Removal Efficiency Of Mining And Metallurgical Waste Residues For Nitrogen, Phosphorous And Organic Matter In Sewage

Mining and metallurgical waste residues of Jiangxi province were selected for this research, including: steel slag, blast furnace slag and titanium-procession residues. This research simulated removal process of organic matter and nutrient in a long period under real application environment, analysised removal efficiency of single substrates and composite substrates and cleared their possibility in practical application. Geochemical modeling(PHREEQC) was undertaken to analysis the interaction of water and mineral in column sorption experiments. Geochemical modeling using PHREEQC yielded information provided a basis for understanding geochemical changes about the dissolution and sedimentation of minerals.Multiple linear regression analysis was undertaken to analysis the significant influence of chemical composition on the dissolved organic carbon and nutrient. The result revealed the major chemical composition about removal capability of mining and metallurgical waste residues.The including as follows:1. Mineralogical characterization of steel slags showed that the major materials were larnite and srebrodolskite, and the elementary composition were Ca, Fe, Si and Mg; the major materials of JX2, JX4 and JX7 blast furnace slags were amorphous material, the major material of JX5 blast furnace slag was gehlenite, and the elementary composition were Ca, Si, Al and Mg; the major material of titanium-procession residues were Calcium sulfate and Iron(III) oxide, and the elementary composition were Ca, Fe and S. Component analysis of trace elements in substrate showed that it was necessary to checked biological availability and leachability of trace elements in slags before these slags were applied to the actual environment.2. A series of column sorption experiments were undertaken to analysis removal efficiency of organic matter and nutrient by single substrates, the result showed that:(1)The order of excellence for removing COD from wastewater was JX8, JX4, JX5, JX6, JX2, JX1, JX7, JX3 and JX9.(2)The order of excellence for removing TN from wastewater was JX3, JX2, JX7, JX8, JX6, JX4, JX5, JX1 and JX9; the order of excellence for removing NOx-N was JX3, JX2, JX4, JX7, JX5, JX1, JX6, JX9 and JX8; NH3-N just could be removed by titanium-procession residues; liquid of the most blast furnace slags and titanium-procession residues appeared net increase, DON could be removed by steel slags.(3)The removal rates of TP of steel slags and blast furnace slags were above 90%, the removal rate of titanium-procession residues was 82%.3. A series of column sorption experiments were undertaken to analysis removal efficiency of organic matter and nutrient by composite substrates, the result showed that:(1)The order of excellence for removing COD from wastewater was JX7/JX9, JX6/JX9, JX2/JX9, JX4/JX9, JX8/JX9 and JX3/JX9.(2)The order of excellence for removing TN from wastewater was JX8/JX9, JX7/JX9, JX6/JX9, JX2/JX9, JX4/JX9 and JX3/JX9; the order of excellence for removing NOx-N was JX7/JX9, JX8/JX9, JX4/JX9, JX2/JX9, JX6/JX9 and JX3/JX9; beside of JX4 / JX9, other combined substrates could removed NH3-N, the order of excellence for removing NH3-N from wastewater was JX3/JX9, JX2/JX9, JX8/JX9, JX7/JX9, JX6/JX9 and JX4/JX9; beside of JX7 / JX9, other combined substrates could removed DON, the order of excellence for removing DON from wastewater was JX8/JX9, JX6/JX9, JX3/JX9, JX2/JX9, JX4/JX9 and JX7/JX9.(3)The removal efficiency of TP from wastewater by composite substratest was very significant; the removal rates were above 90%.(4)In conclusion, combined with the removal efficiency of organic matter and nitrients by single substrates, it showed that the removal efficiency of DOC by composite substrates was slightly increased, of nitrogen was obviously enhanced, and of phosphorus was slightly lower but still high. It is necessary to research the different ratio of steel slag, blast furnace slag with titanium-procession residues for removal efficiency of organic matter and nutrients, and discuss the most suitable ratio of composite substrates.4. In terms of the different influence of 3 indexes, the synthetical order of excellence of single substrates was JX8, JX4, JX6, JX5, JX1, JX2, JX7, JX3 and JX9; the synthetical order of excellence of composite substrates JX7/JX9, JX8/JX9, JX6/JX9, JX2/JX9, JX4/JX9 and JX3/JX9.5. Geochemical modeling was undertaken to estimate the saturation index(SI) of Al, Fe minerals, carbonate, sulfate and phosphate minerals and clay minerals, and it could reflect the interaction between water and mineral in cylinder.