Performing backwashing of your filters with the proper frequency and in the correct manner ensures the efficiency of your filtration system, providing cost savings and maintaining water quality. It is a preventive measure to avoid the bypass of material that should be removed by filtration.

It is a simple process that involves cleaning the filter bed by inserting a reverse flow against the normal filtration direction. It should be applied to any filter designed for use with water where the filter bed needs cleaning after the filtration cycle ends. Sand filters, activated carbon filters, zeolites, and screen filters are examples that require the backwashing process.

Filters that are not backwashed regularly are ineffective in removing contaminants and solids, as their bed becomes saturated. There is also a risk of screen rupture, sand clogging, preferential channeling, and sludge balls, depending on the filter bed.

When should you perform backwashing on your filters?

Backwashing should be performed whenever there is a recorded pressure drop (differential pressure) that exceeds a pre-set value or when the established filtration cycle time is reached. In this way, the quality of the raw water will determine the backwash frequency.

How to perform backwashing on your filters?

The backwashing process is simple but should be conducted following certain requirements to ensure the efficient cleaning of the bed.

Upward Flow – If the filter uses an upward flow, a bottom discharge should be performed for a sufficient time to clean the base of the bed. Then, upward washing is done, applying enough flow to expand the upper sand layer for a specified time. The duration of each stage can be determined by observing the reduction in the turbidity of the filter wash water.

Downward Flow – For downward flow filters, backwashing begins by introducing a flow counter to the filtration direction. This flow should be set according to the supplier’s recommendations regarding the rate, which is associated with the bed’s particle size, to ensure the minimum recommended expansion. Its duration can also be determined by observing the turbidity of the discard water.

The Importance of Backwashing Automation

The possibility of automating backwashing of sand filters ensures an increase in filtration safety and efficiency. For example, if automation is based on the pressure difference between the filter’s inlet and outlet, when the pre-set value is reached, the pressure switch sends an electronic signal to the control panel, indicating that backwashing should start. This eliminates issues such as unnecessary or excessive backwashing.

Hidro Solo offers a backwashing automation system that works with pressurized filters (PLUVITRON control panel), allowing the automation of a single filter or a series of filters using the same controller.

Learn more about the PLUVITRON Control Panel on our website or speak with one of our specialists.