Pool Water Treatment Research Articles

Ecotoxicity of Biocides (Chemical Disinfectants) - Lethal and Sublethal Effects on Non-target Organisms

The aim of this paper was to assess de ecotoxicity effects of four biocides, used as chemical disinfectants for swimming pool water treatment, on non-target organisms such as Daphnia magna and Heterocypris incongruens crustaceans. The tests showed a significant difference of sensitivity between species. The biocides, at the recommended disinfection doses, induced a very toxic or toxic effect on Daphnia magna, based on their mortality percentage. On the contrary, the observed ostracods lethal effects were generally less than 50% mortality and no significant growth inhibitions were observed. Overall, the ostracods had a higher tolerance to subacute doses, including disinfection doses of 20 mg/L (potassium mono persulfate), 5 mg/L (sodium dichloroisocyanurate), 8 mg/L (trichloroisocyanuric acid 90%) and 7 mg/L (trichloroisocyanuric acid 87-88%). In the context of a continuous biocides market expansion, the paper highlighted that our research proposed testing methods to obtain fast and accurate ecotoxicity data for a sustainable biocide production / authorization and also for an environmental hazard assessment.

Application of UVOX Redox® for swimming pool water treatment: Microbial inactivation, disinfection byproduct formation and micropollutant removal

Alternative disinfection technologies may overcome some of the limitations of conventional treatment applied in swimming pools: chlorine-resistant pathogens (e.g. Cryptosporidium oocysts and Giardia cysts) and the formation of chlorinated disinfection byproducts. In this paper, results of full scale validation of an alternative disinfection technology UVOX Redox® (hereinafter referred to as UVOX) that combines ozonation and UV irradiation are presented. The performance was assessed in terms of microbial inactivation, disinfection byproduct formation and micropollutant removal. UVOX was able to achieve 1.4–2.7 log inactivation of Bacillus subtilis spores at water flows between 20 and 76 m³/h. Lower formation of trichloromethane and dichloroacetic acid was observed with UVOX followed by chlorination when compared to chlorination alone. However, due to the use of ozone and the presence of bromide in the pool water, the formation of trihalomethanes and haloacetic acids shifted to more brominated byproducts. Chlorine alone was able to remove the target micropollutants: acetaminophen, atenolol, caffeine, carbamazepine, estrone, estradiol, and venlafaxine (>97% removal) after 24 h, with the exception of ibuprofen (60% removal). The application of UVOX in chlorinated water enhanced the removal of ibuprofen. The application of UVOX could lower the usage of chlorine to the level that provides an adequate residual disinfection effect.

N2 yields from monochloramine conversion by granular activated carbons are decisive for effective swimming pool water treatment

Inorganic chloramines (mono-, di- and trichloramine) are formed in swimming pool water from the unintended reaction of free chlorine with ammonia that is introduced by bathers. Monochloramine is of particular interest as it is known to react further in pool water forming harmful DBPs, such carcinogenic N-nitrosodimethylamine (NDMA). During pool water treatment with granular activated carbon (GAC) filters, monochloramine is transformed by chemical reactions on the carbon surface to N2 and ammonia. As ammonia is led back into the pool where it is chlorinated again under the renewed formation of inorganic chloramines, it is recommended to use GACs with a high N2 yield for monochloramine transformation in pool water treatment.In this study, yields of N2 and ammonia from monochloramine conversion by commercially available GACs were determined using a fixed-bed reactor system under conditions that are typical for swimming pool water treatment. The N2 yields remained constant with on-going exposure of the GAC to monochloramine and ranged from 0.5% to 21.3%, depending on the type of GAC used. Correlation analyses were conducted to identify carbon properties that can determine the N2 yield for monochloramine conversion, such as the amount of oxygen groups, the elemental composition and the trace metal content. It was found that the N2 yield significantly correlates with the copper content of the tested carbons. Model calculations combining pool hydraulics with formation/abatement of inorganic chloramines and NDMA as well as chloramine transformations in GAC filters showed that the concentration of inorganic chloramines and carcinogenic NDMA can be decreased by a factor of ∼2, if the tested GACs could be modified to convert up to ∼50% of the monochloramine to N2.

Occurrence of Antibiotic-Resistant Bacteria in Therapy Pools and Surrounding Surfaces.

The number of patients colonized with antibiotic-resistant bacteria is increasing in health care facilities. Because transmission of antibiotic-resistant bacteria is feared, there exist reports that the affected patients are frequently excluded from hydrotherapy, which is a non-invasive and beneficial treatment used for patients with different diseases. Data from the literature suggest that deficient water disinfection measures exist, which are not always sufficient to kill all released bacteria. If the pool water is not disinfected properly, it may also infect the bathers. Immunocompromised patients are particularly susceptible to be infected with (antibiotic-resistant) bacteria. In order to determine the distribution of antibiotic-resistant bacteria in the pool water treatment system and the pool environment and to estimate the associated transmission risk we analyzed samples from eleven health care facilities. Antibiotic-resistant bacteria were found in the water and surface samples collected. One hundred and two antibiotic-resistant isolates from water samples and 307 isolates from surrounding surfaces were obtained, respectively. The majority of the isolates belonged to non-fermenting Gram-negative rods, like Pseudomonas spp. Some isolates were resistant to a wide range of the tested antibiotics. The results indicate a relation between the number of isolates in water samples and the number of patients using the pools in combination with deficiencies in water treatment. In the pool environment the highest number of isolates was obtained from barefoot areas and floor cleaning equipment.

Lonza to sell water treatment business

Lonza has signed a definitive agreement to sell its water treatment business to the private equity firm Platinum Equity for $630 million. The pharmaceutical and specialty ingredient maker says the divestment will allow it to focus on its core health care business. Lonza acquired the pool and industrial water treatment operation as part of its acquisition of Arch Chemicals in 2011.

Degradation of UV-filter Benzophenon-3 in aqueous solution using TiO2 coated on quartz tubes.

BackgroundBenzophenone-3 (BP-3), one of the emerging pollutants, is commercially synthesized as UV filter used in cosmetics and other personal care products and its occurrence in the aquatic environment has widely been reported. The goal of this study was to enhance an AOP method for degradation of UV filter Benzophenone-3 in aqueous solutions.MethodIn this study, sol-gel method was applied to synthesis TiO2 nanoparticles. Subsequently, the nanoparticles were successfully coated on quartz tubes. The synthesized catalyst was characterized using XRD, FE-SEM and EDX analysis. Then, the efficiency of photocatalytic process using TiO2 coated quartz tubes for BP-3 degradation from synthetic and real aqueous solution was assessed.ResultThe optimum contact time and solution pH for the highest BP-3 degradation in the synthetic solution were found at 15 min and 10, respectively. The maximum degradation (98%) of BP-3 by photocatalytic process was observed at 1 mg/L initial BP-3 concentration using 225 cm2 of catalyst surface area. Among the three applied kinetic models, the experimental data were found to follow the first-order equation more closely with the rate constant of 0.2, 0.048 and 0.035 1/min for 1, 3 and 5 mg/L of initial BP-3 concentration, respectively. In order to investigate the potential of this process for real effluent, the treatment of swimming pool water and wastewater treatment plant was examined and BP-3 degradation close to 88% and 32.1 was achieved, respectively.ConclusionBased on the obtained data, the photocatalytic process could successfully be applied for water treatment in swimming pools and other effluent containing BP-3 with low turbidity. The advantage of this study is that the synthesized catalyst can be used repeatedly needless to remove catalyst from the treated solution. In addition, AOPs can effectively eliminate organic compounds in aqueous phase, rather than transferring pollutants into another phase. The limitation of this study is that in solution with high turbidity photocatalytic degradation can be hampered and pre- treatment is needed to reduce turbidity.

Ocena wpływu systemu cyrkulacji na poziom stężeń mikrozanieczyszczeń w układzie oczyszczania wody basenowej

Ocena wpływu systemu cyrkulacji na poziom stężeń mikrozanieczyszczeń w układzie oczyszczania wody basenowej

Nanofiltration treatment of swimming pool water in the aspect of the phenolic micropollutants elimination

Nanofiltration treatment of swimming pool water in the aspect of the phenolic micropollutants elimination

Contemporary aspects in the assessment of quality and treatment of swimming pool water

Recent reports in the literature relate to the identification of various substances in the pool water, including low-molecular weight pharmaceuticals that can react with chlorine residues contributing to the formation of a large group of irritant and toxic compounds. These substances are not covered by standard monitoring. As part of this work, the authors present information on the methods for assessing the quality of the swimming pool water. Common processes used in swimming pool water treatment systems were described. Previous experience of the authors in the use of a detailed assessment of the quality of the swimming pool water on the basis of toxicity tests was presented. The authors have researched the application of pressure driven membrane filtration for the improvement of the efficiency of the swimming pool water treatment.

The Reuse of Washings from Pool Filtration Plants After the use of Simple Purification Processes

Abstract The main purpose of the research is to show the possibility of using washings after applying simple processes and devices. It is being considered whether they may be drained to watercourses, to the ground, used for watering plants, sprinkling tennis courts and playing fields, flushing toilets or recycled into pool systems. The research concept consisted of comparing the results of physico-chemical analysis of washings samples with the limit values for pollutants in wastewater discharged to water and ground. The research was carried out for 20 pool water treatment plants. It has been shown that the concentration of TSS (total suspended solids) and free chlorine in washings are the main parameters preventing their drainage to the natural environment. The processes of sedimentation or sedimentation assisted by coagulation allow to reduce the TSS concentration below the limit value and leaving the washings to stand for up to several hours or subjecting them to a few minutes of aeration decreases the concentration of free chlorine to an acceptable level. The obtained research results allow to assume that the management of washings in all tested swimming pools would be possible after applying a settler or a settling tank with a coagulant chamber and then a chamber for aeration.

Impact of the UV Lamp Power on the Formation of Swimming pool Water Treatment By-Products

Abstract The operation of swimming pools requires a constant monitoring of water quality parameters and protection of water against pathogens. This is implemented by various disinfection methods, among which the most commonly used are based on chlorine action supported by ozone or UV irradiation. The paper presents the comparison of the effectives of organic micropollutants decomposition occurring in swimming pool water during UV irradiation emitted by a 15 and 150 W UV lamp. The tests were conducted on real swimming pool water collected from a sport basin. The identification and the determination of micropollutants concentration were performed by the use of gas chromatography GC-MS (EI) preceded by solid-phase extraction SPE. It was shown that the concentration of micropollutants decreases with the increase in the irradiation time of pool water. The 150 W UV lamp allowed for an over 33% removal of micropollutants from the group of pharmaceuticals compounds (except for caffeine) and more than 76% decrease of other compounds, which belong to the group of personal care products additives, food additives and phthalates. In addition, it has been demonstrated that during the irradiation of such complex water matrixes as swimming pool water, a significant number of micropollutants degradation by-products were formed, which are not found in water before UV irradiation.

Pore diffusion limits removal of monochloramine in treatment of swimming pool water using granular activated carbon.

Overall apparent reaction rates for the removal of monochloramine (MCA) in granular activated carbon (GAC) beds were determined using a fixed-bed reactor system and under conditions typical for swimming pool water treatment. Reaction rates dropped and quasi-stationary conditions were reached quickly. Diffusional mass transport in the pores was shown to be limiting the overall reaction rate. This was reflected consistently in the Thiele modulus, in the effect of temperature, pore size distribution and of grain size on the reaction rates. Pores <2.5 times the diameter of the monochloramine molecule were shown to be barely accessible for the monochloramine conversion reaction. GACs with a significant proportion of large mesopores were found to have the highest overall reactivity for monochloramine removal.

Test of precoat filtration technology for treatment of swimming pool water.

The technical performance of a precoat filter was compared with that of a traditional sand filter. Particle concentration and size distribution were measured before and after the filtration of swimming pool water. Both the sand and precoat filters could reduce the particle concentration in the effluent. However, higher particle removal efficiency was generally observed for the precoat filter, especially for particles smaller than 10 μm in diameter. Adding flocculant improved the removal efficiency of the sand filter, resulting in removal efficiencies comparable to those of the precoat filter. Three powders, i.e., two types of perlite (Harbolite® and Aquatec perlite) and cellulose fibers (Arbocel®), were tested for the precoat filter, but no significant difference in particle removal efficiency was observed among them. The maximum efficiency was reached within 30-40 min of filtration. The energy required for the pumps increased by approximately 35% over a period of 14 days. The energy consumption could be reduced by replacing the powder on the filter cloth. The sand filter was backwashed once a week, while the powder on the precoat filter was replaced every two weeks. Under these conditions, it was possible to reduce the water used for cleaning by 88% if the precoat filter was used instead of the sand filter.

Assessment of the possibility of using flocculation to improve properties of ultrafiltration membranes used in the purification of swimming pool water system washings

The paper presents the possibility of using an in-line mode flocculation–ultrafiltration system for the purification of backwash water from flushing the beds of pressure filters used in the indoor swimming pool water treatment circulation. The effect of flocculation operational conditions (the flocculant dose in the range from 16 to 240 mg/dm 3 and the process temperature of 8–30°C) on the transport-separation properties of ultrafiltration membranes has been examined. To establish the effectiveness of the conducted processes, the contaminant retention coefficients, among others, were determined (based on the measurements of turbidity and UV254 ultraviolet absorbance). A significant influence of the flocculation process operational parameters on the performance of ultrafiltration was noted. With increasing flocculant dose, the efficiency of contaminant removal in the ultrafiltration process increased simultaneously. Moreover, the change in the temperature conditions of the flocculation process had a fundamental effect on the transport properties of the ultrafiltration membranes. The most advantageous temperature for conducting the processes was considered to be 21°C. Under those conditions, all flocculant doses contributed to a significant improvement in the transport properties of the ultrafiltration membranes. High values of the contamination retention coefficients and the permeate volumetric flux were obtained already at a flocculant dose of 80,160 and 240 mg/dm 3 .

Combined UV treatment and ozonation for the removal of by-product precursors in swimming pool water

Both UV treatment and ozonation are used to reduce different types of disinfection by-products (DBPs) in swimming pools. UV treatment is the most common approach, as it is particularly efficient at removing combined chlorine. However, the UV treatment of pool water increases chlorine reactivity and the formation of chloro-organic DBPs such as trihalomethanes. Based on the similar selective reactivity of ozone and chlorine, we hypothesised that the created reactivity to chlorine, as a result of the UV treatment of dissolved organic matter in swimming pool water, might also be expressed as increased reactivity to ozone. Moreover, ozonation might saturate the chlorine reactivity created by UV treatment and mitigate increased formation of a range of volatile DBPs. We found that UV treatment makes pool water highly reactive to ozone. The subsequent reactivity to chlorine decreases with increasing ozone dosage prior to contact with chlorine. Furthermore, ozone had a half-life of 5 min in non-UV treated pool water whereas complete consumption of ozone was obtained in less than 2 min in UV treated pool water. The ozonation of UV-treated pool water induced the formation of some DBPs that are not commonly reported in this medium, in particular trichloronitromethane, which is noteworthy for its genotoxicity, though this issue was removed by UV treatment when repeated combined UV/ozone treatment interchanging with chlorination was conducted over a 24-h period. The discovered reaction could form the basis for a new treatment method for swimming pools.

Effects of UV-based treatment on volatile disinfection byproducts in a chlorinated, indoor swimming pool

Ultraviolet (UV) irradiation and chlorination are commonly used together in treatment of swimming pool water because they function as complementary disinfectants and because UV-based processes have been shown to promote photodecay of chloramines. However, UV-based treatment also has the potential to promote formation of some disinfection byproducts (DBPs). As a result, the overall effects of UV irradiation with chlorination on swimming pool chemistry remain unclear. To address this issue, a three-year study was conducted in a chlorinated, indoor swimming pool under three different operating conditions: conventional chlorination (1st year) which served as a control, chlorination augmented by MP UV irradiation (2nd year), and chlorination augmented by LP UV irradiation (3rd year). Water samples were collected from the pool for measurement of pH, temperature, total alkalinity, free and combined chlorine, eleven volatile DBPs, and urea concentration. After installation of MP UV, the concentrations of most volatile DBPs decreased; similar effects were observed after inclusion of LP UV. Collectively, these results imply an overall improvement in water quality as a result of the inclusion of the both UV systems. In general, MP UV was more efficient than LP UV for reducing the concentrations of most of the volatile DBPs measured in this pool. However, a need exists to standardize the application of UV systems in recreational water settings.

Assessment of the possibility of recycling backwashing water from the swimming pool water treatment system

Assessment of the possibility of recycling backwashing water from the swimming pool water treatment system

Occurrence and simulation of trihalomethanes in swimming pool water: A simple prediction method based on DOC and mass balance

Trihalomethanes (THM) are the most typical disinfection by-products (DBPs) found in public swimming pool water. DBPs are produced when organic and inorganic matter in water reacts with chemical disinfectants. The irregular contribution of substances from pool visitors and long contact time with disinfectant make the forecast of THM in pool water a challenge. In this work occurrence of THM in a public indoor swimming pool was investigated and correlated with the dissolved organic carbon (DOC). Daily sampling of pool water for 26 days showed a positive correlation between DOC and THM with a time delay of about two days, while THM and DOC didn't directly correlate with the number of visitors. Based on the results and mass-balance in the pool water, a simple simulation model for estimating THM concentration in indoor swimming pool water was proposed. Formation of THM from DOC, volatilization into air and elimination by pool water treatment were included in the simulation. Formation ratio of THM gained from laboratory analysis using native pool water and information from field study in an indoor swimming pool reduced the uncertainty of the simulation. The simulation was validated by measurements in the swimming pool for 50 days. The simulated results were in good compliance with measured results. This work provides a useful and simple method for predicting THM concentration and its accumulation trend for long term in indoor swimming pool water.

Secondary formation of disinfection by-products by UV treatment of swimming pool water

Formation of disinfection by-products (DBPs) during experimental UV treatment of pool water has previously been reported with little concurrence between laboratory studies, field studies and research groups. In the current study, changes in concentration of seven out of eleven investigated volatile DBPs were observed in experiments using medium pressure UV treatment, with and without chlorine and after post-UV chlorination.Results showed that post-UV chlorine consumption increased, dose-dependently, with UV treatment dose. A clear absence of trihalomethane formation by UV and UV with chlorine was observed, while small yet statistically significant increases in dichloroacetonitrile and dichloropropanone concentrations were detected. Results indicate that post-UV chlorination clearly induced secondary formation of several DBPs. However, the formation of total trihalomethanes was no greater than what could be replicated by performing the DBP formation assay with higher chlorine concentrations to simulate extended chlorination. Post-UV chlorination of water from a swimming pool that continuously uses UV treatment to control combined chlorine could not induce secondary formation for most DBPs. Concurrence for induction of trihalomethanes was identified between post-UV chlorination treatments and simulated extended chlorination time treatment. Trihalomethanes could not be induced by UV treatment of water from a continuously UV treated pool. This indicates that literature reports of experimentally induced trihalomethane formation by UV may be a result of kinetic increase in formation by UV. However, this does not imply that higher trihalomethane concentrations would occur in pools that apply continuous UV treatment.The bromine fraction of halogens in formed trihalomethanes increased with UV dose. This indicates that UV removes bromine atoms from larger molecules that participate in trihalomethane production during post-UV chlorination.Additionally, no significant effect on DBP formation was observed due to photo-inducible radical forming molecules NO3− (potentially present in high concentrations in pool water) and H2O2 (added as part of commercially employed DBP reducing practices).

Comparison of chloramine concentration in swimming pool water depending on swimming pool intended use

Swimming pool water is a mixture of supplementary water added to a closed pool circuit (usually from water supply system) and water from a pool basin, constantly purified and disinfected because of its pollution caused by bathing people. In public swimming pools, in accordance with hygiene guidelines, disinfection by chlorine compounds is required. The most commonly used is sodium hypochlorite disinfectant. The disinfectant properties of chlorine are related to its ability to oxidize organic and inorganic compounds, and the result of water chlorination is the formation of disinfection by-products (DBP). Among the most troublesome DBPs for bathers and service facility of the swimming-pool are chloramines. Chloramines are responsible for the so-called syndrome of swimmers irritation, dry skin, irritation of the mucous membranes of the nose, throat and eyes. They give the pool water and the air in the pool hall a characteristic odor and have mutagenic properties. Therefore, analyzing chloramines concentrations and taking actions, in the field of pool water treatment, in order to reduce them are very important. The primary purpose of this paper is to present the distribution of chloramines concentrations (monochloramine and dichloramine) in the pool water, depending on the pool intended use (school training pool, sports pool, pool for children to play, pool with hydromassage and water tunnel). The analysis of the results of research takes into account the swimming pool water treatment systems, exploitation parameters and the number of people bathing. The comparison of parameters (physical, chemical and bacteriological) defining the quality of the pool water, with particular emphasis on the chloramines concentrations, allows to assess the efficiency of the treatment system and the usefulness of the water to swim and bathe in relation to DIN 19643 standards.