Marco Bravi

Microalgal biomass production by using ultra- and nanofiltration membrane fractions of olive mill wastewater

Olive milling produces huge amounts of wastewater (OMWW) characterized by an extremely high organic load. Its polyphenols content is a hindrance to conventional biological treatment and to using it as growing medium for common microbial biomasses. The practice to dump it on soil is in conflict with the latest EU directives about waste management. OMWW can be effectively and efficiently treated by means of membrane technology to a fraction of the initial volume, but membrane processing concentrates still require treatment. Reversing the overall cost balance of membrane processing and subsequent treatment requires valorizing the concentrates through their reuse, as well as ensuring long-term service of the membrane system through effective wastewater pretreatment and sustainable, fouling-controlling, membrane operation conduite. Aim of this work is to reuse and valorize the ultra- and nanofiltration membrane concentrates as media for biomass production of microalgae and cyanobacteria. Scenedesmus dimorphus and Arthrospira platensis, usable as a food, feed, nutraceutical component or feedstock for biofuels, were selected for this investigation. Microalgal growth was experimentally determined and related to the composition of the concentrate-based media and to the irradiance distribution within the photobioreactor volume to decouple light limitation and medium chemical composition effects.

Primary nucleation of citric acid monohydrate: influence of selected impurities

An experimental study is presented concerning solubility and primary nucleation kinetics of monohydrate citric acid from pure and selectively impure (KH2PO4, MgSO4·7H2O and FeSO4·7H2O) aqueous solutions. The metastable range of pure solutions is wide, ranging from 6 to 14°C, and the order of primary nucleation, equal to 2.51, is quite low. The addition of the tested impurities, which are usual fermentation aids, at concentrations lower than wt. 1%, produces negligible effects on the solubility and slightly enhances the primary nucleation rate. However, the presence of these compounds modifies the crystal habit at birth: in particular, the addition of MgSO4·7H2O and FeSO4·7H2O makes these crystals more elongated, but this effect diminishes as the crystals grow.

Size dependency of citric acid monohydrate growth kinetics

Abstract An experimental study concerned with the growth kinetics of citric acid monohydrate crystals is presented. Due to the properties of the system, which is very soluble, with low solid-liquid density difference and high liquid viscosity, two different techniques were used: large crystals (710–850 μm) were grown in a fluidized bed crystallizer; small crystals, belonging to three size ranges from 90 to 355 μm, were grown in the cell of a laser light diffraction granulometer. A first order growth kinetics resulted in both cases; a comparative analysis of both the present data and those reported in the literature relevant to larger or smaller crystals, indicates that the system exhibits size-dependent growth, which increases linearly with the crystal size.

Phenolic Content of Hypodaphnis Zenkeri and Its Antioxidant Effects against Fenton Reactions’ Mediated Oxidative Injuries on Liver Homogenate

Under oxidative stress conditions, endogenous antioxidant defenses are unable to completely inactivate the free radicals generated by an excessive production of reactive oxygen species (ROS). This state causes serious cell damage leading to a variety of human diseases. Natural antioxidants can protect cells against oxidative stress. Hypaodaphnis zenkeri (H. zenkiri) is a plant consumed as a spice in the Cameroonian diet, and its bark has been used in traditional medicine for the treatment of several diseases. The present study aims at investigating the antioxidant activity, which includes free radical scavenging and protective properties of an extract from H. Zenkiri against oxidative damage on a liver homogenate. The free radical assays determined the scavenging activities of 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl (OH), nitrite oxide (NO) and 2,2-azinobis(3-ethylbenzthiazoline)-6-sulfonic acid (ABTS) radicals and the enzymes, whose protection was to be considered in the liver homogenate, including superoxide dismutase, catalase, and peroxidase. The antioxidative activities were studied using the ferric reducing antioxidant power (FRAP), reductive activity, and phosphomolybdenum antioxidant power (PAP) methods. In addition, the phenolic contents of the extracts were examined. The results showed that these extracts demonstrated significant scavenging properties and antioxidant activities, with the hydro-ethanolic extract of the bark of H. zenkeri (EEH) being the most potent. This extract had the highest total polyphenol (21.77 ± 0.05 mg caffeic acid (CAE)/g dried extract (DE)) and flavonoids (3.34 ± 0.13 mg quercetin (QE)/g dried extract) content. The same extract had significantly greater protective effects on enzyme activities compared to other extracts. The high performance liquied chromatography (HPLC) profile showed higher levels of caffeic acid, OH-tyrosol acid, and rutin in the leaves compared to the bark of H. zenkeri. In conclusion, the ethanolic and hydro-ethanolic extracts of the bark and leaves from H. zenkeri showed an antioxidant and protective potential against oxidative damage.

Growth kinetics of sodium perborate from batch crystallization

The size distribution of sodium perborate crystals was continually monitored using a Malvern sizer during batch crystallization from aqueous solutions carried out under falling supersaturation established at the experiment onset. The growth rate was determined from the time shift of the crystal size distribution expressed in cumulative oversize numbers. The size independent overall growth rate was first order with respect to supersaturation for crystals larger than 150 μm. Crystals between 20 and 150 μm exhibited a significant size-dependent growth rate. Furthermore, the fraction of crystals smaller than 20 μm, formed by primary nucleation, grew extremely slowly or did not grow at all.

In Vitro Ion Chelating, Antioxidative Mechanism of Extracts from Fruits and Barks of Tetrapleura tetraptera and Their Protective Effects against Fenton Mediated Toxicity of Metal Ions on Liver Homogenates

The aim of the present study was to investigate the antioxidant activity and protective potential of T. tetraptera extracts against ion toxicity. The antioxidant activity of the extracts was investigated spectrophotometrically against several radicals (1,1-diphenyl-2-picrylhydrazyl (DPPH•), 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS•), hydroxyl radical (HO•), and nitric oxide (NO•)), followed by the ferric reducing power, total phenols, flavonoid, and flavonol contents. The effects of the extracts on catalase (CAT), superoxide dismutase (SOD), and peroxidase activities were also determined using the standard methods as well as the polyphenol profile using HPLC. The results showed that the hydroethanolic extract of T. tetraptera (CFH) has the lowest IC50 value with the DPPH, ABTS, OH, and NO radicals. The same extract also exhibited the significantly higher level of total phenols (37.24 ± 2.00 CAE/g dried extract); flavonoids (11.36 ± 1.88 QE/g dried extract); and flavonols contents (3.95 ± 0.39 QE/g dried extract). The HPLC profile of T. tetraptera revealed that eugenol (958.81 ± 00 mg/g DW), quercetin (353.78 ± 00 mg/g DW), and rutin (210.54 ± 00 mg/g DW) were higher in the fruit than the bark extracts. In conclusion, extracts from T. tetraptera may act as a protector against oxidative mediated ion toxicity.

A novel approach for the production of nitrogen doped TiO2 nanoparticles

In this study a visible light active nitrogen doped nanostructure titanium dioxide was synthesized by a simple mixing of Degussa P25 and Urea powder and further thermal treatment under the adequate conditions. Photocatalytic activity of produced nanoparticles was verified by providing of photocatalytic degradation of phenol aqueous solution. Mainly this work was focused on the investigation of the following effects: urea concentration, temperature treatment, catalyst loading and initial phenol concentration. Kinetics study was also carried out. The approach appears to be successful and may be applied for example during the photocatalytic treatment of wastewater streams without or with a limited aid of UV lamps.

Analysis of microalgae growth in residual light: A diagnostics tool for low-cost alternative cultural media

Chapter 1 Most microalgae grow in photoautotrophy and some benefit from mixotrophy and their growth essentially depends on the effective available light intensity. Non transparent media are frequently obtained as the byproduct of bioprocessing but laboratory testing on the suitability of such media may provide misleading results even in laboratory scale photobioreactors. Chapter 2 Cicci et al. (2013) introduced the procedure for calculating a semi-empirical normalised growth rate accounting for a time-varying light limitation inside symmetric photobioreactors and permitting to cancel out the effects of unknown quantities in the photosynthetic response of the microalgal biomass and help diagnose the nutritional suitability of the composite medium. This paper presents the results of applying the semi-empirical normalised growth rate to microalgal growth experiments carried out on media obtained from an anaerobic cattle digestate and from an olive oil mill wastewater (OOMW) and discusses use, inherent opportunities of the proposed diagnostic tool.

Circular extraction: an innovative use of switchable solvents for the biomass biorefinery

The environmental impact of biomass processing can best be minimized by utilizing many components of the biomass and by getting maximum utility out of any solvent used. A Switchable-Hydrophilicity Solvent (SHS) has been used for a complete extraction of hydrophobic and hydrophilic molecules in the solvents opposite-hydrophilicity states, thus simplifying microalgal biomass extraction and increasing the solvent usefulness.

Can sensory analysis and e-noses support the assessment work behind DOC and DOCG wines?

a Department of Land, Environment, Agriculture and Forestry, University of Padua, Padua, Italy. b Department of Agronomy, Food, Natural resources, Animals and Environment, University of Padua, Padua, Italy. c Interdepartmental Centre for Research in Viticulture and Enology, University of Padua, Conegliano, Italy. d Department of Chemical Engineering Materials Environment, Sapienza Università di Roma, Roma, Italy deborah.franceschi@unipd.it