Evaluation of ecological irrigation applicability of mine water and study on the removal of pollutant components
Mine water for ecological irrigation is one of the effective ways to meet the goal that is bilaterally coordinated sup-ply and demand of water resources in coal mining areas.In this paper,the mine water of a mine in Inner Mongolia is taken as the research object,and 7 groups of mine water samples are collected to carry out the detection of conventional ions and main heavy metal elements.Based on analyzing the main ion chemical characteristics of mine water,comprehensive utiliza-tion of modified Nemerow index method,sodium adsorption ratio(SAR(ADJ)),residual sodium carbonate method(RSC),magnesium hazard(MH),permeability index(PI)and comprehensive heavy metal pollution index(HPI),mine water quality and ecological irrigation suitability are evaluated.In addition,the pollutants are removed through coagulation,adsorption,and reverse osmosis purification processes on the basis of identifying the pollution components of mine water.The results show that the mine water is mainly weak alkaline fresh water,and the water chemical type is mainly HCO3-Na;Fe,Zn and fluoride pollution are widespread in mine water,the excess rates of COD and Mn are 71.43％,the excess rates of chroma,turbidity and Escherichia coli are 57.14％,and the excess rates of total number of bacterial colonies,Pb,As,TDS are 14.29％;The modified Nemerow index ranges from 2.45 to 4.75.The water quality of 28.57％of the water samples are rated as good or better,and the water quality of 42.86％of the water samples are rated as worse without good or very poor water quality.The SAR(ADJ)of 71.43％of the water samples ranges from 13.44 to 41.15,suitable for irrigation.The RSC values of 85.71％of the water samples are over 2.5,not suitable for irrigation;The MH values of 85.71％of the water samples range from 9.47％to 33.87％,suitable for irrigation.The PI values are between 125.13％and 166.59％,which is very suitable for irrigation.The HPI values range from 8.11 to 70.04,and the heavy metal pollution levels are within acceptable levels.Combined with the USSL and Doneen diagram methods,most of the water samples have serious sodium hazard and salinization trends,and the content of Na+and HCO3-should be controlled during irrigation.Using purification process of coagulation,adsorption and reverse osmosis can effectively remove suspended solids,turbidity,Fe,Zn,Mn,Na+and HCO3-components in mine water,so as to ensure that sodium hazard and salinization will not occur during the ecological irrigation of mine water.
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