Understanding the Power of Reverse Osmosis

One thing that I feel we take for granted as a society, especially in a country like the United States, is our drinking water supply. Unfortunately, most people aren’t privileged enough to have access to clean drinking water or even fresh water; as a matter of fact, a staggering 1 in 4 people, 25% of the world's population, lack access to a clean water source. This is already a deeply challenging problem, which becomes more complex as we are currently facing an ongoing depletion of the world's freshwater supply. 

To give perspective, only 2.5-3% of water on Earth is fresh water. And through my research, I learned an even more staggering fact: only .03% of all water on Earth is healthy drinking water. Out of all the freshwater, 68% of it is trapped in ice caps, 30% is in groundwater, .3% is in surface water, and .9% is in the atmosphere. This goes to show two critical problems: first, water availability, and secondly, fresh water depletion.

Recently, on a trip to the grocery store, I picked out a drink to complement my lunch. Whenever I get a drink, I look at the ingredients and nutritional facts, but to my surprise, I didn’t see water alone as an ingredient; it stated “reverse-osmosis water.” This piqued my interest as to why this wording was specifically chosen, which led me to this research.

Reverse Osmosis

To understand the process of reverse osmosis, it’s necessary to go back all the way to high school biology. Osmosis itself is the movement of water molecules through a semi-permeable membrane from areas of high concentration to low concentration. To complete the opposite, reverse osmosis uses a high-pressure pump to reverse the natural osmotic gradient of the contaminated water through the semi-permeable membrane. The semi-permeable membrane has been proven to remove up to 98% of pollutants, including lead, asbestos, microorganisms, sediments, bacteria, fluorides, chlorides, sulfates, heavy metals, industrial chemicals, pesticides, total dissolved solids, and more. The job of the membrane is to only allow molecules the size of water molecules through miniature pores, therefore separating the solutes and other undesirable substances from the concentration. The process of reverse osmosis treatment begins with a source, such as seawater, rainwater, river water, well water, and/or others, which is introduced into a pre-treatment center to remove large particles that contaminate the water and could damage the membrane. After pre-treatment, the still contaminated water enters a tube with a semi-permeable membrane sitting in the middle of the tube at an angle. From there, the high-pressure pump pushes the contaminated water through the membrane that should only allow water molecules to pass. The rest that does not pass enters a tube below the membrane, and the fresh water is then served to the faucet. There is also a double filtration system which recycles both the wastewater, known as concentrated brine, and the fresh water. Both are recycled through the filtration system again, separately, creating a larger amount of fresh water supply. The wastewater is then put into a bucket ready for removal.

Pros & Cons

Even though this process is very successful, it can come with some problems, including: Mineral removal that may inadvertently affect kidney and overall body health without the necessary minerals found in most water, such as electrolytes; slow filtration rate, high initial and maintenance costs, and acidity of the water. These are some flaws within this solution; however, the benefits heavily outweigh these negatives. This system has some of the highest filtration rates, which thus reduces waterborne diseases; it is an energy-efficient alternative to other distillation methods; it is widely applicable, especially in water-scarce areas, and it is cost-effective.

This may not be the perfect solution for the large-scale water problem, such as supplying whole countries. This water treatment strategy is, however, a great solution to the drinking water availability problem in third-world countries or isolated populations where the implementation of large-scale water treatment facilities is not a financially viable option. This would provide healthy drinking water to places with toxic water supplies and give the right to hydration to everyone.

Additional Concerns

This is a great solution for the water availability problem, but it still creates one large problem and additional concerns. Like all treatment methods, the fresh water is, of course, separated from all the undesirables, but this creates a sludge of bacteria, metals, chemicals, salts, and all other sorts of materials. We still don’t exactly know what to do with the waste if large-scale water treatment were to occur, some people are extracting the precious metals like lithium or copper for car batteries, others are separating the salts from the sludge, but overall this waste proposes a problem that must be solved in the coming years if we are to successfully solve the fresh water and water availability problems, without creating another world disaster in itself.

Conclusion

Although we are facing one of the hardest challenges of our history, we must not maintain a cynical view of the future; rather, we must look to science and engineering for solutions. We have come up with many solutions for this specific problem, from collection of rain water which undergoes a natural purification process through vegetation and soil filtration to water treatment facilities around the world. We have shown much resilience to this problem, however we must continue to work towards a world where everyone can drink water without worry.