRACT FROM AUTHOR]