The Study On Chemical Stability Assessment And Control Technology Of Water Supply System In Jining City

The chemical stability and adjustment methods of two kinds of drinking water source were studied in this paper. The main contents were as follows:(1) the chemical stability evaluation index system was established according to water supply system in Jining city; (2) the chemical stability of the effluent from groundwater treatment plant was analyzed; (3) the chemical stability of water which treated by different water treatment technology was analyzed and compared; (4) the control methods of chemical stability of water supply system was discussed; (5) a new evaluation index that suitable for Jining city was established. The following were the main results of this paper.1. The LSI, RSI, CCPP, LR and AI were used to establish the evaluation system because the metal pipe and cement pipe were the main water supply pipe in Jining.2. The chemical stability of the effluent from four water treatment plants is different. The effluent from south plant and west plant was slight scaling.The effluent from north plant and east plant was severe corrosion in spring and summer, and it was moderate corrosion in autumn and winter. The effluent from north plant was moderate corrosive for cement pipe and concrete-lined steel pipe.3. The surface water in Jining was severe scaling, and LR value was high, so high risk was exit in old water supply system if the drinking water source was altered from underground water to surface water. The chemical stability of water treated by O3-AC process was better, but it still was severe scaling.4. The surface water was respectively treated by ultrafiltration, sand filter and O3-AC process, the three effluents can be mixed with underground water, the acceptable mix ratio was 1:1,1:2 and 2:1 respectively.5. Dosing alkaline agent can change the chemical stability of effluent. The effect level of controlling pH was NaOH>Ca(OH)2> Na2CO3> NaHC03, but adding alkaline agent could not decrease the degree of scsling.6. Iron release rate was negative correlations with pH, alkalinity, and was positive correlations with the concentration of chloride and sulfates.7. Iron release rate model of Jining city was established by Matlab. Alkalinity, pH, chloride, sulfates, dissolved oxygen, nitrate and calcium ion were the independent variable of this model.A new water quality corrosive evaluation index was established based on this model, and it was used to mixing surface water with underground water.