Feb 22 2021
RUDN University biotechnologists worked with biotechnologists from Lomonosov MSU and Kurchatov Institute to make a significant contribution to the technology of biocapture of nitrate and phosphate from wastewater by making use of Lobosphaera algae placed on filters.
Biotechnologists from RUDN University in collaboration with Lomonosov MSU and Kurchatov institute made an important contribution to the technology of phosphate and nitrate biocapture from wastewater using Lobosphaera algae fixed on the filters. The biomass obtained in the course of this process can be used as a fertilizer. Image Credit: RUDN University.
The biomass produced through this process can be utilized as a fertilizer. The study findings were published in the Journal of Water Process Engineering.
Nitrates and phosphates reach the wastewater along with household and industrial waste, specifically detergents. Both substances are considered as a part of the nitrogen and phosphorus chemical cycles.
However, these cycles are interrupted by the activities of humans, as the increasing amounts of nitrates and phosphates cannot be processed by water ecosystems.
Consequently, such substances transform from beneficial nutrients to pollutants.
Wastewater treatment involves using unique equipment and microorganisms, such as microalgae that use up nitrates and phosphates.
Biotechnologists from RUDN University along with their collaborators from MSU and the Kurchatov Institute have designed a biopolymer filter on which beneficial microalgae can be fixed.
The polymer is chitosan-based, biodegradable, safe for the algae and traps chemical elements from wastewater more efficiently compared to its present equivalents.
Our team was the first to successfully use cross-linked chitosan polymers to immobilize unicellular algae and make them effectively consume nutrients while at the same time not preventing them from growing and photosynthesizing.
Alexei Solovchenko, PhD in Biology, Department of Agrobiotechnology, RUDN University
Chitosan, a polysaccharide, contains amino groups and has a chemical composition quite similar to that of chitin found in mushroom cell walls and shellfish crusts. Chitosan is not water-soluble and thus can be utilized for growing algae, but it is biodegradable.
By employing an original methodology devised in the Kurchatov Institute, it was cross-linked with glutaraldehyde molecules and thus transformed into a robust biocompatible polymer. The researchers then grew the IPPAS C-2047 strain of the Lobosphaera incisa algae on it for a period of seven days.
On the basis of the results obtained from the seven-day-long experiment, the researchers came up to a conclusion that a complex of microalgae cells and chitosan-based polymer with a total molecular mass of 600 kDa was more effective compared to that with a molecular mass of 250 kDa.
The algae on the filter were able to capture the nutrients more effectively compared to those suspended in the wastewater: Particularly, they used up nitrates 1.3 times and phosphates 16.7 times quicker.
Chitosan biofilters that have already been used could be repurposed as fertilizers. As time passes, chitosan would degrade without any harm to the surroundings, and the algae would serve as a source of collected nitrates and phosphates for the plants.
Our team has demonstrated that cross-linked chitosan polymers are safe for the environment and effectively support the biocapture of nutrients from wastewater by unicellular algae. When added to a non-toxic medium, the algae biomass could be used as a fertilizer that would gradually release the accumulated nutrients into the soil.
Alexei Solovchenko, PhD in Biology, Department of Agrobiotechnology, RUDN University
Journal Reference
Vasilieva, S., et al. (2020) Bio-inspired materials for nutrient biocapture from wastewater: Microalgal cells immobilized on chitosan-based carriers. Journal of Water Process Engineering. doi.org/10.1016/j.jwpe.2020.101774.