The first thing to determine in the design of swimming pool is the water quality standard to be implemented. The Hygienic Standard for Water Quality of Artificial Swimming Pool in China's Hygienic Standard for Swimming Places (GB 9667- 1996) generally reflects that the index is too low in the implementation process, which is quite different from the items stipulated by foreign swimming pool water quality standards. If FINA water quality hygiene standards are fully implemented, some indicators are too high, which is not in line with China's national conditions. FINA cancelled the specific requirements for water quality and hygiene in the 2002-2005 edition (Chapter 14) in the 2005-2009 edition of International Competition Rules, and proposed in the general rules that the hygiene, health and safety of swimming pools should comply with the local laws and regulations of the host country. The 2008 Olympic Games will be held in China, so it is obviously impossible to implement GB 9667- 1996. It is necessary to formulate a new Water Quality Standard for Swimming Pools.
According to the requirements of the standard building letterNo. 102 of the Ministry of Construction. 20058 1, the 2005 revision plan of industrial product industry standard of the Ministry of Construction, edited by China Architectural Design and Research Institute, and compiled by China Swimming Association, China Center for Disease Control and Prevention, Environment and Health-related Product Safety Institute and other units 12, the product standard of urban construction industry, Swimming Pool Water Quality Standard (hereinafter referred to as "Standard").
1 the principle of "standard"
(1) The determination of water quality indicators should have sufficient basic data and feasible detection methods.
(2) The water quality limit should ensure good water texture, prevent the outbreak of water-borne infectious diseases and other health hazards, and should also consider its treatment technology and laboratory testing costs.
(3) According to the World Health Organization (WHO) Water Environment Guide for Swimming Pools and Massage Pools (2006 Edition), referring to the swimming pool water quality standards of advanced countries and regions, and combining the comprehensive analysis and demonstration of China's national conditions, relevant items and limits should be formulated.
(4) The "standard" must conform to China's national conditions and be operable.
(5) The Standard applies to artificial swimming pools (including indoor and outdoor competition swimming pools, public swimming pools, commercial swimming pools, special swimming pools and leisure swimming pools).
(6) The water quality standards of international competition swimming pools should also meet the requirements of FINA.
(7) The Standard does not apply to swimming pools with seawater and hot spring water as raw water and swimming pools in natural waters.
2. Main contents of the Standard
The water quality of swimming pool should meet the following requirements: the sensory characteristics of water are good; The water contains no pathogenic microorganisms; Chemicals contained in water shall not endanger human health.
(1) See table 1 for routine inspection items and limits of swimming pool water quality.
Table 1 Routine Inspection Items and Limits of Swimming Pool Water Quality
Serial number item limit value
1 turbidity /NTU ≤ 1
2 PH 7.0~7.8
3 Urea/mg/L ≤3.5
The total number of colonies was (3665438 0)℃, and 48h/cfu/ml was ≤ 200.
5. The total coliform group is (36 1)℃, and it cannot be detected every100 ml for 24 hours.
6 Free residual chlorine/mg/L 0.2~ 1.0
7 combined residual chlorine/mg/l ≤0.4
8 ozone (when ozone is used for disinfection) /mg/m ≤0.2 (air to water)
9 The water temperature is 23~30 degrees Celsius.
(2) See Table 2 for routine inspection items and limits of swimming pool water quality.
Table 2 Unconventional inspection items and limits of swimming pool water quality
Serial number item limit value
1 dissolved total solids (TDS)/ mg/l ≤ raw water TDS+ 1500
2 redox potential (ORP)mV ≥650
3 cyanuric acid/mg/l ≤ 150
4 Trihalomethane (THM) μ g/L ≤200
(3) The water quality standard of the competition pool when holding the world-class competition should meet the relevant requirements of FINA, and you can refer to the water quality standard of the world-class competition pool suggested by FINA (the informative appendix in the standard). The standard takes the Test Method of Cyanuric Acid in Swimming Pool Water as the normative appendix.
3 "Standard" comparison and analysis of the main indicators
3. 1 turbidity
Turbidity is an index reflecting the physical properties of swimming pools. Considering disinfection and safety, the turbidity of pool water should be higher than or equal to the requirements of Hygienic Standard for Drinking Water. Through the preliminary investigation of domestic swimming pools, under normal and reasonable operating conditions, the turbidity can be purified to ≤2NTU by conventional water treatment (sedimentation-sand filtration-chlorination). The World Health Organization's Guide to Swimming Pool Water Environment points out that the water quality standard for swimming pools in Germany is 0.2 (lower limit after filtration) ~ 0.5NTU (upper limit of pool water), and that for swimming pools in Spain is 0.5 ~ 1 NTU. Looking at the development of foreign swimming pool water quality standards, the turbidity limit tends to decrease. Considering China's national conditions, the intermediate limit of the Standard is 1NTU.
3.2 pH
The allowable PH value of drinking water is 6.5 ~ 8.5, which will not affect people's drinking and health. However, in swimming pool water treatment, it is very important to adjust the pH value of pool water. The germicidal efficacy of most disinfectants depends on the pH value, so the pH value must be kept within the best effective range of a disinfectant. Taking chlorine-containing disinfectants as an example, we can see the relationship between hypochlorite and pH value from Table 3.
Table 3 Effect of pH value on chlorine
pH HOCI/% OCI-/%
6 97.5 2.5
6.5 92.4 7.6
7 79.3 20.7
7.2 70.7 29.3
7.4 60.4 39.6
7.5 54.8 45.2
7.6 49 5 1.0
7.8 37.8 62.2
8 27.7 72.3
8.2 19.5 80.5
8.5 10.8 89.2
Hydrogen chloride is a stronger oxidant than OCI. With the increase of pH value, the percentage of HOCI decreased and the percentage of OCI- increased. When disinfected with chlorine, the pH value should be kept at 7.2 ~ 7.8. Disinfection is the most effective and economical at this time. GB 9667- 1996 sets the pH value of pool water at 6.5 ~ 8.5, while other western countries stipulate that the pH value of pool water is 7.2 ~ 7.
3.3 Total dissolved solids (TDS)
Total dissolved solids refer to the sum of all inorganic substances, metals, salts and organic substances dissolved in water, but do not include substances suspended in water. Its monitoring significance lies in controlling the renewal of pool water. See Table 4 for the regulations on TDS of swimming pool water quality abroad.
Table 4 Provisions on TDS in Foreign Swimming Pool Water Quality Standards
Total dissolved solids (TDS)/ mg/L in a country or region.
The swimming pool water in USA (ANSI/NSPI- 1) is higher than the source water 1500.
American (Nebraska) swimming pool water 1000-2000, massage pool is higher than source water 1500.
The swimming pool water in Britain can't be higher than the source water 1000, with a maximum of 3000.
The swimming pool water in Australia is ≤ 1000, and the ideal value is 400 ~ 500.
3.4 Disinfectant allowance
The World Health Organization's Guide to Swimming Pool Water Environment stipulates that the dosage of disinfectant is:
(1) The residual chlorine in the pond should be ≤5mg/L (in line with WHO drinking water standards), and it is suggested that the residual chlorine in the whole pond should be kept at1mg/L.
(2) The concentration of bound residual chlorine is less than or equal to half of free residual chlorine, and the ideal value should be 0.2 mg/L. ..
(3) Ozone disinfection system should adopt low concentration of free residual concentration (≤0.5mg/L), and SPA and spa pool should adopt high concentration of 2 mg/L..
(4) The cyanuric acid in the chlorine isocyanurate disinfection system should be kept at100 mg/L..
(5) The disinfection residue of bromine-based disinfection system in swimming pool is1~ 6 mg/L. When bromine-based disinfectant is combined with ozone, the bromine ion concentration should be maintained and controlled at 15 ~ 20 mg/L throughout the whole process.
(6) If the bromine source BCDMH is used, the DMH (dimethyl hydantoin) should be kept below 200mg/L. ..
(7) It is not a good method to make up for improper water treatment by impact dosing, because it can cover up the shortcomings in operation and design, and may also produce disinfection by-products (THMS and chloramines).
In order to achieve satisfactory microbial indicators, free residual chlorine should be kept as low as possible. According to foreign experience, the residual chlorine in well-designed public and semi-public swimming pools is not less than 1 mg/L, which can meet the requirements of routine disinfection and achieve disinfection effect. When the conditions are not ideal, the required residual chlorine in the swimming pool can exceed 1 mg/L, but should not exceed1.5 ~ 2mg/L. We refer to the WHO swimming pool water environment guide, and put forward the residual chlorine in the swimming pool1~ 3 according to the "Control Scope of Residual Chlorine" report of Aoqi Company and the scientific research summary report of leisure water impact treatment. ..
Combined residual chlorine can cause laryngitis and nasal mucositis. This highly irritating compound is also a substance that causes "indoor swimming pool odor", so countries all over the world have made different regulations on the combined residual chlorine in swimming pool water. Germany 0.2 mg/L; Denmark 0.2 mg/L; Italy 0.3 mg/L; Switzerland 0.4 mg/L; Norway 0.5 mg/L; Britain ≤2/ 1 free residual chlorine, with a maximum of 0.2 mg/l; American swimming pool 0.2 mg/L, massage pool 0.5 mg/L; China ≤ 0.4mg/l.
3.5 ozone
Ozone is a gas at room temperature, which has low solubility in water and is unstable in water at 20℃. Usually, its half-life is about 25 minutes. Ozone is easy to decompose in sunlight and volatilize in water, which has certain toxicity, and its exposure concentration is only 0. 1 mg/L(0.2mg/m3). In the American ANSI/NSPI-2003 version, there is no regulation on the O3 concentration in the pool water, and the O3 concentration in the air above the swimming pool and spa pool should meet the OSHA standard (0.2mg/m3). At the same time, referring to the relevant standards in China, the limit value of O3 in the Standard is 0.2mg/m3.
3.6 urea
In China, urea in swimming pool water has been an important index to evaluate the water quality and hygiene of swimming pool water for a long time. GB9667- 1996 stipulates that urea is less than 3.5 mg/L, and its content exceeding the standard will be harmful to human body. Therefore, the national standard for the analysis and detection of urea in swimming pool water was established. According to the literature of China, urea is directly proportional to oxygen consumption at the initial stage of open use of pond water. With the passage of time, the index of urea is more obvious than oxygen consumption. This is because oxygen consumption is an indirect indicator of organic pollution, but it represents an organic matter that is easily oxidized, so its content will not change significantly with time, so oxygen consumption is not sensitive enough as a pollution indicator, while urea can reflect the old and new degree of pool water. Most experts recommend adopting GB 9667. More in line with China's national conditions.
3.7 cyanuric acid
Disinfectants of sodium dichloroisocyanurate (dichloro, NaC3O3CI2) and trichloroisocyanuric acid (trichloro, C3N3O3CI2) are organic compounds, which are decomposed into cyanuric acid and chlorine in water, in which cyanuric acid is the stabilizer. The reason why it can be stable is to control the hypochlorous acid to produce only a certain amount at a time, and the chlorine in the medicine is gradually released. Even in the sun, only a small part of hypochlorous acid is lost.
When sodium dichloroisocyanurate and trichloroisocyanuric acid are put into the pool, cyanuric acid will accumulate continuously, and the amount of cyanuric acid is too small, and the remaining amount will soon be decomposed by sunlight; Too little chlorine may also reduce the effect of chlorine, increase the flora and produce algae. So cyanuric acid must be monitored and controlled.
The regulations of cyanuric acid in swimming pools in developed countries are as follows:
(1) USA: The lowest cyanuric acid is 10 mg/L, the highest is 150 mg/L, and the ideal is 30 ~ 50mg/L. ..
(2) Australia: The stable concentration of cyanuric acid is 100 mg/L, so isocyanuric acid should not be used in indoor swimming pools and public spas.
(3) UK: Organic disinfectants are used in swimming pool water treatment with heavy crowd load and low requirements. The maximum concentration of cyanuric acid is 200 mg/L, and the ideal range is 50 ~100 mg/L. ..
Too much cyanuric acid may cause the water quality to be too stable, so that the disinfectant can not fully play its role. At present, sodium dichloroisocyanurate and trichloroisocyanuric acid disinfectants are widely used in China. We think it is necessary to increase the control index of cyanuric acid.
3.8 trihalomethane (THMs)
THMs (also known as haloform) is a potential carcinogen, and the foreign swimming water quality standards are not stipulated except FINA and Germany (the limited value is 20ug/L). The tentative target of THMS value in Japan (20065438+0) is about 200 ug/L; The regulations in Britain are the same as those of Class II drinking water, and the limit is100ug/l/l..
Although the detection of THMs in swimming pool water in China is not perfect, it is obvious that THMs in chlorinated pool water may be far greater than the drinking water regulations.
Experts believe that it is not appropriate to copy the drinking water standard into the swimming pool water quality standard. Generally speaking, it is almost impossible to know exactly how much pool water is swallowed during swimming, and how many different by-products will enter human tissues, and the quantity will also be affected by swimming intensity and time, so it is difficult to determine this limit. Due to the difficulty and high cost of detecting THMs in the pool, the United States, Britain and other countries have not included THMs monitoring in their daily monitoring projects.
At present, there is a tendency to relax the limit of THMs in the world. We also think that the requirements of FINA and Germany THMs are a little high, but controlling THMs has a certain effect on the disinfection of chlorine abuse preparations, and these substances do have certain carcinogenicity, which may affect athletes and frequent swimmers and should be controlled.
3.9 Total number of colonies
Limit value of total bacteria in swimming pools in developed countries; Germany stipulates that after filtration > 20CFU/mL, the pool water
As long as the circulation cycle is appropriate, there is enough disinfectant residue, the pH value is maintained at a certain level, the water quality is balanced, the filter is backwashed frequently, and the swimming pool management is perfect, it is not difficult to control the microorganisms in the pool water. Because indicators such as microorganisms are directly related to human health, higher standards should be adopted.
3. 10 total coliforms
The total coliform bacteria in water is expressed by the maximum possible number (MPN) of total coliform bacteria in 100mL water sample internationally. National limit requirements (OMPN/ 100mL) cannot be detected.
In this water quality standard, the total number of colonies is ≤200 CFU/mL, and the total coliform group is 100mL, which shall not be detected. When disinfection fails, which affects the bacterial reproduction in the filter, especially the activated carbon filter, the water quality of the pipeline system and the balance tank deteriorates and the water quality is polluted, it is necessary to carry out unconventional detection of Staphylococcus aureus and Staphylococcus aureus.
3. 1 1 redox potential
The control index of disinfectant dosage is oxidation-reduction potential (ORP). The main advantage of using ORP is to measure the activity of disinfectant dose, rather than measuring disinfectant dose with ordinary detection methods. Swimming pools in various countries often keep ORP above 650mV, which can prevent the breeding of germs and microorganisms.
ORP can reflect the function of disinfectants, the performance of activated carbon and other indicators, and can be monitored online, which is a good daily maintenance parameter for swimming pools.
3. Other operating parameters not listed in12 standard are also very important for maintaining the chemical balance of pond water.
Alkalinity: Alkalinity is the determination of alkaline salts with solubility in water. The higher the alkalinity, the stronger the resistance of water to PH changes caused by disinfectants and pH regulators. If the alkalinity is too high, it will make it difficult to adjust the PH value and lock it. If the alkalinity is too low, there may be a sharp increase in PH value. The ideal total alkalinity value should be 80 ~1.20 mg/l; The acceptable alkalinity value is 60 ~ 200 mg/L; There are problems with high and low levels. The PH value of the pool water will be too high or too low, and the water will be turbid or corroded.
Calcium hardness: calcium hardness refers to the sum of calcium ions contained in all different calcium compounds in pool water. Usually it is a relatively stable factor in water, but it is often ignored in swimming pool water treatment. In fact, too high or too low calcium hardness in swimming pool water will cause corrosion and scaling. If the hardness of calcium in the pool water is low, as long as the alkalinity is appropriate, it will not have much impact on the water quality. However, the hardness of calcium in pool water is high, and once the PH value or total alkalinity of swimming pool is high, corrosion or scaling will occur. The ideal calcium hardness is 200 ~ 400 mg/L.
Total dissolved solids: Limit values are listed in the standard as an early warning of overload or underdilution. If TDS is too high, dilution may be the correct treatment.