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Desalination provides a quality effluent for either urban or industrial use, but it produces waste that has an environmental impact. Zero-liquid discharge (ZLD) of brine aims to increase the efficiency of the desalination process, obtaining a solid that can be reused while minimizing environmental impacts. This article reviews the research on ZLD in order to measure the interest of the scientific community and evaluate the challenges of ZLD processes. A total of 238 publications were analysed. The temporal evolution of the number of published papers shows the growing interest of the scientific community in this field. Results highlight that in the future, ZLD processes need to improve several aspects, such as improving membranes to increase their performance at lower operational costs. In addition, it is necessary to reduce energy consumption and improve the control of scaling and fouling. The incorporation of more environmentally friendly energy sources could also help reduce energy costs of ZLD processes. Moreover, more suitable ways are needed to collect and separate the solids from the obtained concentrate and make better use of them.

Compressible cake formation in membrane bioreactors, a key fouling mechanism in domestic wastewater reclamation, results from the deformable nature of foulants. This study investigates the combined impact of air scouring, shear stress, and consolidated residual fouling on compressible cake formation. A simple mathematical model is proposed that describes the net stress of attracted material on the membrane with a convective shear transport flux, which is dependent on applied shear stress and consolidated residual fouling. The convective flux is linked to the threshold flux, providing a straightforward relationship between step flux trials and cake formation. Results indicate that residual fouling reduces the effectiveness of membrane aeration and accelerates cake build-up. In addition, the cake’s specific resistance decreases exponentially with the net attractive force of materials during its accumulation, influencing the compressibility coefficient. The proposed model identifies a threshold net material attraction flux, allowing fouling without exceeding an acceptable compressibility level.

The limitation of the membrane bioreactors treating municipal wastewater to manage peak flux conditions have often led to conservative design, which negatively impacts on capital and operating costs. This paper discusses the effectiveness of an alternative operation mode, tested under various peaking conditions and different experimental unit sizes. In this mode, the initiation of the backwashing is regulated by a transmembrane set-point value, which determines the degree of membrane fouling permitted. At low peaking factor, results showed a suitable fouling control, comparable to that obtained with the conventional temporized mode, but with higher process productivity (14–16%). During the long-term tests, this control mode demonstrated its capability to achieve a sustainable operation at high peaking fluxes (Jp= 70 L/h m2) and peak periods of 6 h.

Introduction:Vascular tortuosity is considered one of the main barriers for mechanical thrombectomy in stroke. We developed a fully automatic algorithm for vascular tortuosity characterization and explored the association of several anatomical features with baseline characteristics and procedural outcomes.Methods:An automatic software integrating segmentation, centerline extraction and vessel labelling, was used to extract features directly from computed tomography angiograms (CTA) of stroke patients undergoing transfemoral endovascular treatment. Mean diameter and tortuosity index (TI) of the carotid arteries and brachiocephalic trunk were used as relevant tortuosity indicators. Patients were compared according to seven different clinical conditions and four procedural measures.Results:518 patients (51% female, 74.8±12.9 years) were included in this study. Women presented significantly smaller vessels and increased TI in both carotid arteries (p<.01). Hypertension and atrial fibrillation were associated with higher TI in both carotid arteries (p<.01). Age correlated with TI in all vessels (.35

Digital breast tomosynthesis (DBT) is a promising alternative approach to overcome the limitations of tissue superposition found in full-field 2D digital mammography. However, due to the absence of anti-scatter grids in DBT, accurate scatter estimation for each projection is necessary for modelling the image reconstruction stage. In this work we identify the limitations associated with scatter estimation using spatial invariant scatter kernels, in particular at the edge region where such methods result in scatter overestimation. Such approaches show an overestimation of scatter-to-primary ratio of over 50% at the edges when compared with results from direct Monte Carlo simulation. This problem was found to increase with projection angle. Simulation work presented here shows that this overestimation in scatter is largely due to air gap between the lower curved breast edge and the detector. We propose a new fast, accurate scatter field estimator for use in DBT which not only considers the breast thickness and primary incidence angle, but also accounts for scatter exiting the breast edge region and traversing an air gap prior to absorption in the detector. The new proposed scatter estimator represents an alternative approach to this problem which reduces discrepancies at the edge of a breast phantom. Moreover, the time required for generating scatter has dropped from approximately 12 hours using Monte Carlo simulations for 1010 photons to just a few minutes per projection. The insertion of scatter from the compression paddle to aforementioned methodologies is also discussed.