Dissolved Oxygen Concentration Research Articles

Dissolved Oxygen Prediction Model for the Yangtze River Estuary Basin Using IPSO-LSSVM

Water ecology has always been key to environmental protection, and the combination of human activities and natural factors has caused eutrophication in the Yangtze estuary and adjacent waters. Among them, dissolved oxygen (DO) concentration is the key indicator to judge the quality of water. Firstly, using principal component analysis (PCA) to determine the number of parameters affecting dissolved oxygen concentration, the least squares support vector machine (LSSVM) prediction model with improved particle swarm optimization (IPSO) is proposed to be applied to the dissolved oxygen prediction in Shanghai’s Yangtze River basin through the data-driven modeling approach and the regression prediction capability of the neural network. Eight parameters of water temperature (WT), pH, potassium permanganate (KMnO4), ammonia nitrogen (NH4+-N), total phosphorus (TP), total nitrogen (TN), conductivity (Cond), and nephelometric turbidity unit (NTU) are selected as model inputs in the published public data, and the output is the dissolved oxygen concentration. The optimal combination of model parameters is found according to the IPSO algorithm, which effectively overcomes the parameter selection problem of regular support vector machines (SVM). The mean absolute error (MAE), root mean square error (RMSE), mean absolute percentage error (MAPE), and correlation coefficients of the evaluation indexes of this model (R2) are 0.1702, 0.2221, 0.0267, and 0.9751, respectively. Compared with other similar data driven models, this model has improved model accuracy and stability in predicting DO concentrations in the estuary, and thus it provides technical support for assessing and monitoring offshore water quality.

Enhanced nitrogen removal from rural domestic sewage via partial nitrification-anammox in integrated vertical subsurface flow constructed wetland

This study aimed to improve the removal of nitrogen treating rural domestic sewage by developing a novel strategy for achieving partial nitrification-anammox (PNA) in an integrated vertical subsurface flow constructed wetland (VSFCW). The influent ammonia was oxidized to nitrite in the partial nitrification VSFCW (VSFCWPN), and 5 mg/L of hydroxylamine was added under the appropriate dissolved oxygen concentration level (1.2 ± 0.2 mg/L) to stabilize the average nitrite accumulation rate at 88.24% and maintain the effluent NO2--N/NH4+-N ratio at 1.26 ± 0.15. The effluent from VSFCWPN was introduced to the following chamber (VSFCWAN), where ammonia and nitrite were removed by the autotrophic anammox process. This implementation achieved high removal efficiencies for chemical oxygen demand, total nitrogen, and PO43--P, reaching 86.26%, 90.22%, and 78.94%, respectively, with influent concentrations of 120.75 mg/L, 60.02 mg/L, and 5.05 mg/L. Substrate samples were collected from 10 cm height (PN1, AN1) and 25 cm height (PN2, AN2). Microbial community analysis showed that Nitrosomonas dominated the community composition in VSFCWPN, with an increase from 1.61% in the inoculated sludgePN to 16.31% (PN1) and 12.09% (PN2). Meanwhile, Ca. Brocadia accounted for 44.81% (AN1) and 36.50% (AN2) in VSFCWAN. These results confirm the feasibility of the proposed strategy for establishing PNA and efficiently treating rural domestic sewage in an integrated VSFCW.

Controlled mechanism and removal performance of phosphorus in black and odorous water bodies by Fe-based layered double hydroxides

The effective approach for controlling internal phosphorus loading remains a longstanding challenge to the maintenance of remediated black and odorous water bodies. Here, three Fe-based LDHs materials were developed for alleviating the phosphorus pollution in black and odorous water through synergistic functions of phosphate adsorption, controlled release of phosphorus, and microbial metabolism. The mechanism of phosphate removal in overlying water is mainly specific electrostatic attraction and coordination. After the addition of Fe-based LDHs, the water quality indexes of black and odorous water bodies were significantly improved, including TP concentration (from 0.8 to 0.2 mg/L), the dissolved oxygen content (from 0.1 to 3.0 mg/L), COD, turbidity (from 34 to 18 FTU), and redox potential. Moreover, the morphology and physicochemical properties of sediments were regulated by Fe-based LDHs. Fluffier and smaller sediments particles due to the destruction of extracellular polymeric substances structure, which was beneficial to the release of endogenous phosphorus. Furthermore, the results of microbial community structure analysis illustrated that Proteobacteria and Dechloromonas played the most important role in phosphorus elimination in Fe-based LDHs system. That is, based on the biocompatibility of Fe-based LDHs, which act as a medium of the electron transfer in the microbial metabolism, combining with microorganisms for the synergistic remediation of black and odorous water bodies. Our study emphasizes the feasibility of Fe-based LDHs materials for the remediation of internal phosphorus loads in black and odorous water bodies, towards sustainable control.

Experimental studies on active oxygen control performance of solid PbO mass exchanger in liquid lead–bismuth eutectic loop

The precise control of dissolved oxygen in lead–bismuth eutectic (LBE) reactors is very important. Solid phase oxygen control is a promising solution for regulating dissolved oxygen in the LBE. In order to better develop solid phase control technology, we designed a bypass mass exchanger holding PbO pellets. The dissolved oxygen in the LBE loop was controlled by PbO mass exchanger (PbO MX) technology. PbO MX is composed of a packed bed charging bucket, PbO ceramic pellets and bypass. The oxygen concentration in LBE under different conditions was measured using electrochemical oxygen sensors. The dissolution rate of PbO at different temperatures and flow rates were obtained. The effect of LBE flow rate and temperature parameters on the oxygen supply performance was obtained from the experimental results. The high-precision control of the dissolved oxygen concentration was achieved in the LBE loop.

The interaction of tide and river flow on water quality in Hai Phong coastal waters (Lach Huyen - Do Son) drawn from field observation

This paper presents the results of a study on the impacts of the interaction of tide and river flow on water quality at the Hai Phong coastal water, outside the Nam Trieu estuary and Lach Huyen, drawn from field observation from October 14, 2022, to October 17, 2022. During the field observation, the dissolved oxygen concentration was measured, and water samples were taken at the surface, mid-depth, and bottom of 8 observational points at 1:00, 7:00, 13:00, and 19:00 h. Five sewage wastewater samples at Do Son coast and 6 coastal and river water samples were also taken. The collected seawater samples were laboratory analyzed to determine the concentration of BOD5, COD, TN, and TP. Additionally, the concentration of ions NH4+, NO2-, NO3-, and PO43- are determined by analyzing collected coastal, river, and sewage water samples and seawater samples at mid-depth at all observational points in a laboratory. It was found that the concentration of essential nutrients and other environmental components in wastewater samples generally does not exceed those specified in Vietnam regulations. The discharge of wastewater during the field observation was minimal. Thus it could be expected that the wastewater would not have a notable influence on seawater quality in the marine study area. Consequently, the study area’s primary source of nutrient pollutants was rivers. Time variation of the concentration of environmental components reveals that the nutrient concentration in the marine study area strongly influences by the interaction of the tide and river flow. The concentration of dissolved oxygen and major nutrient components in seawater at 8 points was within the limit of Vietnam standard for coastal water. However, significant nutrient concentration exceeds thresholds for eutrophication.

Reactive Mass Transfer around Isolated Bubbles Rising in a Thin‐Gap Cell

AbstractThe reactive mass transfer around isolated bubbles of pure oxygen rising in a thin‐gap cell filled with acetonitrile at rest is investigated. A colorimetric technique based on the bio‐inspired copper(I) complex [Cu(TMG2tol)]OTf is used. The gap‐ and time‐averaged dissolved oxygen concentration fields can be measured in the far‐wake of the bubbles with 3 < d < 47 mm. The variations of the Sherwood numbers with the Péclet numbers indicate that the mass transfer results obtained are identical with the ones measured earlier with the copper(I) complex [Cu(btmgp)I]. This demonstrates the independency of mass transfer from the properties of the chemical system used. The results significantly enlarge the existing database, which is of great importance to establish robust scaling laws.

Workflow for shake flask and plate cultivations with fats for polyhydroxyalkanoate bioproduction

Since natural resources for the bioproduction of commodity chemicals are scarce, waste animal fats (WAF) are an interesting alternative biogenic residual feedstock. They appear as by-product from meat production, but several challenges are related to their application: first, the high melting points (up to 60 °C); and second, the insolubility in the polar water phase of cultivations. This leads to film and clump formation in shake flasks and microwell plates, which inhibits microbial consumption. In this study, different flask and well designs were investigated to identify the most suitable experimental set-up and further to create an appropriate workflow to achieve the required reproducibility of growth and product synthesis. The dissolved oxygen concentration was measured in-line throughout experiments. It became obvious that the gas mass transfer differed strongly among the shake flask design variants in cultivations with the polyhydroxyalkanoate (PHA) accumulating organism Ralstonia eutropha. A high reproducibility was achieved for certain flask or well plate design variants together with tailored cultivation conditions. Best results were achieved with bottom baffled glass and bottom baffled single-use shake flasks with flat membranes, namely, >6 g L-1 of cell dry weight (CDW) with >80 wt% polyhydroxybutyrate (PHB) from 1 wt% WAF. Improved pre-emulsification conditions for round microwell plates resulted in a production of 14 g L-1 CDW with a PHA content of 70 wt% PHB from 3 wt% WAF. The proposed workflow allows the rapid examination of fat material as feedstock, in the microwell plate and shake flask scale, also beyond PHA production.Key points• Evaluation of shake flask designs for cultivating with hydrophobic raw materials• Development of a workflow for microwell plate cultivations with hydrophobic raw materials• Production of polyhydroxyalkanoate in small scale experiments from waste animal fatGraphical

Research on Improving Urban River Micro-Ecological Environment by Combining CaO2 with Microorganisms

Improving the micro-ecological environment in urban rivers is crucial for preventing river black and odorous phenomena. This study examined the effectiveness of using CaO2 and microorganisms in treating urban rivers with black and odorous phenomena. The results indicated that this method had a high removal rate for ammonia nitrogen and COD in the overlying water, reaching 95.1% and 72.1%, respectively, and the dissolved oxygen concentration increased to 6.5 mg/L. The overall water quality met Class III water standards, and the sediment’s removal rates of AVS and organic matter were 87.4% and 33.3%, respectively, reducing the potential risk of black and odorous phenomena in the water. Amplicon sequencing analysis showed that the combination of CaO2 and microorganisms improved the micro-ecological environment of the sediment by increasing dissolved oxygen concentration, regulating redox potential, promoting oxidation of organic matter, ammonia nitrogen, and sulfides, and inhibiting microorganisms that cause black and odorous phenomena.

Optimizing selective withdrawal strategies to mitigate hypoxia under water-level reduction in Germany's largest drinking water reservoir

Water-level reduction frequently occurs in deep reservoirs, but its effect on dissolved oxygen concentration is not well understood. In this study we used a well-established water quality model to illustrate effects of water level dynamics on oxygen concentration in Rappbode Reservoir, Germany. We then systematically elucidated the potential of selective withdrawal to control hypoxia under changing water levels. Our results documented a gradual decrease of hypolimnetic oxygen concentration under decreasing water level, and hypoxia occurred when the initial level was lower than 410 m a.s.l (71 m relative to the reservoir bottom). We also suggested that changes of hypoxic region, under increasing hypolimnetic withdrawal discharge, followed a unimodal trajectory with the maximum hypoxic area projected under the discharge between 3 m3/sec and 4 m3/sec. Besides, our results illustrated the extent of hypoxia was most effectively inhibited if the withdrawal strategy was applied at the end of stratification with the outlet elevation at the deepest part of the reservoir. Moreover, hypoxia can be totally avoided under a hybrid elevation withdrawal strategy using surface withdrawal during early and mid stratification, and deep withdrawal at the end of stratification. We further confirmed the decisive role of thermal structure in the formation of hypoxia under water-level reduction and withdrawal strategies. We believe the conclusions from this study can be applied to many deep waters in the temperate zone, and the results should guide stakeholders to mitigate negative impacts of hypoxia on aquatic ecosystems.

Robustness enhancement study of augmented positive identification controller by a sigmoid function

The dissolved oxygen concentration in the wastewater treatment process (WWTP) must remain in a specific range while the factory operates. The augmented positive identification (PID) controller with a nonlinear element (sigmoid function) is proposed to assure stability and reduce uncertainties in the wastewater direct reuse/recycling model. The nonlinear controller gains (PID controller with sigmoid function) for uncertain wastewater treatment processes are tuned using the particle swarm optimization (PSO) technique. The proposed robust method for controlling wastewater treatment processes has good robustness during model mismatching, reduces treatment time compared to traditional positive identification (PID) controllers tuned by PSO, is easy to apply, and has good performance, according to simulation results.

Morphological and Compositional Analysis on Thermal Deposition of Supercritical Aviation Kerosene in Micro Channels.

The integration of active cooling systems in super or hypersonic aircraft using endothermic hydrocarbon fuels is considered an effective way to relieve the thermal management issues caused by overheating. When the temperature of aviation kerosene exceeds 150 °C, the oxidation reaction of fuel is accelerated, forming insoluble deposits that could cause safety hazards. This work investigates the deposition characteristic as well as the morphology of the deposits formed by thermal-stressed Chinese RP-3 aviation kerosene. A microchannel heat transfer simulation device is used to simulate the heat transfer process of aviation kerosene under various conditions. The temperature distribution of the reaction tube was monitored by an infrared thermal camera. The properties and morphology of the deposition were analyzed by scanning electron microscopy and Raman spectroscopy. The mass of the deposits was measured using the temperature-programmed oxidation method. It is observed that the deposition of RP-3 is highly related to dissolved oxygen content (DOC) and temperature. When the outlet temperature increased to 527 °C, the fuel underwent violent cracking reactions, and the structure and morphology of deposition were significantly different from those caused by oxidation. Specifically, this study reveals that the structure of the deposits caused by short-to-medium term oxidation are dense, which is different from long-term oxidative deposits.

Detailed evaluation of physicochemical properties and microbial activities of Hanna Lake and Spin Karez

Abstract Access to clean drinking water is a major issue in many regions of the world, particularly in areas where groundwater is scarce. This study aims at determining the water quality of two lakes. Some parameters in this investigation were found to be above the WHO limit, while most were within the limit. For instance, the average value of electrical conductivity in Hanna Lake was 537.4 μS/cm, while it was 758.9 μS/cm in Spin Karez, which was above the WHO limits (>500 μS/cm). Turbidity in Hanna Lake was 4.17 nephelometric turbidity units (NTU), within the WHO limits (<5 NTU), while in Spin Karez, it was 9.5 NTU above the WHO limits, and dissolved oxygen concentration average values were 9.06 mg/l in Hanna Lake and 8.86 mg/l in Spin Karez, above the permitted limits provided by the WHO (6.5–8 mg/l). The study also found that both lakes had high concentrations of microbial colonies, with 65 CFU/100 ml in Hanna Lake and 56 CFU/100 ml in Spin Karez. Based on these findings, an efficient water treatment technique should be adopted to remove these highly concentrated parameters in both lakes for purified water and future water demands.

Longitudinal patterns of abundance, diversity and functional feeding guilds of benthic communities in East African tropical high‐altitude streams

AbstractIn temperate and tropical rivers, macroinvertebrates are commonly utilised for biological monitoring. Therefore, it is important to understand their functional feeding guilds and assemblage structure. However, there have been few studies in high‐altitude rivers in East Africa aimed at assessing macroinvertebrate functional guilds. In this study, we examined the macroinvertebrate assemblage characteristics using abundance/diversity metrics and the functional feeding groups (FFGs). We collected physicochemical data and macroinvertebrate samples at seven sites along the Gura River and three sites on the Sagana River. Dissolved oxygen concentration, water temperature, electrical conductivity, pH, turbidity, ammonia, and soluble reactive phosphorus showed significant differences among the sites (p < 0.05). A total of 32 families belonging to 11 orders of macroinvertebrates were collected during the study period. Overall, scrapers were the most abundant FFG, dominated by Heptageniidae (Afronurus). Collector filters and collector gatherers were the second most abundant, while shredders and predators exhibited the least relative abundance. Across all the dominant orders, macroinvertebrate abundance decreased from upstream to downstream sites, with upstream sites exhibiting high diversity and abundance of Ephemeroptera, Diptera, Coleoptera, and Trichoptera taxa. Furthermore, the FFGs in this study differed widely from the River Continuum Concept predictions. Our findings provide crucial understanding of macroinvertebrate assemblage characteristics in high‐altitude rivers. Thus, this study provides additional evidence on the high abundance and diversity of Ephemeroptera and Trichoptera taxa in tropical rivers.

Spatial Variation of Tetracycline-Resistant E. coli and Relationships with Water Quality Variables in Irrigation Water: A Pilot Study

Irrigation waters may facilitate the spread of antibiotic-resistant bacteria or genes to humans and animals. Monitoring of resistance in irrigated waters has become common; however, many studies do not incorporate a spatial component into sampling designs. The objective of this work was to assess spatiotemporal variations in tetracycline-resistant E. coli in an irrigation pond. Water samples were collected at 10 locations and two different water depths, and in situ and laboratory water quality measurements were performed. The percentage of E. coli resistant to the low (4 μg mL−1) and high (16 μg mL−1) tetracycline doses varied by date and location but were observed to be as high as 12.7% and 6.3% of the total population throughout the study, respectively. While significant differences were not observed between resistance levels measured at different depths, on one date resistant E. coli were only detected in samples collected at depth. Nitrate, fluorescent dissolved organic matter, and dissolved oxygen concentrations were found to be the leading control variables for the percentage of resistant E. coli. This work demonstrates that there may be substantial spatial variability in concentrations of antibiotic-resistant E. coli in irrigation ponds which should be accounted for in the design of monitoring programs.

Innovative passive aeration process for synthetic deoxygenated water

ABSTRACT Aeration is a process of diffusing oxygen into water in order to stimulate the aerobic bacteria for starting wastewater aerobic treatment process. Zero energy aeration systems that do not require electric or mechanical power are known as passive aerators. A new technology for passive aerators using inverted bell siphon principle is innovated, which requires a lot less volume for its installation compared to other passive aeration systems as cascade, spray and perforated tray aerators. A laboratory experimental program investigated the inverted bell siphon system using deoxygenated water with almost zero dissolved oxygen concentration like anaerobic treatment effluent. The system is used to build water pressure through a distribution system used for scattering water in air to diffuse oxygen into it. Holed arm pipe with different hole diameters and numbers, showerhead, fire sprinkler and modified fire sprinkler were tested as distributors to reach the optimum type which verify good oxygen diffusion in water and ensure least possibility of clogging of distributors. Dissolved oxygen concentration was measured for each distributor water effluent. The experiments showed that the modified fire sprinkler achieved higher oxygen diffusion in water and best distribution, in addition to its geometry that prevents the distribution system from clogging.

Photobioreactors for utility-scale applications: effect of gas-liquid mass transfer coefficient and other critical parameters.

Cultivation of microalgae and controlling its growth and performance in closed photobioreactors (PBRs) are easier than open pond systems for wastewater treatment. The performance of PBRs is influenced by geometry, hydrodynamic behavior, and mass transfer. Horizontal and vertical configurations as common designs of PBR are reviewed based on their features, advantages, and disadvantages. However, vertically operated PBRs like bubble columns are preferably used for utility-scale applications of microalgae-based processes. Moreover, an appropriate reactor design reduces the inhibitory effect of dissolved oxygen concentration produced by microalgae and consequently increases the level of available CO2 in the medium. Medium properties, superficial gas velocity, gas holdup, bubble sizes, shear stress, mixing time, sparger design, and the ratio of inner diameter to effective height are shown to influence the overall volumetric mass transfer coefficient (KLa) and PBR's performance. The vertical PBRs like bubble columns provide a high mass transfer, a short liquid circulation time, and a long frequency of light/dark cycle for utility application of microalgae. Different flow regimes are obtained in PBRs based on the gas flow rate, inner diameter, and medium properties. Hydraulic retention time as the main operational parameter is determined in a batch mode for continuous wastewater treatment.

Kinetics of the complexation reaction of iron with dissolved oxygen in liquid sodium

This work aims to study the kinetics of pure iron corrosion by liquid sodium in the presence of dissolved oxygen. The corrosion rate of pure iron in liquid sodium was estimated from the mass loss in the samples as a function of immersion time. The parameters tested were dissolved oxygen content, temperature and velocity of the liquid sodium. The rate of pure iron dissolution in liquid sodium increases with dissolved oxygen content and follows a power law of order 2 as a function of the initial oxygen content (50−400ppm). The mechanism of iron corrosion by liquid sodium is activated in the temperature range between 525∘C and 600∘C. The experimental activation energy is estimated to be 168±10kJ/mol. The dissolution rate also increases with the liquid sodium agitation rate.Under the same experimental conditions, S. Meddeb et al. in [J. Nucl. Mater. 566 (2022) 153785] demonstrated that the iron dissolution is homogeneous and is explained by the formation of the NaFeO2 complex at the iron/liquid sodium interface. The corrosion kinetics measured is limited by the transfer of this complex through the mass transfer boundary layer. In the case of static sodium, the associated transfer coefficient is equal to (2.2 ± 0.8)·10−8 m/s. The proposed kinetic corrosion model estimates an excellent order of magnitude for our measurements of average iron thickness loss. Based on our experimental measurements, calculations lead to a diffusivity of the NaFeO2 complex in static liquid sodium of (1.6 ± 0.6)·10−9 m2/s. The Stokes-Einstein law can then be used to estimate an equivalent complex molecule radius of 2 · 10−9 m. These data, combined with the Stokes-Einstein equation, can be used in industrial applications to simulate the mechanism of iron corrosion in non-isothermal heat transfer loop systems.

An in situ study to shed light on the formation of goethite spindles by pseudomorphic transformation of intermediate phases

Size and shape control of nanoparticles is fundamental to tune their material properties and to identify structure property functions. Herein, the shape of goethite (α-FeOOH) particles is varied from needle to spindle upon sodium carbonate modulation. Our in-depth study sheds light on the formation path of goethite particles by in situ monitoring the pH, the dissolved oxygen concentration and Raman spectroscopy in the presence and in the absence of sodium carbonate. The pH evolution indicates two distinct plateaus, at 7–6.5, and 6–6.3, respectively: the time when the dissolved oxygen concentration vanishes is correlated with the time required to oxidize Fe(II) to Fe(III). Raman spectroscopy enabled the identification of the intermediate phases green rust at 500 cm−1 and siderite at 1080 cm−1. Their formation and depletion was correlated with the kinetics of goethite formation. The evolution of the olation reaction is monitored through the bending vibration of water at 1640 cm−1. Finally, goethite particles are characterized ex situ via X-ray diffraction to assess the crystalline phase, scanning electron microscopy (SEM) for evaluating the size and shape of particles and transmission electron microscopy (TEM) for the analysis of the three-dimensional arrangement of self-assembled layers. The evaluation of reflectance spectra with CIELAB color metrics show that goethite spindles have enhanced color properties in comparison to the needle-shaped particles.

Effects of brood viability and rising temperature on oxygen consumption of freshwater mussel glochidia (Bivalvia: Unionidae)

Unionid mussels are imperiled worldwide. Understanding the impacts of thermal and hypoxia stress on larval (glochidia) and adult physiology is critical for understanding the potential impacts of climate change. We tested whether brood viability (proportion of glochidia competent to attach to a host) was correlated with oxygen demand (MO2), ability to regulate oxygen consumption (regulation index (RI)), and/or critical dissolved oxygen concentration (DOcrit). We then examined the effects of temperature on MO2, RI, and DOcrit. The results were coupled with a previous study to estimate the fraction of brooding female oxygen demand comprised of glochidial respiration. We found little evidence that respiratory patterns of glochidia changed with declining brood viability, but strong evidence for decreasing glochidial RI and increasing DOcrit with increasing temperatures. Glochidial respiration temperature coefficient ( Q10) values were approximately 2–3× those estimated for brooding females, indicating greater temperature sensitivity. The proportion of gravid female respiration comprised of glochidial respiration reached its maximum at temperatures (23–28 °C) coinciding with brood expulsion. These patterns suggest high temperatures may have deleterious effects on unionids by decreasing the hypoxia tolerance of glochidia, increasing the rate at which glochidia deplete energy reserves, and increasing the proportion of oxygen consumption by gravid females that is comprised of glochidial oxygen demand.

Enhancing oxygen scavenging properties of erythorbic acid through transition metal catalysis

The presence of oxygen in pipelines used in power plants and the oil industry requires vigilant attention and utilization of oxygen scavenging to prevent the deleterious effects of corrosion. This study aims to investigate the efficacy of four transition metal catalysts (manganese, copper, nickel, and chromium) on the effectiveness of erythorbic acid as an oxygen scavenger. The experimental approach involved injecting varying concentrations (5 ppm, 10 ppm, and 20 ppm) of transition metal catalyst solutions with erythorbic acid at concentrations of 20 ppm, 50 ppm, and 100 ppm, while maintaining a controlled temperature of 25 °C and a pH of 9.0 at a saturated oxygen concentration. The outcome of the study demonstrated that nickel and chromium did not improve the oxygen removal rate, while copper exhibited notable results compared to the control catalyst (manganese). Specifically, the copper (I) chloride solution proved to be the most efficient in reducing dissolved oxygen content to levels below 20 ppb.