Removal of ammonium from wastewater with geopolymer sorbents fabricated via additive manufacturing

Geopolymers have been recently explored as sorbents for wastewater treatment, thanks to their mechanical and chemical stability and to their low-energy manufacturing process. One specific application could be the removal of ammonium (NH4+) through exchange with Na+ ions. Additive manufacturing (AM) represents an especially interesting option for fabrication, as it allows to tailor the size, distribution, shape, and interconnectivity of pores, and therefore the access to charge-bearing sites. The present study provides a proof of concept for NH4+ removal from wastewater using porous geopolymer components fabricated via direct ink writing (DIW) AM approach. A metakaolin-based ink was employed for the fabrication of a log-pile structure with 45\ub0 rotation between layers, producing continuous yet tortuous macropores which are responsible for the high permeability of the sorbents. The ink consolidates in an amorphous, mesoporous network, with the mesopores acting as preferential sites for ion exchange. The printed sorbents were characterized for their physicochemical and mechanical properties and the NH4+ removal capacity in continuous-flow column experiments by using a model effluent. The lattices present high permeability and high cation exchange capacity and maintained a high amount of active ions after four cycles, allowing to reuse them multiple times

Identification of most relevant variables and processes to assess the environmental impacts of remediation technologies along their life cycles: Focus on the waste management scenarios

The application of Life Cycle Assessment (LCA) to remediation technologies is still not a consolidated practice and it is especially lacking in the assessment of the environmental impacts associated to the management of the waste produced during remediation. This study aims at addressing these methodological gaps by identifying the typologies of waste typically generated during the remediation of a contaminated site and classifying them according to the European Waste Catalogue (EWC) codes. Thereafter, the following steps are: (i) the identification of the waste management scenarios (WMSs) applicable to the identified waste typologies, (ii) the selection of Life Cycle Assessment processes that can be used to assess the impacts of the different WMSs and (iii) the quantification and comparison of the environmental impacts caused by the different WMSs applied considering hazardousness levels to which the same waste may belong in relation to its contamination levels and characteristics: inert, non-hazardous and hazardous waste (Waste Framework Directive 2008/98/EC). As results, a matrix reporting the classes and typologies of waste, their EWC codes, their different WMSs and the suitable LCA processes from the Ecoinvent database that can be applied to each EWC within a specific WMS, has been developed. Additionally, the comparative assessment of the impacts caused by the Ecoinvent processes applicable to the same waste typology within the same WMS has been performed to support the selection of the most appropriate WMS case by case

Impact of respirator versus surgical masks on SARS-CoV-2 acquisition in healthcare workers: a prospective multicentre cohort.

BACKGROUND There is insufficient evidence regarding the role of respirators in the prevention of SARS-CoV-2 infection. We analysed the impact of filtering facepiece class 2 (FFP2) versus surgical masks on the risk of SARS-CoV-2 acquisition among Swiss healthcare workers (HCW). METHODS Our prospective multicentre cohort enrolled HCW from June to August 2020. Participants were asked about COVID-19 risk exposures/behaviours, including preferentially worn mask type when caring for COVID-19 patients outside of aerosol-generating procedures. The impact of FFP2 on (1) self-reported SARS-CoV-2-positive nasopharyngeal PCR/rapid antigen tests captured during weekly surveys, and (2) SARS-CoV-2 seroconversion between baseline and January/February 2021 was assessed. RESULTS We enrolled 3259 participants from nine healthcare institutions, whereof 716 (22%) preferentially used FFP2. Among these, 81/716 (11%) reported a SARS-CoV-2-positive swab, compared to 352/2543 (14%) surgical mask users; seroconversion was documented in 85/656 (13%) FFP2 and 426/2255 (19%) surgical mask users. Adjusted for baseline characteristics, COVID-19 exposure, and risk behaviour, FFP2 use was non-significantly associated with decreased risk for SARS-CoV-2-positive swab (adjusted hazard ratio [aHR] 0.8, 95% CI 0.6-1.0) and seroconversion (adjusted odds ratio [aOR] 0.7, 95% CI 0.5-1.0); household exposure was the strongest risk factor (aHR 10.1, 95% CI 7.5-13.5; aOR 5.0, 95% CI 3.9-6.5). In subgroup analysis, FFP2 use was clearly protective among those with frequent (> 20 patients) COVID-19 exposure (aHR 0.7 for positive swab, 95% CI 0.5-0.8; aOR 0.6 for seroconversion, 95% CI 0.4-1.0). CONCLUSIONS Respirators compared to surgical masks may convey additional protection from SARS-CoV-2 for HCW with frequent exposure to COVID-19 patients

A methodology to assess a mobile urban street cleaning activity

An experimental methodology to assess the human exposure of a street cleaning service, performed by a worker handling a leaf blower followed by a water-flushing sweeper, was developed. The sampling campaign was achieved by considering data from road dust, personal air sampling and portable particulate matter detector. The experimental design allowed to obtain qualitative and quantitative information on the chemical composition of road dust, the size and chemical composition of potentially inhalable particles suspended during the street cleaning activity, as well as the duration of the particles' suspension effect. The methodology employed showed: i) the compliance with the occupational exposure threshold values for the total inhalable dust and with the occupational exposure limit values according to national and international regulatory approaches for polycyclic aromatic hydrocarbons (PAH) and inorganic elements; ii) a good agreement of the metals concentrations from the road dust (i.e., calcium, magnesium, potassium, iron, aluminium and sodium) with those from the material collected by the personal air sampler, highlighting the negligible effect of the investigated sweeping activity compared to the material already present on the road; iii) a similar pattern of inorganic elements within the three different monitoring areas; iv) a “dust wave” effect detected by the particle counter lasting no more than 2 min. Thus, such information suggested that performing the urban sweeping activity in the early mornings, when there is a general low PM10-PM2.5 average concentration, low traffic intensity, and the almost absence of passers-by, lead to a low probability of citizens’ exposure

An innovative stabilization/solidification treatment for contaminated soil remediation: demonstration project results

Background, aim, and scope: An innovative stabilization/solidification (S/S) process using high-performance additivated concrete technology was developed for remediating soil contaminated by metals from abandoned industrial sites. In order to verify the effectiveness of this new ex situ S/S procedure, an area highly contaminated by metallic pollutants (As, Cd, Hg, and Pb), due to the uncontrolled discharge of waste generated from artistic glass production on the island of Murano (Venice, Italy), was selected as a case study. The technique transforms the contaminated soil into an aggregate material suitable for reuse as on-site backfill. This paper reports the main results of the demonstration project performed in collaboration with the local environmental protection agency (ARPAV). Materials and methods: An ex situ treatment for brownfield remediation, based on the transformation of contaminated soil into very dense, low porous, and mechanically resistant granular material, was set up and tested. Specific additives (water reducers and superplasticizers) to improve the stabilized material properties were developed and patented. A demonstration plant assembled on the study area to treat 6 m3 h -1was then tested. After excavation, the contaminated soil was screened to remove coarse material. The fraction ∅>4 mm (coarse fraction), mainly composed of glass, brick, concrete, and stone debris, was directly reused on site after passing through a washing treatment section. The highly polluted fraction ∅ 4 mm (fine fraction) was treated in the S/S treatment division of the plant (European patent WO/2006/097272). The fine fraction was mixed with Portland cement and additives defined on the basis of the high performance concrete technique. the mixture was then granulated in a rolling-plate system. After 28 days curing in an onsite storage area to allow for cement hydration, the stabilized material was monitored before its in situ relocation. The chemical, mechanical, and ecotoxicological reliability and performance of the treatment was checked. Metal leachability was verified according to four leaching test methods: Italian Environmental Ministry Decree (1998), EN 12457 (2002) tout court, amended only with MgSO4 and, lastly, with artificial sea water. The mechanical properties were measured according to BS (1990) and AASHTO (1999) to obtain the Aggregate Crushing Value and California Bearing Ratio, in that order. Moreover, leachate samples prepared with artificial seawater were assessed via the Crassostrea gigas embryotoxicity test and Vibrio fischeri bioluminescence inhibition test to discriminate the presence of potential ecotoxicological effects for the brackish and saltwater biota. Results: Outcomes from all leachate samples highlighted the effectiveness of the remediation treatment, fully complying with the Italian legislation for non-hazardous material reuse under a physicochemical viewpoint. The stabilized granular material demonstrated high mechanical strength, low porosity, and leachability. Moreover, ecotoxicological surveys indicated the presence of low toxicity levels in leachate samples according to both toxicity tests. Discussion: Remediated soil samples revealed a significant decrease in leachability of heavy metals as a consequence of the application of additivated cement that enhanced granular material properties, resulting in improved compactness due to the reduction in water content. The toxicity data confirmed this state-of-the-art technique, indicating that leachates could be deemed as minor acutely toxic. Conclusions: The proposed S/S treatment proved to be able to remediate soil contaminated by heavy metals through trapping pollutants in pellet materials presenting adequate physicochemical, mechanical, and ecotoxicological properties in order to prevent leachability phenomena, their reclamation, and reuse being made easier by its granular form. Recommendation and perspectives: This project foresees long-term monitoring activity over several years (until 2014) to consider treatment durability

Layer-by-Layer Deposition of Titanium Dioxide Nanoparticles on Polymeric Membranes: A Life Cycle Assessment Study

Membrane processes are widely used in wastewater treatment and for removal of contaminants from drinking water. Engineered nanomaterials (ENMs) can be integrated into membranes structure to enhance their performance (e g, fouling mitigation and improvement of permeate quality). However, in order to ensure a sustainable use of nanoactivated membrane, the potential environmental impacts should be evaluated in an early stage of their development. In this study, we performed a cradle to gate life cycle assessment (LCA) to evaluate the environmental impacts due to the integration of titanium dioxide (TiO2) engineered nanoparticles (ENPs) in polyethersulfone (PES) membrane using the layer-by-layer (LbL) technology. The PES membrane manufacturing and electrostatic deposition of TiO2 ENPs on PES membrane were investigated in this case study. The results show that the LbL deposition stage of TiO2 ENPs on membrane has an insignificant effect on all selected impact categories, in comparison to PES membrane manufacturing stages investigated. The electricity use during the membrane production as well as the solvents and polymers needed for making PES membrane are the main contributions to the overall environmental impact