Biotechnologists from RUDN University in cooperation with Lomonosov MSU and the Kurchatov Institute made an important contribution to the technology of bio-phosphate capture and nitrate from wastewater using Lobosphaera algae installed on filters, and the biomass obtained in the course of this process can be used as fertilizer. The results of the study were published in Journal of Water Process Engineering.
Phosphates and nitrates reach wastewater with industrial and household wastes, especially detergents. Both materials are parts of phosphorous and the chemical nitrogen cycles. However, these cycles are affected by human activity, as increasing amounts of phosphates and nitrates cannot be processed by aquatic ecosystems. As a result, these substances turn from beneficial nutrients into pollutants. Wastewater is treated with special equipment and microorganisms, including microalgae that consume phosphates and nitrates. A team of biotechnologists from RUDN University along with colleagues from Michigan State University and the Kurchatov Institute have developed a biopolymer filter on which beneficial microalgae can be placed. The polymer is based on chitosan, which is safe for algae, is biodegradable, and captures chemical elements from wastewater more effectively than its current counterparts.
“Our team was the first to successfully use chitosan cross-linked polymers to immobilize single-celled algae and make them effectively consume nutrients while not preventing them from growing and acting out,” said Alexei Solovchenko, a PhD in Biology from the Department of Biology from the Department of Biology. Photosynthesis. ” Agricultural Biotechnology, RUDN University.
Chitosan is a polysaccharide with amino groups and its chemical composition is similar to that of chitin that can be found in the shells of oysters and the cell walls of mushrooms. Chitosan is insoluble in water and thus can be used in growing algae. However, it is biodegradable. Using an original methodology developed at the Kurchatov Institute, they were bound to glutaraldehyde particles and thus transformed into a strong biocompatible polymer. Then the team grew the IPPAS C-2047 strain of Lobosphaera incisa on it for seven days.
Based on the results of the seven-day experiment, the team concluded that a compound of microalgae and chitosan-based polymer with a total molecular mass of 600 kDa was more effective than a molecular mass of 250 kDa. The algae in the filter absorbed nutrients more efficiently than those suspended in wastewater: specifically, phosphates consumed 16.7 times and nitrates 1.3 times faster.
Bio-Filters Chitosan can be reused as fertilizer. Over time, chitosan will degrade without causing any harm to the environment, while the algae act as a source of phosphate and nitrate accumulation for plants.
“Our team has demonstrated that chitosan cross-linked polymers are environmentally safe and effectively support the biological capture of nutrients from wastewater by unicellular algae. When added to a non-toxic medium, the algae biomass can be used as a fertilizer that gradually releases nutrients accumulated in the soil,” added Alexei Solovchenko of RUDN University.