Application of nanosilver in swimming pool water treatment technology Joanna Wyczarska-Kokot and Florian Piechurski joanna.wyczarska-kokot@polsl.pl Silesian University of Technology florian.piechurski@polsl.pl Institute of Water and Wastewater Engineering Poland 2 nd International Electronic Conference on Water Science (ECWS-2), 16- 30 November 2017’
The main aim of this work is to present possibility of applying a colloidal solution of nanosilver in a closed circuit of swimming pool water treatment. The applied nanosilver solution is characterized as having a very high biocidal effect, with no negative impact on the human and animal body, or the environment. Silver nanoparticles are known as excellent antimicrobial agents and therefore they could be used as alternative disinfectant agents for the disinfection of drinking water or recreational water ( O’Brien et al. 2010; Zang Introduction 2013; Tugulea et al. 2014; Yang 2017 ). In the tested swimming pool, during morning hours, there are physiotherapy sessions for patients suffering from various injuries. In the afternoon, there are swimming lessons for infants and their parents. Strict requirements regarding swimming pool water ( WHO 2006; DIN 19643, 2012; Decree of the Health Minister 2015 ) caused traditional and one-stage filtration systems to be insufficient ( Lee et al. 2010; Cheema et al. 2017, Chowdhury et al. 2014, Wyczarska-Kokot 2014 ). 2 nd International Electronic Conference on Water Science (ECWS-2), 16- 30 November 2017’
Materials and Methods Water treatment system in the tested swimming pool 2 nd International Electronic Conference on Water Science (ECWS-2), 16- 30 November 2017’
Samples of pool water for the control of water quality variation in the treatment cycle were taken from 5 points: from pool basin ( SP ), retention tank ( RT ) just before filter ( BF ), Materials and just after filter but before UV lamp ( AF ) Methods from water supply system replenishing water lost from swimming pool circuit ( WS ). Sampling points 2 nd International Electronic Conference on Water Science (ECWS-2), 16- 30 November 2017’
The water samples were subjected to bacteriological and physicochemical analyses that measured basic control parameters of pool water quality. The obtained tests results were compared against the recommendations of: Guidelines for safe recreational water environments. Vol.2: Guidance for the Swimming pools and similar environments, WHO 2006. quality of DIN 19643. Water treatment for swimming and bathing pools, swimming pool 1997 and 2012 (German). water ZHK NIZP-PZH. Recommendations on sanitary and hygienic requirements for swimming pools and water quality in pools for babies and children from 6 months to 3 years old, 2012 (Poland). Decree of the Health Minister on the requirements for water in swimming pools, 2015 (Poland). 2 nd International Electronic Conference on Water Science (ECWS-2), 16- 30 November 2017’
Recommended Parameter SP RT BF AF WS value in SP [1-5] Total plate count in 2.5·10 3 5.7·10 2 2.8·10 3 2.6·10 3 36 ° C after 48 hours 1 1 1 0 18 5 0 0 42 1 12 2 4 0 0 23 <100 (CFU/1ml) Results and Coliform bacteria of the fecal type <5 0 0 0 <5 0 0 0 <5 0 0 0 <5 0 0 0 <5 0 0 0 0 Discussion (CFU/100ml) Escherichia coli <5 0 0 0 <5 0 0 0 <5 0 0 0 <5 0 0 0 <5 0 0 0 0 (CFU/100ml) Bacteriological parameters of water quality in tested Legionella sp. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 140 14 4 0 (CFU/100ml) pool circuit Pseudomonas aeruginosa 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 (CFU/100ml) Coagulase-positive staphylococci 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 - (CFU/100ml) 2 nd International Electronic Conference on Water Science (ECWS-2), 16- 30 November 2017’
7.45 7.42 7.40 7.35 The parameters of water quality pH (-) in the pool basin were compliant Results and 7.30 7.31 7.30 with the requirements in this 7.25 Discussion regard. 7.25 7.24 Water pH in every collection 7.20 point was within the required 7.15 range, i.e. 6.5 ÷ 7.6 SP RT BF AF WS Physical and chemical parameters of water 780 quality in tested pool 760 758 circuit: The redox values further 740 740 738 pH, 720 confirmed the effectiveness Redox (mV) 715 700 Redox of protecting the pool water 680 against bacteriological 660 contamination. 640 650 The required minimum in SP 620 is 750 mV. 600 580 SP RT BF AF WS 2 nd International Electronic Conference on Water Science (ECWS-2), 16- 30 November 2017’
0.45 A systematic decrease in free chlorine 0.40 concentration was observed in water 0.41 Free chlorine (mgCl 2 /dm 3 ) 0.38 0.35 samples taken from the subsequent parts 0.35 of the pool circuit (filtering the water 0.30 through a filtration bed with an anthracite 0.25 Results and layer decreased it by 88.6%). 0.20 The required range in SP is 0,3 ÷ 0.6 mgCl2/L. 0.15 Discussion 0.10 0.05 0.04 0.02 0.00 SP RT BF AF WS Physical and chemical 0.35 Due to the adverse effects on the bathers, parameters of water the permissible content of combined quality in tested pool Combined chlorine (mgCl 2 /dm 3 ) 0.30 0.31 chlorine in pool water according to WHO 0.30 0.30 circuit: 0.28 and DIN 19643 is 0.2 mgCl2/L, and according 0.25 to Decree of the Health Minister of Poland Free chlorine, 0.20 is 0.3 mgCl2/L. There were no complaints Combined chlorine from the bathers when the concentrations 0.15 of combined chlorine in water in the pool 0.10 basin exceeded the concentrations stipulated in DIN19643, on average, 0.05 0.06 by 0.11 mgCl2/L. 0.00 SP RT BF AF WS 2 nd International Electronic Conference on Water Science (ECWS-2), 16- 30 November 2017’
0.070 The low levels of silver in 0.060 pool water samples about 0.060 0.060 0.008 mg/L did not cause a 0.050 Silver (mg Ag/dm 3 ) risk to the health of bathers. 0.040 Results and Silver concentrations up to 0.030 0.1 mg/L may be tolerated in Discussion 0.020 the case of silver salts to 0.010 maintain the bacteriological 0.008 0.002 0.002 quality of drinking water. 0.000 Physical and chemical SP RT BF AF WS parameters of water 1.40 quality in tested pool 1.20 During the tests, in the majority circuit: 1.15 1.00 COD (mgO 2 /dm 3 ) of samples, oxidisability index Silver, 0.80 0.86 COD 0.84 (COD) was below 1.0 mgO2/L and 0.82 0.60 the permissible value is 0.59 4*mgO2/L. 0.40 0.20 * Difference in COD values in swimming pool water and COD in water supplementing circulation 0.00 system. SP RT BF AF WS 2 nd International Electronic Conference on Water Science (ECWS-2), 16- 30 November 2017’
250 200 202 Chlorides (mgCl - /dm 3 ) The systematic increase 150 Results and 153 153 150 of chlorides and nitrates in SP 100 during the filtration cycle Discussion indicated that an insufficient 50 amount of water was taken 12 into the pool circuit. 0 Physical and chemical SP RT BF AF WS parameters of water The permissible value in SP for 4.50 quality in tested pool chlorides is 250 mgCl - /L and for 4.00 4.07 4.03 4.03 4.03 circuit: - /L. nitrates is 20 mgNO 3 3.50 - /dm 3 ) Chlorides, 3.00 Nitrates (mgNO 3 Nitrates 2.50 2.00 1.86 1.50 1.00 0.50 0.00 SP RT BF AF WS 2 nd International Electronic Conference on Water Science (ECWS-2), 16- 30 November 2017’
The performed tests indicate the effectiveness of the proposed pool water treatment system incorporating dosing of nanosilver colloidal solution, vacuum filter with multilayered bed, and irradiating the circuit water with UV light. Despite the use of the colloidal solution of nanosilver, as bacteriostats product, it was found that favorable conditions for the development of bacterial colonies were present in the bed. Conclusions The anthracite and sand filtration bed facilitated the growth of bacteria which then were washed out to the filtrate. Although CFU of bacteria in the filtrate samples was high, water from the pool basin contained only 1 CFU/1mL (permissible number: 100 CFU/1mL). Thus, the two-step disinfection (UV + NaOCl) was sufficient to ensure safe bath. 2 nd International Electronic Conference on Water Science (ECWS-2), 16- 30 November 2017’
Joanna.Wyczarska-Kokot@polsl.pl Florian.Piechurski@polsl.pl Acknowledgments Institute of Water and Wastewater Engineering, Gliwice, Poland This research was financed from the resources allocated by the Ministry of Science and Higher Education, Poland 2 nd International Electronic Conference on Water Science (ECWS-2), 16- 30 November 2017’
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