Applications for Anthracite Filter Media in Desalination Water Purification Processes
In the process of removing impurities from water, the typical method is to use a filter medium in order to efficiently accomplish that goal. In some cases, the use of two media such as in applications involving anthracite and sand are involved.
What makes anthracite water treatment filter media so effective? It all comes down to the chemical composition of anthracite itself and, more specifically, how that interacts with impurities often found in water.
For this article, we are going to outline the properties and applications of anthracite coal filter media.
We’ll discuss why anthracite for water filtration is a common application and the various ways in which this is configured in the real world involving both dual media and a single medium.
Beyond that, we will explore the ways in which anthracite can be used to render salinated water potable and drinkable and how this can be used to bring much needed relief in terms of usable water to regions that lack easy access to fresh sources.
Anthracite - Properties and Applications
What is anthracite?
Anthracite is a form of coal that is densely packed and has a high carbon content, relatively few adulterations, and the second highest calorific content of any type of coal with only graphite beating it.
Calorific content refers to the amount of energy produced by the combustion of an object or the energy it would produce in that event. Principle uses of anthracite in the industrial sector include power production as well as the fields of metallurgy and water purification.
Representing only one percent of all of the coal in the world, anthracite is mined in a select number of countries such as China (the world’s leading producer), Russia, Vietnam, Canada, and the United States. Anthracite can often be distinguished from other types of coal due to its metallic appearance which reflects light in a manner similar to the mineraloid (and fellow ignite) jet, a substance used in jewelry products.
The high carbon content of anthracite makes it particularly suitable for filtration.
Because this ensures that anthracite for water filtration is not impacted by the chemicals it encounters. In other words, it does not absorb or retain dangerous chemicals which can then be drained into runoff water that passes through the anthracite filter media. Further, the shape of anthracite itself helps to provide an effective means for preventing impurities from remaining in water.
Anthracite as a Water Filtration Mechanism
How does a media filter such as anthracite work?
Anthracite coal filter media and others work through a combination of chemical composition as well as using the laws of gravity and physics to purify contaminated water.
A filter media is any kind of substance - such as crushed gravel, sand, anthracite, or even glass - which acts as a sieve from which solids are removed. The finer the grain of your filter media, the more granular it can get in removing these impurities.
Because things readily dissolve in water but do not readily dissolve entirely, substances that are not completely dissolved in water can be “caught” in the filter media with only the water passing through at the end of the filter.
As anyone can readily see, this has a myriad of uses in the modern world from managing runoff from a storm to keeping water clean and drinkable. It is this last concern that has anthracite water treatments gaining traction in many arid parts of the world where access to fresh water is limited and the resource itself is scarce. In fact, anthracite filter media suppliers around the world are pushing it as a solution to many impending water crises in different locations across the globe.
The only question is: Are anthracite water treatment filter media effective at removing the impurities found in seawater which are myriad and microscopic?
Is Using Anthracite for Water Filtration Effective at Removing Impurities in Salt Water?
Given that anthracite is one among many mediums that can be used for removing impurities in water, is it the most effective at doing so with salt water specifically? While there is little question about anthracite’s effectiveness as a filter, it is not the only option when it comes to desalination.
In fact, many uses of anthracite involve industrial use scenarios. Nonetheless, it was demonstrated in research presented at the Desalination and the Environment conference in 2007 by the European Desalination Society and Center for Research and Technology, Hellas, that anthracite is not only an effective medium for desalination but is performatively on par with processed expanded clay (another popular material).
In every test case scenario brought forward by the team, the two media performed at nearly identical levels with optimal performance achieved in the summer months because of what they attributed to higher aggregations of material caused by hotter temperatures. The team looked at an intake in the Thermaikos Gulf in northern Greece and measured according to “filtrate quality parameters relevant to feeding RO membrane desalination systems, that is, turbidity, silt density index (SDI), total organic carbon (TOC)” according to their published research.
The only differences in performance arose from the coagulant material used in each scenario. What is the coagulant material? It is how media such as anthracite work in tandem with another filter media to remove impurities from water.
How Anthracite Water Treatment Methods Work with Salt Water
Because the impurities in salt water are quite tiny indeed, filter media such as anthracite often work in tandem with a coagulant substance for optimal performance and filtration of water. What is a coagulant?
Coagulants are chemicals that aid in the creation of what are called aggregates or clumps of impurities that are larger in sum than they are in their parts. When a coagulant helps create larger aggregates, this makes the impurities easier to remove for filter media like sand and anthracite.
To look at it a different way: Using coagulants with anthracite makes anthracite more effective at removing the impurities in salt water by increasing their weight and surface area. In the research presented at the 2007 Desalination and the Environment conference in Greece, findings showed that not only was anthracite water treatment effective at desalination across a wide range of performance environments (temperature, etc.) but also that it was comparable to the clay material in building up water resistance or what is called hydrostatic head.
Here’s how the process works in its simplest form: You start with a pretreatment process which is where you take untreated or “raw” seawater and remove algae and organic materials from the water. This is accomplished by pumping the raw seawater into what are called multimedia filter tanks consisting of a layer of anthracite, sand, and then gravel at the bottom. Water moves from the top of the tank out through the bottom, passing through the anthracite, sand, and gravel layers as it does so.
The treated salt water that results from this process then goes through another treatment which is often called microfiltration. What microfiltration refers to is the removal of small matter in your treated seawater such as things so tiny they would require a microscope to see. At this point, the water is ready for a process referred to as reverse osmosis.
This means that the water is pushed through a porous material at high pressures in order to remove the small particulate salts, bacteria, and viruses that may remain in the water. Once this process is complete, the water is then pumped into storage tanks to await consumption.
Proposed as a solution to the problem that 4 billion people - or nearly half of the world’s population - will be short of potable water by 2030, anthracite filter media suppliers will be working in concert with others such as sand and gravel presents one among many possible solutions to this problem. Given its demonstrated efficacy in this area, the use of anthracite water treatment methods is expected to grow in the coming decades .