Variation Analysis Of Water Quality Of Water Cellars In Rainwater Safety Harvesting

In many rural areas of our country, rainwater becomes the only drinking water resource for the life due to the characteristics of bitter and salty for surface water and typical high-fluorine for groundwater. Storage and utilization of rainwater by cellars is an important way to solve the drinking water problem in some areas of the deficiency of water resource, and it has great social-economic effects. With the large-scale application of the cellar in solving the rural drinking water safety, the water quality of cellars has received much attention. To solve the problem of water quality in storage and utilization of rainwater, this paper analyzed the variation of storage water quality of different material cellar,different cellar storage water sources and cellar water used for rural areas by long-time monitor, based on the new National Standards for Drinking water. The results obtained are described as follows:(1) The changes of storage water quality of different materials water cellars were different. The turbidity of cement mortar plastering cellar kept low, while the pH values was high during the storage process; pH value of rubber-plastic cellar decreased but the COD value increased; the other indicators of solidified soil cellar were better except the high turbidity in initial stage. Beside rubber-plastic cellar storage time was short, the rest material cellar presented that storage rainwater fluctuated greatly in early time, while in long-term storage period, water quality indexes become stable equilibrium gradually, and all can basically meet the standards of drinking water. Practical application should be adapted to local conditions.(2) Impact on water quality of storing different water sources by cellars. In Yangling,the water quality index values of groundwater and rainwater were low and met the drinking standard; In storage process, groundwater quality was better and stable; 15 days cellar rainwater can reach an overall optimum of stability. Cellar storage of different sources water could reach the drinking water standard the initial water quality had a direct relationship with the process of water quality variation. Low turbidity rainwater had played a significant role on water purification,disinfection and the limiting the growth of micro-organisms. The purification degree was related with the initial conditions, also with the cellar materials and construction techniques etc.(3) Building artificial catchment is an important guarantee to water safety in poor inferior water rural area. In Dingbian study area, surface water had many indexes exceed the National standard, which showed the characteristics of bitty and salty, and groundwater was typical high-fluorine water, so rainwater is the best choice of drinking water source. Under the condition of building catchment and maintain clean sanitation, combined with the local rainfall, wind conditions, etc., determine the rainwater harvesting time allocation, that not only can ensure the water quality and quantity, but also have not the desilting basin.(4) The basic mode of safe rainwater harvesting was artificial catchment+storage device+purification technology+utilization for drinking. The mode had strict requirements on water quality, so purification before utilization, and reaching Nation standard were important. Collection for irrigation utilization could use the catchment of roof,yard,roads,wasteland + desilting basin + cellar + crop utilization. When the condition was that non- artificial catchment and high sediment content, it needed to build desilting basin to ensure the cellar quality to satisfy the irrigation requirement.