The plus side of electropositive filtration
The advantages over traditional sieve-type filters are numerous and potentially lifesaving .
HEALTH AND SANITATION 27
By
Yuly Vesga , PhD
Electropositive filtration takes advantage of surfacecharge effects . The net effect is the creation of a strong broad-spectrum particle magnet capable of filtering particles smaller than its pore size . Here , we present a brief explanation of how and where electropositive filters can be used .
To describe what makes a positively charged filter special , we can start by discussing the mechanisms of filtration used . Filters , in general , are classified depending on the mechanism they employ to remove particles , as well as on the type of particles they isolate . There are two main types of separation mechanism : sieve retention and adsorption . Sieve retention is the most common mechanism used for conventional filtration .
This type of filter retains particles that are bigger than the filter ’ s pores . While sieve retention depends on physical blockage , adsorption uses attractive forces to attain particles present in water ( typically negatively charged ). Accordingly , it is very easy to see which mechanism has the advantage . In the case of adsorption , the filter is capable of retaining particles that are so small they are practically impossible to hold with sieve retention . Additionally , since the adsorption process is based on adhesive forces , the pore size is not required to be smaller than the desired contaminant ’ s particle size .
Electropositive filters have several advantages over traditional sieve-type filters . Filtration of colloidal and nanometer-sized particles at low head pressure , elimination of water waste , high filtration efficiency , high dirt-holding capacity , and the potential of filtering certain soluble contaminants are among the advantages observed when using electropositive filters . There are numerous applications for the separation of a wide range of particle sizes . Two outstanding applications are as a polisher and pre-filtration for RO systems . Additionally , they can also be employed in the filtration of contaminants from the water waste stream in pharmaceutical and chemical plants and the filtration of soluble and insoluble dyes . However , a significant and often overlooked ability of electropositive filtration is the removal of microbial pathogens without the need for chemical treatment .
As previously mentioned , electropositive filtration is based on the adsorption mechanism , which is considered the most efficient process for the separation of viruses and bacteria from water . Most viruses and bacteria are known to be negatively charged at a neutral pH . As a result , there is an attraction force that exists between the negatively charged viruses and bacteria and the overall positive charge from the surface-modified media . In other words , the media exhibits a positive zeta potential . It is important to remove microbial pathogens from water because microbes are not only potentially pathogenic contaminants , but also foulants in HVAC ( heating , ventilation , and air conditioning ). Additionally , they have a tendency to attach to surfaces and form biofilms . Finally , bacteria can play a role in corrosion .
Fortunately , these types of filters are manufactured and readily available to the public . While the worldwide population could use this type of filter , those most vulnerable to bacteria and viruses ingestion , like children , the elderly , and the immune compromised , would most benefit from this unique capability .
Filter manufacturers are doing an excellent job at offering options for implementing water filtration systems for residential use . There are two main types of system : POU ( point of use ) and POE ( point of entry ). POU systems are easily identifiable because they are connected under the sink . POE systems , more commonly known as wholehouse systems , are another very convenient option . These two systems , either by themselves or in unison , can provide the homeowner protection from many unplanned and potentially dangerous ‘ water events ’.
One such ‘ water event ’/ concern for the homeowner should be the boil water notice / warning . There are more than 5 000 boil water notices per year in the United States alone . These are issued when the water distributed by a municipality plant is suspected to be contaminated with microbiological agents . Some of
Russ Chaney
In the spirit of the sharing of unique experiences that shape the plumbing industries in our respective nations , the following article looks at how and where electropositive filters can be used . Written by Yuly Vesga , PhD , of Argonide Corp ., it is the next in a regular series of similar articles that will run in this magazine .
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www . plumbingafrica . co . za April 2018 Volume 24 I Number 2