Application Of The New Backwashig Technology Of Removing Iron With Filtering Tank In Groundwater

Groundwater is an important part of water resources in China. What's more, in the northeast region, groundwater is the main water supply source of urban and rural domestic water and industrial water. The quality of groundwater in northeast region is better, but the phenomenon of excessive iron and manganese is so common. Excessive iron and manganese directly affected people's normal life and production in industry and agriculture. With the development of science and technology, the phenomenon of excessive iron and manganese groundwater has attracted wide attention from the experts, scholars and masses.The subject is based on the background of the application of iron filter backwash tank innovative technology in the first water supply branch of Daqing City, Heilongjiang Province. The company regards the exploitation of groundwater as the main task, the process is mainly through the exploitation of groundwater by deep wells, and the raw water is transported to the water source through the water catchment link, then the iron and manganese in raw water are removed after flowing through the filter tank, finally the filtered water will be pressurized by pressure pump and delivered to the users. Iron filter tank is the most important water treatment facility in groundwater treatment, the quality of its operation directly affects stable water quality and the completion of the economic and technical indicators. The backwash of the filter tank is the key process to ensure the quality of water treatment; the backwash effects directly affect the normal operation of filter tank.This study mainly focuses on the issue that water quality is not up to standard caused by insufficient backwashing strength of iron filter tank. Operating parameters of the deep water wells and filter tank water treatment process have been determined, sedimentation test and recovery technology of the backwash water have been studied, and the shortcomings of traditional process have been improved, so that a new backwash system technology has been developed and applied to groundwater sources. After a period of running and debugging, the following results are achieved:(1) In order to solve the problem of inadequate backwashing strength, new process using the homogeneous quartz sand (0.8-1.2mm) instead of the traditional non-homogeneous manganese sand filter (0.5-2.0mm), the containing sewage capacity of the filter layer has been increased, the anti-flushing intensity of the quartz sand filter backwash higher efficiency filtration layer zone (≥90%) has been determined to be 18L/s·m~2.(2) In the new process, the backwash high-pressure water is provided by the boost pump, which has replaced pressure water after filtration in the traditional process. After the transformation of the backwash system, the water deep back pressure has been reduced by 25% on average, the water production of the deep well pump has increased an average of 10-20% in the case of the same pump. To some extent, the energy consumption has been reduced, and the production efficiency greatly improved.(3) Water distribution system with small resistance is first applied to groundwater sources. Compared with the traditional water distribution system with great resistance, the uniformity of water distribution, the total amount of water treatment and processing efficiency has been improved, the flow resistance has been reduced, and the backwash duration has been shortened by a 15minutes to 10minutes.(4) After studying on the settlement performance of the backwash water, we conclude that the iron mud has the efficiency of flocculation. Therefore, the inlet of the recovery tank is designed to horizontal shear water flow instead of vertical water flow, in order to drive the tank water for the rotation and improve the coagulation process. After transforming the recovery tanks in water resources, the total amount of recycling backwash water is about 3800m~3/d, and the backwash water recovery rate is 63.93%, so that the recovery of backwash water can be achieved.(5) After the application of the new process, the economic benefits has been accounted of the following four aspects, including the electricity consumption of taking water, recycling backwash water, backwash duration and maintenance costs. The results show that the new process creates benefits about 3,452,400 yuan each year. The application of new process makes the backwash wastewater recycling be achieved, to some extent, the groundwater resources can be protected, but also the waste emissions and environmental pollution will be reduced.