Pressure swing adsoprtion, also known as PSA, is emerging as the most popular biogas upgradation technology in many parts of the world. A typical PSA system is composed of four vessels in series that are filled with adsorbent media which is capable of removing water vapor, CO2, N2 and O2 from the biogas stream.
During operation, each adsorber operates in an alternating cycle of adsorption, regeneration and pressure buildup. Dry biogas enters the system through the bottom of one of the adsorbers during the first phase of the process. When passing through the vessel, CO2, N2 and O2 are adsorbed onto the surface of the media. The gas leaving the top of the adsorber vessel contains more than 97% CH4
Biogas upgradation through PSA takes place over 4 phases: pressure build-up, adsorption, depressurization and regeneration. The pressure buildup is achieved by equilibrating pressure with a vessel that is at depressurization stage. Final pressure build up occurs by injecting raw biogas. During adsorption, CO2 and/or N2 and/or O2 are adsorbed by the media and the gas exits as CH4.
Depressurization is performed by equalizing with a second pressurizing vessel, and regeneration is achieved at atmospheric pressure, leaving a gas that contains high concentrations of CH4 to be re-circulated. During the regeneration phase, the bed must be regenerated by desorbing (or purging) the adsorbed gases. Purging is accomplished by reducing the pressure in the bed and back-flushing it with some of the concentrated gas product. The gas pressure released from one vessel is used by the other, thus reducing energy consumption and compressor capital costs.
Special adsorption materials are used as a molecular sieve, preferentially adsorbing the target gas species at high pressure. The adsorbent media is usually zeolites (crystalline polymers), carbon molecular sieves or activated carbon. Aside from their ability to discriminate between different gases, adsorbents for PSA systems are usually very porous materials chosen because of their large surface areas.
The reality is that drinking water has contaminants, and that’s something you have to address to ensure the safety of your family. The good thing is you can address this by simply investing in a good water filtration system. The following will help you understand how one would work.
Microfiltration Goes First
Okay, there are many water filtration systems out there to choose from. Some of these systems are whole-house systems you can have installed and will filter all of the water going into your home. The drawback is that these systems will have to be uninstalled if you decide to move to a new home.
Those who value portability may want to consider smaller water filtration that you can take with you wherever you go. Whatever you choose, the internal process of each water system normally starts with microfiltration. A reliable water filter system is going to have a complex filtration system with millions of pores to destroy potential contaminants like parasites, cysts, bacteria, herbicides, pesticides, and heavy metals, just to name a few things.
The microscopic pores do not allow pathogens and contaminants to pass through. Those contaminants become trapped within the filter. Of course, this is the reason your filters are going to have to be replaced sooner or later. The amount of times you replace your filter depends on how often the filter is used and the construction of the filter itself.
Adsorption is Key
The second step water filters take to ensure that your water is as clean as possible is adsorption. This is a process where an ionic barrier is formed to help the microscopic porous filter work more effectively.
The truth is some contaminants are a little smaller than the tiny pores of the porous filter. These contaminants could make their way out of the first stage without this second stage. The barrier seems to be strong enough to make contaminants like submicron viruses stop in their tracks. It also helps stop iodine or chlorine, both of which are quite common in tap water.
You should remember that the metals that could be in your water such as cadmium, copper, lead, and mercury are also extracted at this point. These questionable heavy metals are extracted through an Ion exchange process, thanks to the electronically charged barrier formed within the filter. Remember that all filters are not this sophisticated, so make sure you find out if the filter you are considering removes heavy metals.
There is no way you want to allow heavy metals to contaminate your home. A high concentration of these metals can lead to all sorts of other issues, such as organ damage. Some say that prolonged exposure to these metals could put people at risk of developing some types of cancer. Dangers like these shouldn’t plague your mind, and they don’t have to with the help of a good filter.
A Different Method
One more thing that needs to be pointed out is that good quality water filters usually use the long contact period filtration method. Okay, most water filters do what they are supposed to by relying on the water pressure in your home. In essence, the water pressure in your home pushes water through the filtration system, which is how contaminants are removed.
Technically, this type of filtration isn’t bad, and it is effective enough to give you clean water, but the long contact period filtration system takes another approach. What these types of filters do is allow water to flow through the first stage using gravity rather than pressure.
Gravity is a little slower, meaning the water has a long contact period as opposed to regular filters where the water shoots through the filter. Yes, this kind of filtration is a lot slower, but the results are much more impressive. You’d be surprised how many contaminants make it through a filtration system that relies purely on pressure. If you want to give your family the best clean water you can give, then be sure to choose a long contact period filtration system.
Now that you know how water filters work and why they are so important in living a healthy life, you can begin your search. The best thing is you won’t need to worry about buying water from the store nor will you have to pollute the earth with dozens of water bottles that you have to discard often.
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