The shallow sand filter uses quartz sand filter material as the medium filter element, and the water is filtered from top to bottom. The device is generally composed of multiple standard high-speed sand tank units, and there are unique water distributors and water collectors inside. , has a unique two-way automatic flushing valve, which can realize multiple standard high-speed sand cylinders backwashing one by one in normal system operation, fully automatic program control. It has the advantages of small water consumption for backwashing, convenient equipment installation, and easy operation. The equipment has a fast filtration flow rate and a good treatment effect. The normal filtration rate can be around 40m/h, and there is no need for a booster pump and a backwash pump for filter backwashing. Backwashing takes 2-3 minutes, and the backwashing water volume is <3m³.
Shallow sand filter working principle:
1. Positive washing and filtering state
When the system is in the filtering state, the unfiltered water is evenly distributed through the unique water distributor, and the water passes through the packing layer in the filter in a laminar flow state. When water flows through the packing layer, impurities are trapped in the packing layer. There are multiple evenly distributed water collectors at the bottom of the shallow sand filter, which collect and lead out the filtered water evenly, and filter in advection, so that the filter can filter at a high flow rate and still achieve a better filtering effect.
2. Backwash filter state
As impurities continue to accumulate in the packing layer, the internal head loss will continue to increase. When the loss of the inlet and outlet water pressure head reaches the set value, the system will automatically activate the constant pressure device to switch to the backwashing state. When the backwashing of this unit is over, the hydraulic valve will change the water supply direction to realize backwashing one by one, which is more convenient Cleans away accumulated impurities.
When the system is in the state of backwashing, the filtration continues, and the standard unit sand tank to be backwashed does not filter, while other standard unit sand tanks in the system are still filtering. Part of the filtered clean water is used to backwash the standard unit sand tank, and the rest is still sent to the user. The backwash sewage is discharged through the backwash drain of the hydraulic valve. In the high-speed sand cylinder automatic high-efficiency filtration system, the special design of the water collector can make the fillers between the fillers wash each other, maximize the efficiency of backwashing, reduce the required backwashing water (clean water), and at the same time when backwashing There is no material running phenomenon. The backwashing time of a standard unit sand tank is 2 minutes. After the backwash is over, the internal pressure head loss of the standard unit sand tank is reduced to a reasonable range. The constant pressure device gives a recovery signal, and the hydraulic valve returns to the filtering state. The next standard unit sand tank Then it is ready to enter the backwash state.
Shallow sand filter application range:
1. The filtration of industrial water has certain system requirements for water quality. Such as: steel plant oxygen lance water, boiler, heat exchanger water supply filtration, etc., can filter out impurities in the water and avoid blockage of several nozzles in the pipeline.
2. Filtration system for industrial circulating water.
3. The treatment of raw water can filter surface river water, lake water, sea water, reservoir water, well water, and city tap water as the water source for urban community differentiated water supply, etc., to remove sand, suspended solids, algae, organic matter, etc. in the water.
4. Agricultural irrigation, especially suitable for water sources with high flow and good impurity content, such as irrigation of farmland water conservancy, irrigation of lawns on parks and golf courses, etc.
5. Food processing industrial water, paper industry, power plant industrial circulating water treatment, etc., industrial and medical pure water pretreatment. Recycling of industrial process water, industrial wastewater treatment.
6. Aquaculture, swimming and water parks and other industries.
