Ensuring clean, safe, and sustainable water is critical in today’s world. Water treatment technologies, like multi-grade filters, are a key to promoting the sustainability of freshwater. From brushing our teeth to manufacturing a car, water is needed everywhere, and that’s why wastewater treatment is an essential process to save freshwater.
In different forms of wastewater treatment, multi-grade filters play a paramount role in improving water treatment. In this article, we will understand all the core facets of multi-grade filters and how it is beneficial for water treatment. Let’s begin with the basics.
A multi-grade filter is a wastewater treatment system that can remove suspended particles and turbidity from the wastewater. As the name indicates, it employs multiple layers of filter media with different grades or particle sizes to remove these impurities. The multi-layered design allows for efficient filtration of particles of varying sizes, improving the overall filtration performance.
These are mostly used in municipal water treatment plants to remove suspended solids and turbidity from raw water sources. They help produce clearer water, making it suitable for drinking and meeting regulatory standards. There are also various industries that use multi-grade filters to treat process water, cooling water, and wastewater to ensure the removal of particulate matter.
The major components of a multi-grade filter are:
This is a cylindrical or rectangular tank that contains the filter media. It is generally made of steel or concrete with inlet and outlet connections.
There are different grades of filter media with different particle sizes in the multigrade filter. The media layers are arranged in a specific sequence within the filter vessel. Some of the commonly used filter media are anthracite coal, silica sand, and garnet. The media with larger particle sizes are placed at the top, followed by finer media at the bottom.
The role of distribution is to ensure even distribution of the influent wastewater across the filter media. It typically consists of underdrains, lateral pipes, and nozzles that distribute the water uniformly over the surface of the media.
The usage of the backwash system is to periodically clean the filter media and remove accumulated solids. There is a backwash pump, valves, and a wash water collector system in the backwash system. The backwashing process involves reversing the water flow and fluidizing the media to dislodge trapped particles.
The control system is used to monitor and regulate the operation of the multigrade filter. It controls flow rates, backwashing cycles, and other parameters to optimize the filtration process and ensure efficient operation.
There are 5 major processes involved in the working of Multi-grade filters:
In this step, the wastewater enters the filter vessel from the inlet connection. The wastewater gets evenly distributed across the top layer of the larger media by the distribution system. This wastewater, when it passes through the media layers, suspended solids and turbidity get trapped within the filter.
By eliminating larger particles and acting as a pre-filter, the large media at the top layer shield the smaller media underneath. Smaller particles are captured and further filtered by the finer media in the bottom layers.
After a time, the suspended solids will accumulate in the filter media, which will result in an increase in pressure drop across the filter. This indicates the need for backwashing to revitalize the efficiency of the multi-grade filter.
When there is a pressure drop to the threshold level, the control system initiates a backwash cycle. In this cycle, the backwash pump reverses the water flow, fluidizing the media bed from the bottom to the top. This action dislodges and removes the trapped solids, which are carried out through the wash water collection system.
After backwashing, a rinse cycle may be performed to settle the filter media and remove any remaining impurities. The filter is then returned to filtration mode, and the cycle continues.
The combination of different media grades allows for efficient filtration and improves solids removal compared to single media filters.
There is an extension of duration between backwashing cycles by the multigrade configuration. It results in lower operational costs and water consumption.
Different combinations of media grades can be used to tailor the filtration system to specific wastewater characteristics and treatment goals.
Backwashing helps in the maintenance of filter media performance and increases its lifespan.
In this article, we have understood all the necessary concepts of the multi-grade filter media and how it improves the wastewater treatment system. At Wipro Water, we have expertise in developing wastewater treatment systems with multi-grade filters for high-quality water and maximum treatment plant life. Let us know your requirements.