The multi-media filter uses two kinds of filter materials, quartz sand and anthracite, to remove suspended solids in raw water. It belongs to ordinary fast filter equipment.

This kind of filter contains water containing suspended particles and flocculants are fully mixed, so that the electric double layer forming colloidal particles in the water is compressed. When the colloidal particles flow through the filter material layer of the multi-media filter, the gaps in the filter material play a role in filtering the suspended solids, making the suspended solids easy to adsorb on the surface of the filter material. When the dirt is trapped on the surface of the filter material to form a filter membrane, the pressure difference between the front and back of the filter will increase over time until it fails.At this time, it is necessary to use reverse water flow to backwash the filter material to suspend and loosen the quartz sand and anthracite layer in the filter, so that the intercepted matter adhering to the surface of the quartz sand and anthracite is peeled off and taken away by the water flow to restore the filtering function. The double-layer filter material used in this project is to place lighter large-grained anthracite on the upper part of the filter layer, and the lower part to be small-grained quartz sand with a large specific gravity, so that the efficiency of the entire filter layer can be fully utilized and the sewage interception capacity can be improved.

㈠，Daily operation inspection: After entering normal production, the operator should regularly inspect the equipment site every hour. Record the inspection results truthfully, and summarize them together with the operation records, as the information for regular maintenance

Inspection cycle Inspection item Inspection method or inspection point Remarks

Once every shift, check whether there is any water leakage in the sealing parts of the equipment and the auxiliary valves. If there is water leakage, find out the location and cause of the water leakage, and stop the leakage in time. Vibration, find out the cause, and take timely solutions

Once a month, check the flow rate and check the indication value of the flowmeter to verify whether it indicates normal flow rate. If the flow rate display is abnormal, find out the cause in time and eliminate the fault.

㈡, regular inspection: 

The equipment should be inspected regularly, the purpose is to ensure the safe operation of the system in a long period of time. This equipment is a relatively large equipment, and inspection work takes a long time. In order to shorten the parking time for regular inspection, it should be carried out at the same time as possible with the maintenance of other equipment and devices of the raw water treatment plant. If any abnormality is found, it should be dealt with in time.

1 Packing inspection Check the quartz sand anthracite filter material, if the quartz sand anthracite is seriously polluted, all of them should be replaced.

2 Filter cap inspection Take out the filler, rinse it with water, check the filter cap on the perforated plate, if it is damaged or loose, replace or fix it in time.

3 Inspection of the rubber lining layer If bubbles, cracks, glue peeling, micropores, etc. are found in the rubber lining layer, it must be repaired.

4 Inspection of internal fasteners Check the fasteners such as bolts and nuts inside the filter, and tighten them if they are loose.

5 Manhole seal inspection Replace the deformed manhole seal; immerse the bolts and nuts in cleaning oil to remove rust; when installing the manhole cover, the bolts and nuts should be coated with butter