Issues with cleaning multi-media filters?
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How are quartz sand and anthracite used as packing materials in multi-media filters, and what are the flushing standards? What does it mean for rinsing to be successful?
After being in use for a certain period of time, the filter must be cleaned, that is, flushed. This is generally done through water backwashing or air backwashing, with the aim of ensuring that the water passing through the filter meets the design specifications. Filters from different manufacturers have different cleaning standards; therefore, LZ can ask the manufacturer, who will provide all the specific parameters.
The fragments found were: “Start the backwash pump, open the backwash valve; the water flow will wash away the debris.” When the discharge turbidity is <3 NTU, stop the backwash pump and close the backwash valve and the upper discharge valve. The backwash flow rate is controlled at around 30 m/h, so as to prevent the normal particles of anthracite from being washed away. d. Resting: After backwashing, allow the anthracite and quartz sand to settle. e. Forward washing: Open the water inlet valve and the drain valve; the operating flow rate remains the same as that in the water production mode. Continue forward washing until the turbidity of the discharged water is ≤1 NTU or SDI ≤4, after which the drain valve is closed and the system switches to standby mode. ” The standard is essentially a manufacturing process; as for what level of turbidity is required, etc., that depends on the requirements of your membrane
Cleaning is necessary; currently, high-flow backwashing is the popular method. The effect is quite good, I think. The design flow rate is as mentioned above; adding a bit of pressure will do. The quality of the water discharged after cleaning must meet the requirements of subsequent processes; SDI and SS levels are inevitable in such water.
All non-mechanical (media) filters require backwashing, with the timing of this backwashing determined based on the turbidity of the incoming water (time control)……There is also pressure difference control; generally, backwashing should be carried out when the pressure difference in a media filter reaches 0.05. ······ Backwashing intensity: The backwashing intensity for multi-media filters is generally between 8–12 L/m2·s, while for activated carbon filters it is 8–15. For other types of filters, refer to Chapter on Filters in Volume 2 of the Water Supply and Drainage Manual. Nowadays, backwashing is usually carried out using a high flow rate with low pressure; moreover, the flow velocity is kept at around 30 m/h, as mentioned earlier. I’m not quite sure about this… If there isn’t enough backwashing intensity or insufficient water volume for backwashing, then… Keep it at 30 m/h and let’s see how you handle it :)) ； What does 30 m/h mean? Can someone explain it? ? ? ? ? ? ?
I think it’s roughly possible to determine whether the backwashing is complete by using the senses (just by checking the clarity of the water after backwashing)