The Study Of Tanggu Municipal Water Quality Stability

The organism concentration of municipal raw water changes significantly with the seasons. Effective removal of organic compounds is the key to improve the municipal source water quality. Seawater desalinated water is one of an effective ways to resolve the shortage of fresh water resource. Due to the lack of chemical stability of desalinated water, the desalinated water has strong aggressiveness and corrosivity to cast iron municipal water pipes. The Tanggu seasonal water properties of municipal source water are important to the research of the chemical stability of municipal source water blending with desalinated water. And this research is of significant meaning for the transportation of desalinated water by using of old municipal pipes. In this work, the resin absorption method was used to remove the organism of Tanggu municipal raw water. The mechanism and craft of resin absorption process was studied. The process technical parameters for improving the desalinated water’s chemical stability were developed. First of all, aiming at different seasonal Tanggu municipal water, the oganism adsorption process by using of the magnetic ion exchange resin (MIEX) was studied. The best additive dosage of MIEX for spring, summer, autumn and winter municipal raw water was 6mL/L,8mL/L,8mL/L,8mL/L, respectively. And the reaction time was 30min. The results indicated that the removal rate of CODMn was increased about 45% by combining the MIEX resin following with coagulation process. Furthermore, absorption mechanism investigation showed that the MIEX had good properties of desorption and regeneration. The adsorption process could be express by the Freundlich model and the pseudo-second-order model. The adsorption reaction was exothermic process. The effect of MIEX for the removal of organism in municipal water was remarkable. Secondly, the process of blending desalinated water with municipal raw water was studied. The effect of blending ratio, pH and stirring rate on the stability of the blended water were studied. To optimize the process conditions, the orthogonal test was carried out. The optimal parameters of the blending technology for both desalinated water and municipal raw water was showed as below. The blending volume ratio of desalinated water with spring municipal raw water was 1:2.5, the pH was 8.2and the stirring rate was 100r/min. Correspondingly, the blending volume ratio of desalinated water with summer municipal raw water was 1:2.5, the pH was 8.2 and the stirring rate was 100r/min. The blending volume ratio of desalinated water with autumn municipal raw water was 1:2.5,the pH was 8.4 and the stirring rate was 100r/min. Finally, the blending volume ratio of desalinated water with winter municipal raw water was 1:2, the pH was 8.4 and the stirring rate was 100r/min. The Langelier Saturation Index (LSI) of desalinated water was increased from-5.11 to 0.5. The Lason index (IL) was decreased from 2.16 to 1.In the end, the effect of the existing municipal water pipes networks on the chemical stability of water was studied by using of a 20 years old municipal pipe cast iron pipe. The variation of tap water, blended water and desalinated water on total iron concentration, hardness, turbidity and chromaticity were studied. After continous operation of 72 hours, the total iron concentration of desalinated water was increased from 0 to 0.27ug/mL. At the same time, the total iron concentration of blended water was increased from 0.05μg/mL to 0.20μg/mL. The chemical stability of the desalinated water was impvoved by the blending process effectively.