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177 result(s) for "Monroy, Oscar"
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Do Ballast Water Management Systems Reduce Phytoplankton Introductions to Canadian Waters?
Global coastal aquatic ecosystems are negatively impacted by the introduction of harmful aquatic species through the discharge of ships’ ballast water. To reduce discharges of harmful aquatic organisms and pathogens, such as toxic phytoplankton species, ships are now transitioning to the use of ballast water management systems (BWMS) instead of ballast water exchange (BWE). This study examines the abundance and diversity of phytoplankton in ballast water managed by BWMS (or a combination of both BWE + BWMS) in comparison to those in ballast water managed by BWE alone (collected from ships arriving to Canada’s Pacific coast in 2017–2018 and 2008, respectively). The abundance and diversity of phytoplankton species were also examined in relation to key variables such as ballast water salinity and ballast water age. Total abundance of phytoplankton was significantly lower in preserved samples managed by either a BWMS or BWE + BWMS compared to BWE alone. Abundances in preserved samples were higher than observed in fresh (unpreserved) samples at the time of collection, with all samples managed by a BWMS meeting international limits for the number of viable organisms ≥10 and <50 μm in minimum dimension (based on six 1-mL live counts). While there was no apparent influence of factors such as treatment type [e.g., ultraviolet (UV) or chlorine], presence of filtration, ballast water salinity, ballast water age, nor location of last ballast water uptake on phytoplankton abundances in preserved samples, power to detect differences may be limited by sample size. Ballast water managed by BWMS also tended to have lower abundances of harmful phytoplankton species, although the difference was not statistically significant – additional research into the community composition of live cells in fresh samples could be valuable to discriminate the risk associated with phytoplankton surviving ballast water treatment.
Membrane Water Treatment for Drinking Water Production from an Industrial Effluent Used in the Manufacturing of Food Additives
An integrated membrane process for treatment of effluents from food additive manufacturing was designed and evaluated on a laboratory scale. The principal focus was water recovery with the possibility of its reuse as potable water. The industrial effluent presented high content of dyes and salts. It was red in color and presented brine characteristics. The whole effluent was fed into the integrated process in continuous flow. The steps of the process are as follows: sedimentation (S), adsorption by activated carbon (AC), ion exchange using resins (IEXR), and reverse osmosis (RO) (S–AC–IEXR–RO). The effect of previous operations was evaluated by stress-rupture curves in packaged columns of AC and IEXR, membrane flux, and fouling dominance in RO. Fouling was evaluated by way of the Silt Density Index and membrane resistance examination during effluent treatment. The integrated membrane process provided reclaimed water with sufficiently high standards of quality for reuse as potable water. AC showed a high efficiency for color elimination, reaching its rupture point at 20 h and after 5L of effluent treatment. IEXR showed capacity for salt removal, providing 2.2–2.5 L of effluent treatment, reaching its rupture point at 11–15 h. As a result of these previous operations and operating conditions, the fouling of the RO membrane was alleviated, displaying high flux of water: 20–18 L/h/m2 and maintaining reversible fouling dominance at a feed flow rate of 0.5–0.7 L/h. The characteristics of the reclaimed water showed drinking water standards
Start-up and performance of a downflow fluidised bed reactor for biological treatment of yellow wastewater and nutrient recovery
The treatment of yellow water (human urine) in a downflow fluidised bed reactor (DFFBR) was investigated to evaluate biological ureolysis and nutrient recovery. The reactor was operated at 30±4 °C in batch mode, and reaction time = 1 d. The average immobilised biomass (as volatile solids, IVS) in the reactor was 2.5±0.9 g L−1support, and specific ureolytic activity was 121 g Urea-N g−1 IVS d−1. The kinetic parameters were 0.152 mol L−1 (Km) and 8 mol g−1 IVS d−1 (Vmax). The ureolysis efficiency was 93.4% and chemical oxygen demand removal efficiency was 31.2%, while total ammonium nitrogen (NH4+-N) production rate was 7 g L−1 d−1 and phosphate removal reached 26%. Precipitates recovery during biological treatment was 1.72±0.8 g. These results suggest that the treatment of yellow water in a DFFBR is a viable option for partial recovery of N and P.
Multiple syntrophic interactions in a terephthalate-degrading methanogenic consortium
Terephthalate (TA) is one of the top 50 chemicals produced worldwide. Its production results in a TA-containing wastewater that is treated by anaerobic processes through a poorly understood methanogenic syntrophy. Using metagenomics, we characterized the methanogenic consortium inside a hyper-mesophilic (that is, between mesophilic and thermophilic), TA-degrading bioreactor. We identified genes belonging to dominant Pelotomaculum species presumably involved in TA degradation through decarboxylation, dearomatization, and modified β-oxidation to H 2 /CO 2 and acetate. These intermediates are converted to CH 4 /CO 2 by three novel hyper-mesophilic methanogens. Additional secondary syntrophic interactions were predicted in Thermotogae , Syntrophus and candidate phyla OP5 and WWE1 populations. The OP5 encodes genes capable of anaerobic autotrophic butyrate production and Thermotogae , Syntrophus and WWE1 have the genetic potential to oxidize butyrate to CO 2 /H 2 and acetate. These observations suggest that the TA-degrading consortium consists of additional syntrophic interactions beyond the standard H 2 -producing syntroph–methanogen partnership that may serve to improve community stability.
Biological testing of ships’ ballast water indicates challenges for the implementation of the Ballast Water Management Convention
Ships’ ballast water and sediments are vectors that contribute to the unintentional spread of aquatic non-native species globally. Ballast water management, as well as commissioning testing of ballast water management systems and compliance monitoring under the regulations of the International Maritime Organization (IMO) aim at minimizing the unwanted spread of organisms. This study compiles data for treated ballast water samples collected and analyzed from 228 ships during 2017–2023. The samples were collected from the ballast discharge line or directly from the ballast tank for enumeration of living organism concentrations in the categories of ≥50µm and <50 to ≥10µm -sized organisms, as well as indicator microbes in comparison to the ballast water performance standard of the IMO (Regulation D-2). In addition, several ship-specific factors were examined to infer potential factors affecting compliance rates. Nearly all ships were compliant with the ballast water performance standard for indicator microbes and <50 to ≥10µm -sized organisms, whereas almost half of all samples exceeded the limit of ten viable organisms m -3 for the ≥50µm -sized organisms. Compliance testing results did not differ significantly between sampling years, indicating that compliance rate did not change through time. The rate of compliance was higher for commissioning testing than compliance testing. Clear ship- or system-specific factors that lead to compliance or non-compliance were not detected, even though type of ballast water management system, filter mesh size associated with the system and source of ballast water affected compliance significantly either for the samples taken from the discharge line, or ballast tank. As compliance did not improve significantly over time, compliance testing of ships’ ballast water should be undertaken to ensure that the systems remain operational after commissioning and ships meet requirements of the D-2 standard. Furthermore, the study outcomes promote further research on the efficiency of filter mesh sizes and different filtration units associated with ballast water management systems, to improve mechanical removal of larger organisms. Finally, as several ships exceeded the compliance limit by hundreds or thousands of living organisms, technological advancements and operational measures may be needed to improve the overall reliability of ballast water management.
Characteristics of patients with Type 2 Diabetes in Mexico: Results from a large population-based nationwide survey
To describe the clinical characteristics of the diabetic population that formed part of a population-based survey conducted in México. In 2000, information was obtained from 42,886 subjects aged > or =20 years using a multistage sampling procedure. Standardized questionnaires were used. Anthropometric measurements, blood pressure, and capillary glucose concentrations were taken. Type 2 diabetes was found in 3,597 subjects (age-adjusted prevalence 8.18%), of which 2,878 (80%) had previously been diagnosed. The average age of the diabetic participants was 55.2 +/- 13.5 years; 13% were <40 years of age. Nine percent had been diagnosed for >10 years. The average BMI was 29.2 +/- 5.7 kg/m(2); three-quarters of the cases had BMI >25 kg/m(2). The average waist circumference was 102 +/- 13.4 cm, and increased waist circumference was more common among women. Arterial hypertension was found in half of the cases and, of those on treatment, only one-third had a blood pressure <140/90 mmHg. Smoking was reported in 34% of the diabetic group, a higher rate than in the nondiabetic subjects. There was at least one modifiable coronary risk factor in 67.6% of the cases. Very few followed an exercise or dietary regimen and a small percentage used insulin. Diabetes affects a large proportion of Mexican adults (8.18%). This figure may be underestimated. The majority of the subjects had modifiable risk factors for the chronic complications of diabetes. Only a few achieved adequate blood pressure control and other treatment goals.
Relative Invasion Risk for Plankton across Marine and Freshwater Systems: Examining Efficacy of Proposed International Ballast Water Discharge Standards
Understanding the implications of different management strategies is necessary to identify best conservation trajectories for ecosystems exposed to anthropogenic stressors. For example, science-based risk assessments at large scales are needed to understand efficacy of different vector management approaches aimed at preventing biological invasions associated with commercial shipping. We conducted a landscape-scale analysis to examine the relative invasion risk of ballast water discharges among different shipping pathways (e.g., Transoceanic, Coastal or Domestic), ecosystems (e.g., freshwater, brackish and marine), and timescales (annual and per discharge event) under current and future management regimes. The arrival and survival potential of nonindigenous species (NIS) was estimated based on directional shipping networks and their associated propagule pressure, environmental similarity between donor-recipient ecosystems (based on salinity and temperature), and effects of current and future management strategies (i.e., ballast water exchange and treatment to meet proposed international biological discharge standards). Our findings show that current requirements for ballast water exchange effectively reduce invasion risk to freshwater ecosystems but are less protective of marine ecosystems because of greater environmental mismatch between source (oceanic) and recipient (freshwater) ecoregions. Future requirements for ballast water treatment are expected to reduce risk of zooplankton NIS introductions across ecosystem types but are expected to be less effective in reducing risk of phytoplankton NIS. This large-scale risk assessment across heterogeneous ecosystems represents a major step towards understanding the likelihood of invasion in relation to shipping networks, the relative efficacy of different invasion management regimes and seizing opportunities to reduce the ecological and economic implications of biological invasions.
Organic Leachate and Biogas Utilization in Outdoor Microalgae Cultivation Under Alkaline Conditions at Pilot-Scale
The performance of an outdoor pilot-scale system consisting of a high rate algal pond interconnected to an absorption bubble column and seeded with a microalgal-bacterial consortium is presented. Biogas and organic leachate (from food waste anaerobic hydrolysis) were used as sources of CO 2 and nutrients for the consortium, respectively. The removal efficiencies for CO 2 and H 2 S from biogas were 80.0% and 99.9%, respectively, provoking a methane content in the utilized biogas of approximately 55 vol% for anaerobically-produced biogas and 90 vol% for a prepared gaseous mixture. The molecular oxygen produced by microalgae photosynthesis induced undesirable cumulation of O 2 in utilized biogas up to 5%vol. The organic leachate was diluted in an alkaline mineral medium (15:1 v/v), and this rich-nutrient mixture was fed to the system at a hydraulic retention time of 138 d. The biomass productivity applying organic leachate and anaerobically-produced biogas was 2.6 g m −3 d −1 , nine times lower than biomass productivity achieved when only mineral salt medium was fed, suggesting the existence of limited nutrient bioavailability. Microalgal-bacterial community shifts evaluated through molecular and morphological methods showed that a robust and stable photosynthetic population was maintained throughout the entire operation of the system, formed mainly by Picochlorum sp., Pseudanabaena sp., Spirulina sp., and Nitzschia sp., as well as heterotrophic bacteria and some microalgae predators. The valued by-products after waste utilization were clean and highly calorific biogas besides microalgae biomass, where the commercialization of the latter would determine the economic viability of biogas and leachate utilization. Graphical Abstract
Diabetes and hypertension increases in a society with abdominal obesity: results of the Mexican National Health Survey 2000
To determine the prevalences of overweight, obesity, type 2 diabetes mellitus (DM) and hypertension (HT) in the Mexican population and compare them with those of a previous Mexican urban survey and an American survey. A structured, randomised, nationally representative Mexican sample was compared with a 1993 Mexican urban survey and the US Third National Health and Nutrition Examination Survey (NHANES III) of non-Hispanic Whites. The Mexican National Health Survey 2000. SUBJECTS were 12,856 men and 28,332 women, aged 20-69 years, who had their body weight, height, waist circumference (WC), blood pressure and fasting capillary blood glucose measured. Mexican adult men and women had a high prevalence of overweight (41.3 and 36.3%, respectively) and obesity (19.4 and 29.0%, respectively), similar to those in the USA in 1988-1992 and exceeding those of the 1993 Mexican survey. The prevalence of HT was 33.3% in men and 25.6% in women, with inferred DM rates of 5.6 and 9.7%, respectively. Abdominal obesity affected 46.3% of men (WC>or=94 cm) and 81.4% of women (WC>or=80 cm). There was a high prevalence of abdominal obesity in normal-weight women, with co-morbidities relating better to WC than to body mass index (BMI) in both sexes. Rates of DM and HT exceeded US rates on a comparable BMI or WC basis in adults aged <50 years. The high prevalence of obesity and abdominal obesity in Mexicans is associated with markedly increased prevalences of DM and HT to levels comparable with, or even higher than, those in NHANES III of non-Hispanic Whites.