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In this paper, the water supply system of the Shenzhen Special Economic Zone as the main object, the chemical stability of water quality of the water supply system and its control method, the following research: 1) Shenzhen Special Economic Zone of water quality in chemical stability Survey; 2) to the inner wall of the pipe network corrosion tumor physical and chemical properties; 3) the variation of the chemical stability of water quality of the water supply system; 4) chemical stability of the water quality of the water supply system control methods. Comprehensive, objective evaluation of water quality chemical stability, stability index used to evaluate water quality chemical stability: calcium carbonate precipitation potential for internal corrosion of metal pipes, CCPP, Larsen ratio LR analysis; cement pipe, cement mortar lined metal pipe, erosion index AI the Larsen ratio LR. Investigation of the chemical stability of the water quality of the water supply system of the Shenzhen Special Economic Zone, it is found that all raw water, finished water, the water pipe network perennial corrosive, erosive, while there anions penetrate the pipe wall corrosion tumor, causing \risk. Physical and chemical characteristics of the water supply network for internal corrosion tumor, and found that the corrosion of the inner wall of the pipe network tumors usually have similar the internal stratification morphology, surface layer, hard shell layer and porous core layer. The hard shell layer and the surface layer of the main chemical components as Fe3O4, alpha-FeOOH is the main component of the inner nuclear layer as Fe3O4, alpha-FeOOH, gamma-FeOOH. Cement mortar lining of metal pipe, cement mortar layer in the process of long-term use will form similar layered morphology and corrosion tumor, its main chemical composition of iron corrosion products. The variation of the chemical stability of water quality in the results show that the same source of water, regardless of the conventional process or the ozone activated carbon process, poor water quality chemical stability than the original water. To the water supply network, water quality chemical stability along the flow direction forward, little change. Therefore, to improve the chemical stability of the water pipe network, the key is to control the chemical stability of the finished water. Dosing alkali agent to control the chemical stability of the finished water test results show that the control of the finished water pH between 8.0 to 8.5, close to the stable finished water can. Dosing the effect of the alkali agent to raise the pH, NaOH GT; Ca (OH) 2 gt; Na2CO3 GT; NaHCO3. For Shenzhen raw water, before adding alkali dosing of Ca (OH) 2 is appropriate dosing point the coagulant dosing 1min, the dosage is 3 to 5 mg / L; after alkali should be using NaOH dosing point in the filter , the dosage of 2 to 3 mg / L, can make the finished water pH between 8.0 and 8.5. Before adding alkali dosage of Ca (OH) 2 lower than the cost of the added alkali. Dosing Ca (OH) 2 and NaOH, control the factory water pH between 8.0 to 8.5, effectively solve the pipe network area \For lower small water turbidity of the water all year round, the use of micro-flocculation direct filtration, the filter after the vote plus NaOH control the chemical stability of the finished water, pharmaceutical equipment costs, and preceded by the alkali dosing Ca (OH) 2 compared to lower cost. Dosing alkali agent can not fully meet the For Shenzhen raw water, water quality and stability, can effectively reduce the ratio Larsen, remineralization process by adjusting the dosage of CO2 and lime to control the finished water alkalinity, thereby reducing the the Larsen ratio, reduce reduce anions penetrate the inner wall of the pipe network corrosion tumor, lead to the risk of \Shenzhen Special Economic Zone factory total alkalinity of water should be controlled in the 50 mg / L CaCO3. Remineralization process, Shenzhen raw water dosing CO218mg / L, Ca (OH) 2 20mg / L, finished water quality can be completely stable.
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