Stabilization of MSW combustion residues by accelerated carbonation treatment and their potential carbon dioxide sequestration

The material residues produced during the waste to energy (WtE) process are represented by bottom ash (BA), fly ash (FA) and flue gas cleaning ash. FA and flue gas cleaning are collected together in electrostatic precipitators or fabric filter devices and it is normally called air pollution control (APC). MSW combustion BA and APC residues potentially release metals and salts into the environment, thus landfilling or recycling options require a pre-treatment. Among the different treatment options, the carbonation process and the water washing treatment have been recently introduced. The carbonation process stabilises the material by changing its mineralogical and chemical characteristics and, it has shown a general reduction of the metal mobility. Carbonation treatment combines the clearly positive effect caused on reduction of metal mobility with the effect of CO₂ emission reduction. The water washing treatment seems to be the best option in order to remove soluble salts from APC ash. The main objectives of this doctoral thesis were to: (i) investigate the effects of the direct aqueous accelerated carbonation process, applied on BA, its particle size fractions and APC ash residues, (ii) evaluate the effect of a combined treatment “carbonation + washing”, applied on APC ash, (iii) evaluate the CO₂ sequestration capacity of BA and APC ash. As for the effects of accelerated carbonation on the metal leaching behaviour, significant results were obtained for both BA and APC residues. In the case of combined treatment, the Sb and Cr mobility is strongly influenced by the extent of carbonation. The carbonation treatment can be considered as a potentially viable option in order to improve the environmental behaviour of combustion residues and reduce CO₂ emissions from WtE plants. ---------------------------------------------------------- Il materiale residuo prodotto dalla termovalorizzazione dei rifiuti urbani è costituito dalle scorie di fondo, dalle ceneri leggere e dalle polveri provenienti dal trattamento dei gas acidi. Le ultime due componenti del residuo sono raccolte insieme nei sistemi di filtrazione e cosituiscono le ceneri APC. Le scorie di fondo e le ceneri APC rilasciano metalli e sali nell’ambiente, così è necessario pre-trattare i residui prima dello smaltimento in discarica o di un riutilizzo. Tra i diversi trattamenti, il processo di carbonatazione e il lavaggio con acqua sono i più recenti. La carbonatazione stabilizza il residuo attraverso la variazione delle caratteristiche mineralogiche e chimiche che causano una riduzione della mobilità dei metalli. La carbonatazione combina gli effetti positive sulla mobilità dei metalli con l’effetto della riduzione della CO₂ atmosferica. Il lavaggio con acqua permette la rimozione dei sali solubili dalle ceneri APC. I principali obiettivi di questa tesi di dottorato sono stati: (i) valutare gli effetti della carbonatazione accelerate in fase acquosa applicata alle scorie di fondo, le sue frazioni granulometriche e le ceneri APC, (ii) valutare l’effetto causato dall’applicazione del trattamento combinato “ carbonatazione + lavaggio” sulle ceneri APC, (iii) valutare la capacità di sequestro della CO₂ da parte dei suddetti residui. Per quanto riguarda gli effetti prodotti della carbonatazione accelerata sul comportamento dei metalli alla lisciviazione, sono stati ottenuti globalmente risultati positivi, sia per le scorie che per le ceneri APC. Nel caso del trattamento combinato, la mobilità di Cr e Sb sembra essere fortemente influenzata dal grado di carbonatazione. La carbonatazione consente di migliorare il comportamento ambientale dei residui e ridurre le emissioni di CO₂ prodotte dallo stesso termovalorizzatore

Stabilization of MSW combustion residues by accelerated carbonation treatment and their potential carbon dioxide sequestration

The material residues produced during the waste to energy (WtE) process are represented by bottom ash (BA), fly ash (FA) and flue gas cleaning ash. FA and flue gas cleaning are collected together in electrostatic precipitators or fabric filter devices and it is normally called air pollution control (APC). MSW combustion BA and APC residues potentially release metals and salts into the environment, thus landfilling or recycling options require a pre-treatment. Among the different treatment options, the carbonation process and the water washing treatment have been recently introduced. The carbonation process stabilises the material by changing its mineralogical and chemical characteristics and, it has shown a general reduction of the metal mobility. Carbonation treatment combines the clearly positive effect caused on reduction of metal mobility with the effect of CO₂ emission reduction. The water washing treatment seems to be the best option in order to remove soluble salts from APC ash. The main objectives of this doctoral thesis were to: (i) investigate the effects of the direct aqueous accelerated carbonation process, applied on BA, its particle size fractions and APC ash residues, (ii) evaluate the effect of a combined treatment “carbonation + washing”, applied on APC ash, (iii) evaluate the CO₂ sequestration capacity of BA and APC ash. As for the effects of accelerated carbonation on the metal leaching behaviour, significant results were obtained for both BA and APC residues. In the case of combined treatment, the Sb and Cr mobility is strongly influenced by the extent of carbonation. The carbonation treatment can be considered as a potentially viable option in order to improve the environmental behaviour of combustion residues and reduce CO₂ emissions from WtE plants. ---------------------------------------------------------- Il materiale residuo prodotto dalla termovalorizzazione dei rifiuti urbani è costituito dalle scorie di fondo, dalle ceneri leggere e dalle polveri provenienti dal trattamento dei gas acidi. Le ultime due componenti del residuo sono raccolte insieme nei sistemi di filtrazione e cosituiscono le ceneri APC. Le scorie di fondo e le ceneri APC rilasciano metalli e sali nell’ambiente, così è necessario pre-trattare i residui prima dello smaltimento in discarica o di un riutilizzo. Tra i diversi trattamenti, il processo di carbonatazione e il lavaggio con acqua sono i più recenti. La carbonatazione stabilizza il residuo attraverso la variazione delle caratteristiche mineralogiche e chimiche che causano una riduzione della mobilità dei metalli. La carbonatazione combina gli effetti positive sulla mobilità dei metalli con l’effetto della riduzione della CO₂ atmosferica. Il lavaggio con acqua permette la rimozione dei sali solubili dalle ceneri APC. I principali obiettivi di questa tesi di dottorato sono stati: (i) valutare gli effetti della carbonatazione accelerate in fase acquosa applicata alle scorie di fondo, le sue frazioni granulometriche e le ceneri APC, (ii) valutare l’effetto causato dall’applicazione del trattamento combinato “ carbonatazione + lavaggio” sulle ceneri APC, (iii) valutare la capacità di sequestro della CO₂ da parte dei suddetti residui. Per quanto riguarda gli effetti prodotti della carbonatazione accelerata sul comportamento dei metalli alla lisciviazione, sono stati ottenuti globalmente risultati positivi, sia per le scorie che per le ceneri APC. Nel caso del trattamento combinato, la mobilità di Cr e Sb sembra essere fortemente influenzata dal grado di carbonatazione. La carbonatazione consente di migliorare il comportamento ambientale dei residui e ridurre le emissioni di CO₂ prodotte dallo stesso termovalorizzatore

The effects of multilayer blue-green roof on the runoff water quality

In the context of climate changes, characterized by an increase of short but intense rainfall events and rise of the average temperature, the fast population growth and consequent urbanization require the implementation of innovative solutions to mitigate pluvial floods and, at the same time, reduce the water demand. Among the different nature-based solutions, multilayer blue-green roofs have been widely recognized for their high capacity of reducing runoff generation from rooftops, and their additional storage layer enables to collect water, which could be reused for different purposes. However, the quality of the collected water in a multilayer blue-green roof and the influence that the additional storage layer has on it have not been analysed yet. Following this knowledge gap, we investigated the potential benefits of a multilayer blue-green roof installed in Cagliari, with respect to a traditional roof. The outflow triggered by artificial irrigation and natural rainfall events was analysed, both from a quantitative and qualitative perspective. Results confirm the high contribution of multilayer blue-green roofs in mitigating runoff generation, which is however influenced by antecedent soil moisture and water level conditions. The outflow from the multilayer blue-green roof presents lower suspended solids and heavy metals concentrations than from a traditional roof. On the other hand, Carbon Oxigen Demand (COD) concentrations in the multilayer blue-green roof outflow exceed the limits defined by the Italian regulations (125 mg/l) for water discharge or reuse, partially due to the high residence time in the storage layer. Specific treatments could be planned to reuse the collected water for urban purposes

Ex situ phytoremediation trial of Sardinian mine waste using a pioneer plant species

The mitigation of metals contamination is currently a crucial issue for the reclamation of mine sites. Indeed, mine wastes are often disposed in open dumps and consequently pollutants are subjected to dispersion in the surrounding areas. In this study, the potential use of Helichrysum microphyllum subsp. tyrrhenicum for phytostabilization was evaluated in ex situ conditions. Ninety specimens were randomly selected and were planted in three substrates (reference substrate, mine waste materials, and mine wastes with compost). Mineralogical compositions of substrates, rhizosphere, and roots were assessed through X-ray diffraction (XRD). Zn, Pb, and Cd concentrations of substrates, rhizosphere, soil pore waters, and plant tissues were determined. The phytostabilization potential was determined through the application of biological accumulation coefficient (BAC), biological concentration factor (BCF), and translocation factor (TF). Moreover, survival and biometric parameters were assessed on plant specimens. The polluted substrates and related rhizosphere materials were mainly composed of dolomite, quartz, pyrite, and phyllosilicate. Zn was the most abundant metal in substrates, rhizosphere, and soil pore waters. XRD analysis on roots showed the presence of amorphous cellulose and quartz and Zn was the most abundant metal in plant tissues. H. microphyllum subsp. tyrrhenicum restricts the accumulation of the metals into roots limiting their translocation in aereal parts, indicating its potential use as phytostabilizer (BCF, BAC, TF < 1). Survival and growth data showed a great adaptability to different substrates, with an evident positive effect of the implementation of compost which increased the plant survival and decreased the metals uptake into roots

A Case Study of Implementation of Circular Economy Principles to Waste Management: Integrated Treatment of Cheese Whey and Hi-Tech Waste

In a global context characterized by severe environmental problems and increasing resource scarcity, waste represents both a challenge and an opportunity. This study aims to demonstrate with a real case the potential for optimizing the waste valorization action attainable through the synergic application of different treatments to residues of equally different nature and origin. In particular, bio-chemical (dark fermentation), chemical-physical (selective leaching) and thermo-chemical (hydrothermal carbonization) treatments were applied for the integrated valorization of whey from sheep cheese production and Hi-Tech waste (discarded electrical and electronic equipment). The treatments were applied at a laboratory scale on real samples of these residues. The organic acids used for selective leaching of valuable metals from Hi-Tech waste were obtained by dark fermentation of the cheese whey, while hydrothermal carbonization was used to convert the waste from previous stages into hydrochar feasible as solid fuel or soil improver. The dark fermentation tests have highlighted the possibility of recovering ≈ 100 g of organic acids from 1 L of whey; furthermore, it is also possible to recover bio-hydrogen depending on the operating conditions applied and the type of targeted organic acids. The leaching tests have demonstrated how the organic acids from whey fermentation have selective and quantitative mobilization capacities comparable to those of the same acids available on the market. The carbonization tests produced carbon-enriched hydrochar with promising fuel properties, as well as process waters suitable for anaerobic digestion with methane production. The results of the project led to the filing of an international patent

A comparison among bio-derived acids as selective eco-friendly leaching agents for cobalt: the case study of hard-metal waste enhancement

Peculiar chemical, mechanical, and magnetic properties make cobalt a key metal for a variety of “hot” applications like the cathode production of Li-ion batteries. Cobalt is also the preferred metallic binder for tungsten carbide tool manufacturing. The recent increasing criticality of cobalt and tungsten is driving the interest of manufacturers and researchers toward high-rate recycling of hard-metal (HM) waste for limiting the demand for raw materials. A simple and environmentally friendly hydrometallurgical route for Co-selective dissolution from HM wastes was developed by using weak, bio-derived, and biodegradable organic acids (OAs). In this study, OAs, namely, acetic (HAc), citric (H3Cit), maleic (H2Mal), lactic (HLac), succinic (H2Suc), lactobionic (HLB), and itaconic (H2It) acids, were selected for their pKa1 values spanning from 1.8 to 4.7 and systematically tested as selective cobalt leaching agents from WC-Co-based wastes in water, isolating the formed complexes in the solid state. Thereby, all of them seemed to be efficient in selective Co leaching, achieving almost quantitative Co dissolution from HM by-products still at low concentration levels and room conditions in a short time, leaving the residual WC unreacted and ready to be re-employed for industrial purposes. Nevertheless, two main categories of organic acids were distinguished depending on their oxidizing/complexing behavior: class 1 OAs, where the metal oxidation is carried out by H+, and class 2 OAs, where oxidation is carried out by an external oxidant like O2. A combined experimental/theoretical investigation is described here to show the reasons behind this peculiar behavior and lay the foundation for a wider discussion on the leaching capabilities of OAs toward elemental metals. Due to the demonstrated effectiveness, low cost, eco-friendliness, and large availability through biotechnological fermentative processes, particular attention is devoted here to the use of HLac in hydrometallurgy as an example of class 2 OA. WC-Co materials recovered by HLac mild hydrometallurgy demonstrated a metallurgical quality suitable for re-employment in the HM manufacturing process

IDH-wild type glioblastomas featuring at least 30% giant cells are characterized by frequent RB1 and NF1 alterations and hypermutation

: Giant cell glioblastoma (GC-GBM) is a rare variant of IDH-wt GBM histologically characterized by the presence of numerous multinucleated giant cells and molecularly considered a hybrid between IDH-wt and IDH-mutant GBM. The lack of an objective definition, specifying the percentage of giant cells required for this diagnosis, may account for the absence of a definite molecular profile of this variant. This study aimed to clarify the molecular landscape of GC-GBM, exploring the mutations and copy number variations of 458 cancer-related genes, tumor mutational burden (TMB), and microsatellite instability (MSI) in 39 GBMs dichotomized into having 30-49% (15 cases) or\u2009 65\u200950% (24 cases) GCs. The type and prevalence of the genetic alterations in this series was not associated with the GCs content (<\u200950% or 65\u200950%). Most cases (82% and 51.2%) had impairment in TP53/MDM2 and PTEN/PI3K pathways, but a high proportion also featured TERT promoter mutations (61.5%) and RB1 (25.6%) or NF1 (25.6%) alterations. EGFR amplification was detected in 18% cases in association with a shorter overall survival (P\u2009=\u20090.004). Sixteen (41%) cases had a TMB\u2009>\u200910 mut/Mb, including two (5%) that harbored MSI and one with a POLE mutation. The frequency of RB1 and NF1 alterations and TMB counts were significantly higher compared to 567 IDH wild type (P\u2009<\u20090.0001; P\u2009=\u20090.0003; P\u2009<\u20090.0001) and 26 IDH-mutant (P\u2009<\u20090.0001; P\u2009=\u20090.0227; P\u2009<\u20090.0001) GBMs in the TCGA PanCancer Atlas cohort. These findings demonstrate that the molecular landscape of GBMs with at least 30% giant cells is dominated by the impairment of TP53/MDM2 and PTEN/PI3K pathways, and additionally characterized by frequent RB1 alterations and hypermutation and by EGFR amplification in more aggressive cases. The high frequency of hypermutated cases suggests that GC-GBMs might be candidates for immune check-point inhibitors clinical trials

A new facile solvometallurgical leaching method for the selective Co dissolution & recovery from hard metals waste

Hard Metals (HM) production plays a fundamental role in economy and technological development. Due to the criticality of its main raw materials, W and Co, a sustainable HM waste recycling is hence desirable for both environmental and economic reasons and strongly encouraged by European waste management directives. This work describes a new solvometallurgical leaching method based on diluted maleic acid (H2Mal) ethanolic solutions, which demonstrated to couple effectiveness in materials enhancement from HM waste, with mildness and sustainability of operative conditions. Specifically, H2Mal (0.5 M, EtOH) selectively and quantitatively leached Co trapped within WC-Co powders, to afford [Co(HMal)2(H2O)4] complex within 4 h at room temperature and leaving WC unreacted and ready for re-employment in HM manufacturing. Characterization of the resultant materials i.e. treated powders (SEM-EDS, p-XRD, ICP-OES) and Co-leaching solutions (ICP-OES), confirmed the near quantitative Co removal as well as the possibility to finely tune the composition of WC-Co mixtures. Parameters for best leaching conditions, i.e. time and liquid-to-solid ratio, were obtained. A scale-up experiment addressed to test the leaching conditions and the quality of the recycled material is also described. The quality of the recycled material for direct re-employment in HM manufacturing was validated by Metallurgical Quality Control, to good effect. Finally, preliminary experiments on cobalt metal recovery from the metal complex by electrowinning and by quantitative precipitation as CoCO3 were performed with encouraging results: a step forward resources circularity

Diabetic ketoacidosis at the onset of disease during a national awareness campaign: a 2-year observational study in children aged 0-18 years

After a previous survey on the incidence of diabetic ketoacidosis (DKA) at onset of type 1 diabetes in children in 2013-2014 in Italy, we aimed to verify a possible decline in the incidence of DKA at onset during a national prevention campaign

Lack of association of CD44-rs353630 and CHI3L2-rs684559 with pancreatic ductal adenocarcinoma survival.

Although pancreatic ductal adenocarcinoma (PDAC) survival is poor, there are differences in patients' response to the treatments. Detection of predictive biomarkers explaining these differences is of the utmost importance. In a recent study two genetic markers (CD44-rs353630 and CHI3L2-rs684559) were reported to be associated with survival after PDAC resection. We attempted to replicate the associations in 1856 PDAC patients (685 resected with stage I/II) from the PANcreatic Disease ReseArch (PANDoRA) consortium. We also analysed the combined effect of the two genotypes in order to compare our results with what was previously reported. Additional stratified analyses considering TNM stage of the disease and whether the patients received surgery were also performed. We observed no statistically significant associations, except for the heterozygous carriers of CD44-rs353630, who were associated with worse OS (HR = 5.01; 95% CI 1.58-15.88; p = 0.006) among patients with stage I disease. This association is in the opposite direction of those reported previously, suggesting that data obtained in such small subgroups are hardly replicable and should be considered cautiously. The two polymorphisms combined did not show any statistically significant association. Our results suggest that the effect of CD44-rs353630 and CHI3L2-rs684559 cannot be generalized to all PDAC patients