How do you remove phosphorus from wastewater using algae?
Phosphorus (P) is a popular fertiliser product that is widely utilized throughout the world. In truth, Morocco has 70% of the world's phosphate deposits, with the other 30% divided between China, India, and the United States. These reserves, however, are not infinite. Phosphorus can be found in wastewater.
Algae are used in the elimination of phosphorus!
Algae collects carbon dioxide (CO2) and releases oxygen into the atmosphere via photosynthesis. While the use of wastewater as a fertilizer source limits its value, algae may still be collected and sold as a biomass for a variety of purposes.
Nevertheless, ideal circumstances for the employment of algae in Phosphorus removal can be difficult to achieve, as they require Nitrogen, light for photosynthesis, and a regulated amount of CO2.
There are currently two options for Phosphorus removal methods employing algae:
Open ponds or closed ponds and compact bioreactors.
Open ponds, also known as raceways, are inexpensive to create and maintain, but they have a wide area and are highly dependent on weather and lighting. As a result, their total output is low.
Compact suspended-solid phase photobioreactors, on the other hand, have a much smaller footprint and better productivity, but they also have a much higher OPEX cost to build and run.
A wastewater treatment facility would also need to establish a source or technique of CO2 generation to supplement ambient CO2 in order for the algae to thrive. Because nitrogen and phosphorus encourage algal development, they can be taken from wastewater.
In terms of appropriate illumination for photosynthesis, artificial lighting can give 24-hour production, but it is expensive. Natural light can also be used as an alternative. This, however, would necessitate enormous open plants, which would be less expensive to maintain but would only be productive during natural daylight hours. Seasonal variations must also be taken into account, however this can be avoided by installing the reactor within a greenhouse structure.
It's vital to remember that, while algae absorbs CO2 as part of the photosynthetic process, using an artificial light source might have a detrimental impact on the plant's CO2 footprint. For carbon neutrality, the plant's electricity use must be considered.
Techniques for Harvesting
There are now a variety of recognized strategies for harvesting algae.
Sedimentation, flotation, centrifugation, and filtering are examples of these processes.
In addition to the advantages and disadvantages of each approach, the harvesting technique chosen will be influenced by the type of algae and the planned application of the biomass. Furthermore, it is vital that the process does not produce contamination or have an impact on the quality of the resulting biomass, since this would reduce its value.
A number of researchers are now underway to investigate ways to modify existing procedures, as well as the creation of new technologies, to simplify the algae harvesting process. As prospective solutions, this emphasis includes spiral-plate centrifugation, electro-assisted flotation, and bio-flocculated settling.
While there are instances of functional algae plants all over the world, the key to wider deployment is the development of an energy-efficient approach that can be simply and cost-effectively adopted.
Netsol Water has pioneered Phosphorus removal using a range of technologies, in addition to our continuous research into alternative sources such as algae, which are presently employed by thousands of wastewater treatment plants across the world.