Classical Greek cult of beauty and personal hygiene first wastewater treatment systems. This interest in eliminating waste and enjoying clean water dates back to ancient Rome. The famous Cloaca Maxima enabled the elimination of waste in one of the most populous cities of the ancient world.
These advances were cut short in the Middle Ages. Very few cities have preserved Roman sewer structures. The blind wells overflowed in a short time. And even though it sounds crazy now, just throw the feces out the window and say “the water goes away!” shouting. This has become common practice. As you can imagine, this practice has attracted countless pests and diseases, as well as conflicts between neighbors.
Nowadays, in developed countries, you no longer see wastewater flowing on the streets. But as believers know, this does not mean that they do not exist. To see these, all you have to do is go a few kilometers to any treatment facility operating outside the cities.
These facilities are responsible for removing contaminants from wastewater.allowing them to be safely poured or reused. These have been great advances and are very important. However, the removed contaminants cannot be recovered and are expensive processes that require large amounts of energy.
Microalgae: efficient and sustainable purifiers
In the era of climate change, wastewater regeneration is vital for sustainable development. There is an old saying; Water is not missing until the well dries up. The truth is that the well is not dry yet, but we are slowly drying it. The situation is already dramatic. One in three people do not have access to safe drinking water. Approximately 4 billion people lack basic sanitation services. Moreover, Dirty water is the leading cause of death worldwide.
Considering this situation, one of the main goals of the United Nations is to ensure universal and equitable access to water. Microalgae named as one of the keys to integrated management of water resources. It allows us to treat wastewater with lower energy consumption and at the same time increase the sustainability of the process. They consume less energy because they perform photosynthesis and therefore feed on sunlight.
Another great advantage of these microorganisms is that they consume carbon dioxide. producing and accumulating compounds of interest. Let’s not forget that one of the main causes of climate change is carbon dioxide. These interesting products, such as agricultural biostimulants, allow benefits to be achieved where previously only costs were incurred.
Their ability to purify wastewater gives them a dual role: It allows the recovery of pollutants in wastewater and the simultaneous production of valuable compounds. This is one of his greatest virtues. In processes based on microalgae, the word rescue is key. While nutrients and pollutants in wastewater are removed by conventional processes, microalgae have the ability to restore them.
These microorganisms More individuals recover carbon, nitrogen and phosphorus from wastewater to reproduce and produceor biomass, which is the same. We can use the produced biomass as an ecological and sustainable fertilizer or animal feed ingredient.
Microalgae-based biostimulants are a guarantee of sustainability. They consume carbon dioxide during their production and It enables obtaining quality fruits and vegetables with less fossil fertilizer and water consumption.. Its use in feed is also sustainable. It not only improves animal health, but also minimizes the need to import products such as soybeans.
Challenges of large-scale implementation
Purifying wastewater using microalgae is a new technology. It is still under development and faces a number of challenges.. Microalgae with intense color shade each other. Due to the need for light, it is necessary to work in shallow waters.
One of the main goals of studies in this field is to increase the efficiency of these processes, allowing the purification of larger volumes of water in smaller reactors. Additionally, little is known about how environmental and operating parameters affect the quality of microalgae produced. This is vital as it directly affects the quality of the final product.
Great efforts are also being made to understand how these organisms interact with bacteria. Bacteria occur naturally in wastewater and the environment. They cooperate with microalgae in water purification. Knowing this process in more detail will allow us to design more efficient and sustainable systems.
While wastewater was black water in the Middle Ages, it turned into black gold in the 21st century.. Although there is still a long way to go, the results to date are promising. There are cities such as Chiclana in Andalusia that already use microalgae purifiers. Within the scope of the H2020 SABANA project, one of the largest microalgae treatment plants in Europe is being built in Mérida. We will gradually learn to benefit from the great advantages that these small and precious creatures offer us.
Ana Sánchez Zurano is a researcher in Biotechnology at the University of Almería.
Tomás Lafarga is a researcher in Chemical Engineering at the University of Almería.
The article was originally published on The Conversation
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