Geochemical modeling of chromium release in natural waters and treatment by RO/NF membrane processes.

In this work, a geochemical approach was used as strong-scientific tool for pre-selection of suitable remediation systems to treat Cr-contaminated groundwaters. The geochemical characterization allowed to select Nanofiltration (NF) and Reverse Osmosis (RO) as suitable remediation processes, whereas through a new geochemical modeling, the evolution of water chemistry during the water-rock interaction was also studied. The new reaction path modelling was performed re-evaluating the role of Fe as main oxidant in the system and the analytic concentrations of relevant solutes, including Cr(VI), were reproduced. The spring with the highest Cr(VI) content was treated to lower its concentration below the threshold values. A laboratory-scale set-up was used to carry out both NF and RO experiments. The experiments were conducted on different commercial membranes varying the operating pressures. The results showed high Cr(VI) rejections (around 95%) for all tested membranes, leading to Cr(VI) concentrations below the threshold limits. The high flux, obtained already at lower operating pressures, combined with high selectivity towards Cr(VI) makes NF a favorable remediation option.

Pressure-driven and thermally-driven membrane operations for the treatment of arsenic-contaminated waters: A comparison.

The presence of arsenic in water beyond the admitted limits is becoming an important concern for many Countries. Methods usually employed for the arsenic removal from water are based on coagulation followed by filtration, ion-exchange, adsorption. Drawbacks like the use of chemicals and the production of sludges (in case of coagulation) have, however, to be mentioned. Membrane operations, based on the features of membrane materials involved in the separation, do not need chemicals and are easy to scale-up, due to their modularity. In this contribution, the potential of membrane operations for the treatment of arsenic-polluted water is presented and discussed. In particular, two classes of membrane operations are illustrated and compared, the pressure-driven, like Nanofiltration (NF) and Reverse Osmosis (RO) and the thermally-driven ones, like Membrane Distillation (MD).

Enzymatic escharolysis with nexobrid® on partial thickness burn wounds: pre- and post-debridement histological assessment.

Enzymatic escharolysis is an innovative, non-surgical treatment method for severe burn patients as it allows very early, nontraumatic removal of necrotic tissue even on patients whose overall clinical conditions would mandate delaying traditional surgical escharectomy. The aim of this work was to examine aspects related to the "quality" of enzymatic debridement, which is inherently different from surgical debridement. To this end, biopsies harvested from partial thickness burn wounds, before and after enzymatic treatment, were histologically assessed. As is well known, surgical escharectomy removes the necrosis as well as some of its neighbouring healthy tissue, sharply and radically, leaving a perfectly clean and viable wound bed. On the other hand, enzymatic escharolysis is more selective, as it completely wipes out the necrotic portion while sparing unharmed and partially damaged tissue. In this study, only mid-deep partial thickness wounds were examined, and it was observed that partially damaged dermis was always spared by the lytic action. This dermis, however, showed some "homogenization" characteristics, had few vital skin annexes in it, and therefore looked very similar to the scaffold of dermal matrices currently available on the market. This scaffold should be safeguarded with a view to possibly achieving a more complete and functional spontaneous tissue regeneration. Conversely, if this dermal portion is mismanaged, it could desiccate, thus leading to the formation of a neo-eschar with unpredictable clinical evolution. Understanding how escharolysis actually works allowed us to extrapolate fruitful usage suggestions to optimize the procedure and fully exploit its potential.

La détersion enzymatique est une technique innovante non chirurgicale permettant l'ablation très précoce et non traumatique des tissus nécrosés même chez des patients dont l'état général nécessiterait de repousser une excision chirurgicale. Le but de ce travail était d'évaluer la « qualité ¼ du débridement enzymatique, par essence différent du traitement chirurgical. À cette fin, nous avons examiné histologiquement des biopsies réalisées avant et après détersion. Il est bien connu que la chirurgie emporte totalement et radicalement la nécrose et une partie du tissu environnant, laissant en place un tissu parfaitement propre et viable. Le débridement enzymatique est plus sélectif, emportant tout le tissu nécrosé sans affecter les tissus sains ou viables. Cette étude ne s'est intéressée qu'aux brûlures intermédiaires et nous avons observé que les régions saines étaient toujours préservées. Ce derme restant apparaît toutefois homogénéisé, avec peu d'annexes viables ce qui fait penser aux matrices des dermes artificiels actuellement commercialisés. Il doit être préservé afin de promouvoir une régénération tissulaire complète et fonctionnelle. Ainsi, si ce derme restant n'est pas correctement pris en charge, il peut se dessécher et aboutir à la formation d'un nouvel escarre, d'évolution imprévisible. Le compréhension du mécanisme exact de la lyse de la brûlure permet de développer des protocoles d'optimisation de la technique de lyse enzymatique.

Headaches attributed to visual disturbances.

Ocular pain due to ophthalmological diseases is most commonly associated with redness and inflammation of the ocular surface and surrounding tissues. Pain in a quiet eye can be referred as headache and can be the first sign of a number of ocular or orbital conditions. Painful symptoms may be considered non-specific if signs of targeted diseases are not identified. Collection of appropriate history of pain around the eye and associated symptoms or signs should be considered to recognize when ophthalmological examination is needed. Some painful diseases such as intermittent angle closure glaucoma, uveitis or optic neuritis, can lead to severe and permanent visual loss and require a prompt diagnosis and treatment.

Quantitative analysis of optic nerve damage in idiopathic intracranial hypertension (IIH) at diagnosis.

Optic neuropathy secondary to idiopathic intracranial hypertension (IIH) may be a severe complication which must be early identified, adequately monitored and treated to avoid blindness. The aim of this study was to quantify optic nerve involvement at time of diagnosis in a prospectively series of IIH investigated at a single Institution and to identify objective parameters for early diagnosis and follow-up. 38 consecutive patients (9 men, 29 females, mean age 39.8 years) with IIH underwent a complete neuro-ophthalmological evaluation including standardized automated perimetry as functional measurement of optic neuropathy and spectral domain optical coherence tomography (SD-OCT) measurements to grade papilledema or optic nerve atrophy. An overall diagnosis of optic nerve involvement was made in 50 out of 76 eyes (66 %); ophthalmoscopic signs of papilledema were identified in 35 eyes (46 %) while optic disc pallor was found in 13 (17 %). In all patients mean visual field deviation (MD, dB) was -7.2 (range 5.3-33.2). SD-OCT measurements of peripapillary retinal nerve fiber layer thickness (PRNFLT) and of macular ganglion cell complex thickness (MGCCT) obtained in 40 eyes (20 subjects) showed normal PRNFLT in 12 eyes (30 %), increased in 16 (40 %) and reduced in 12 eyes (30 %); normal MGCCT in 26 eyes (65 %), reduced in 14 (35 %). In all eyes average RNFLT was increased (mean 130 µm, range 219-59) and average MGCCT was decreased compared to normal values (mean 89.5 µm, range 198-65). Increased PRNFLT was associated with reduced MGCCT in 4 eyes (10 %) indicating early retrograde optic nerve damage. Decreased PRNFLT was associated with decreased MGCCT in 10 eyes (83 %). These results indicate that, in IIH patients, signs of optic neuropathy can be identified in more than half of cases, even without papilledema evidenced on ophthalmoscopic examination. Moreover, an SD-OCT analysis, which can be definitively useful to quantify optic nerve edema or atrophy, can show damage of retinal ganglion cells in an early phase of the disease.

Recovery and concentration of polyphenols from olive mill wastewaters by integrated membrane system.

The purpose of this work was to analyse the potentialities of an integrated membrane system for the recovery, purification and concentration of polyphenols from olive mill wastewater (OMW). The proposed system included some well-known membrane operations such as microfiltration (MF) and nanofiltration (NF), as well as others not yet investigated for this specific application, such as osmotic distillation (OD) and vacuum membrane distillation (VMD). The OMW was directly submitted to a MF operation without preliminary centrifugation. This step allowed to achieve a 91% and 26% reduction of suspended solids and total organic carbon (TOC), respectively. Moreover, 78% of the initial content of polyphenols was recovered in the permeate stream. The MF permeate was then submitted to a NF treatment. Almost all polyphenols were recovered in the produced permeate solution, while TOC was reduced from 15 g/L to 5.6 g/L. A concentrated solution enriched in polyphenols was obtained by treating the NF permeate by OD. In particular, a solution containing about 0.5 g/L of free low molecular weight polyphenols, with hydroxytyrosol representing 56% of the total, was produced by using a calcium chloride dihydrate solution as brine. The obtained solution is of interest for preparing formulations to be used in food, cosmetic and pharmaceutical industry. Besides the OD process, VMD was applied as another way for concentrating the NF permeate and the performance of both processes was compared in terms of evaporation fluxes.

Treatment of dye solutions by vacuum membrane distillation.

In this work, the vacuum membrane distillation (VMD) process has been applied to treat water containing different types of dyes. The influence of operating parameters, as feed temperature, feed flow rate, feed concentration, on the permeate flux and on rejection has been investigated. In all experimental tests, a complete rejection has been achieved and pure water has been recovered at the permeate side. Furthermore, experiments with water as feed have been carried out before and after the tests with dyes, in order to analyze the effect of fouling on the performance of the VMD. The water vapor fluxes immediately after the tests with dyes were higher than the values registered before the tests, probably due to an interaction with the polymeric membrane material which promotes a swelling of the membrane when in contact with the dye solutions. However, initial fluxes are recovered after prolonged cleaning with only water.

Membrane distillation of human plasma ultrafiltrate and its theoretical applications to haemodialysis techniques.

Membrane Distillation (MD) is a technique that allows the extraction of water from aqueous solutions. The basic principle is that vapour, but not liquid water, can pass through hydrophobic micro-porous membranes, along a temperature gradient, with consequent separation of water from solutes. In this study we evaluated the possibility to utilise MD to extract water from Plasma Ultrafiltrate (PU) of patients with Chronic Renal Failure (CRF). The experiments were carried out in vitro by a hydro-phobic polypropylene hollow-fibre distillation module; PU was obtained by a CRF patient utilising a high permeability polisulphone membrane. The results show that water can be extracted by MD from PU of CRF subjects at a constant rate and that none of the substances analysed in PU was able to pass through the polypropilene membrane. In the future MD could integrate extra-corporeal blood purification techniques allowing the re-utilisation of plasmatic water thus ameliorating the treatment of uraemia.