Evaluation of the influence of filter medium composition on treatment performances in an open-air green wall fed with greywater.

According to the European Research and Innovation Policy Agenda, nature-based solutions (NBSs) are key technologies to improve the sustainability of urban areas. Among NBSs, green walls have been recently studied for several applications, among the others the treatment of lowly polluted wastewater flows as greywater (GW, e.g. domestic wastewater excluding toilet flushes). This work is aimed at the evaluation of the influence of four additives (compost, biochar, granular activated carbon, polyacrylate) mixed with a base filter medium made of coconut fibre and perlite, on the performances of a green wall fed in batch mode with synthetic GW. The green wall was operated with a high hydraulic loading rate of GW (740.8 L/m2/day) in open-air winter conditions (3.5-15 °C measured for GW) between January and April. The performances of the green wall have been assessed though the monitoring every 1-2 weeks of physicochemical and biological parameters (pH, electric conductivity, total suspended solids, dissolved oxygen, BOD5 and COD, nitrogen and phosporus compounds, chlorides and sulphates, anionic surfactants and E. coli). Removal performances were excellent for BOD5 (>95%) and E.coli (>98%) for all additives; compared to the base medium, biochar was the best performing additive over the highest number of parameters, achieving removals equal to 51% for COD, 47% for TKN and nitric nitrogen and 71% for anionic surfactants. Compost also achieved high removal performances, but the frequent clogging events occurred during the monitoring period do not make its use recommendable. Granular activated carbon and the combination of biochar and polyacrylate performed better than the base medium, but only about the removal of nitric nitrogen. These results demonstrated that, in the considered experimental boundaries, biochar could improve the overall treatment performances of a green wall fed by GW and operated in challenging conditions.

Stress among university students: the psychometric properties of the Italian version of the SBI-U 9 scale for Academic Burnout in university students.

Several authors have highlighted the importance of creating a useful tool to evaluate academic Burnout through the construction and validation of specific scales to evaluate academic Burnout. Based on the literature, the aim of this study is to evaluate in Italian university the psychometric properties of the SBI-U 9 scale for Academic Burnout in university students in Italy developed by Boada-Grau and colleagues. Study 1 (N=609) examined the factor structure of the scale (Male=45.6%, Female=54.4%; Mage= 21.9; SD=2.92). Study 2 (N=412) advanced the previous SBI-U 9 validation by testing its measurement equivalence across gender (Male=48.8%, Female= 51.2%) and different type of course of study (Technical-Mathematical-Scientific=33.5%, Medical- Scientific=32.5%, Scientific-Humanistic=34%) through Multigroup Confirmatory Factor Analysis. Results confirmed a one higher-order factor structure with three first-order factors, the scale was found to be invariant across gender and different type of course of study. The findings advanced the general claim of SBI-U 9 showed an important tool for detecting the academic Burnout in university students in the Italian context, this is confirmed by the good psychometric properties of the scale.

A review of nature-based solutions for greywater treatment: Applications, hydraulic design, and environmental benefits.

Recognizing greywater as a relevant secondary source of water and nutrients represents an important chance for the sustainable management of water resource. In the last two decades, many studies analysed the environmental, economic, and energetic benefits of the reuse of greywater treated by nature-based solutions (NBS). This work reviews existing case studies of traditional constructed wetlands and new integrated technologies (e.g., green roofs and green walls) for greywater treatment and reuse, with a specific focus on their treatment performance as a function of hydraulic operating parameters. The aim of this work is to understand if the application of NBS can represent a valid alternative to conventional treatment technologies, providing quantitative indications for their design. Specifically, indications concerning threshold values of hydraulic design parameters to guarantee high removal performance are suggested. Finally, the existing literature on life cycle analysis of NBS for greywater treatment has been examined, confirming the provided environmental benefits.

River bedform inception by flow unsteadiness: A modal and nonmodal analysis.

River bedforms arise as a result of morphological instabilities of the stream-sediment interface. Dunes and antidunes constitute the most typical patterns, and their occurrence and dynamics are relevant for a number of engineering and environmental applications. Although flow variability is a typical feature of all rivers, the bedform-triggering morphological instabilities have generally been studied under the assumption of a constant flow rate. In order to partially address this shortcoming, we here discuss the influence of (periodic) flow unsteadiness on bedform inception. To this end, our recent one-dimensional validated model coupling Dressler's equations with a refined mechanistic sediment transport formulation is adopted, and both the asymptotic and transient dynamics are investigated by modal and nonmodal analyses.