Quartz sand filter

What is a multimedia backwash water filter

Multi-media backwash water filter is a backwash filter that uses quartz sand and other substances as filter media, which can effectively remove suspended solids, microorganisms, and other fine particles in the water, and finally achieve the effect of reducing water turbidity and purifying water quality. This system is a fully automatic system. If there is no human operation, the system will automatically backwash once every 12H (the backwash interval parameter can be changed according to the user's situation). Commonly used in water purification and sewage treatment occasions. Common filters are made of stainless steel 304 and carbon steel, and epoxy or rubber lining is often used internally to achieve anti-corrosion purposes.
 

Multimedia water filter structural unit

1. Shell: carbon steel is generally used as the material, and the internal and external surface treatment processes are painting, epoxy resin spraying, electrostatic powder spraying, rubber lining, etc.; the shell diameter ranges from 1200-3000mm.
2. Pipelines: Connect several tanks and access the system, which are divided into water inlet pipes, water outlet pipes and sewage pipes. And equipped with valve, air release valve, pressure gauge and so on.
3. Three-way valve: Three-way valve is commonly used as electromagnetic diaphragm valve, electric three-way ball valve, electromagnetic pneumatic valve (requires an external air source, and is not used much), etc.
4. Water distributor: the material is stainless steel, carbon steel, polyamide (nylon), polypropylene, etc. The function is to distribute the water evenly on the filter material. Let the water pass through the filter material smoothly; and when backwashing, intercept the filter material to prevent the filter material from flowing out of the system with the water during backwashing. There are two common structures of star-shaped water distributor or water distribution board.
5. Water collector: polypropylene or stainless steel filter cap, during filtration, the water through the filter material is discharged from the system and the filter material and impurities are intercepted. 6. Control system: generally consists of electric control cabinet, plc, touch screen, cables and other equipment.

How multimedia sand water filters work?

The working state of the multi-media sand water filter is divided into two types:

1. Filter status:

The filtering state is the state when the water filter is working normally. The water to be purified flows through the water distributor through the water inlet pipe through the three-way valve, and cooperates with the spherical shell to evenly reach the packing layer in the filter in a state of advection. When the water flows When passing through the packing layer, the impurities are trapped in the packing layer, and the filtered water is discharged through the pipeline.

2. Backwash status:

When the filter reaches the predetermined working time or the set pressure difference, it will enter the backwashing process. The shallow sand filter adopts the method of backwashing one by one. When the filter is instructed to start backwashing, the first filter sand tank starts to clean, and the other filter sand tanks work normally. First of all, the first three-way valve of the sand filter tank begins to prepare for action, closes the water inlet channel, and opens the water outlet channel and sewage channel. Unfiltered water cannot enter the filter through the three-way valve, while the water filtered by other filters can enter the No. 1 filter in the reverse direction, wash the sand, and discharge the impurities from the sewage outlet through the water distributor. , the water distributor can ensure that the sand will not be brought out with the impurities, and avoid the occurrence of sand running. After the cleaning of the No. 1 filter unit is completed, the three-way valve of the No. 1 unit starts to operate, opens the water inlet and outlet channels, and closes the sewage channel. The water is filtered normally through the filter. In the same way, until all the filter units are cleaned one by one, the backwashing ends, waiting for the next backwashing command.
The design of the automatic quartz sand backwashing water filter system can realize the continuous water during backwashing, and the filtration and backwashing states are carried out at the same time to ensure the normal operation of the whole system.

Control method of shallow sand filter

1. Differential pressure control: After the system runs for a period of time, the impurities intercepted in the tank will increase, and the pressure difference between the inlet and outlet water will increase. When the pressure difference between the inlet and outlet water of the system reaches the set value, the system will automatically turn on the backwash function to remove impurities. , so that the equipment returns to normal differential pressure.
2. Time control: We can change the automatic backwash cycle and backwash time of the filter according to on-site requirements, when the equipment running time reaches the set value of the backwash cycle. The filter automatically turns on the backwash function. For example: you can set the backwash cycle of the filter to 8h and the backwash time of each tank to be 60s. When the water filter runs for 8 hours, the automatic backwash function is turned on to clean the filter tanks one by one. Each filter tank is cleaned successively for 60s until the last filter is cleaned. At this time, the timer will be reset, and the backwash will be started again after 8h.
3. Manual control: The filter tank that needs to be cleaned can be manually opened according to the needs of use, so that it starts the automatic backwashing function.

Technical parameters of quartz sand water filter

The maximum water flow of a single working unit: 40m³/h
Pressure level: 0.25MPa~0.5MPa
Working water temperature range: 0~65℃
Turbidity of effluent: <3FTU;
Inlet and outlet connection: flange
Backwash water volume: 1~3% of filtered water volume
Control mode: differential pressure control, timing control
Sewage discharge method: automatic sewage discharge, safe, reliable and trouble-free
Rated operating voltage: 380v 50HZ
Installation method: The installation method is flexible, and can be stacked up and down or placed in parallel, multiple columns in parallel, etc.

Matrial that can be used in backwash water filters

1. Quartz sand
Quartz sand filter material is one of the most effective means of filtering suspended solids in the medium, and is an important unit in advanced sewage treatment, reclaimed water reuse and water supply treatment. Its function is to further remove the flocculated pollutants in the water, and it achieves the purpose of water purification through the retention, sedimentation and adsorption of the filter material. 2. Activated carbon
The activated carbon filter material mainly uses the strong adsorption performance of activated carbon to remove impurities in the water and purify the water body. Its adsorption capacity is mainly reflected in the following aspects:
It can absorb organic matter, colloidal particles and microorganisms in water.
It can adsorb non-metallic substances such as chlorine, ammonia, bromine and iodine.
Can adsorb metal ions, such as; silver, arsenic, bismuth, cobalt, hexavalent chromium, mercury, antimony, tin and other ions.
Effectively removes chroma and odor. 3. Manganese sand
Manganese sand filter material is mainly used to remove ferric ions in water. When the iron content in the water is high, the water has an iron smell, which will reduce the product quality for some water production industries. The iron-containing water can cause rust spots on the production equipment, and the iron sediment Fe2O3 will grow iron bacteria, block the pipeline, and sometimes appear red. water. The water with high manganese content is similar to the situation with high iron content, which can make the water change color and taste, and damage the quality of textile, paper, brewing, food and other industrial products. Drinking water with high iron and manganese content for a long time will also seriously affect the health of the body, and it has a strong corrosive ability to production equipment. After the groundwater containing iron (manganese) is aerated or added with an oxidant, the iron (manganese) ions in the water begin to oxidize. When the water flows through the manganese sand filter layer, a contact oxidation reaction occurs in the filter layer, and the biochemical and physical effects of the surface of the filter material occur. The adsorption is intercepted, and the iron (manganese) ions are precipitated and removed from the water.

When does the sand need to be replaced?

Quartz sand is used as the filter material of the backwash filter. After a long time of use, there will be serious wear and tear. Due to the improper control of the backwash water pressure and natural aging, the filter material will run out of material and pulverize. , which causes the loss of the filter material, so we need to replace the filter material regularly.
There is no fixed time for how often to replace the quartz sand. In general, the water pressure difference between the inlet and outlet water after backwashing is not large, so it is not necessary to replace it. We recommend that the quartz sand water filter used for pure water treatment should be replaced with quartz sand after 2-3 years of use.

How do you add sand to the filter?

The filter material in the water filter jar is not completely mixed, and the wrong packing method will only affect the working efficiency of the filter. The correct sand filling sequence of the filter should be that the large-sized particles are at the bottom, and the small-sized filter material is at the top. . For example: the first layer (below) at the bottom is the particle with a diameter of 4-8mm, which is the cushion layer, and the upper layer is the specifications of 2-4mm, 1-2mm, 0.5-1mm. The customer can determine the number of filling layers according to the design requirements, and fill them in sequence. Do not mix layers, as it is easy to cause sand running and slow flow rate.
Quartz sand filter replacement steps:
1. Prepare the necessary tools for replacing the quartz sand filter material: pipe wrench, sand suction pipe, raw tape.
2. Before replacing quartz sand, conduct a comprehensive inspection of the equipment and record the operating parameters of the equipment.
3. The equipment is out of operation, and the related equipment of the inlet water pump is closed.
4. Disassemble the equipment.
5. When replacing the quartz sand, fill the quartz sand in the order of the large sand on the bottom and the small sand on the top. The filling volume of the quartz sand is about 70% of the sand tank.
6. After the quartz sand is filled, reinstall the equipment.

Matters needing attention when filling the quartz sand filter with sand:
1. When filling the quartz sand tank, the central tube should be sealed with raw tape to prevent the quartz sand from entering the central tube.
2. When cleaning the quartz sand tank, be sure to wash it first and then backwash it.
3. The filling volume of the quartz sand tank should not exceed 70% of the total volume, so that there is space for backwashing.
4. After filling the quartz sand, the control valve head can be installed;
5. After replacing the quartz sand, the user can first clean the quartz sand, open the water inlet and outlet valves, first wash, then backwash, and then alternate between forward and backwash.
6. After confirming again that there is no water leakage, it can be put into use.

Features

The equipment shell, water inlet and outlet pipes and sewage pipes are welded and processed by high-quality steel and pipe fittings, and the structure is stable to ensure the normal use of the equipment and a longer service life.
The two-position three-way valve adopts special solenoid valve or electric ball valve to effectively reduce the valve failure rate.
The water distributor and water collector are made of pp or stainless steel, which ensures that the water flow evenly flows through the filter material, and at the same time ensures that the filter material will not run out and affect the water quality.
The filter material is made of high-quality quartz sand, so as to avoid the force becoming powdery during the work and affecting the quality of the effluent.
The control system adopts the plc touch screen intelligent control system, which is more convenient to operate, and can be remotely connected to the computer room to observe the system status in real time.

Application of Backwashing Quartz Sand Water Filter

Shallow sand filters are often used in:
1. Filtration of clean ring water and turbid ring water in steel mills;
2. Filtration of circulating cooling water and wastewater treatment in petrochemical plants;
3. Municipal engineering greening water filtration and purification;
4. Filtration of agricultural irrigation water;
5. High-pressure flushing water and circulating water treatment and filtration in the machining industry.

Installation method