The possibility of using Chlorella algae to reduce the mining industry load on a Karelian lake-river system

Abstract

Inorganic nitrogen compounds in wastewater are a serious problem for aquatic ecosystems and various industries, including mining. These compounds can enter the wastewater of quarries when explosives containing ammonium nitrate are used, resulting in environmental damage, water pollution, human illnesses and fines for companies that exceed binding pollution limits. Biological methods are widely used to remove nitrogen from wastewater, but their efficacy in northern regions of Russia is limited by unfavorable climatic conditions, which inhibit the growth of organisms. Therefore, it is crucial to develop new techniques to remove nitrogen compounds from wastewater. The aim of this study was to investigate the ability of Chlorella algae grown on nitrogen-free medium to recycle nitrogen compounds from mining wastewater, using Karelsky Okatysh JSC open pit water as an example. A special nitrogen-free culture medium was prepared for the experiments, on which the algae were grown before inoculation. The concentration of algal biomass was estimated by the colorimetric method, and the concentration of ammonium and nitrite in the water was estimated by the ion-selective method. As a result, a special algae culture medium without nitrogen sources was tested. Due to such conditioning of algae on the new medium the cultivation of algae in wastewater in the experiment was successful, providing 94% removal of ammonium and 96% removal of nitrates from wastewater. These results indicate the development of a technology for wastewater treatment to remove inorganic nitrogen using microalgae of the genus Chlorella has good prospects