Changes of inorganic nitrogen compounds concentration in a mining enterprise wastewater by the microalgae Chlorella vulgaris

Abstract

Wastewater contamination by nitrogen compounds is a serious problem for the mining, industrial and utility companies. Nitrogen can enter quarry effluent when explosives containing ammonium nitrate are used in blasting operations. This nitrogen pollution of water leads to environmental damage and human disease, companies that exceed the legal limits for nitrogen pollution are subject to fines. Nitrogen is removed from wastewater by biological methods, but their efficiency is low in the Northern regions of Russia due to climatic factors that hinder the vital activity of organisms. Therefore, it is essential to develop wastewater treatment technologies for the removal of nitrogen compounds. This study focuses on the ability of the microalgae Chlorella vulgaris to absorb and utilize various inorganic nitrogen compounds in mining effluents using the example of effluents from the "Karelsky Okatysh" mine and tailings dam (Kostomuksha, Republic of Karelia). Concentrations of ammonium, nitrate and nitrite in water and microalgal biomass in water samples have been investigated. A novelty of the study is the evaluation of pollutant concentrations in parallel experiments with different cultivation conditions. It has been found that when Chlorella vulgaris is cultivated at 26 °C, aeration and artificial light, the concentration of ammonium decreases. These results show the promising application of bioreactor technologies for the treatment of ammonium polluted wastewater.