The impurities in swimming pool water are mainly dirt, bacteria, cosmetics, grease and sweat secreted by human body, as well as sundries, dust, leaves, fungi and algae bred in the pool. Most of these impurities are insoluble in water. Because of the different specific gravity, some float to the surface, some mix in the water, and some precipitate to the bottom. The ups and downs of impurities have a process and time interval. The speed of floating and sinking is not only affected by the specific gravity, but also by the current.
If circulating filtration backwater systems are installed on both the water surface and the bottom, the water surface backwater system can suck impurities with specific gravity less than 1kg/L equal to 1kg/L, and the bottom backwater system can suck impurities with specific gravity greater than 1kg/L equal to 1kg/L into the circulating filtration system. In this way, only the impurities on the water surface and the bottom need to be treated at the same time.
If there is no backwater system to make the pool water circulate on the water surface, then the surface of the pool water is a dead water area; If the pool water is not filtered by circulating flow at the bottom of the pool, then the bottom of the pool is a dead water area. When the treated pool water enters the pool for water supply, it is required to distribute the water evenly, without dead zone and short flow.
2. Structure and facilities of pool surface backwater system: skimmer or overflow pool; Structure and facilities of pool bottom backwater system: bottom drain pipe
1. Slag skimmer and backwater mode of bottom hole, overflow tank and bottom hole.
Foam skimmers are used in small and medium swimming pools. Generally, when the pool water area is ≦350㎡, when the pool water area is not 25 ㎡-50 ㎡, only one foam skimmer is used, and a swimming pool should not be less than two foam skimmers. The outdoor swimming pool is installed in the downwind of the swimming season (the wall pool in the north), and 50% to 70% of the water flow can be treated by foam skimmer. Different pollution situations can become special. Only when the skimmer treats impurities with specific gravity less than 1kg/l and equal to 1kg/l, and the bottom row treats impurities with specific gravity greater than 1kg/l and equal to 1kg/l, can pollutants with different specific gravity be treated scientifically.
When the swimming pool of Zhong Da University adopts overflow tank for physical treatment, it must be equipped with a balanced water tank. 70%- 100% of the water flow can be treated by an overflow tank, which can overflow around the edge of the tank or the two long sides of the tank, and the bottom row also participates in circular filtration. The overflow tank plays the role of skimmer, treating impurities whose specific gravity is less than 1kg/L and equal to 1kg/L, and discharging impurities whose specific gravity is greater than 1kg/L with the bottom. It is also scientific to treat pollutants with different specific gravity by this recycling method.
Note: the balance water tank is not installed in the computer room, but is built with concrete next to the swimming pool, which can easily suck and add medicine. In the static state, the water surface of the swimming pool is at the same level as the water surface of the balance pool, which is lower than the ground. After the system works, the circulating water pump sucks water from the equalization pool, and after circulating, filtering, heating and disinfection, it makes water supply to the swimming pool, so that the water level in the equalization pool drops and the water level in the swimming pool rises, forming a water level difference, and the water flows back through the overflow pool. Impurities with specific gravity less than 1kg/l equal to 1kg/l flow to make the bottom row work at the same time, while impurities with specific gravity greater than 1kg/l equal to 1kg/l flow. It should be noted that if water is supplied from the bottom of the pool, the so-called "short flow" phenomenon can be ignored, because the water entering the swimming pool from the water supply port is mixed with untreated pool water immediately after entering the pool, and the water mixed with dirty water cannot be called "short flow" when it flows back to the bottom of the pool.
3. Swimming pool water supply mode and other circulation modes
1. Two water supply modes: horizontal water supply on the wall and vertical water supply at the bottom.
There are two ways of water supply for swimming pools: horizontal water supply for pool wall and vertical water supply for pool bottom, which are used independently. Water is supplied horizontally to the pool wall, which is very convenient for construction, installation and operation. It is the most commonly used water supply method, but its disadvantages are uneven heat distribution and chemical dosing. The biggest advantage of vertical water supply at the bottom of the pool is that the heat distribution and dosing are relatively uniform, but it is difficult to construct and install.
2. Swimming pool scientific circulation mode
There are two ways of water supply: vertical water supply at the bottom of the pond and horizontal water supply at the wall of the pond. There are also two backwater modes: skimmer with bottom drain backwater and overflow tank with bottom drain backwater. By arranging and combining 2×2 water supply and backwater modes, four circulation modes can be obtained, all of which are used abroad. They are: a. The best circulation mode: ① vertical water supply at the bottom of the pool, overflow tank and bottom drainage backwater system. B. The most commonly used circulation methods: ② horizontal water supply to the tank wall, foam skimmer, bottom drainage and backwater system. C available circulation modes: ③ vertical water supply at the bottom of the pool, foam skimmer and bottom drainage and backwater system. (4) Horizontal water supply of the tank wall, overflow tank and bottom drainage backwater system.
Conclusion: The scientific circulation mode is to ensure that pollutants with different specific gravity circulate in the circulating filtration system, and then intercept, stratify and remove them. If the water surface of the swimming pool does not circulate, the water surface is a dead water area; If there is no circulation at the bottom of the pool, then the bottom of the pool is a dead water area. The dead water area on the surface and the dead water area at the bottom of the pool occur in our parallel circulation mode and counter-current circulation mode, which should be avoided abroad.
In the circulating filtration system of swimming pool, the balance water tank, balance water tank, filter medium and biofilm on the inner wall of pipeline and valve are important links that have not been paid attention to in the water treatment of swimming pool in China, and should be treated by combining physical treatment with chemical treatment. The traditional downstream circulation mode, countercurrent circulation mode and mixed-flow circulation mode in China have not considered the treatment of this biofilm, and these three circulation modes have affected and hindered the treatment of balanced water tanks or balanced water tanks to varying degrees in structure and construction.
In the practice of swimming pool engineering abroad, the backwater mode of skimmer and bottom drainage does not need to balance the water tank, but only adopts the backwater mode of overflow tank and bottom drainage, which can conveniently carry out physical (such as sewage absorption) and chemical (adding disinfectant, flocculant and chemical shock treatment) treatment.