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Double flow filter

Sep 25, 2017

Double flow filter

Double flow filter is different from the single flow, is the middle of the drainage system; filter layer is higher in the middle of the drainage system above the filter layer height of 0.6-0.7m, the following 1.5-1.7m. The effective particle size and the nonuniformity coefficient of the filter medium are larger than those of the single flow type. For example, when the quartz sand is used, the particle size of the filter is 0.4-1.5mm, the average particle size is 0.8-0.9mm, the unevenness coefficient is 2.5- 3. 


Abnormal phenomenon 




Filter cyclical water reduce

1. filter sand and suspended solids agglomeration;

2. Backwash intensity is not enough or not thorough;

3. The backwash cycle is too long;

4. Water distribution device or drainage device damage caused by drift;

5. Filter height is too low;

6. Raw water quality suddenly muddy (a sharp increase in suspended solids).

1. to strengthen anti-washing and water quality clarification;

2. Strengthen water pressure and flow;

3. Appropriate increase in the number of backwash to shorten the backwash cycle;

4. Check the water distribution unit or drainage device;

5. Appropriate increase in filter height;

6. To strengthen the analysis and clarification of raw water quality, master the law of water quality changes.

The filter flow is not enough


The filter flow is not enough

1. water pipe or drainage system head resistance is too large;

2. The upper part of the filter layer is blocked by sludge or agglomerated.

1. Eliminate water pipeline or drainage system failure;

2. Remove the sludge or agglomerate, thoroughly wash the filter, try to reduce the suspended solids content in the water.


Backwashing filter sand loss

1. Backwash strength is too large;

2. Damage to drainage or water distribution equipment results in uneven distribution of backwash water in the filter section.

1. immediately reduce the intensity of backwash;

2. Check, repair drainage or water distribution device.


Backwash time is very long turbidity to reduce

1. backwash water in the filter section is uneven or dead angle; 2. filter layer is dirty.

 1. Check, repair water distribution or drainage device, eliminate dead ends;

2. Appropriate increase in the number of backwash and anti-wash strength.


Filtered water turbidity can not meet the requirements

1. filter layer surface is seriously polluted by sludge;

2. Filter layer height is not enough;

3. Filtration speed is too fast.

1. Strengthen and improve the water coagulation, clarify the work, increase the intensity of backwash;

2. Increase the filter height;

3. Adjust the height of the filtered water


There is sand in the running water

Drainage device is damaged

Unloading filtered sand,check the drain