Four Common Methods Of Swimming Pool Water Treatment And Filtration And Their Comparison

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Four common methods of swimming pool water treatment and filtration and their comparison 2023-06-16 15:56:53

Four common methods of swimming pool water treatment and filtration and their comparison

Swimming pool water treatment is divided into two parts: physical process and chemical process, both of which are indispensable in the process of swimming pool water treatment. The physical process is that the swimming pool water is purified through the filtration of the circulating water treatment equipment. The chemical process refers to the addition of chemical agents to disinfect, flocculate, and remove algae while the pool water is circulating, and then make the pool water clean and hygienic through the action of physical processes.

The turbidity of swimming pool water not only affects the water quality, but also easily causes safety accidents. Reduce the disinfection effect and directly affect the sensory comfort of swimmers. It can be said that in the pool water treatment process, the core of the process is to purify the water quality. At present, the filtration systems commonly used in the swimming pool water treatment industry are mainly based on quartz sand pressure filtration and diatomite pressure filtration, as well as relatively small wall-mounted integrated filters and gravity filters.

This article focuses on four common methods of using physical filtration: quartz sand filters diatomaceous earth filter units wall-mounted integrated filters and gravity filters.

1. Introduction of four filtering methods

1 Brief introduction of quartz sand filtration process

Quartz sand filter materials are generally made of high-quality carbon steel lining rubber anti-corrosion stainless steel and reinforced glass fiber materials, which are required to resist dual corrosion of ozone and chloride ions, and the design pressure is 0.6MPa. There is an automatic exhaust valve on the top of the device to timely discharge the air sucked in due to careless operation. Holes are provided in the middle or top of the tank for easy access and replacement or filling of filter material. The quartz sand filter material should be 0.45-0.8mm refined quartz natural sea sand filter material, and the lower part of the cylinder should be equipped with a pebble (particle size 2mm-32mm) support layer. In order to achieve the purpose of deep filtration, the thickness of the effective filter layer should not be less than 700mm, and it must be equipped with a water head of 4-5 meters. Considering the increase in fouling of the filter material during the filtration process, the pressure in the sand box increases, so the pressure bearing capacity of the cylinder is required to be greater than 0.6MPa. The tank is provided with a sight glass, a low pressure waterproof light can be fitted if required, and moderate levels of dirt in the sand box can be observed.

2 Brief introduction of diatomite filtration process

Pressure diatomite filters can be divided into plate type and frame type diatomite filters and candle type diatomite filters. The plate and frame diatomite filter is composed of multiple filter units, each filter unit is composed of a filter plate, a filter frame, and a filter cloth, and the filter cloth is sandwiched between the plate frames as an adsorption filter medium

The shape of the candle-type diatomite filter is similar to that of a vertical quartz sand filter, and its interior is composed of a candle-like filter element, so it is called a candle-type diatomite filter. When filtering, a diatomaceous earth precoat is first formed on the filter candle. When the material passes through the diatomite filter layer attached to the surface of the filter candle column, the suspension and colloidal particles are intercepted to achieve the purpose of filtration.

Diatomite filter material is a siliceous biosedimentary rock with opal as the main mineral component, which is mainly formed by the deposition of the remains of diatoms, a single-celled aquatic plant. It has the characteristics of porosity, large surface area and chemical stability, and is a natural filter aid. In addition, diatomaceous earth also has unique ion selectivity and the characteristics of killing chlorine-resistant pathogens. Diatomaceous earth filter With the passage of time, more and more impurities will be filtered out on the pre-coating, and will block the filter channel, so it is necessary to add a certain amount of diatomite, so that the diatomite will be filtered out with the filtrate The suspended solids in the filter can be intercepted and adsorbed by the filter at the same time, forming a new filter layer, preventing all the microfiltration pores of the new filter layer from being blocked, maintaining its filtration performance, thereby prolonging the filtration cycle and increasing the total amount of filtration at one time.

3. Brief introduction of wall-mounted integrated filter process

Wall-mounted integrated filters generally use high-quality paper filter elements, or PP filter elements as filter media, with built-in circulating water pumps, automatic dosing devices, underwater lights and other equipment. Its circulation mode is a suction cycle, inhaled from the water suction port of the equipment body, and discharged from the water supply port of the equipment body after filtration and purification. Its service scope is only in the limited area around the equipment, and there will be problems of dead angle and eddy current when using it. It is a non-mainstream filtration process and has a low market utilization rate. It is only suitable for swimming pools with no machine room, small water volume, and few swimmers, such as: High-end villa outdoor swimming pool, private club swimming pool, etc.

4. Process introduction of gravity filter

The best place for gravity filters is to improve the water quality of natural or artificial landscape water bodies. Its aeration and melting of oxygen activates water bodies. Sand bed filtration is beneficial to remove organic pollutants and reduce turbidity in such water bodies. It belongs to environmental microorganisms. Water treatment process in the field of science. The water treatment of swimming and recreational water belongs to the medical disinfection process of disinfection and sterilization of medical microorganisms, and there is an essential difference between the two. Gravity filtration technology was first used in water treatment of natural or artificial landscape water bodies. In the past ten years, there have been use cases of gravity filtration systems in swimming pools and water parks and other similar entertainment water treatment technologies and equipment in my country, but the overall market Occupancy rate is less.

The working process of the gravity filter is to send the raw water into the water distribution tank for uniform distribution, and then pass through the air isolation device to aerate the raw water to melt oxygen. Come out, and then inhale the oxygen in the air. This system is also called (respiratory system). After completion, it enters the fine filter, (the fine filter is composed of multiple layers of repeated composite filter materials) to filter from top to bottom, as shown in the following schematic diagram of the filtration process. As the filter layer continuously intercepts suspended solids in the water body, the resistance of the filter layer gradually increases, causing the water level of the siphon to rise. When the water level rises to the set position, it enters the suction device in the siphon auxiliary pipe, and the air in the siphon is taken away by the hydraulic action. , forming a negative pressure. When the negative pressure reaches the design value, a siphon phenomenon occurs. At this time, the water in the water tank forms a backflow, and the filter layer is continuously flushed from bottom to top, and the filter layer is "regenerated". The schematic diagram of the backwashing process is shown in the figure below. Due to the continuous backwashing of the filter layer, the backwashing sewage is discharged to the sewer pipe, and when the water level in the water tank drops to a specified value, the siphon effect is destroyed, and the backwashing ends, and the filter starts working again.

2. Analysis of the characteristics of the four filtering methods

1. Characteristics of quartz sand filtration process

advantage:

a. It belongs to the international/domestic mainstream swimming pool water treatment and filtration technology. Many international and domestic high-level swimming competitions adopt this kind of filtration method, which is mature and reliable, and suitable for national conditions (domestic swimming places are basically in an overloaded state during the peak season. ) market share of more than 95%;

b. The filter medium is mainly quartz sand, which is easy to obtain;

c. The equipment has stable performance, high cost performance and long service life;

d. The filtration speed belongs to medium-speed filtration, and the filtration accuracy can reach the international/domestic swimming pool water quality standards. At the same time, it has strong resistance to summer peak passenger flow and can run continuously;

e. The equipment is easy to operate, the operation and maintenance costs are low, and the equipment management in the computer room is convenient.

shortcoming:

a. Compared with other filtration processes, there are strict requirements on the floor area and floor height of the equipment room

b. Filtration accuracy is slightly lower than diatomaceous earth filter.

2. Features of diatomite filtration process

advantage:

a. The filtration accuracy can reach 2-3µm, which is higher for other processes and belongs to low-speed fine filtration;

b. The filter area is large, the equipment volume is small, and the area occupied by the machine room is small;

c. High degree of automation, automatic dosing of filter material, which can be partially recycled;

shortcoming:

a. Under the condition of the same treatment water volume, the investment cost of single equipment is higher than that of quartz sand filter;

b. The amount of backwashing water is large and the consumption of filter material is large. After each backwash, the diatomite filter material needs to be reloaded. It is necessary to have a stacking space for diatomite for more than 15 days of operation, and the operating cost is relatively high;

c. The high degree of automation of the equipment has high requirements on the quality of the operators. In case of failure, the equipment must be completely disassembled for maintenance, which is time-consuming and laborious;

d. The ability to cope with the peak passenger flow in summer is weak, it cannot operate continuously, and the water quality effect cannot be guaranteed;

e. The specific gravity of diatomite filter material is small, and part of the diatomite filter material is easily taken away by equipment recoil. It is necessary to set up a special reclaimed water treatment system, otherwise it will cause secondary pollution, and may even block the drainage pipe network of the machine room.

3. Features of the wall-mounted integrated filter process

advantage:

a. Low operation and maintenance costs, which can save a lot of water, electricity, labor costs, etc.;

b. The equipment is simple in structure, easy to operate, and does not need special care;

c. There is no need for a special equipment room, the installation method is simple, and the investment is small.

shortcoming:

a. It needs to be installed on the edge of the swimming pool, and the structure design of the pool needs to reserve equipment installation space;

b. The service area is limited, the filtration accuracy is low, and the water quality treatment effect is average;

c. It is not suitable for high-level competition venues, and the market share is low.

4. Characteristics of gravity filter process

advantage:

a. No pressure gravity design, no power filter, energy saving;

b. The filter medium is mainly quartz sand, which is easy to obtain;

c. No valves, no replacement parts, no maintenance, saving manpower;

d. Siphon principle automatic backwashing technology.

shortcoming:

a. The standards and specifications of the swimming pool and the atlas are not mentioned, and the technology has yet to be verified;

b. Strict requirements on the area of the computer room, especially the floor height;

c. The filter layer is shallow, the filtration efficiency is low, and the water treatment effect is average;

d. The advantages of no maintenance and no need to replace parts are yet to be verified.

e. It is a niche technology, and its application effect in the field of entertainment water treatment such as swimming pools and water parks needs to be verified.

3. Summary

This article lists four common swimming pool filtration processes on the market. Each filtration method has its advantages and disadvantages, and the method of selecting a filtration process is not static. Even the perfect product cannot achieve the best effect if it is not used correctly. The usual cycle cycle is 4-6 hours for swimming pools, and no more than 1 hour for hot spring baths. In order to meet the target requirements and clean and healthy water quality, it is necessary to design a reasonable cycle cycle according to local habits and flow of people. Cycle design plays a key role. In addition, the rationality of the allocation of various equipment, the operation mode of the filtration equipment, water quality disinfection and water quality balance, the nature of the use of pool water, and the configuration of washing facilities before and after swimming will all have an impact. The project's construction conditions, funding situation, swimming pool characteristics, human flow and the ability of the post-maintenance team should be considered comprehensively, and the most suitable filtration process should be selected to achieve the desired effect.

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