With the improvement of coal-mining mechanizations and the intensification of human activities, the organic matter pollution of mine water is becoming severe. In this study, the chemical compositions of the influents and effluents from 15 mine water treatment stations in the mining area bordering Mongolia and Shaanxi were measured. The occurrence of DOM (dissolved organic matter) in the effluent from the mine water treatment stations in this area was determined by the EEM (excitation emission matrix), combined with the PARAFAC (parallel factor analysis) method. The DOM removal from the mine water treatment station in the Caojiatan coal mine is specifically discussed here, although trends are similar across the 15 mines. The treatment capacity of this treatment process for different types of pollutants is also evaluated, and a mine water treatment process suitable for the current coal-mining mode is suggested. The results show that the DOM of the mine water treatment stations in this area mainly has four components: a fulvic-acid-like substance (C1/C3), a protein tryptophan-like substance (C2), and a protein tyrosine-like substance (C4). The coagulation, filtration, and disinfection process has a removal efficiency of more than 90% for the protein-like tryptophan components, COD (chemical oxygen demand), and NO2−, and an efficiency of ~50% for TOC (total organic carbon), <30% for Cu2+ and F−, and almost no removal effect for protein-like tyrosine components, EC (electrical conductivity), TDS (total dissolved solids), and NH4+. These conclusions show that aliphatic hydrocarbons, such as alkanes and cycloalkanes, in mine water are removed by the treatment process, whereas macromolecular aromatic hydrocarbons and other groups are not removed by the treatment process. Based on this, an ozone-demulsification process for the special removal of protein tyrosine-like pollutants in mine water is proposed. This conclusion can provide theoretical support for research on the source and fate of the carbon trajectory in the water-cycle process and provides technical guidance for the removal of DOM from mine water.

In order to find out the status of organic pollutants in coal mine area of Ordos Basin in northwest China, we used an excitation emission matrix combined with parallel factor analysis to study the compositional characteristics and fluorescence intensity of dissolved organic matter (DOM) in mine water. In this way, we found that the DOM in the Mongolia-Shaanxi border mining area of Ordos Basin has four main components: two that resemble fulvic acid (C1/C3), a protein-like tryptophan substance (C2), and a protein-like tyrosine substance (C4). The fluorescence intensity of the fulvic acid-like component increased from 334.73 a.u to 440.33 a.u after treatment, and the fluorescence intensity of the protein-like tyrosine-component decreased from 330.18 a.u to 295.78 a.u. And then we investigated the removal efficiency of DOM and other pollution in the Caojiatan mine water treatment plant’s coagulation - filter – ultrafiltration process. In this process, the removal efficiency of the protein-like tryptophan components reaches 90%, while that of chemical oxygen demand / NO2− and the total organic carbon is about 50%. The removal efficiency of the Cu2+ and F−is less than 30%, and almost none of the protein-like tyrosine components, electrical conductivity, total dissolved solids, and NH4+. Thus, It’s proved that aliphatic hydrocarbons such as alkanes and cycloalkanes in mine water were removed in the treatment process, whereas macromolecular aromatic hydrocarbons and other groups were not removed. In the end, we put forward the ozone air flotation process, ozone effect makes the water of oxygen functional groups such as carboxyl, hydroxyl content increased, allowing more of the aluminum, iron, magnesium, and calcium ion complexing, precipitation, leading to desorption from the particulate organic matter, reduce the space steric hindrance and electrostatic repulsion, the effect of enhanced coagulation, Promote the condensation of particulate matter by means of adsorption bridge. This provides theoretical support for research on the source and fate of the carbon trajectory in the water cycle in a coal mine area and provides guidance on the removal of DOM from mine water.