Effect of Major Ions on Induction Time of Struvite Precipitation

Struvite precipitation from wastewaters has gained importance as a means of nitrogen and phosphorus treatment and recovery. While the aspects of process modeling and application have been widely studied, little attention was paid to process kinetics. This study attempted to evaluate the induction time of struvite precipitation for low ammonia concentrations and in the presence of ions commonly found in natural waters. Determination of induction time was based on absorbance measurements while conductivity and pH of the solutions were also monitored during the process. Results of the experimental study indicate that the presence of foreign ions is important in determining the induction time along with the degree of supersaturation. The presence of over 50 x 10–3 mol dm–3 sodium ions retarded induction time significantly. Calcium ions at 2.5 x 10–4 mol dm–3 concentration caused no marked change in the induction time. While carbonate ions had a slight effect, sulfate ions increased the induction time. Crystal morphology was also observed to be affected by supersaturation and the presence of foreign ions

Effect of Major Ions on Induction Time of Struvite Precipitation

Struvite precipitation from wastewaters has gained importance as a means of nitrogen and phosphorus treatment and recovery. While the aspects of process modeling and application have been widely studied, little attention was paid to process kinetics. This study attempted to evaluate the induction time of struvite precipitation for low ammonia concentrations and in the presence of ions commonly found in natural waters. Determination of induction time was based on absorbance measurements while conductivity and pH of the solutions were also monitored during the process. Results of the experimental study indicate that the presence of foreign ions is important in determining the induction time along with the degree of supersaturation. The presence of over 50 x 10–3 mol dm–3 sodium ions retarded induction time significantly. Calcium ions at 2.5 x 10–4 mol dm–3 concentration caused no marked change in the induction time. While carbonate ions had a slight effect, sulfate ions increased the induction time. Crystal morphology was also observed to be affected by supersaturation and the presence of foreign ions

Characterization of disturbed hemodynamics due to stenosed aortic jets with a Lagrangian Coherent structures technique

Isfahan University of Technology. The aortic valve is located at left ventricular outlet and is exposed to the highest pressure in the cardiovascular system. Problems associated with the valve leaflet movement can cause complications for the heart. Specifically, aortic stenosis (AS) arises when aortic leaflets do not efficiently open. In the present study, Lagrangian Coherent Structures (LCSs) were utilized by processing a variety of Computational Fluid Dynamics (CFD) models velocity vector data further to identify the characteristics of AS jets. Particularly, effective orifice areas (EOA) for different cases were accurately identified from unstable manifolds of finite time Lyapunov exponent (FTLE) fields. Calcified leaflets were modeled by setting the leaflet's Young modulus to 10 MPa and 20 MPa for moderately and severely calcified leaflets respectively while a healthy leaflet's Young modulus was assigned to be 2 MPa. Increase in calcification degree of the leaflet caused destruction of the vortex structures near the fibrosa layer of the leaflet indicating a malfunctioning for the movement mechanism of the leaflet. Furthermore, when we analyzed stable manifolds, we identified a blockage region at the flow upstream due to the stagnant blood here. Compared to a healthy case, for the calcified valve, this blockage region was enlarged, implying an increase in AS jet velocity and wall shear stress on leaflets. As a conclusion, results from the present study indicate that aortic leaflet malfunctioning could be accurately evaluated when LCS technique was employed by post processing velocity vector data from CFD. Such precise analysis is not possible using the Eulerian CFD approach or a Doppler echocardiography since these methods are based on only analyzing instantaneous flow quantities and they overlook fluid flow characteristics of highly unsteady flows

Techno-economic and environmental evaluation of producing chemicals and drop-in aviation biofuels via aqueous phase processing

Novel aqueous-phase processing (APP) techniques can thermochemically convert cellulosic biomass into chemicals and liquid fuels. Here, we evaluate these technologies through process design and simulation, and from a techno-economic and environmental point of view. This is the first peer-reviewed study that conducts such an assessment taking into account different biomass pretreatment methods, process yields, product slates, and hydrogen sources, as well as the historical price variation of a number of core commodities involved in the production. This paper undertakes detailed process simulations for seven biorefinery models designed to convert red maple wood using a set of APP technologies into chemicals (e.g. furfural, hydroxymethylfurfural and gamma-valerolactone) and liquid fuels (e.g. naphtha, jet fuel and diesel). The simulation results are used to conduct a well-to-wake (WTW) lifecycle analysis for greenhouse gas (GHG) emissions, and minimum selling price (MSP) calculations based on historical commodity price data from January 2010 to December 2015. An emphasis has been given towards aviation fuels throughout this work, and the results have been reported and discussed extensively for these fuels. It is found that the WTW GHG emissions and the MSP of jet fuel vary across the different refinery configurations from 31.6–104.5 gCO2e per MJ (64% lower and 19% higher, respectively, than a reported petroleum-derived fuel baseline) and $1.00–6.31 per gallon ($0.26–1.67 per liter, which is 61% lower and 146% higher, respectively, than the average conventional jet fuel price of the above time frame). It has been shown that the variation in the estimated emissions and fuel selling prices is primarily driven by the choice of hydrogen source and the relative production volumes of chemicals to fuels, respectively. The latter is a consequence of the fact that the APP chemicals considered here have a higher economic value than the liquid transportation fuels, and that their production is less carbon intensive compared to these fuels. However, the chemical market may get saturated if they are produced in large quantities, and increasing biofuel production over that of chemicals can help the biorefinery benefit under renewable fuel programs

Características principales de pastas minerales de relaves de manganeso preparadas en espesador de escala de laboratorio

Tailings disposal in the form of mineral slurry has a number of advantages, among which we can highlight the environmental, social, operational and technical nature. This alternative arrangement of the tailings is a technology that has been developed rapidly highlighting the sector thickening equipment manufacturers and transportation. The main objective of this work was to evaluate the production of concentrated suspensions minerals known as pasta tailings from beneficiation processes manganese obtained by a paste thickener scale laboratory. The study includes the characterization of the solid sample, evaluation of flocculation (type and dosage), use of a producer of pulp laboratory scale equipment with a useful capacity of 7 liters for the formation of mineral paste through continuous feed of pulp, evaluation of influence on the solids concentration using generator floc (RGF), characteristics of mineral pulps produced as% of depression or slump, angle of repose or flume, solids concentration profile in the thickener, apparent viscosity and yield stress. Regarding the chemical composition it was obtained which are the predominant elements: Mn, Fe, Si and Al with a distribution fine grain size, represented by a d50 equivalent to 4,63μm. The nonionic flocculant was the one who showed best performance while settling in trials with recirculation pulp and flocculant addition, the best condition was reached for a recirculation of the lower zone and maximum layer Compression (4 to 1) obtaining a value of 53.7% solids by weight. In the continuous trials total duration of 180 minutes, the highest value reached% solids with a slurry feed linear flow was 52.7% for 50 gpt dose of flocculant. In feeding trials using curvilinear RGF a value of 55.5% it was obtained solids by weight; It was verified by means of the concentration profile of the compression zone there is a transitional stage pulp high density mineral pulp in the range of 40 to 45% solids by weight. The manganese tailings slurry form mineral between 47 and 56% solids by weight. They were hit angles of repose in the upper mineral pasta to 8th. The rheological behavior of all the tested pastes presented a mixed nature and reotrópico thixotropic. The yield stress reached values close to 100Pa to 56% solids by weight in the mineral pulp produced using the best operating conditions found in this study.La disposición de relaves en forma de pasta mineral presenta una serie de ventajas, entre las cuales se pueden destacar las de índole ambiental, social, operacional y técnica. Esta alternativa de disposición de los relaves es una tecnología que se ha desarrollado rápidamente destacando el sector de fabricantes de equipos de espesamiento y transporte. El principal objetivo de este trabajo fue evaluar la producción de suspensiones concentradas conocidas como pastas minerales de relaves provenientes de procesos de beneficio de manganeso obtenidas mediante un espesador de pasta en escala de laboratorio. El estudio incluye la caracterización de la muestra sólida, evaluación de floculantes (tipo y dosificación), uso de un equipo productor de pasta de escala de laboratorio con una capacidad útil de 7 litros para la formación de pasta mineral a través de alimentación contínua de pulpa, evaluación de influencia sobre la concentración de sólidos con el uso del generador de flóculos (RGF), características de las pastas minerales producidas como % de abatimiento o slump, ángulo de reposo o flume, perfil de concentración de sólidos en el espesador, viscosidad aparente y esfuerzo de fluencia. En relación a la composición química se obtuvo que los elementos predominantes son: Mn, Fe, Si y Al con una distribución granulométríca muy fina, representada por un d50 equivalente a 4,63μm. El floculante no iónico fue el que mostró mejor desempeño en sedimentación mientras que en los ensayos con recirculación de pulpa y adición de floculante, la mejor condición fue alcanzada para una recirculación de la zona más baja y máxima capa de compresión (4 para 1) obteniéndose un valor de 53,7% de sólidos en peso. En los ensayos contínuos con duración total de 180 minutos, el mayor valor del % de sólidos alcanzado con una alimentación de pulpa en flujo lineal fue de 52,7% para una dosis de 50 gpt de floculante. En los ensayos con alimentación curvilínea utilizando el RGF se obtuvo un valor de 55,5% de sólidos en peso; se verificó por medio del perfil de concentración de la zona de compresión que existe una etapa de transición de pulpa de alta densidad a pasta mineral en el rango de 40 a 45% de sólidos en peso. El relave de manganeso forma pasta mineral entre 47 y 56% de sólidos en peso. Fueron alcanzados ángulos de reposo en las pastas minerales superiores a los 8°. El comportamiento reológico de la totalidad de las pastas ensayadas presentó un carácter mixto: tixotrópico y reotrópico. El esfuerzo de cedencia alcanzó valores próximos a los 100Pa para 56% de sólidos en peso en la pasta mineral producida utilizando las mejores condiciones de operación encontradas en este estudio

Asperities and barriers on the seismogenic zone in North Chile: state-of-the-art after the 2007 Mw 7.7 Tocopilla earthquake inferred by GPS and InSAR data

The Mw 7.7 2007 November 14 earthquake had an epicentre located close to the city of Tocopilla, at the southern end of a known seismic gap in North Chile. Through modelling of Global Positioning System (GPS) and radar interferometry (InSAR) data, we show that this event ruptured the deeper part of the seismogenic interface (30–50 km) and did not reach the surface. The earthquake initiated at the hypocentre and was arrested ~150 km south, beneath the Mejillones Peninsula, an area already identified as an important structural barrier between two segments of the Peru–Chile subduction zone. Our preferred models for the Tocopilla main shock show slip concentrated in two main asperities, consistent with previous inversions of seismological data. Slip appears to have propagated towards relatively shallow depths at its southern extremity, under the Mejillones Peninsula. Our analysis of post-seismic deformation suggests that small but still significant post-seismic slip occurred within the first 10 d after the main shock, and that it was mostly concentrated at the southern end of the rupture. The post-seismic deformation occurring in this period represents ~12–19 per cent of the coseismic deformation, of which ~30–55 per cent has been released aseismically. Post-seismic slip appears to concentrate within regions that exhibit low coseismic slip, suggesting that the afterslip distribution during the first month of the post-seismic interval complements the coseismic slip. The 2007 Tocopilla earthquake released only ~2.5 per cent of the moment deficit accumulated on the interface during the past 130 yr and may be regarded as a possible precursor of a larger subduction earthquake rupturing partially or completely the 500-km-long North Chile seismic gap

Analysis and modelling of tsunami-induced tilt for the 2007, M = 7.6, Tocopilla and the 2010, M = 8.8 Maule earthquakes, Chile, from long-base tiltmeter and broadband seismometer records

We present a detailed study of tsunami-induced tilt at in-land sites, to test the interest and feasibility of such analysis for tsunami detection and modelling. We studied tiltmeter and broadband seismometer records of northern Chile, detecting a clear s

High-risk HPV infection after five years in a population-based cohort of Chilean women

<p>Abstract</p> <p>Background</p> <p>The need to review cervical cancer prevention strategies has been triggered by the availability of new prevention tools linked to human papillomavirus (HPV): vaccines and screening tests. To consider these innovations, information on HPV type distribution and natural history is necessary. This is a five-year follow-up study of gynecological high-risk (HR) HPV infection among a Chilean population-based cohort of women.</p> <p>Findings</p> <p>A population-based random sample of 969 women from Santiago, Chile aged 17 years or older was enrolled in 2001 and revisited in 2006. At both visits they answered a survey on demographics and sexual history and provided a cervical sample for HPV DNA detection (GP5+/6+ primer-mediated PCR and Reverse line blot genotyping). Follow-up was completed by 576 (59.4%) women; 45 (4.6%) refused participation; most losses to follow-up were women who were unreachable, no longer eligible or had missing samples. HR-HPV prevalence increased by 43%. Incidence was highest in women < 20 years of age (19.4%) and lowest in women > 70 (0%); it was three times higher among women HR-HPV positive versus HPV negative at baseline (25.5% and 8.3%; OR 3.8, 95% CI 1.8-8.0). Type-specific persistence was 35.3%; it increased with age, from 0% in women < 30 years of age to 100% in women > 70. An enrollment Pap result ASCUS or worse was the only risk factor for being HR-HPV positive at both visits.</p> <p>Conclusions</p> <p>HR-HPV prevalence increased in the study population. All HR-HPV infections in women < 30 years old cleared, supporting the current recommendation of HR-HPV screening for women > 30 years.</p

The 2021 EULAR/American College of Rheumatology Points to Consider for Diagnosis, Management and Monitoring of the Interleukin-1 Mediated Autoinflammatory Diseases: Cryopyrin-Associated Periodic Syndromes, Tumour Necrosis Factor Receptor-Associated Periodic Syndrome, Mevalonate Kinase Deficiency, and Deficiency of the Interleukin-1 Receptor Antagonist

BACKGROUND: The interleukin-1 (IL-1) mediated systemic autoinflammatory diseases, including the cryopyrin- associated periodic syndromes (CAPS), tumour necrosis factor receptor-associated periodic syndrome (TRAPS), mevalonate kinase deficiency (MKD) and deficiency of the IL-1 receptor antagonist (DIRA), belong to a group of rare immunodysregulatory diseases that primarily present in early childhood with variable multiorgan involvement. When untreated, patients with severe clinical phenotypes have a poor prognosis, and diagnosis and management of these patients can be challenging. However, approved treatments targeting the proinflammatory cytokine IL-1 have been life changing and have significantly improved patient outcomes. OBJECTIVE: To establish evidence-based recommendations for diagnosis, treatment and monitoring of patients with IL-1 mediated autoinflammatory diseases to standardise their management. METHODS: A multinational, multidisciplinary task force consisting of physician experts, including rheumatologists, patients or caregivers and allied healthcare professionals, was established. Evidence synthesis, including systematic literature review and expert consensus (Delphi) via surveys, was conducted. Consensus methodology was used to formulate and vote on statements to guide optimal patient care. RESULTS: The task force devised five overarching principles, 14 statements related to diagnosis, 10 on therapy, and nine focused on long-term monitoring that were evidence and/or consensus-based for patients with IL-1 mediated diseases. An outline was developed for disease-specific monitoring of inflammation-induced organ damage progression and reported treatments of CAPS, TRAPS, MKD and DIRA. CONCLUSION: The 2021 EULAR/American College of Rheumatology points to consider represent state-of-the-art knowledge based on published data and expert opinion to guide diagnostic evaluation, treatment and monitoring of patients with CAPS, TRAPS, MKD and DIRA, and to standardise and improve care, quality of life and disease outcomes