We consume water for everyday activities like drinking, showering, and washing our dishes. Our water comes from natural sources of surface water and groundwater (1). Since our water sources are often exposed to the air and the surrounding environment, they can become contaminated by pollutants like nitrates, bacteria, and lead (2). However, the work of living organisms found in these waters, coupled with Safe Drinking Water Standards by the EPA (3), ensure that we have clean water in our homes.
Still, have you ever wondered where the used water goes after it goes down the drain or the toilet? The answer may not be too far from your home. In many towns, there are reclamation centers (4) that replicate nature’s water cleaners on a broader scale. These centers take in wastewater and place it in a process that makes it reusable. The “recycled” water is so clean it provides another supply of water without sacrificing human health. In result, the once wastewater can be reused for various purposes like irrigation. The water reclamation process is intriguing to explore in its entirety. However, let’s look closer into what organisms take part in the purification process in bodies of water and how their work is replicated in water reclamation centers.
The organisms behind this essential process are microscopic sessile suspension feeders, which are small organisms constituted by one or a few cells. These small organisms live attached to underwater surfaces like rocks, animals, or leaves. They use their hair-like parts to take in water through their feeder disks and filter it. By feeding on the bacteria and debris in the water, they carry out a principal role in cleaning up bodies of water.
Considering their size, it is hard to imagine that these microscopic feeders are able to survive in the midst of surrounding substances and the restraints of water circulation. However, these microorganisms have a strategy in which they orient their bodies to feed at a particular angle. When scientists studied the various methods of different feeders in water, they found that some feeders could filter water more efficiently than others. For example, scientists have found that protozoans (5), called Vorticella Convallaria, constantly change their body orientation relative to the surface they are attached to. This allows the organisms to efficiently absorb nutrients through their feeding disks, while speeding up the water’s flow and combating its resistance (6).
Scientists have sparse knowledge on the process the feeders use to filter out the contaminants and recycle them. However, they can compare the efficiencies of various feeders in order to form estimates on how much water the organisms can purify(7). This information can be used to estimate how quickly bodies of water, which have been affected by human-induced contamination, can be filtered out and cleaned.
With the knowledge that some organisms can feed on contaminants, scientists and “bug farmers” utilize bioremediation in order to clean up water (8). Bioremediation is using organisms or their ecological processes to resolve an environmental problem. This is applied in water reclamation centers where organisms are grown in engineered ecosystems that enable organisms to efficiently filter the water. In a multiple staged process (9), microscopic bacterial organisms are grown in aeration basins where water is mixed with oxygen. There, organisms feed on organic matter and convert it into a form of matter that can be easily separated from the water.
The solids removed from the water are called biosolids. After being removed from the water, they are further broken down in a later stage. After many stages, these nutrient-rich biosolids can be used in agriculture or as a compost.
In a later stage, the microscopic organisms are also removed from the water. Chlorine is used to eliminate all of the bacteria in the water, and sulfur dioxide is subsequently used to remove the chlorine from the water. These steps ensure that usable water is produced. Once the water is nice and purified, it is returned to the environment.
Even though the microorganisms’ role in water reclamation is only a snippet of the overall process, it is evident that they help make the process simple and efficient.
References and Footnotes
- Surface Water is the water that fills lakes, rivers, and streams. Groundwater is water that is accessible by wells and springs.
- Fetter, Jennifer R, and James A Clark. “The Water We Drink.” Penn State Extension, 2018, https://extension.psu.edu/the-water-we-drink
- EPA stands for the Environmental Protection Agency. Safe Drinking Water Standards state how much of a pollutant can safely be present in drinking water. The public water suppliers would need to notify families if the water they supply does not meet these standards. They might do this by a recommendation that families should boil their water prior to drinking it.
- Water reclamation is the process where wastewater is gathered and treated so that it can be reused for irrigation and other purposes.
- A protozoan is a single-celled organism that is a part of the animal kingdom Protista.
- Pepper, Rachel E. et al. “A New Angle on Microscopic Suspension Feeders near Boundaries.” Biophysical Journal 105.8 (2013): 1796–1804. PMC. Web. 28 June 2018.
- Cell Press News. “How Tiny Organisms Make a Big Impact on Clean Water.” EurekAlert!, American Association for the Advancement of Science (AAAS), 15 Oct. 2013, www.eurekalert.org/pub_releases/2013-10/cp-hto100813.php.
- “Bioremediation.” World of Microbiology and Immunology, edited by Brenda Wilmoth Lerner and K. Lee Lerner, vol. 1, Gale, 2003, pp. 73-74. Gale Virtual Reference Library, link.galegroup.com/apps/doc/CX3409800088/GVRL?u=caro78187&sid=GVRL&xid=c2c9dea0 Accessed 28 June 2018.
- San Antonio Water System. “Water Recycling and Reuse | Region 9: Water | US EPA.” EPA, Environmental Protection Agency, 2018, www.saws.org/Your_Water/Recycling/Centers/treatment.cfm .