Microbial-induced MnO2 precipitation in a carbonate coastal aquifer.

A study was carried out to identify biogeochemical reactions along a transect of a coastal dolomitic aquifer. In this transect, the physicochemical parameters of the groundwater as well as the microbial composition of samples taken at different depths and salinities were measured. Many of the dissolved ions measured in the groundwater follow a pattern that reflects the distribution of the water masses (fresh, interface and salt) in the aquifer, while others such as Ca and Mg ions deviate from this trend by identifying the zones of maximum dissolution of the carbonate matrix. The concentrations of minor ions, such as Fe and Mn, also follow a singular pattern, with maximum concentrations in the reducing zones of the aquifer and lower values in the oxidizing zones. Precipitates of Mn oxides along with other metals, such as Fe, Ba, Zn and Ni, were observed in the saline zone displaying oxidizing conditions close to the coastline, where a continuous core was recovered. This zone, which is located below the freshwater-seawater mixing zone and features percentages of seawater higher than 80 %, is characterized by the presence of Marinobacter as the predominant genus. These bacteria are also related to the formation of Mn-rich polymetallic oxides in other contexts such as the ocean floor (Wang et al., 2012; Cao et al., 2021). All in all, a biogeochemical reaction model is proposed that describes the formation of these oxides in areas close to the discharge zone of coastal aquifers. To do this, it has been necessary to integrate the results obtained from geochemical, hydrogeological and microbiological information.

Sedation with propofol/remifentanil versus dexmedetomidine / remifentanil for patients undergoing transcatheter aortic valve implant: A retrospective study between 2012 and 2019.

BACKGROUND AND OBJECTIVES: Percutaneous implantation of an aortic valve prosthesis is a therapeutic alternative for patients with severe aortic stenosis. The procedure is traditionally performed under general anaesthesia; however, sedation is now gaining in popularity because it reduces the need for vasoactive drugs and shortens the patient's stay in the critical care unit and on the ward. The aim of this study is to evaluate the clinical efficacy, safety and potential benefits of sedation with dexmedetomidine in patients undergoing percutaneous implantation of an aortic valve prosthesis in terms of haemodynamic and respiratory complications. MATERIALS AND METHODS: We performed a retrospective study of 222 patients that had undergone percutaneous implantation of an aortic valve prosthesis between 2012 and 2019 under sedation with either dexmedetomidine plus remifentanil (DEX-RMF) or propofol plus remifentanil (PROPO-RMF). We collected data on complications, mainly haemodynamic and respiratory, during and after the procedure. RESULTS: No significant differences were found between sedation with dexmedetomidine and propofol (in combination with remifentanil) in terms of haemodynamic stability and intraprocedural cerebral blood oxygen. In the DEX-RMF group, however, mean blood pressure, midazolam dose, and duration of anaesthesia were lower compared with the PROPO-RMF group, but the incidence of haemodynamic and respiratory complications did not differ significantly between groups. CONCLUSIONS: Our results show that sedation, particularly with adjuvant dexmedetomidine, is a valid anaesthetic techniques in percutaneous aortic valve prosthesis implantation.

Incidental detection of raised serum levels of vitamin B12 and its association with neoplasms.

BACKGROUND AND OBJECTIVES: Elevated serum levels of vitamin B12 have been associated with oncohematological diseases. However, the relevance of its incidental detection in subjects without a previous diagnosis of cancer is unknown. The aim of this study was to evaluate the relationship between incidental hypercobalaminemia (vitamin B12 > 1000 pg/mL) and the diagnosis of a tumor process in patients without a diagnosis and to establish the risk factors. MATERIAL AND METHODS: Retrospective observational study of a cohort of patients with hypercobalaminemia. The incidence of neoplasms was compared with a cohort of patients with vitamin B12 levels <1000 pg/mL. RESULTS: Vitamin B12 determinations of 4800 subjects were selected. Of them, 345 (7.1%) had levels >1000 pg/mL. 68 (28.4%) were excluded due to exogenous administration, 12 (5%) due to insufficient data and 15 (3%) due to having an active neoplasia, selecting 250 patients, with a median follow-up of 22 (IQR 12-39) months. Structural liver disease was detected in 59 (23.6%). 18.2% (44 patients) had solid organ cancer and 17 (7.1%) had malignant hemopathy. The average time from the detection of hypercobalaminemia to the diagnosis of cancer was about 10 months. The median until the diagnosis of neoplasia was higher in the high vitamin B12 group (13 vs. 51 months p < 0.001). Hypercobalaminemia (HR 11.8; 95% CI 2.8-49.6; p = 0.001) and smoking (HR 4.0; 95% CI, 2.15-7.59; p < 0.001) were independent predictors of neoplasia in the multivariate analysis. CONCLUSIONS: Incidental detection of serum vitamin B12 levels >1000 pg/mL is high in the population. The diagnosis of solid organ and hematological neoplasia is frequent during the following year of follow-up, with hypercobalaminemia and smoking being predictors of a higher risk of cancer.

Assessment of the marine microalga Chrysochromulina rotalis as bioactive feedstock cultured in an easy-to-deploy light-emitting-diode-based tubular photobioreactor.

Marine microalgae have potential to be low-cost raw materials. This depends on the exploitation of different biomass fractions for high-value products, including unique compounds. Chrysochromulina rotalis, an under-explored haptophyte with promising properties, was the focus of this study. For the first time, C. rotalis was successfully cultivated in an 80 L tubular photobioreactor, illuminated by an easy-to-use light-emitting-diode-based system. C. rotalis grew without certain trace elements and showed adaptability to different phosphorus sources, allowing a significant reduction in the N:P ratio without compromising biomass yield and productivity. The design features of the photobioreactor provided a protective environment that ensured consistent biomass production from this shear-sensitive microalgae. Carotenoid analysis showed fucoxanthin and its derivatives as major components, with essential fatty acids making up a significant proportion of the total. The study emphasizes the tubular photobioreactor's role in sustainable biomass production for biorefineries, with C. rotalis as a valuable bioactive feedstock.

A step forward in sustainable pesticide production from Amphidinium carterae biomass via photobioreactor cultivation with urea as a nitrogen source.

This study addresses the problem of replacing nitrate and ammonium with urea as a greener nitrogen source in the mass cultivation of the microalga Amphidinium carterae for the development of amphidinol-based phytosanitary products. To solve this problem, a nuclear magnetic resonance assisted investigation evaluated the effect of nitrogen sources on growth and metabolic profiles in photobioreactors. Urea-fed cultures exhibited growth kinetics comparable to nitrate-fed cultures (µmax = 0.30 day-1, Pbmax = 43 mgL-1day-1). Urea-fed cultures had protein, lipid, and carbohydrate contents of 39.5%, 14.5%, and 42.4%, respectively, while nitrate-fed cultures had 27.9 %, 17.5% and 48.1%, respectively. Metabolomics revealed nitrogen source-dependent metabotypes and a correlation between amphidinols and polyunsaturated fatty acids. The amphidinol-to-nitrogen yield coefficient in urea-fed cultures (135 mg/g) was approximately 2.5 times higher than in nitrate-fed cultures. The potent antiphytopathogenic activity exhibited by extracts from urea-fed cultures underscores the potential of urea as a sustainable nitrogen source in microalgae-based biorefineries.

[Family planning in men and women with multiple sclerosis. Analysis of the Andalusian Registry (2018-2022)]. / Planificación familiar en hombres y mujeres con esclerosis múltiple. Análisis del Registro Andaluz (2018-2022).

INTRODUCTION: The Andalusian Registry of Pregnancies in patients with multiple sclerosis is the largest Spanish registry on multiple sclerosis (MS) and family planning. For the first time, it includes information on the fertility of men with MS. The influence of the use of a disease-modifying treatment (DMT) on the health of the foetus/newborn and the impact of breastfeeding on MS are also analysed. SUBJECTS AND METHODS: This is a multicentre, prospective and observational study. Recruitment of patients took place between December 2018 and December 2020. Women were followed up for one year after delivery. Altogether 100 women and 16 men were included, with a total of 103 newborn infants. RESULTS: The annualised relapse rate of the women with MS decreased significantly during pregnancy (from 0.23 to 0.065). A total of 11.2% of patients resorted to assisted reproductive techniques in order to conceive a child. No association was found between the use of a DMT at conception and/or pregnancy and the risk of miscarriage, prematurity or low birth weight. Over half the women with MS (54.2%) chose to breastfeed (26.7% of them while on a DMT). CONCLUSIONS: MS does not affect the fertility of men. Neither does the use of a DMT at the time of conception affect their fertility or their children's health. Assisted reproductive techniques did not have a negative impact on the course of MS. Breastfeeding is a common practice among women with MS and there is no evidence of positive or negative effects on disease progression.

TITLE: Planificación familiar en hombres y mujeres con esclerosis múltiple. Análisis del Registro Andaluz (2018-2022).Introducción. El Registro Andaluz de Embarazos en pacientes con esclerosis múltiple (EM) es el mayor registro español sobre EM y planificación familiar. Por primera vez se incluye información sobre la fertilidad de hombres con EM. También se analizan la influencia del uso de un tratamiento modificador de la enfermedad (TME) en la salud del feto o recién nacido y el impacto de la lactancia materna en la EM. Sujetos y métodos. Es un estudio observacional, prospectivo y multicéntrico. El reclutamiento de pacientes se hizo entre diciembre de 2018 y diciembre de 2020. El seguimiento de las mujeres tras el parto fue de un año. Se incluyó a 100 mujeres y 16 hombres, con un total de 103 recién nacidos. Resultados. La tasa anualizada de brotes de las mujeres con EM descendió durante el embarazo de forma significativa (de 0,23 a 0,065). Un 11,2% de los pacientes recurrieron a técnicas de reproducción asistida para conseguir la gestación. No se encontró relación entre el uso de un TME en la concepción y/o embarazo y el riesgo de aborto, prematuridad o bajo peso al nacer. El 54,2% de las mujeres con EM optaron por dar lactancia (el 26,7% de ellas usando un TME). Conclusiones. La EM no afecta a la fertilidad de los hombres. Tampoco influye en ésta, ni en la salud de sus hijos, el uso de un TME en el momento de la concepción. Las técnicas de reproducción asistida no impactaron negativamente en la evolución de la EM. La lactancia se impone como una práctica habitual entre las mujeres con EM y no se evidencian efectos positivos o negativos sobre la evolución de la enfermedad.

Life-cycle assessment of a microalgae-based fungicide under a biorefinery approach.

The aim of this work was to perform a life-cycle analysis of the production process of a fungicide based on amphidinols. Two scenarios were evaluated: (1) biorefinery process -biofungicide, fatty acids and carotenoids were considered as co-products-, and (2) biofungicide as only product. Inventory data were taken and scaled-up from previous work on pilot-scale reactors, as well as lab-scale downstream equipment. A yearly production of 22,000 L of fungicide, was selected as the production objective. Despite, photosynthetic biomass is a sink of anthropogenic CO2, harvesting and downstream processing have large carbon footprints that exceed the biomass fixed carbon. Producing the biofungicide resulted in 34.61 and 271.33 ton of CO2e (15 years) for the Scenarios 1 and 2, respectively. Different commercial agricultural fungicides were compared with the microalgal fungicide. A lower impact of the microalgal product for most of the indicators, including carbon footprint, was shown.

Alternatives to classic solvents for the isolation of bioactive compounds from Chrysochromulina rotalis.

This paper demonstrates a sequential partitioning method for isolating bioactive compounds from Chrysochromulina rotalis using a polarity gradient, replacing classic and hazardous solvents with greener alternatives. Seventeen solvents were evaluated based on their Hansen solubility parameters and for having a similar polarity to the solvents they would replace, four of which were selected as substitutes in the classic fractionation process. Considering the fatty acid and carotenoid recovery yields obtained for each of the solvents, it has been proposed to replace hexane (HEX), toluene (TOL), dichloromethane (DCM) and n-butanol (BUT) with cyclohexane, chlorobenzene, isobutyl acetate and isoamyl alcohol, respectively. In addition, cytotoxic activity was observed when the TOL and DCM solvent extracts were tested against tumour cell lines, demonstrating the antiproliferative potential of compounds containing, for example, fucoxanthin, fatty acids, peptides, isoflavonoids or terpenes, among others.

Fibrous hamartoma of infancy. Radiologic-pathologic study of 21 cases: 8 with predominant pseudoangiomatous pattern.

Fibrous hamartoma of infancy (FHI) is a very rare benign soft tissue lesion that principally affects the axilla, trunk, and upper extremities of children younger than 2 years. It is usually cured by local excision. Histologically, these lesions have a triphasic morphology in an organoid pattern: mature adipose tissue, fibroblastic/myofibroblastic trabeculae, and small round cell nests in a myxoid matrix. However, morphologic variants have recently been described. Focal areas with a pseudoangiomatous pattern have been found in some FHI, but few cases with predominant pseudoangiomatous areas have been previously described in the medical literature. We report 21 new cases of FHI, 8 of them with a predominant pseudoangiomatous pattern. Our cases with a predominant pseudoangiomatous pattern did not present specific radiological findings.

Calcifying aponeurotic fibroma: Radiologic-pathologic analysis of ten cases and review of the literature.

Calcifying aponeurotic fibroma (CAF) is a very rare benign entity that principally affects the volar fascia, tendons, and aponeuroses of the hands and feet with a peak incidence of between 5 and 15 years, although there have been cases found for a wide age range and at various anatomical sites. We present ten CAF cases; consisting of eight children and two adults. CAF occurred in the extremities in nine of the cases and in the chest wall in one case. CAF ultrasound and radiological findings are nonspecific but may help orientate diagnosis. Magnetic resonance imaging should be performed when there are doubtful cases, when occurring in nontypical sites, and when there are cases of nontypical clinical presentation. Histologically, all cases showed two components, a fibromatosis-like component and a nodular component. Chondroid areas were present in five cases. Calcifications were observed in nine cases. ERG immunostaining showed the same patterns in all the cases; diffuse positivity in pericalcified areas, and patchy positivity in areas away from calcifications. CAF has distinctive histopathological features which should aid in the differential diagnoses with other entities.

Successive extraction using natural deep eutectic solvents and pressurized liquids for a greener and holistic recovery of proteins from pomegranate seeds.

This work describes a novel and sustainable strategy for the recovery of proteins by successive extractions using natural deep eutectic solvents (NADES) and pressurized liquid extraction (PLE). This strategy was applied to the valorisation of pomegranate seeds. Nine different NADES were screened and that constituted by choline chloride and acetic acid was chosen due to its best performance. A Response Surface Methodology was employed to optimize other conditions in this extraction step: time, temperature, amount of sample, and HIFU amplitude. Protein recovery, under optimal conditions, was 13.3 g of proteins/100 g of milled and dried defatted seeds. Proteins were next characterized by their separation using RP-HPLC, SDS-PAGE, isoelectrofocusing electrophoresis, and by the evaluation of their digestibility and antioxidant properties. Comparison of these results with those from extracts obtained by other techniques supported the interest of combining the extraction using acid NADES with PLE, under alkaline conditions. The successive extraction by both methodologies enabled to double the total recovery of proteins. The analysis of samples by UHPLC-MS/MS, after a simulated gastrointestinal digestion, and de novo identification revealed the presence of 19 peptides in the NADES hydrolysate, while the successive extraction by PLE enabled to observe 15 additional peptides. Additional 83 peptides were found by database searching against Punica granatum and by homology with other organisms. Differences between peptides and the proteins in both hydrolysates confirmed the different protein selectivity of both strategies and the potential of NADES for extracting larger proteins and PLE for the extraction of smaller ones. Some phenolic compounds, amino acids, and fatty acids were also co-extracted with proteins in both extractions.

Acute pulmonary embolism: Appropriateness of emergency department management according to clinical guidelines.

BACKGROUND AND AIMS: To evaluate the frequency of acute pulmonary embolism, the use of clinical probability scores, and the appropriateness of the management of patients for whom computed tomography angiography (CTA) was requested from the emergency department for suspected acute pulmonary embolism. MATERIALS AND METHODS: This was a retrospective observational study of CTA studies requested from the emergency department to rule out acute pulmonary embolism. We analyzed clinical variables and the explicit use of clinical probability scores. We determined the appropriateness of management according to the Wells Score and Geneva Score and the simplified versions of these two scores, calculated retrospectively. RESULTS: We included 534 patients (52.8% women; mean age, 73 years). The frequency of acute pulmonary embolism was 23.0% and the Wells Score was explicitly used in 15.2%. The appropriateness of the management varied depending on the clinical probability score used to assess it (54.5%-75.8%) and on whether the standard d-dimer or age-adjusted d-dimer was used. CONCLUSIONS: The failure to use the Wells Scores in all cases does not necessarily imply inappropriate management, and the performance of global clinical judgment can be similar to that of clinical probability scores; however, specific studies are necessary to confirm this hypothesis.

Nosocomial outbreak of COVID-19 in an internal medicine ward: Probable airborne transmission.

BACKGROUND AND OBJECTIVES: Despite the increasing evidence supporting the importance of airborne transmission in SARS-CoV-2 infection, it has not been considered relevant in the vast majority of reported nosocomial outbreaks of COVID-19. The aim of this study is to describe a nosocomial outbreak of SARS-CoV-2 infection whose features suggest that aerosol transmission had an important role. METHODS: This is a descriptive analysis of a nosocomial outbreak of SARS-CoV-2 infection in an internal medicine ward that occurred in December 2020. All cases were confirmed by a positive PCR test for SARS-CoV-2. RESULTS: From December 5 to December 17, 21 patients and 44 healthcare workers (HCWs) developed a nosocomial SARS-CoV-2 infection. Fifty-one of the 65 cases (78.5%) were diagnosed between December 6 and 9. The attack rate in patients was 80.8%. Among HCWs, the attack rate was higher in those who had worked at least one full working day in the ward (56.3%) than in those who had occasionally been in the ward (25.8%; p = 0.005). Three days before the first positive case was detected, two extractor fans were found to be defective, affecting the ventilation of three rooms. Sixteen cases were asymptomatic, 48 cases had non-severe symptoms, and 2 cases required admission to the intensive care unit. All patients eventually recovered. CONCLUSION: The high attack rate, the explosive nature of the outbreak, and the coincidence in time with the breakdown in air extractors in some rooms of the ward suggest that airborne transmission played a key role in the development of the outbreak.

Treatment of secondary urban wastewater with a low ammonium-tolerant marine microalga using zeolite-based adsorption.

The low tolerance of marine microalgae to ammonium and hyposalinity limits their use in urban wastewater (UWW) treatments. In this study, using the marine microalga Amphidinium carterae, it is demonstrated for the first time that this obstacle can be overcome by introducing a zeolite-based adsorption step to obtain a tolerable UWW stream. The maximum ammonium adsorption capacities measured in the natural zeolite used are among the highest reported. The microalga grows satisfactorily in mixtures of zeolite-treated UWW and seawater at a wide range of proportions, both with and without adjusting the salinity, as long as the ammonium concentration is below the threshold tolerated by the microalgae (6.3 mg L-1). A proof of concept performed in 10-L bubble column photobioreactors with different culture strategies, including medium recycling, showed an enhanced biomass yield relative to a control with no UWW. No noticeable effect was observed on the production of specialty metabolites.

Influence of nanoemulsion/gum ratio on droplet size distribution, rheology and physical stability of nanoemulgels containing inulin and omega-3 fatty acids.

BACKGROUND: New consumer habits are forcing the food industry to develop new and healthy products. In response to this tendency, in this investigation, we obtained nanoemulgels by microfluidization containing inulin fibre and omega-3 fatty acids. First, the influence of the number of microfluidization cycles on the physical properties of the nanoemulsions was studied. Subsequently, an advanced-performance xanthan gum was added to the nanoemulsion in different nanoemulsion/xanthan ratios (1:1, 2:1, 3:1, 4:1, 1:2, and 1:3). RESULTS: Laser diffraction, multiple light scattering, and rheology techniques were used to characterize nanoemulsions and the corresponding nanoemulgels. The nanoemulsion with the lowest Sauter mean diameter (138 nm) and the longest physical stability was obtained after three passes through a microfluidization device at a fixed pressure of 103 421 kPa. Thus, these processing conditions were always used to obtain the nanoemulsion; these were subsequently mixed with a xanthan gum solution to produce nanoemulgels that showed weak gel-like viscoelastic and shear-thinning flow behaviours. A decrease in the nanoemulsion/xanthan ratio (i.e. by an increase in the content of xanthan gum in the nanoemulgel) increased the viscoelastic moduli and the zero shear viscosity values. A rise in the droplet size was observed with aging time, probably due to flocculation. The nanoemulsion/xanthan gum mass ratio of 1:3 yielded the most stable nanoemulgel. CONCLUSIONS: This work is a contribution to the development of functional foods. It has been demonstrated that it is possible to obtain a stable nanoemulgel-based food matrix containing fibre and omega-3 fatty acids. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

[Nosocomial outbreak of COVID-19 in an internal medicine ward: Probable airborne transmission]. / Brote nosocomial de COVID-19 en una planta de medicina interna: probable transmisión aérea.

Background and objectives: Despite the increasing evidence supporting the importance of airborne transmission in SARS-CoV-2 infection, it has not been considered relevant in the vast majority of reported nosocomial outbreaks of COVID-19. The aim of this study is to describe a nosocomial outbreak of SARS-CoV-2 infection whose features suggest that aerosol transmission had an important role. Methods: This is a descriptive analysis of a nosocomial outbreak of SARS-CoV-2 infection in an internal medicine ward that occurred in December 2020. All cases were confirmed by a positive PCR test for SARS-CoV-2. Results: From December 5 to December 17, 21 patients and 44 healthcare workers developed a nosocomial SARS-CoV-2 infection. Fifty-one of the 65 cases (78.5%) were diagnosed between December 6 and 9. The attack rate in patients was 80.8%. Among workers, the attack rate was higher in those who had worked at least one full working day in the ward (56.3%) than in those who had occasionally been in the ward (25.8%, p = 0.005). Three days before the first positive case was detected, 2 extractor fans were found to be defective, affecting the ventilation of 3 rooms. Sixteen cases were asymptomatic, 48 cases had non-severe symptoms, and 2 cases required admission to the intensive care unit. All patients eventually recovered. Conclusion: The high attack rate, the explosive nature of the outbreak, and the coincidence in time with the breakdown in air extractors in some rooms of the ward suggest that airborne transmission played a key role in the development of the outbreak.

Association between antibiotic pressure and the risk of colonization/infection by multidrug-resistant Acinetobacter baumannii complex: a time series analysis.

OBJECTIVE: To analyze the association between antibiotic pressure and the risk of colonization/infection by Acinetobacter baumannii complex (AB), evaluating both the individual and general prescriptions of antibiotics. METHODS: This is an analytical, observational, case-control study on patients admitted to an Intensive Care Unit (ICU) during an AB outbreak (14 months). A five-year time series was constructed with the monthly incidence of cases of infection/colonization with strains of AB resistant to each antibiotic administered and with the monthly consumption of these antibiotics in the ICU. RESULTS: We identified 40 patients either infected (23) or colonized (17) by AB and 73 controls. We found an epidemic multidrug-resistant clone of AB in 75% of cases. Risk factors associated with the development of AB infection/colonization were: greater use of medical instruments, the presence of a tracheostomy, cutaneous ulcers, surgical lesions and prior antibiotic therapies. The regression analysis of individual use of antibiotics showed that prior treatment with ceftazidime, ceftriaxone, amoxicillin/clavulanate, imipenem, levofloxacin, linezolid, and vancomycin was a risk factor for acquiring AB. ARIMA models showed that the relationship were greatest and statistically significant when the treatment occurred between 6 months (ceftazidime) and 9 months (imipenem and levofloxacin) prior. CONCLUSIONS: The dynamic and aggregate relationship between the incidence of infection/colonization by multidrug-resistant strains of AB and prior antibiotic treatment was statistically significant for intervals of 6 to 9 months.

An integrated approach for the efficient separation of specialty compounds from biomass of the marine microalgae Amphidinium carterae.

An amphidinol-prioritized fractioning approach was for the first time developed to isolate multiple specialty metabolites such as amphidinols, carotenoids and fatty acids using the biomass of the marine microalgae Amphidinium carterae. The biomass was produced in a raceway photobioreactor and the exhausted culture media were reused, thus fulfilling sustainability criteria employing a circular economy concept. The integrated bioactive compounds-targeted approach presented here consisted of four steps with which recovery percentages of carotenoids, fatty acids and amphidinols of 97%, 82% and 99 %, respectively, were achieved. The proposed process was proved to be a better extraction system for this microalga than another based on a sequential gradient partition with water and four water-immiscible organic solvents (hexane, carbon tetrachloride, dichloromethane and n-butanol). The proposed process could be scaled-up as a commercial solid-phase extraction technology well-established for industrial bioprocesses.

CFD-based prediction of initial microalgal adhesion to solid surfaces using force balances.

Adhesion of microalgal cells to photobioreactor walls reduces productivity resulting in significant economic losses. The physico-chemical surface properties and the fluid dynamics present in the photobioreactor during cultivation are relevant. However, to date, no multiphysical model has been able to predict biofouling formation in these systems. In this work, to model the microalgal adhesion, a Computational Fluid Dynamic simulation was performed using a Eulerian-Lagrangian particle-tracking model. The adhesion criterion was based on the balance of forces and moments included in the XDLVO model. A cell suspension of the marine microalga Nannochloropsis gaditana was fed into a commercial flow cell composed of poly-methyl-methacrylate coupons for validation. Overall, the simulated adhesion criterion qualitatively predicted the initial distribution of adhered cells on the coupons. In conclusion, the combined Computational Fluid Dynamics-Discrete Phase Model (CFD-DPM) approach can be used to overcome the challenge of predicting microalgal cell adhesion in photobioreactors.