Search Results (295)

Water is a vital resource for sustaining life; however, it is increasingly at risk due to escalating demand and heightened pollution levels. Swimming pool facilities generate diverse wastewater streams whose management offers opportunities for water recovery within a circular economy framework. The quantitative and qualitative analysis of research identifies five primary categories of wastewater: swimming pool basin outflow, filter washings, rainwater and meltwater, sanitary wastewater, and technological sludge, at a public swimming pool complex in Poland. Annual volumes were determined through direct measurements and calculations: pool basin outflow—2829.7 m³/year; filter washings—7179.2 m³/year; rainwater and meltwater—1172.6 m³/year; sanitary wastewater—5849.3 m³/year; and technological sludge—90.1 m³/year. Laboratory testing included physicochemical parameters (pH, redox potential, conductivity, COD, BOD, nutrients, heavy metals) and microbiological parameters (Escherichia coli, Pseudomonas aeruginosa, Legionella spp., Salmonella spp., Ascaris sp., Trichuris sp., Toxocara sp., Coagulase-positive Staphylococcus). The results showed that the filter washings, despite exceeding the limits for total suspended solids and combined chlorine, exhibited stable quality and significant volume, making them the most promising candidate for reuse after treatment. Rainwater quality was compromised by elevated heavy metal concentrations (Zn: 244.67 mg/L, Pb: 92.33 mg/L), while technological sludge exceeded the legal pollutant thresholds, classifying it as hazardous waste. The experimental conditions included year-round monitoring of operational flows, standardised backwash cycles every three days, and sampling under routine operational load. The findings support the development of targeted treatment systems that allow the recirculation of up to 7000 m³/year of water, thus reducing the demand for potable water and operational costs in swimming pool facilities. Full article

The use of seawater in public swimming pools could offer a more sustainable solution given the challenges posed by climate change and the growing scarcity of potable water across Europe. However, the swimming pool sector currently lacks a unified European legislative framework and faces significant fragmentation, particularly regarding the use of seawater. This scoping review applies a methodology to collect and analyze the international and national regulations of 23 coastal European countries relevant to swimming pool water safety. It provides an overview of existing European legislation on the use of seawater in public swimming pools and outlines the permitted disinfection methods. The review also highlights the highly variable and fragmented regulatory frameworks for microbiological and chemical water quality parameters, as well as the limits imposed on disinfection by-products (DBPs). Furthermore, it addresses the potential risks associated with seawater use in pools, with particular attention to the toxicity of DBPs that may form under such conditions. The findings underscore the urgent need for legislative updates in the pool sector and highlight the potential for developing specific European regulations. These would help harmonize practices across the sector and improve the management of both sustainability and public health in recreational aquatic environments. Full article

Background: Estimating race times for open-water swimming based on pool swimming times could be useful for talent identification and training optimisation. We aimed to compare the swimming speeds of the world’s top and other swimmers in the 2023 Aquatics Championship men’s 10 km OWS race. Methods: Sixty-five swimmers were divided into four groups: G1 (1st–10th positions), G2 (11st–30th positions), G3 (31st–47th positions), and G4 (48th–65th positions). Swimming speed, stroke frequency (SF), and stroke length (SL) for each lap (laps 1–6) were recorded. Critical speed (CS) was calculated from each participant’s personal best times in the 400, 800, and 1500 m freestyle events in the pool. Swimming speed against CS was calculated (%CS). Results: The top performance group (G1) maintained their swimming speed from beginning (lap 1, 1.53 m/s) to end (lap 6, 1.50 m/s), at 92.7 ± 1.9% of CS, characterised by longer SL (1.26 m) and lower SF (72.86 rpm). G3 and G4 were unable to maintain their swimming speed, which decreased from G3: 97.64 ± 1.62% and G4: 96.10 ± 1.96% of CS at lap 1 to G3: 88.39 ± 3.78% and G4: 85.13 ± 5.04% at lap 6. This reduction in swimming speed is consistent with the increased reliance on anaerobic metabolism reported in previous studies under similar conditions. Conclusions: Race pacing for maintaining speeds of 92%CS throughout the race could be an important resilient index in open-water swimming. %CS might be a useful index for estimating the athletic performance level in open-water swimming. Full article

Objective: As performance progression provides an essential indicator for talent selection and development, this study aimed to compare annual swimming performance progression between different competitive levels and to establish benchmarks for long-term athlete development. Methods: Annual best times of swimmers who competed up to the age of 21 years and achieved over 450 World Aquatics points were extracted from the database of European Aquatics. A total of 13,310 male and 7798 female pool swimmers of all race distances were grouped into three performance levels. Results: The results showed a continuous decline in annual performance progression throughout the years across all race distances (all p < 0.001) and in both sexes. There were differences between performance level across the age groups for all race distances in male swimmers, but only for the 100–400 m races in females (p < 0.05). Absolute performance showed significant main effects for level and age over all race distances for both sexes (all p < 0.001). Conclusions: Annual performance progression of swimmers consistently decreases across the competitive lifetime in both sexes, regardless of race distance and performance level. The event-specific benchmarks should be used as a framework to set realistic goals for both sexes and swimmers of different competitive levels, as well as to guide swimmers throughout their careers. Full article

The aim of the study is to carry out a technical assessment of a Hungarian baths complex, which is a major tourist center with approximately 180,000 visitors per year. The bath complex had been partially closed. Following the partial closure of the spa, a comprehensive survey was carried out, identifying four main problem areas: operational difficulties with the thermal and cold-water wells, outdated water treatment technology, structural damage to the swimming pool and general mechanical deficiencies. Based on these investigations, recommendations were made for a safe and sustainable reopening of the spa, such as the reactivation of the geothermal system, the installation of modern filtration and dosing systems, and the application of energy-efficient and intelligent technologies. Based on the recommendations, the safe, economical, and sustainable reopening of the spa can be achieved, while also providing guidance for the modernization of other spa complexes. A separate section presents detailed development proposals, such as restarting the geothermal system, applying modern water treatment technologies and intelligent control systems, renovating the pool structure, and modernizing the mechanical and electrical systems. These proposals contribute to the modernization of the spa infrastructure and can also provide guidance for solving technical problems in other similar facilities. Full article

The dynamic scheduling optimization of sports facilities faces challenges posed by real-time demand fluctuations and complex interdependencies between facilities. To address the adaptability limitations of traditional centralized approaches, this study proposes a decentralized multi-agent reinforcement learning framework based on graph neural networks (GNNs). Experimental results demonstrate that in a simulated environment comprising 12 heterogeneous sports facilities, the proposed method achieves an operational efficiency of 0.89 ± 0.02, representing a 13% improvement over Centralized PPO, while user satisfaction reaches 0.85 ± 0.03, a 9% enhancement. When confronted with a sudden 30% surge in demand, the system recovers in just 90 steps, 33% faster than centralized methods. The GNN attention mechanism successfully captures critical dependencies between facilities, such as the connection weight of 0.32 ± 0.04 between swimming pools and locker rooms. Computational efficiency tests show that the system maintains real-time decision-making capability within 800 ms even when scaled to 50 facilities. These results verify that the method effectively balances decentralized decision-making with global coordination while maintaining low communication overhead (0.09 ± 0.01), offering a scalable and practical solution for resource management in complex built environments. Full article

The aim of this study was to elucidate all the degradation byproducts (DBPs) of bemotrizinol (BEMT) that are associated with sodium hypochlorite treatment. BEMT is a UV filter that is found not only in many personal care products, such as sunscreen and cosmetics, but also as an additive in plastics or clothing to protect them from damage that results from absorbed radiation. BEMT has been detected in wastewater, surface water, and some lake sediments, in quantities from a few ng/L to hundreds of ng/L, to such an extent that, today, it is considered an emerging pollutant. In this study, the UV filter was subjected to oxidation with sodium hypochlorite, which is an oxidant at the base of the disinfection process that is used in most wastewater treatment plants or in swimming pools. Using different chromatographic methods (CC, TLC, HPLC, and GC), the resulting DBP mixture was separated into its main components, which were then identified using one- and two-dimensional nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry. Nineteen DBPs were isolated, and a plausible reaction mechanism was proposed to explain how they were obtained. Full article

The purpose of the study is to investigate the energy performance of a PVT collector in combination with a heat pump. First, a test system combining a heat pump and PVT module is built, and then its performance is carefully measured, assessing the electricity and heat production. The paper focuses on increasing the efficiency of a photovoltaic (PV) panel (as part of the PVT module) by cooling it with a heat pump. The main idea is to use the heat generated by the warming panels as a low-temperature source for the heat pump. The research aims to maximize the use of solar energy in the form of both electricity and heat. In traditional PV systems, the panel temperature rise reduces the solar-to-electric conversion efficiency. Therefore, cooling with a heat pump is increasingly used to keep panels at optimal temperatures and improve performance. The tests confirm that cooling the panels with a heat pump results in an 11.4% improvement in electrical efficiency, an increase from 10.8% to 12.0%, with an average system efficiency of 11.81% and a temperature coefficient of –0.37%/°C. The heat pump achieves a COP of 3.45, while thermal energy from the PVT panel accounts for up to 60% of the heat input when the air exchanger is off. The surface temperature of the PVT panels varies from 11 °C to 70 °C, and cooling enables an increase in electricity yield of up to 20% during sunny periods. This solution is especially promising for facilities with year-round thermal demand (e.g., swimming pools, laundromats). Full article

Polyurea failures in reinforced concrete tanks, such as swimming pools and sewage treatment plants, require a thorough analysis of the causes of failures during renovation. Urban agglomerations are increasingly relying on these facilities for maintaining city functioning, and the increasing concentration of pollutants in these facilities necessitates urgent repairs due to frequent failures. More thorough analysis should be given to repeated failures on the same object or “twin” objects within a short period, causing high renovation costs and long shutdowns. The causes of failures can be found not only as a result of insufficient knowledge but also in a limited analysis of the entire project from the assumption phase to completion. The article analyzed water and sewage tanks on which failures of applied polyurea coatings occurred many times. The posteriori uses of the risk management analysis with the assessment of the impact and probability of occurrence of the planned activities that failed allows it to be applied a priori and treated as a necessary analysis. For this purpose, in selected repairs, those activities that had the greatest impact on failure and a relatively high probability of occurrence during implementation were distinguished from the entire project. Based on the risk management analysis, it was shown that the basic cause of the failure was the poor knowledge and insufficient experience of the entities performing the repairs, and the errors that occurred could be minimized by conducting good diagnostics of the facility, selecting professional designers and contractors, and constant monitoring of each important activity. Full article

Background/Objectives: This study aimed to investigate the associations of anthropometric characteristics with performance and potential biomarker changes resulting from a continuous 10 h ultra-marathon swimming effort in regional-level swimmers. Methods: Nine adult male swimmers (age: 43 ± 6 years) participated in a 10 h swim in a 50 m outdoor pool, self-managing their nutrition and hydration breaks. Pre- and post-swim measurements included body weight (BW), body fat percentage (BF%), limb lengths (LL), circumferences (C), lean mass (LM), body mass index (BMI), skinfold thicknesses, heart rate (HR) and blood pressure (BP). Results: A significant reduction was observed in bicep skinfold thickness (Fb) (p = 0.022), while both HR and systolic BP increased post-effort (p = 0.030 and p = 0.045, respectively). Also, most anthropometric parameters, such as BMI, LM, and some C, remained unchanged (p ≥ 0.05). A statistically significant negative correlation was found between post-swim hip circumference (Ph) and total swimming distance (r = –0.682, p = 0.043). Conclusions: While most anthropometric traits remained stable and unrelated to performance, isolated changes in specific biomarkers indicate a physiological response to prolonged exertion. Although pacing and nutritional strategies were not directly examined, observational data—such as consistent swimming rhythm, time allocation for active recovery (AR), and structured carbohydrate intake—suggest these factors may have contributed to performance maintenance and probably the lack of body composition differences after the ultra-marathon effort. These insights are interpretive and align with the existing literature, highlighting the need for future studies with targeted experimental designs. Full article

Free-living amoebae (FLA) such as Acanthamoeba spp., Balamuthia mandrillaris, Naegleria fowleri, Sappinia pedata, Vermamoeba vermiformis and Vahlkampfia spp. are causal agents of deadly and/or disabling infections in humans. Despite recent data showing an increase in infection cases worldwide, studies on the prevalence of these emerging pathogens in water sources are scarce. Moreover, climate change is believed to facilitate the expansion and persistence of these environmental pathogens, further emphasizing the need for comprehensive surveillance. Therefore, the current study investigates the variety and abundance of free-living amoebae in different water sources in the autonomous community of Castilla y León, Spain, during different seasons of the year. Vermamoeba vermiformis was the most prevalent species and was detected in rivers, swamps, irrigation waters, swimming pools and recreational fountains. Moreover, genera such as Acanthamoeba and Naegleria and Vahlkampfia were also identified. This study highlights the diversity of FLA in the region and their relationship with local water characteristics. Given that certain FLA species are opportunistic pathogens, these results emphasize the necessity of monitoring this area and water sources. Full article

Background/Objectives: This study aimed to identify and analyze the risk factors associated with Cryptosporidium infection in hospitalized patients in western Romania. Methods: A total of 312 patients, aged between 2 months and 90 years and residing in both urban and rural communities, were included. Stool samples were collected and analyzed using the CerTest Crypto qualitative chromatographic test and the modified Ziehl–Neelsen staining method (Henricksen & Pohlenz). Risk factors were assessed through a questionnaire completed by patients or by the parents of pediatric patients. Results: The overall prevalence of Cryptosporidium infection was 5.77%. Among the evaluated risk factors, only the area of residence showed a statistically significant association (p < 0.05), with a higher prevalence in urban areas (9.2%) compared to rural areas (3.6%). Other factors—including age, gender, contact with animals, pet ownership, handwashing after animal contact, type of housing, fruit washing habits, use of potable water, use of public transportation, international travel, and visits to playgrounds or swimming pools—were not significantly associated with infection. Conclusions: These findings suggest that urban residency may be a significant factor in Cryptosporidium transmission and may inform future research and the development of targeted public health strategies. Full article

Ground-based movable roof construction offers advantages such as flexible adjustment, energy conservation, environmental protection, improved comfort, structural stability, and high space utilization. However, it faces technical challenges such as complex structure, high cost, and high maintenance expenses. This paper, based on the practical experience of the Hainan Lingshui Swimming Pool project, uses numerical calculations to analyze the mechanical characteristics of a ground-based movable roof’s track beam and roof structure. The results show that by using a two-point lifting method based on the center of gravity and structural characteristics, finite element simulations indicate that the top of the inverted L-shaped main beam deflects upward by 0.27 cm, and the cantilever end deflects downward by 2.08 cm. Under the combination of dead load + live load, the semi-ground-based roof has a mid-span deflection of 70 mm, with linear and nonlinear stability safety factors of 5.9 and 3.2, respectively. After optimizing the track beam, the deformation at 15 m did not meet the requirements, and the cost at 20 m was too high. Ultimately, a pile length of 18 m was selected. Full article

Background: It is thought that swimming might elicit remarkable chronic lung function improvements that were not observed in land-based sports. However, there is no consensus on whether this is mainly attributable to genetic predisposition or specific training. This study aimed to characterize athletes’ lung function according to their swimming experience. Methods: The sample consisted of 45 male athletes, including 15 swimmers, 15 triathletes, and 15 runners. Spirometry tests were conducted under four conditions: seated on land, prone on land, seated while immersed in water, and prone while immersed in water. The tests were performed on the pool deck and pool, with the order of conditions randomized for each participant. Conclusions: The results of this study do not support the idea that there is a window of opportunity for greater lung function adaptations during childhood due to swim training. The accumulated years of swim training are the reason for the increased measurements of FVC and FEV₁ of swimmers. The immersed seated condition measures differences in lung function more accurately relative to swim training experience. Swim training appears to primarily enhance FVC in healthy athletes, while in allergic and asthmatic athletes, it mainly promotes improvements in FEV₁/FVC and FEF_25–75%. Full article

The traditional method for the establishment of the green laser underwater transmission model is purely based on the laser transmission mechanism in waterbodies, while neglecting a few exterior conditions. This paper proposes a novel method to establish the underwater transmission model from a maximum measurement depth perspective by refining the dynamic relationship between the effective received power P_A and the background noise power P_B. Different from the traditional empirical model of fixed P_A/P_B, this method combines the sensor, flight, and environmental parameters of airborne LiDAR (ALB) to achieve the dynamic calibration of P_A and P_B. In particular, the empirical relationship between the maximum underwater measurement depth and the laser attenuation coefficient, coupled parameters, etc., is considered. The established model is verified by different types of experiments. The experimental results discovered that the errors are approximately 0.86 m and 1.28, under the same water conditions, when compared to the existing models. The validation experiments demonstrated that the errors for the maximum depth prediction were 0.38 m (indoor tank), 1.58 m (indoor swimming pool), 0.44 m (Li River, Guangxi), and 1.20 m (Beibu Gulf, Pacific Ocean). The experimental results demonstrated that the established model enables us to widely predict the maximum water depth measurable using an airborne LiDAR under different environmental conditions. Full article