An Approach to the Simulation of a Batch-respirometer

Dynamic models in activated sludge processes have demonstrated to be a reliable and useful instrument in design and management of wastewater treatment plants. The biochemical nature of the processes involved the models which need a specific calibration to local conditions. A common method to determine kinetic and stoichiometric parameters of the biomass or wastewater/sludge fractionations is respirometry. Theoretically, nearly all biomass parameters and fractions can be estimated by respirometry, but a lot of difficulties rise when some parameters, such as saturation and hydrolysis rate constants, have to be drawn from experimental data. The aim of our work is the setting up of a simple method to calibrate Activated Sludge Model No. 1 applying traditional batch respirometric tests together with dynamic simulations of the respirometer itself

Treatment of Landfill Leachate by H2O2 Promoted Wet Air Oxidation: COD-AOX Reduction, Biodegradability Enhancement and Comparison with a Fenton-type Oxidation

Treatment experiments of a landfill leachate were performed by wet air oxidation (WAO) with the addition of H2O2 (as free radical promoter), and a Fenton-type (at pH ≈ 7) process, in order to compare COD (chemical oxygen demand) and AOX (adsorbable organic halogen) reduction as well as biodegradability enhancement measured by OUR respirometric parameter. The WAO reactions were performed in a batch reactor at various temperatures in the range of T = 430-500 K employing a concentration of c = 0.88 mol L–1 of H2O2. The same H2O2 concentration was used in the Fenton-type-pH ≈ 7 experimental session considering H2O2/Fe(II) mole ratios of 5, 10 and 15. Similar results were obtained in COD abatement but appreciably different performance in AOX removal and biodegradability enhancement was observed. A comparison between the treatment trials brought to the evidence that Fenton-Type-pH ≈ 7 process has poor performance in biodegradability enhancement, diversely the H2O2 promoted WAO get to better performances even at mild temperature. This process could be considered as advantageous solution in landfill leachate pre-treatment when the main objectives are COD and AOX degradation together with the biodegradability enhancement for final treatment in common biological aerobic wastewater treatment plants

Super-heavy fermion material as metallic refrigerant for adiabatic demagnetization cooling

Low-temperature refrigeration is of crucial importance in fundamental research of condensed matter physics, as the investigations of fascinating quantum phenomena, such as superconductivity, superfluidity and quantum criticality, often require refrigeration down to very low temperatures. Currently, cryogenic refrigerators with $^3$He gas are widely used for cooling below 1 Kelvin. However, usage of the gas is being increasingly difficult due to the current world-wide shortage. Therefore, it is important to consider alternative methods of refrigeration. Here, we show that a new type of refrigerant, super-heavy electron metal, YbCo$_2$Zn$_{20}$, can be used for adiabatic demagnetization refrigeration, which does not require 3He gas. A number of advantages includes much better metallic thermal conductivity compared to the conventional insulating refrigerants. We also demonstrate that the cooling performance is optimized in Yb$_{1-x}$Sc$_x$Co$_2$Zn$_{20}$ by partial Sc substitution with $x\sim$0.19. The substitution induces chemical pressure which drives the materials close to a zero-field quantum critical point. This leads to an additional enhancement of the magnetocaloric effect in low fields and low temperatures enabling final temperatures well below 100 mK. Such performance has up to now been restricted to insulators. Since nearly a century the same principle of using local magnetic moments has been applied for adiabatic demagnetization cooling. This study opens new possibilities of using itinerant magnetic moments for the cryogen-free refrigeration

2D versus 3D human induced pluripotent stem cell-derived cultures for neurodegenerative disease modelling

Neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD) and amyotrophic lateral sclerosis (ALS), affect millions of people every year and so far, there are no therapeutic cures available. Even though animal and histological models have been of great aid in understanding disease mechanisms and identifying possible therapeutic strategies, in order to find disease-modifying solutions there is still a critical need for systems that can provide more predictive and physiologically relevant results. One possible avenue is the development of patient-derived models, e.g. by reprogramming patient somatic cells into human induced pluripotent stem cells (hiPSCs), which can then be differentiated into any cell type for modelling. These systems contain key genetic information from the donors, and therefore have enormous potential as tools in the investigation of pathological mechanisms underlying disease phenotype, and progression, as well as in drug testing platforms. hiPSCs have been widely cultured in 2D systems, but in order to mimic human brain complexity, 3D models have been proposed as a more advanced alternative. This review will focus on the use of patient-derived hiPSCs to model AD, PD, HD and ALS. In brief, we will cover the available stem cells, types of 2D and 3D culture systems, existing models for neurodegenerative diseases, obstacles to model these diseases in vitro, and current perspectives in the field

Nuovi approcci metodologici per dimensionare gli impianti di depurazione

Rassegna Tecnica del FV