The Study Of Water Quality Characteristics And Reasons Of Percolating Water Abstraction Project

Based on the filter projects at Baishajiangjing and Nanxikou in Chongqing, the present thesis has studied the long-term monitored data of filter bed characteristic and water quality, and then analyzed the causes and factors for the change of water quality at natural filter belt, as well as the reliability of filter water quality. Hydrogeochemical method, probability analysis method, numerical analysis method, and indoor model test have been employed to make systemic analysis of the change of turbidity, total number of bacteria, total amount of Oxygen Consumed, total Hardness, and the feasibility of direct iron removal at stratum in water filtering. From synthetic analysis by various methods, the following main findings have been gained:(1) The total number of bacteria is showing a decreasing tendency, which is quite obvious at the beginning. In July and August which is the annual flood period, there is a sharp increase. Turbidity of filter water at Baishayulu rises regularly with correspondent abundant water period, but generally stands at 5 or so. Turbidity of filter water at Nanxikou is 0, which also changes steadily.(2) There is an obvious increase in the content of Fe and Mn at Baisha in both Spring and Summer. Regression analysis has found a positive correlation between the change of Fe content and Mn content, with a correlation coefficient of 0.655507.(3) There is a positive correlation between the total hardness and chloride index of filter water both at Baisha and Nankou, with a correlation coefficient of 0.789818 and 0.949597 respectively. The amount of oxygen consumed, F, Pb, H, Zn, TDS, nitrate, sulphate and so on change irregularly.(4) Reliability theory is applied to analyze the reliability of water quality at natural filter beds. The minimal reliability value found in present research is 0.6491 and the maximum 1. The high reliability of water quality indicates that the natural-bed-filter-water technology which is creative and new is feasible and it can directly filter water of high turbidity and minor pollution.(5) It has been found that: the appropriate aeration intensity is 11.0L/min when oxygen is inflated into the stratum to realize aeration iron removal; interval aeration is adopted by opening the aeration device for 3 hours with 20 minutes' break; economically the aeration density is controlled above 1.5m~2 with 4 aeration holes.