The results of the successful implementation of a treatment based on the injection of ozone (O3) and oxygen (O2) into a contaminated body of water are reported for the first time. Three ...decontaminating units (SCAVENGER™), which have the capacity to inject up to 120 g O3/h and 250 Kg O2/h in the form of microbubbles (90 ± 10 μm in diameter), were placed in the contaminated Valsequillo reservoir, Central Mexico. In order to evaluate the efficacy of the treatment, 20 physicochemical parameters, 18 organic compounds, 66 inorganic compounds and 11 biological indicators were measured before, during and after the treatment; all of them in several representative sites of the east side of the Valsequillo reservoir. After 5 months of operating the SCAVENGER™ units in the eastern part of the reservoir, the concentration of Dissolved Oxygen (DO) increased 68%. Likewise, the chemical reducing conditions of the reservoir reflected by the low oxidation-reduction potential (ORP; −237 ± 75 mV) became quasi-oxidant (10 ± 58 mV). The treatment was efficient in water disinfection, presenting an 80% reduction in Fecal Coliforms (FC). Some heavy metals also showed a decrease in their concentration, being as follows: Al (65%), Cr (35%), Pb (46%), Zn (60%), Mn (20%), Mo (40%), Fe (32%), As (58%) and Co (26%). Due to the selective reactivity of ozone towards aliphatic and aromatic unsaturated compounds, several organic compounds reduced in their concentration by up to two orders of magnitude. Based on the above, it is evident that the treatment with ozone and oxygen was effective in substantially improving the quality of water in the east side of the Valsequillo reservoir.
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•Ozone‑oxygen oxidation decreases the concentration of organic matter in contaminated water.•Ozone‑oxygen decreases the concentration of heavy metals, major elements and rare earths.•Fecal coliforms are susceptible to disinfection via ozone‑oxygen.•Aromatic compounds in water are degraded through ozone‑oxygen oxidation.•Ozone‑oxygen in-situ is an alternative to transform contaminated reservoirs to new water sources.
River Atoyac is considered to be one of the most polluted rivers in Mexico due to the discharges of untreated or partially treated wastewater from industrial and municipal activities. In order to ...improve the river water quality, it is obligatory to identify the possible contaminant sources for upholding a well-balanced ecosystem. Henceforth, the present study incorporates the application of a continuous real-time monitoring system to identify the provenance of pollutants of the river mainly from anomaly events. Four monitoring stations were installed all along the River Atoyac in the State of Puebla, Central Mexico. The real-time monitoring systems have an ability to measure various water quality parameters for every 15 minutes such as Temperature (T), pH, Conductivity (EC), turbidity (TURB), Dissolved Oxygen (DO), Oxidation Reduction Potential (ORP) and Spectral Absorption Coefficient (SAC). In total, eight water samples of anomaly events (i.e.) 2 per monitoring station during rainy (August–September) and winter seasons (November–December), that were detected using the parameters previously mentioned were procured and also analyzed in the laboratory for evaluating almost 54 physicochemical, inorganic and organic characteristics. Statistical results of factorial analysis explained that 30% of the total variance corresponded to textile effluents, 23% related to discharges produced by automobile and petrochemical industries, and 18% of the total variance defined the agricultural activities. Additionally, indices like Overall Index Pollution, Heavy Metal Evaluation Index, Screening Quick Reference Table and Molecular ratios of hydrocarbons for PAH sources was also calculated to estimate the grade of pollution and associated ecotoxicological risks. The present study also enlightens the fact that the assessed results will definitely provide valuable information for the management of river water quality by developing stringent public policies by governmental agencies for the sustainable conservation of Atoyac River.
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•Real time monitoring is regarded to be a fundamental tool for wastewater management.•Identification of pollutant sources is vital to improve river water quality.•River Atoyac is highly impacted by industrial and agricultural effluents.•Pb, Hg and Cd reflect acute toxicity.
The quality of life and human survival is dependent on sustainable development and sanitation of water bodies in an environment. The present research focuses on cyclicity data of more than 750,000 ...records of parameters associated with the water quality from a rural-urban river monitoring stations in real-time from River Atoyac in Central Mexico. The events detected in the instrumental records correlated with 2528 laboratory and instrumental determinations. The 64 polluting compounds were grouped into inorganic compounds (metals and metalloids) and organic compounds (pesticides, herbicides, hydrocarbons). Metal associated compounds were grouped along mechanical, pharmaceutical and textile industries which associates itself with the entry of polluting components. The cyclicity of the events was detected through Discrete Fourier Transformation time series analysis identifying the predominant events in each station. These highlight the events at 23–26 h corresponding to a circadian pattern of the metabolism of the city. Likewise, pollution signals were detected at 3.3, 5.5, and 12–14 h, associated with discharges from economic activities. Multivariate statistical techniques were used to identify the circadian extremes of a regionalized cycle of polluting compounds in each of the stations.
The results of this research allow pollution prevention using a mathematical analysis of time series of different quality parameters collected at monitoring stations in real-time as a tool for predicting polluting events. The DFT analysis makes it possible to prevent polluting events in different bodies of water, allowing to support the development of public policies based on the supervision and control of pollution.
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•Periodic identification of pollution events though Discrete Fourier Transform.•Detection on the occurrence frequency and pattern of anomalies of water quality events.•Circadian cycle composition of a polluted river.•Creating a base for developing new public policies based on polluting events.
Fluvial sediment analysis and water quality assessment are useful to identify anthropic and natural sources of pollution in rivers. Currently, there is a lack of information about water quality in ...the Pixquiac basin (Veracruz state, Mexico), and this scarcity of data prevents authorities to take adequate measures to protect water resources. The basin is a crucial territory for Xalapa, the capital city of Veracruz state, as it gets 39% of its drinkable water from it. This research analyzed 10 physicochemical parameters and 12 metal concentrations in various rivers and sources during two seasons. Dissolved metals presented average concentrations (µg/L): Al (456.25) > Fe (199.4) > Mn (16.86) > Ba (13.8) > Zn (7.6) > Cu (1.03) > Pb (0.27) > As (0.12) > Ni (0.118) (Cd, Cr and Hg undetectable). Metals in sediment recorded average concentrations (ppm): Fe (38575) > Al (38425) > Mn (460) > Ba (206.2) > Zn (65.1) > Cr (29.8) > Ni (20.9) > Cu (16.4) > Pb (4.8) > As (2.1) (Cd and Hg undetectable). During the rainy season, Water Quality Index (WAWQI) classified stations P17 and P18’s water as “unsuitable for drinking” with values of 110.4 and 117.6. Enrichment factor (EF) recorded a “moderate enrichment” of Pb in sediment in P24. Pollution was mainly explained by wastewater discharges in rivers but also because of erosion and rainfall events. Statistical analysis presented strong relationships between trace and major metals which could explain a common natural origin for metals in water and sediment: rock lixiviation.
In this investigation, ROS-based robust attitude control is designed for a two-wheeled self-balancing mobile robot (TWSBR) using the active disturbance rejection control (ADRC) technique. The ...designed ROS framework contemplates communication between topics for the desired robot commands and distributed framework design. This open architecture allows the integration of sensors, actuators, and processors. The architecture includes User-Friendly Interface, storage, navigation, control, and drivers. The low-cost robot was designed for educational purposes. It uses an Arduino Mega as a low-level processing unit, a Raspberry Pi 4 as a companion computer where high-level commands are processed, an MPU6050 Inertial Measurement Unit sensor, DC motors GW4058-555 with quadrature type encoder with two phases, the VNH2SP30 controller module used as the power stage and a Lithium Polymer (Li-Po) battery (11.1 V, 2200 mah) is used as the power source. The robust control algorithm is designed through the ADRC methodology based on the extended state observer (ESO). The ESO simultaneously estimates external disturbances, model uncertainties, and unmodeled dynamics such as friction, engine wear, and tire slippage. The stability of the developed controller is analyzed via the Lyapunov stability theory. Real-time experimental results are carried out under the regulation and rejection of external disturbances. The control algorithm is light and easy to implement and adjust in integrated systems with low computer resources.
This work is devoted to the study of the formation of periodic relief on the InP surface during ion sputtering by bismuth ions with an energy of 30 keV and an angle of incidence of 45° respect to ...normal incidence. We compared the reliefs formed by sputtering with atomic and cluster bismuth ions, as well as the relief appearing on the surface of the sample irradiated at elevated temperature (290 °C). Three different types of reliefs were found: surface waves with nanodots on the surface “waves”, nanodots with uniform distribution and relief in the form of columnar micro crystallites during sputtering of a heated target. With increasing irradiation dose, insignificant changes in characteristic surface dimensions were observed for all three reliefs. Based on the nonlinear character of surface sputtering (“thermal spot” sputtering mode), we described the formation of relief in the form of nano-dots and in the form of micro crystallites as a result of local melting areas formation and subsequent solidification (crystallization) on the target surface. Regarding wave relief, in our opinion, an adequate physical description is given by a model based on the stress driven dynamics of ion irradiated surface.
Glucose is the principal source of energy for humans and its quantification in physiological samples can diagnose or prevent diseases. Commonly, glucose determination is based on ...spectrophotometric-enzymatic techniques, but at least since a decade ago, electroanalytical strategies have emerged as promising alternatives providing accuracy and precision in the determination of biomolecules. This review focuses on the development of non-enzymatic methodologies based on modified electrochemical sensors with Metal-Organic Frameworks (MOF) for glucose detection sensors in physiological samples (blood and urine). Glassy carbon electrodes (GCE), carbon paste electrodes (CPE), and screen-printed electrodes (SPE) are the main transductors modified with MOF for the electrochemical oxidation of glucose, and the maximum anodic peak current is taken to the analytical signal. The reported results demonstrated that this electroanalytical approach represents a viable alternative for fast and confident analysis of the glucose molecule.
The present work aims to elucidate the possibility of injecting ozone into surface waters combined with urban wastewaters in order to improve the water quality of the High Atoyac Sub-basin (HAS) in ...Central Mexico. For this purpose, twenty physicochemical parameters, eight heavy metals, seven organic compounds, and one biological indicator were assessed in water from different sites of the studied area (the Alseseca River, the Atoyac River and the Valsequillo Reservoir). Results demonstrated that O3 injection led to the decrease of the aromatic fraction of organic molecules since the Spectral Absorption Coefficient at 254 nanometers (SAC254) reduction was found to be 31.7% in the Valsequillo Reservoir water samples. Maximum Chemical Oxygen Demand (COD) removal was observed to be 60.2% from the Alseseca River with a 0.26 mg O3/mg initial COD dose. Among all the phthalates studied in the present work, Di(2-ethylhexyl) phthalate (DEHP) exhibited the highest concentration (5.8 μg/L in the Atoyac River). Treatment with O3 was not effective in eliminating fecal coliforms (FC) in waters that host high organic matter (OM) loads as opposed to waters with low OM. After the injection of 4.7 mg O3/mg COD in the VO3-AT water sample, a 90% removal of Iron (Fe) and Aluminum (Al) was registered; while Manganese (Mn), Nickel (Ni), Zinc (Zn), and Cooper (Cu) showed a 73%, 67%, 81%, and 80% removal, respectively; Chromium (Cr) registered the highest removal (~100%). The present work demonstrated that while finding a suitable O3 dose to improve the quality of water in the HAS, the 5-days Biochemical Oxygen Demand (BOD5)/COD ratio (i.e., biodegradability) is more important than the overall OM removal percentage proving that O3 injection is a feasible process for the treatment of eutrophic waters from HAS.
The Valsequillo reservoir is a Ramsar wetland due to its importance as a point of convergence of migratory waterfowl. It is located in Central Mexico and is currently endangered by the constant spill ...of municipal and industrial discharges from Puebla city. On this context, we evaluated thirteen potential toxic metals (PTMs) in water, Water hyacinth (E. crassipes) plants and sediments at this site. A combined number of 31 samples were collected from the study area. The degree/extent of metal contamination in sediments was assessed through different geochemical indexes, namely: Geoaccumulation index (Igeo), Enrichment Factor (EF) and Potential Ecological Risk Index (PERI). The ability of Water hyacinth plants residues as a phytodepurator in the Ramsar site was tested in terms of the bioaccumulation factor (BF) and the translocation factor (TF). The results concerning sediments showed that Pb, Cu and Hg pose a threat to the aquatic environment since Igeo and EF indicate sediments ranging from moderately contaminated to contaminated. Moreover, PERI pointed out Hg as the main contributor to the ecological risk in sediments, especially in the part of the reservoir covered by E. crassipes. Water hyacinth plants displayed good capacity to absorb PTMs from the water, since the content of Co, Zn, As, Ni, Cu, Pb, Ti, Cr, Ba, Mo and V in the total plant was (all values in mg/kg of dry weight) 21 ± 9, 408 ± 300, 12 ± 6, 93 ± 21, 93 ± 69, 53 ± 29, 1067 ± 643, 78 ± 55, 362 ± 39, 14 ± 0.6 and 96 ± 35, respectively. Metal content in sediments resembles to that of E. crassipes; especially in the roots, suggesting a constant deposition of plants at the bottom of the reservoir, which contributes to the eutrophication of the water. The present work encourages the need for a sustainable management of Water hyacinth plants in the Ramsar site, since they represent a plague and a natural phyto-depurator at the same time.
Uric acid is one of the most important metabolites as its blood levels can help to diagnose important diseases. Tradicionally, uric acid is determined by enzymatic-spectrophotometric techniques, but ...in recent years new promising alternatives have arisen. This review is devoted to the development over the past decade of non-enzymatic electrochemical studies based on nano-structures of non-noble metal oxides (Fe
2
O
3
, CuO, Cu
2
O, ZnO, NiO, MnO
2
, CeO
2
, MgO, SnO
2
and Co
3
O
4
) for uric acid detection. The proposals showed the application of electrochemical sensors for the determination of uric acid in blood, urine, pharmaceuticals, water, and commercial shellfish. The developed electrodes are based on vitreous carbon electrodes, carbon paste, or screen-printed, mainly modified with nano-structures of metal oxides to electrochemically oxidize uric acid, where the anodic current peak is used as the analytical signal and the results reported are very promising.
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