Study On The Removal Of Water Hardness From Weibei Karst Region

With the improvement of living standards, the demand for drinking water quality iscontinuously increase.It is an important part of building a new socialist countryside to find acomprehensive solution to the problem of rural drinking water safety, it is reflect inpeople-oriented, a necessary requirement to build a harmonious society,it is a top priority toprotect social and economic sustainable development and rural population health. Karstgroundwater as the main water source to Weibei area in recent years, due to the impact ofregional environmental and human activities,The degree of karst water pollution isworsening, The main performance are the content of water total hardness, sulfate, fluorideincreased year by year, that has seriously affected the water quality of drinking water inrural areas. Therefore, study on the removal of water hardness from weibei karstregion,deepen the understanding and awareness of hardness removal to protect the safety ofdrinking water for the future of rural life have important theoretical and social significance.In this paper, the studied water samples collected from Pucheng County, Weinan City,Shaanxi Province, Sun centralized water supply engineering. Raw water quality: pH value isbetween7.21and7.27, the total water hardness is between330.30and332.30mg/L (asCaCO3calculated).On the basis of the existing water softening research, focused on theinfluence of pharmaceutical compound and its dosage, standing time, coagulant dosage andmechanical aeration time on the water softening, discussed the mechanical aeration waterhardness removal reaction mechanism. By using scribble scale inhibitor in the water pipe, toprevent calcium and magnesium ions sedimentary on the water pipe during the water foulingprocess, to ensure the normal use of water pipes. Base on this study, we designed a softeningand scale solutions. Here we draw the conclusions:(1) Soda ash softening: The pH value is not greater than8.50, the dosage of0.1mol/Lsodium carbonate solution is0.45mL, standing time is30min, the reaction temperature isroom temperature, stirring time is45min, the total water hardness reduced to310.28mg/L.(2) Lime-flocculant softening: The pH value is not greater than8.50, the dosage of1%slaked lime solution dosage is3.00mL, the dosage of0.1%PAC solution is2.50mL,standing time is30min, the reaction temperature is room temperature, stirring time is30min, the total water hardness reduced to247.02mg/L.(3) Soda-Lime-flocculant softening: The pH value is not greater than8.50, the dosageof0.1mol/L sodium carbonate solution is0.40mL, the dosage of1%slaked lime solutiondosage is1.50mL, the dosage of0.1%PAC solution is2.50mL, standing time is30min, thereaction temperature is room temperature, stirring time is30min, the total water hardnessreduced to255.44mg/L.(4) Mechanical aeration can improve the removal of the water hardness in a certainextent. Adding above doses of sodium carbonate, lime, lime-flocculants, soda-lime-flocculantto the water samples and aeration2h, after standing2h, the removal of total hardness of waterdescending as follows: sodium carbonate-limestone-flocculants, lime-flocculants, lime,sodium carbonate.(5) By using scan electron microscopy scanning scribble and not scribble scale inhibitorPVC-U pipe, discovered scale inhibitor can prevent the deposition of scale to some extent.(6) The best dissolving ability of PVC solvent for PVC-U material is tetrahydrofuran, thebest amount of it and scale inhibitor are0.3L/m2and0.5L/m2, the best smear mode is:scribble PVC solvent first, after it dry and then scribble scale inhibitor.(7) Based on these studies, for the status quo of water hardness in karst regions Weibei,determine the final softening and scale process: soda-lime-flocculant agents softening andincrease the mechanical aeration, while scribble scale inhibitor and PVC solvent.Througheconomic and technical analysis, which verified that this method is simple, feasible andreasonable.