Updated: Nov 8, 2020
Comparing air purification technologies
We have all wondered, from time to time, what is the best way to protect ourselves from harm, be it through the food we eat, the water we drink, or the air that we breathe.
During these troubled times, what we breathe has become of the utmost importance - how can we stay safe while not endangering others?
This issue now concerns everyone, from the smallest household to the largest company, as we seek to ensure personal safety and stay clear of liabilities.
In this post, we will demonstrate the most common air filtering technologies and summarise their performances.
What is a filter in the first place?
A filter may be considered any substance or device through which liquid or gas passes in order to remove impurities or trap solids.
It is only natural that different substances and different devices have different filtration qualities, based on their chemical or mechanical properties; as an example, pure water itself has a small filtering capacity, deriving from the weak polarity of its molecules (water molecules work like tiny magnets for particles in the air).
Given this introduction, let’s take a look at the different types of technologies that can be found in the air purifiers in your home or office.
Membrane filters are the most common filtration technique. The air is led through the layered cloth inside the device, which physically stops and contains pollutants.
The simplicity of this technology is also its weak spot; all the tiny, empty portions in the cloth that allow the air to flow can also allow the smallest particles to pass through the filter untouched. A denser cloth would simply stop the airflow entirely, which would defy its purpose.
Blocked pollutants also cause issues. As they are trapped in the tangle of the membrane, they are bound to stay there and, with time, saturate the filter which will eventually need to be replaced.
Even the highest performing, the HEPA (High-Efficiency Particulate Air filter) and ULPA (Ultra Low Penetration Air) suffer from the same limitations that this kind of technology poses.
Carbon Active Filters
Carbon Active Filters work similarly to membrane filters as they are composed of carbon grains that purify the airflow.
These grains are exposed to extremely high temperatures to create cracks, which capture the pollutant particles.
Carbon’s structure allows it to adsorb the particles by integrating them into its shape, preventing even the smallest pollutants from passing through the filter.
As a common membrane filter though, carbon active filters reach saturation after a certain amount of time (depending on their size and thickness) and must be replaced.
PECO technology (Photo ElectroChemical Oxidation) is usually used in combination with a membrane filter, which cleans the airflow before it reaches the PECO chamber, hence introducing all of the issues that this kind of filter brings with it.
Once the air flows through the membrane, it enters the PECO filter, where the remaining pollutants are oxidised and destroyed by UV light.
RNA/DNA virus, fumes, and volatile organic compounds (VOCs) found in a typical household can be completely destroyed. However thicker particles (smoke, dust, pollen), are merely blocked by the membrane filter and not captured.
Depending on the kind of UV light, a PECO filter may release traces of ozone due to oxidation.
Furthermore, the PECO filter must be entirely replaced once every 3 months to ensure full protection.
Scrubbers are a large family of filters that are mostly used in industrial environments to remove waste products.
The most commonly used are:
● Burners - when enough oxygen is present.
● Wet scrubbers - which require contact between the pollutants and the scrubbing solution (pure water or solutions of reagents).
Both methods present further complications concerning the disposal of the combusted products or polluted liquid.
U-Earth's technology is very simple - a population of bacteria live on the inside walls of the filter (a bioreactor) and are kept moisturised by a constant water flow, which feeds them the pollutants in the air that have been attracted by molecular electrical charge attraction.
That may sound confusing but it is best summed up by a principle of physics - Fick's Law - which states that particles under random thermal motion tend to spread from a region of higher concentration to a region of lower concentration. As the bioreactor attracts the particles (and the bacteria destroys them), more pollutants rush to fill the space and the cycle continues.
This technology allows a flow of clean air since all the particles in contact with the colony have either been digested or washed away by the water flow.
Wastewater can then be easily disposed of, while new bacteria need to be added into the bioreactor every thirty days in order to allow an ever-thriving colony to prosper.
Independent validations show a significant reduction in pollutants in the environment in which the filter is installed.
As you can see, almost all filters have a lifespan, during which performance tends to decrease, so the right step is to choose one that grants you full safety even when not operating at its maximum capacity.
We can see a drop in the membrane and active carbon filters' performance over time, as well as a minor decrease in the PECO filter. Thankfully there is always a steady purification rate in U-Earth's bioreactor.
Taking into account the straightforward maintenance of the devices, and the fact that they are plug-and-play (no structural work necessary!), U-Earth's bioreactor is the only one that needs no periodical part replacements, merely a refill of the bacteria and a water change, which are tasks that can be easily be performed by anyone.
U-Earth's biotechnology is also significantly more appealing to corporate and industrial customers since it can easily be scaled to solve specific problems and meet different needs.
Explore what's next in a pure air world by visiting U-Earth.