Migration and transformation of nitrite nitrogen in underground reservoir of Bulianta Mine
In the water-scarce western regions of China,the temporary storage and purification of mine water are commonly achieved through the utilization of underground reservoirs for coal gangue backfilling.However,research concerning the migration and transformation of nitrite nitrogen in underground reservoirs has been notably scarce.This study focuses on nitrate nitrogen in mine water containing industrial wastewater from the Bulianta mine,simulates the hydrogeological conditions of the Bulianta mine's underground reservoir,and conducts the dynamic column leaching experiments,which aim to further investigate the migration and transformation laws of nitrite nitrogen within the backfilled gangue in the goaf area.The research findings indicate that the concentrations of nitrate nitrogen(NO3--N),ammonia nitrogen(NH4+-N),total inorganic nitrogen(TIN),and total dissolved solids(TDS)in the effluent exhibited similar overall trends,characterized by three distinct phases:a rapid increase,followed by a gradual decrease,ultimately stabilizing.The removal efficiency of nitrite nitrogen ranged from 78.9％to 89.8％,with the TDS value in the effluent being approximately twice that of the influent.Throughout the experiment,approximately 15.65％of the inorganic nitrogen was adsorbed or converted into nitrogen compounds such as N2,N2O,or NO by the backfilled coal gangue.Ammonia nitrogen within the coal gangue exhibited initial substantial leaching,which progressively decreased over time,eventually stabilizing.The buffering effect of ammonia nitrogen on pH,nitrogen's biological transformation,and the leaching of alkaline components from coal gangue collectively contributed to a gradual increase in the effluent's pH level.However,it consistently remained below the influent pH level.The research findings can enrich the theory of nitrogen cycle,which hold significant importance in assessing the pre-treatment effectiveness of underground reservoirs in western China coal mining areas for mine water and understanding the water purification mechanisms.
underground reservoircoal ganguenitrous nitrogenmigration and transformationinorganic nitrogen
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