The Concept of Multi Media Depth Filter (MMDF)

Recently, I had an argument with a certain technician claiming that he had been doing the installation for more than 15 years.

The topic revolves around the concept of Multi Media Depth Filter (MMDF)

According to him, it is composed of garnet, pebbles, silica sand, manganese green sand and so on and so port.

He even pointed out that filtration happens from the top layer up to the bottom layer of the media elements he mentioned that is why it called Depth Filtration.

So, all the media elements that he mentioned are all doing the filtration process one at a time or by stages as commonly understood.

He was very confident of his FORMULA in loading the media elements and even told me that the water tastes different once his FORMULA was used.

For 15 years, he had been using this TRIED and TESTED FORMULA of HIS.

As Behavioral Science graduate, it has always been my discipline that for every concept, there should always be a theoretical and conceptual background of a certain ideas to be discussed.

Sabi nga sa amin sa Batangas, eh nasaan ga ang proven? Sabi nga ng mga Pastor, saan talata sa bibliya nasusulat?

What I am trying to say is that, it does not matter how many years have you been doing it, the things that matters most is, are you doing it the right way?

Now we go to my rebuttal, First, all the media elements that was mentioned are not capable of depth filtration, the silica sand is just for surface filtration and is considered to be one of the supporting beds.

Second, manganese green sand is an oxidizing media element used for removing iron, manganese and sulfur. It has a different application and not considered as part of the Multi Media Depth Filter Tank.

Third, garnet, pebbles and gravel are also supporting bed and has nothing to do with depth filtration.

When it comes to cartridge, depth filtration happens if the cartridge can trap particulates starting from the outer to the inner surface as per Principle of Mechanism of Travel and Mechanism of Catch in conjunction with the Brownian Motion Principle (filtration efficiency increases as filters start to clog but decreased flow rate).

Talking of tank types filter (MMDF),filtration happens from the top surface to the bottom surface of the major filter media which is for MMDF application is the Anthracite coal,although GAC is also considered for depth filtration,however for purposes of simplicity,we just focuss on the Anthracite Coal

It is the Anthracite coal that does the depth filtration and not the gravel, sand, pebbles, manganese, garnet or others being used in order to show that the more layers would mean efficiency of filtration.

These mentioned media elements are just supporting beds (excluding manganese) to prevent the major filter media from collapsing and during the backwash mode, it provides a greater velocity so that particulates can be pushed up going to the drain.

However, this will only happen if, media elements are layered properly,

Now, after discussing to you these issues, it is up to you guys to evaluate the argument and see for yourself which is the right concept.

As I have mentioned, it is a matter of right concept, all of us in the water industry should always have the initiative of harnessing our skills through self study, experience in line with theoretical concept,

That is why, from time to time I share to all of you my views and comments on certain topics that I have learned, not to impress you but for information purposes and if you think that I have overlooked something or have discussed the wrong concept, you always have the right to refute and I will appreciate it very much since it will increase my knowledge. It is always a healthy exchange of ideas and we should always be open for constructive criticism in order for us to grow.

Telling me that it has been his experience for many years without any technical and theoretical basis is unacceptable fact for me.

How I wish that all of us can work hand on hand in informing the public the right concept.

- Orly Shanghai