Rotating biological contactors : a review on main factors affecting performance

Rotating biological contactors (RBCs) constitute a very unique and superior alternative for biodegradable matter and nitrogen removal on account of their feasibility, simplicity of design and operation, short start-up, low land area requirement, low energy consumption, low operating and maintenance cost and treatment efficiency. The present review of RBCs focus on parameters that affect performance like rotational speed, organic and hydraulic loading rates, retention time, biofilm support media, staging, temperature, influent wastewater characteristics, biofilm characteristics, dissolved oxygen levels, effluent and solids recirculation, stepfeeding and medium submergence. Some RBCs scale-up and design considerations, operational problems and comparison with other wastewater treatment systems are also reported.Fundação para a Ciência e a Tecnologia (FCT

Dynamics of Liver Stiffness Measurement and Clinical Course of Primary Biliary Cholangitis

\ua9 2024 The Author(s)Background & Aims: In primary biliary cholangitis (PBC), static liver stiffness measurement (LSM) has proven prognostic value. However, the added prognostic value of LSM time course in this disease remains uncertain. Methods: We conducted an international retrospective cohort study among patients with PBC treated with ursodeoxycholic acid and followed by vibration-controlled transient elastography between 2003 and 2022. Using joint modeling, the association of LSM trajectory and the incidence of serious clinical events (SCE), defined as cirrhosis complications, liver transplantation, or death, was quantified using the hazard ratio and its confidence interval. Results: A total of 6362 LSMs were performed in 3078 patients (2007 on ursodeoxycholic acid alone; 13% with cirrhosis), in whom 316 SCE occurred over 14,445 person-years (median follow-up, 4.2 years; incidence rate, 21.9 per 1000 person-years). LSM progressed in 59% of patients (mean, 0.39 kPa/year). After adjusting for prognostic factors at baseline, including LSM, any relative change in LSM was associated with a significant variation in SCE risk (P < .001). For example, the adjusted hazard ratios (95% confidence interval) associated with a 20% annual variation in LSM were 2.13 (1.89–2.45) for the increase and 0.40 (0.33–0.46) for the decrease. The association between LSM trajectory and SCE risk persisted regardless of treatment response or duration, when patients with cirrhosis were excluded, and when only death or liver transplantation was considered. Conclusions: Tracking longitudinal changes in LSM using vibration-controlled transient elastography provides valuable insights into PBC prognosis, offering a robust predictive measure for the risk of SCE. LSM could be used as a clinically relevant surrogate end point in PBC clinical trials

CFD modeling of pilot-scale pump-mixer: single-phase head and power characteristics

The present work involves single-phase computational fluid dynamics (CFD) simulations of continuous flow pump-mixer employing top-shrouded Rushton turbines with trapezoidal blades. Baffle—impeller interaction has been modeled using sliding mesh and multiple reference frame approaches. Standard k–ε model has been used for turbulence modeling. Several CFD runs representing different combinations of geometric and process parameters have been carried out. Results of CFD simulations have been used to find out two macroscopic performance parameters of pump-mixer—power consumption and head generated by the impeller. The simulation results have been compared with the experimental data obtained on a pilot-scale setup. Good agreement between CFD predictions and experimental results is observed. In most cases, sliding mesh approach is found to perform better than multiple reference frame approach. Details from CFD simulations have been used to have an insight into the pumping action of the impeller.© Elsevie

Who or what do we care about in the 21st century?

The article explores the importance of Richard Titmuss’s 1970 book, The Gift Relationship. It analyses the substance of the gift relationship, and its steady erosion through the embrace of neoliberalism globally, by seeing how the ‘gift of life’ has become a ‘theft of life’ through the work of Nancy Scheper-Hughes. It sets out the importance of redistribution and recognition to the study of sociology, outlines the lacuna in Honneth and Fraser, and argues that the preciousness of the gift relationship can only be kept alive by scrupulous attention to social structures that nurture this; and by rejecting the death-fetish that is implicitly and explicitly present in scholarship that explores death as resistance (Mbembe). The article calls for an end to the romance with death, and for the work of mourning to be undertaken, without which there can be no going forward into the futures we wish to create