The multi-media filter is the process of using more than two filter media to pass the water with high turbidity through a certain thickness of granular or non-granular materials under a certain pressure, so that the filter can effectively remove suspended impurities and clarify the water. Commonly used filter materials include quartz sand, anthracite, manganese sand, etc., which are mainly used for water treatment to remove turbidity, softened water, pre-treatment of pure water, etc. The turbidity of the effluent can reach below 3 degrees
The operation and forward and backwashing of the multi-media filter in this device are all automatic operations, and should be adjusted according to the following contents during trial operation or after formal operation:
1. Processing capacity: Design processing flow rate: 27m/h, design flow rate 5.5m/h.
2. Continuous running time
The design running time of the system is 24 hours, and then the multi-media filter should be backwashed; and the backwashing cycle should be adjusted according to the seasons and changes in water quality to ensure that the turbidity of the effluent is less than 1 degree. When the pressure difference between the inlet and outlet of the multimedia filter reaches 0.03 Mpa, it should be backwashed.
3. Backwashing flow rate: The purpose of backwashing is to reversely loosen the quartz sand and anthracite, and wash away the intercepted matter on the filter layer to achieve the effect of cleaning the filter layer. Usually, the backwashing flow rate is controlled at 30 m/s Left and right, it is advisable to prevent the anthracite from being washed away.
4. Backwashing time: The length of backwashing time is related to the amount of dirt intercepted by the packing layer. The backwashing time can be determined according to the turbidity of the backwashing drainage. In general, the backwash turbidity should be less than 1NTU, that is, 1 degree, and the time should not be less than 5 minutes, and it can be adjusted appropriately according to the operating conditions.
5. Positive washing flow: the positive washing flow can be around 25m/h.
6. Positive washing time: According to the turbidity of the positive washing water is about 1 degree, usually the normal washing is about 30 minutes.
7. Addition of quartz sand and anthracite: Due to running friction and backwashing, the filler layer will gradually decrease. It is necessary to monitor the change of the filler through the observation hole. It will decrease by about 100-200mm every six months, and add it every six months.
