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Microalgae are photosynthetic microorganisms which may be employed in several fields. Amongst them, an emerging but promising sector of application is their usage for the remediation of wastewaters. They result particularly effective in treating municipal wastewaters, often resulting in nitrate concentrations exceeding the requirements for discharging treated wastewater into the sea. Furthermore, another advantage of using microalgae in civil wastewater treatment is the cooperation with heterotrophic bacteria which may naturally occur in the water or be introduced through sewage sludge in wastewater treatment plants (WTPs). Microalgae, in fact, produce oxygen which may be used by these bacteria reducing the overall operational costs of the WTP. The assessment of nitrogen compound concentrations in wastewater involves various techniques, with ionic chromatography (IC) and spectrometric methods being commonly used in laboratory settings. However, these methods have drawbacks such as the need for skilled personnel, time-consuming processes, and impracticality for in situ and real-time analysis. To address these issues, electrochemical sensors present a viable alternative. These sensors require portable instruments with low power requirements and can be miniaturized using nanotechnology. Electrochemical sensors operate by reducing/oxidizing the target analyte on the working electrode surface. The choice of electrode material is crucial for sensor sensitivity, and copper is found to exhibit excellent electrocatalytic properties for reducing nitrate ions in acidic media. In this study, a cost-effective electrochemical sensor made of copper was developed for quantifying nitrate in wastewater. The entire electrochemical cell was constructed from a common substrate used in Printed Circuit Boards (PCB). The whole fabrication procedure was optimized in order to obtain a reproducible fabrication procedure. The reference and counter electrodes were modified with graphite and Ag/AgCl paste, respectively. The results demonstrated that the sensor can effectively quantify nitrate ions in wastewater. Moreover, it can be employed during microalgal treatment to assess the in vivo reduction of nitrate, offering a practical and efficient solution for real-time monitoring of nitrogen compounds in wastewater treatment processes. [ABSTRACT FROM AUTHOR]

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The Camugnano landslide, located in the Province of Bologna, affects an area of 9.1×105 m². It is considered a complex phenomenon involving both roto-translational kinematics within the Camugnano Formation’s arenaceous flysch and translational slides that affect the degraded products of the flysch and other clay materials in the lower sector of the unstable slope. The activity of the landslide is characterized by very slow displacement rates (4 cm/year), with occasional acceleration events in the past. The most recent significant event occurred in 2014. In response, various surveys and monitoring activities were conducted, including the use of boreholes, geophysical surveys, displacement measurements through inclinometers, Ground Navigation Satellite System (GNSS), and Robotic Total Station (RTS), and groundwater monitoring through pressure transducers installed in piezometers. The aim of this note is to summarize the monitoring results and compare them with the trend of effective rainfall over multiple years. To determine effective precipitation, the Thornthwaite formulation was used, based on mean daily temperature and daily cumulative rainfall data from the Diga del Brasimone gauge station, located approximately 5 km from the landslide site. The inclinometer monitoring helped identify the sliding surfaces and obtain time series data by integrating displacements on these surfaces. GNSS campaigns conducted periodically revealed displacement rates ranging from 30 to 70 mm/year, generally decreasing progressively from 2014 to 2022. RTS monitoring indicated slow but detectable movements within the landslide. Then comparing GNSS displacements with precipitation data, it was found that displacement rates remained relatively constant regardless of variations in effective precipitation. This trend was also observed when analysing inclinometer data. The groundwater monitoring showed seasonal fluctuations, with peak levels occurring during the winter period in most piezometers. However, no long-term groundwater trend was observed. The displacement record highlights a variable sensitivity of the slope to effective rainfall with respect to the last major reactivation event. Temporary, localized accelerations are in fact recorded after 2014, gradually decreasing in magnitude in the next years. These findings suggest that mitigation strategies could by modified according to this style of activity and indicate that assumptions linking rainy or dry periods to variations in movement acceleration or deceleration may be overly simplistic. [ABSTRACT FROM AUTHOR]

As known, microalgae are an appealing source of chemicals and high-value compounds which find application in nutraceuticals, cosmetics and pharmaceutics. Fatty acids (FA), in particular, have drawn attention to the possibility of employing them as a source of biodiesel alternatively to fossil fuels. In addition, several lipid derivatives have been found in microalgae and may be employed in several biotechnological applications. Hydroxy fatty acids can be substrates for several industrial applications thanks to their functionalization, which increases their reactivity and, for this reason, can be used as functional building blocks to produce a multitude of bio-based materials. Recently, a promising method for the chemical modification of unsaturated-FAs (U-FA) has appeared. In fact, U-FA may be modified by members of the hydratase enzyme family to produce saturated and unsaturated hydroxy fatty acids with high stereo- and regio-selectivity. These enzymes are able to introduce a water molecule to the double bond present in the free fatty acids (FFA) Oleic Acid (OA), Linoleic Acid (LA), producing 10-hydroxy fatty acids (10-hydroxy-FAs). Furthermore, the carbohydrate component of the microalgal biomass may be converted into furfuryl compounds and, in particular in 5-hydroxyl methyl furfural (5-HMF). This is one of the chemical bio-compound different from petroleum-derived ones with the highest added value and may be obtained through lignocellulosic biomasses or hexoses sugars through acid catalysis. It is defined platform molecule because it is the precursor of several compounds for the chemical industry. In this work, we aimed to optimize a circular bioprocess by performing, starting from the same biomass, two different processes: the biotransformation of microalgal FFAs through the employment of a genetically modified E. coli on one side, and the conversion of the remaining biomass in furfuryl products. The first process allowed the production of very interesting lipid derivatives with biotechnological applications, including 10 hydroxy-stearic acid and 10-hydroxy-octadecenoic acid. The second process was obtained through heterogeneous catalysis based on niobium phosphate. This procedure represents a high-innovative application of microalgal biomass and allows the simultaneous exploitation of FAs and carbohydrates. This may result in an increase in the commercial value of microalgal biomass. [ABSTRACT FROM AUTHOR]

The benefits of polyunsaturated fatty acids and their implications for human health have gained scientific attention to their extraction from biological sources, not being produced by the human body. Most known industrial productions of omega-3 fatty acids often work under operating conditions that may degrade these components and they often use toxic or flammable solvents that can adversely affect human health. In this sense, innovative and interesting prospects are provided by Supercritical Fluid Extraction (SFE). In this work, two parallel studies were carried out: an experimental activity in a laboratory apparatus using supercritical carbon dioxide (scCO2) and preliminary computational fluid dynamics (CFD) simulations, limited to the hydrodynamic aspects of the process. In the experimental apparatus a Sulzer® EX structured packing, made up of corrugated metal gauze sheets, was used as the column filler. The study made it possible to identify the optimal operating conditions leading to an enrichment of the starting mixture in Eicosapentaenoic acid (EPA) and Docosahexaenoic acid (DHA), target products. CFD simulations were based on the Volume of Fluid (VOF) approach, suitable to the present complex multiphase system with two phases in close contact (transesterified fish oil and scCO2). The meatus created by the corrugations of the metal gauze was chosen as the calculation domain representative of the system. The computations were performed by the commercial software Ansys Fluent®, which allowed the prediction of the hydrodynamic evolution of the system through transient simulations. CFD predictions were in qualitative agreement with the experimental results. [ABSTRACT FROM AUTHOR]

As well known, microalgae are eukaryotic or procaryotic microorganisms able to photosynthesize, namely transforming inorganic substrates and sun light into organic compounds and chemical energy. They result very promising in treating civil wastewaters thanks to their ability to employ nitrates and phosphates as nutrients (Lima et al., 2019). Autotrophic microalgae are, anyway, not useful in decreasing the organic carbon content of wastewaters, and for this reason, they cooperate with heterotrophic bacteria. The usefulness of microalgae- bacteria consortia in treating wastewaters and the ratio of their inoculum was investigated in a previous work (Lima, 2022a). Contrarily to autotrophic microalgae, mixotrophic microalgae are able to decrease the organic content of the matrix in which they are grown. In this work, we preliminarily investigated the capability of the autochthonous microalga Chlorella sp. CW2 to grow in mixotrophy and decrease the organic content of the artificial wastewater in which they are grown. Several batch cultivations were performed with glucose in different concentrations. Kinetic parameters were obtained and employed to determine the dilution rate (D) ideal for the abatement of glucose from the artificial wastewater. [ABSTRACT FROM AUTHOR]

Microalgae are photosynthetic microorganisms that can employ some inorganic pollutant compounds as nutrients, for example nitrates and phosphates. Traditional wastewater treatment comprises oxidation ponds in which the Activated Sludge performs the oxidation of the organic matter. Microalgae may be well applied in these processes. In this work, we tested the potential of remediation of a mixture of a local microalga, Chlorella sp. Pozzillo, and activated sludge and compared it to controls of only microalga and only activated sludge. We found that the mixture of bacteria and microalgae leads to an improvement in nitrogen removal up to the 83,68%, while phosphorous removal is improved when the autochthonous microalgae are used alone. The abatement of the Chemical Oxygen Demand was of 59,17% when using the microalgae and activated sludge consortium, while it was higher (-76,67%±0) when using the only activated sludge. The biomass was also analysed for its content in lipids and carbohydrates. This information may be useful to assess the best industrial application for the biomass obtained from civil wastewaters remediation process, in accordance with principles of circular economy and waste-to-resources view. [ABSTRACT FROM AUTHOR]