Methods for Cleaning Polluted Water

Even though the surface of Earth is nearly two-thirds water, most of it is saltwater, and people still need a way to obtain reliable drinking water within their municipal systems. Decontaminating water can be done one of several ways, both chemically and organically. Choices for treating polluted water vary depending on what contaminants need to be removed and how the removal process interacts with the natural environment. Engineers who work with water purification must balance these factors while meeting the needs of a local population.

Reverse Osmosis

• A popular method of water purification for homeowners and water engineers alike, reverse osmosis removes contaminants from water by forcing the water through a semi-permeable membrane. In its natural state, water will always be drawn from a lower saline solution to a high saline concentrate, even if there is a semi-permeable barrier between the two. This is called osmosis. Reverse osmosis forces water back through a membrane that will not allow salt or other contaminants through. Such units are small enough to fit under a kitchen sink without being obtrusive. Reverse osmosis originally started as a way to desalinate seawater, but proved so effective in removing contaminants that it became available in small commercial home units.

Permeable Reactive Barrier

• The permeable reactive barrier method of removing water contaminants is used when there is a particularly troublesome problem with chemical contaminants affecting a local area's groundwater. This occurs when there is a high concentration of waste water accumulated on the surface of the ground that is leaking pollutants into the natural groundwater. Working with the water's natural flow, water engineers will insert a permeable reactive barrier into the ground to remove the contaminants with the water's natural flow. Permeable reactive barriers are generally made of a porous clay slurry that draws out the contaminants as the water passes through.

Bioremediation

• For restoring the quality of waste treatment water, many public works systems use bioremediation. This is when fungi and bacteria are intentionally introduced into waste water to break down the undesirable elements and make the water cleaner. This is particularly useful for solvents used in such businesses as dry cleaning, car wash facilities and polychlorinated biphenyls, or PCBs for short. This same function is what works -- on a lesser scale -- to turn rain water into drinking water when it is put through a rain barrel filled with sand. The bacteria that collects on the top of the sand breaks down the contaminants and allows them to be removed by scooping them off the top. Cities and states use this method by introducing the bacteria into the water and then pumping it back into the ground.

Solar Water Purification

• A recent development in the hydrosphere, solar technology is fast becoming a popular alternative way of dealing with pollution in water supplies around the world. Since ultraviolet light disinfects, it makes perfect sense to use it in the process of cleaning drinking water. By piping the water through long tubes exposed to concentrated solar energy, the water -- along with a mixture of hydrogen peroxide and iron -- becomes a powerful oxidising agent known as hydroxyl radicals. These essentially destroy the pollutants and make the water safe for human consumption. Some companies have developed solar power that will electrify the water and reduce it to gases, which in turn power a fuel cell. This creates not only clean water but electricity as well and is good news for rural communities worldwide with problems not only obtaining clean water but electricity as well.