Water treatment processes are not exempt from problems that can become a real nightmare. One of them is when the activated carbon does not fulfill its function of removing free chlorine and organic matter from the water, so it is important to know what alternative there is to activated carbon. The solution to this common problem is quite simple: sufficient contact time and backwash flow is required.

Contact time (alternative activated carbon)

This is the time that the flowing water remains in contact with the carbon. If this time is less than required, the carbon is not able to destroy free chlorine (which occurs by chemical reaction with the carbon) and to retain organic matter. The minimum contact time required depends on the average particle size of the carbon and the contaminant content of the water.

Backwash flow

The water flows downward through the carbon bed, so the carbon particles become compacted and stick together. This makes backwashing necessary to loosen them. If backwashing is not performed frequently and with sufficient flow for the bed to expand, the coal bed ends up cracking and the water begins to flow, no longer through the coal particles, but through the cracks. As a result, the water is no longer purified. In these cases, the user often believes that the carbon is saturated, which is not the case.

How can we know what backwash flow rate and contact time are appropriate?

By asking simple questions about the water and your process conditions, Carbotecnia engineers can calculate the contact time and flow rate required for the coal to operate properly.