Comparison of Quartz Sand and Diatomaceous Earth in Swimming Pool Filters

As we all know, swimming pool filters mainly include traditional quartz sand filters and advanced diatomite filters. They are important filter media in swimming pool water treatment. Customers often ask, what about quartz sand filters and diatomite filters? Which soil filter is better? Before answering this question, let's make a detailed comparison of these two filters. 1. Comparison of operation and management of quartz sand and diatomite in the process of swimming pool water treatment 1. Quartz sand filter The main operation content of the quartz sand filter system includes: backwashing and coagulant dosing. Since the quartz sand filter is a deep filter, the filtered particles gather in the entire filter bed, which requires a greater washing intensity and a longer washing time to wash the entire filter bed.

The backwash intensity of the quartz sand filter is 12-15L/(S.M2), the backwash lasts 8-10min, and the backwash interval is<5d, after each backwash, it should be washed for 2-3 minutes. The water flow required for sand filtration is nearly doubled in the filtering condition and the backwashing condition. In the design and operation, attention should be paid to the matching of the circulation flow rate and the backwashing flow rate. It is best to install a dedicated backwashing water pump. The flocculation of coagulant is mainly affected by the type of coagulant, dosage concentration, water temperature, pH and reaction time, so operators with rich management experience are needed to ensure the coagulation effect.

2. Diatomite filter There are two types of diatomite filter systems used in China: reversible and renewable. The filtration speed of the reversible diatomite filtration system is as high as 6-10m/h. The author did not get corresponding data support in the international norms consulted, so it was not included in this analysis. The main operation content of the renewable diatomite filter includes: pre-coating, filter material regeneration and filter material replacement.

Pre-coating refers to the process of using hydraulic power to evenly distribute the diatomite filter material to the surface of the filter element. After each "regeneration" or replacement of the filter material, pre-coating is required to start the next round of filtration. Diatomite filtration mainly occurs on the surface of the filter membrane. The filtered particles and dirt cover the surface of the filter membrane or are adsorbed by the diatomite particles on the surface of the filter membrane, which reduces the filtration effect and passing capacity of the filter membrane. Therefore, it is necessary to pass through " "Regenerate" restores the filtration capacity of the membrane.

The so-called "regeneration" is the process of redistributing the diatomite originally distributed on the surface of the filter membrane and the diatomite in the deep layer of the filter membrane to achieve the filtration effect on the surface of the regenerated filter membrane. The utilization rate of diatomite as a filter material can be improved by regenerating the filter membrane. The filter regeneration frequency should not be greater than 1 time/d.

When the filter membrane resistance reaches 0.7mpa, the filter material should be replaced. To replace the filter material, the filter material can be thoroughly washed off the filter element by pool water recoil and then drained with the water flow, or the filter material can be shaken off the filter element by machinery and then discharged by gravity. Then add new filter material again, and start the next round of filtration cycle after pre-coating.

The filter replacement cycle is usually 15 days to 60 days. Take the swimming pool as an example to compare the time consumption of running operations. Through the above comparison, the operation of diatomite filtration is more cumbersome than that of quartz sand filtration, and its monthly operating time is about 1.18 times that of quartz sand filtration. Therefore, it is recommended to use an automatic control system to reduce the operating intensity.

2. Comparison of filtration mechanism between quartz sand and diatomite filter 1. Quartz sand filtration Quartz sand is a filter medium widely used in swimming pool water treatment. Quartz sand filtration is a depth filtration, and the filtration action occurs within the entire depth of the filter bed. When the water to be filtered passes through the filter layer, the suspended substances contained in the water flow into the tiny gaps of the upper filter material, and are subjected to adsorption and mechanical blockage. And bridging effect, the filter membrane is formed in the filter material layer, and the filter membrane continues to filter, and the effect of purifying water quality can be achieved through such repeated filtration.

The best filtration performance occurs in the last 1/3 of the filtration cycle. The sand filtration speed is usually 20-30m/h, and the filtration accuracy is 15-20umm. When the filtration speed drops to<25m/h and with the use of flocculants, the filtration accuracy can reach up to 7-10um. 2. Diatomite Filtration Diatomite is a filter medium widely used in water treatment of beverages, brewing, medicine, etc., and is also used in water treatment of swimming pools.

As a filter medium for water treatment, it utilizes the porous natural characteristics of diatomite filter material, and has multiple functions such as screening, interception and adsorption. It can not only remove turbidity in water, but also remove organic matter, ammonia nitrogen, cryptosporidium and bacteria etc. In the diatomite filter, diatomite evenly adheres to the surface of the filter element to form a filter membrane. The filter membrane achieves the function of filtration by intercepting and absorbing fine particles in the water passing through.

Interception refers to the process that particles with a particle size larger than the filter material gap are intercepted when passing through the filter membrane. The interception process mainly occurs on the surface of the filter membrane, which is the main mechanism of diatomite filtration. The porous structure of the diatomite filter material makes it have good permeability. When the pool water penetrates the filter membrane, the fine particles in the pool water and the filter material will rub against each other to form static electricity. Fine particles are adsorbed into the pores of the filter material to play an adsorption role and achieve a finer filtration effect. In the swimming pool water treatment process, the diatomite filtration rate usually used is 3-5m/h, the filtration accuracy can reach 1-2um, the turbidity of the effluent can reach 0.0, and the removal rate of Cryptosporidium can reach 99.996%.

Poolking is the best swimming pool equipment manufacturer and supplier in China. Poolking exists to provide the highest quality swimming pool equipment while offering competitive pricing..