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Steel slags, the main waste product from the steel industry, may have several reuse possibilities. Among others, building applications represent a crucial field. However, the potential impact of harmful substances on the environment should be assessed. The aim of this study was to assess the phytotoxicity of steel slags (SS) and concrete mixtures cast with a partial replacement of SS (CSS). Leaching tests were carried out on four SS and four CSS according to EN 12457-2 and UNI EN 15863, respectively. Each leachate was assayed using root elongation tests on 30 seeds of Allium cepa, Cucumis sativus, and Lepidium sativum, respectively, and on 12 bulbs of A. cepa. The latter also allowed the analysis of other macroscopic parameters of toxicity (turgidity, consistency, colour change and root tip shape) and the evaluation of the mitotic index on 20,000 root tip cells per sample. None of the samples induced phytotoxic effects on the organisms tested: all samples supported seedlings emergence, verified by root elongation comparable to, or even greater than, that of the negative controls, and did not affect cell division, as evidenced by mitotic index values. The absence of phytotoxicity demonstrated by the leachates allows SS and SS-derived concrete to be considered as reliable materials suitable for use in civil constructions or in other engineering applications, with economic and environmental advantages, such as the reduction of the final disposal in landfills as well as the consumption of natural resources. [ABSTRACT FROM AUTHOR]

Recently, among AOPs, photoelectrocatalysis (PEC) on TiO2 is gaining interest. In this study, five different real waters sampled in four different points of the integrated urban water management (IUWM) system were tested with PEC and UV alone, for comparison. This work aims to verify the effect of the PEC suggesting the optimal position in IUWM system where the PEC should be located to obtain the best performance. In groundwaters (GWs), PEC effectively removed atrazine-based compounds (> 99%), trichloroethylene, and perchloroethylene (96%), after 15 min of reaction time. However, given the low concentrations of emerging compounds, the synergistic effect of UV radiation with the catalyst and with the polarization of the mesh was not visible, with very few differences compared with the results obtained with UV alone. Pharmaceutical industrial wastewater (IWW) showed a significant increase in biodegradability after 2 h, both if subjected to PEC or UV (200%), despite the absence of COD removal. The PEC applied on IWW from a sewage sludge treatment plant allowed to effectively remove the COD (39.6%) and increase the biodegradability (300%). Good results in terms of COD removal (33.9%) and biodegradability increase (+900%) were also achieved testing PEC on wastewater treatment plant effluent. Except for GWs, PEC allowed significant EEO savings respect to UV alone (76.2–99.1%). [ABSTRACT FROM AUTHOR]

Northern Italy was the most affected by CoViD-19 compared to other Italian areas and comprises zones where air pollutants concentration was higher than in the rest of Italy. The aim of the research is to determine if particulate matter (PM) has been the primary cause of the high CoViD-19 spread rapidity in some areas of Northern Italy. Data of PM for all the 41 studied cities were collected from the local environmental protection agencies. To compare air quality data with epidemiological data, a statistical analysis was conducted identifying the correlation matrices of Pearson and Spearman, considering also the possible incubation period of the disease. Moreover, a model for the evaluation of the epidemic risk, already proposed in literature, was used to evaluate a possible influence of PM on CoViD-19 spread rapidity. The results exclude that PM alone was the primary cause of the high CoVid-19 spread rapidity in some areas of Northern Italy. Further developments are necessary for a better comprehension of the influence of atmospheric pollution parameters on the rapidity of spread of the virus SARS-CoV-2, since a synergistic action with other factors (such as meteorological, socio-economic and cultural factors) could not be excluded by the present study. [ABSTRACT FROM AUTHOR]

In the last years, the upgrading of wastewater treatment plants (WWTPs) could be required in order to comply with the more stringent regulation requirements. Nevertheless, the main issue is related to the surface availability. A proper solution could be represented by the attached biomass processes, in particular the moving bed biofilm reactors (MBBR), that have a significant footprint reduction with respect to conventional activated sludge (CAS). However, MBBR showed an important disadvantage: the poor aeration energy efficiency due to the use of coarse bubble diffusers, which guarantee high reliability and low maintenance costs with respect to fine bubble ones. Moreover, the presence of carriers inside the reactor emphasizes this aspect. The aim of this work is to verify the benefits achievable by installing a fine bubble aeration system inside a MBBR system. The comparison, in terms of oxygen transfer efficiency, between a medium bubble aeration system and a fine ceramic bubble diffuser was studied and the effect of biofilm growth on oxygen transfer was assessed. Several tests were carried out in order to test the operation of a coarse and a fine bubble side aeration at different air flow rates, both in clean water conditions, in order to evaluate the influence of carriers (Chip M type) on the aeration efficiency, both in wastewater conditions with the aim to assess the effect of bacteria growth on the carriers. The main results are the following: (i) the fine bubble system placed off-center ensured good mixing even without using the mixer; (ii) the fine bubble side aeration system compared to the coarse ones did not show significant advantages in terms of oxygen transfer efficiency; (iii) the increase in specific air flow rate negatively influenced the aeration efficiency; (iv) the presence of biomass had a positive effect on the oxygen transfer yield. [ABSTRACT FROM AUTHOR]

The aim of this work was to evaluate the use of solid residues derived from municipal solid waste-derived solid recovered fuel incinerated in a circulating fluidized-bed boiler for concrete production. The concrete mixtures casted by partially replacing the natural aggregates with bottom ash (27 %) and exhausted sand (13 %), according to the European standards for concrete, may be classified in the C16/20 class. The leaching tests performed on monolithic concrete samples showed that the concentrations measured in the leachates were lower than limit values for waste recovery, with the only exception of nickel for the mixture made with the exhausted sand. [ABSTRACT FROM AUTHOR]

The increased use of heavy metals in process industries often results in the generation of large quantities of wastewater (WW) and aqueous waste (AW) containing mixtures of heavy metals such as copper and nickel. This research focuses on the electrochemical recovery of copper and nickel from acid pickling solutions used to treat metal surfaces. Using hull cells, beaker plating, and electrolytic cells in pilot scale (capacity 30 L), the most important parameters influencing the process have been identified (temperature, contact time, and current density). In total, about 60 tests were carried out on AW containing nickel and copper. The results of the tests carried out with copper-containing AW shows that removal yields are often higher than 50%; while the energy consumption is less than 15 kWh kg−1 of metal deposited. The best removal efficiency (100%) was achieved by applying a current density of 6 A dm−2 and the energy consumption was 2 kWh kg−1. The tests carried out with AW containing nickel point out very low removal yields (< 20%) and very high energy consumption (even exceeding 300 kWh kg−1). The best removal yield obtained, applying a current density of 3 A dm−2, is 6.7% with an energy consumption of 40 kWh kg−1 of metal removed. A costs analysis based on Metal Exchange value was carried out. The cost analysis suggests that the results, in terms of removal and recovery, obtained for these metals, in particular for copper, are very promising for an industrial application. [ABSTRACT FROM AUTHOR]