Studies On Source Water Quality Improvement Technology Of Water-lifting And Aeration

Aiming at the water quality problems of eutrophication and pollutants' releasing from sediments in deep water source reservoir,the Water- lifting Aerator was developed to improve water quality.The theoretic model of the Water- lifting Aerator was built up,the regulation of algae' distribution and motion and the characteristic of pollutants' releasing from sediment have been studied,as well as the field of flow velocity,dissolved oxygen and temperature have been modeled.The application qualification and method of the Water-lifting Aerator were determined.The technology of Water-lifting Aerator has been applied to mix water to destratify lakes and reservoirs,restrain alga's growth and oxygenate water in lower lay to control pollutants' releasing from sediment,and a prominent effect has been obtained.The regulation of algae' distribution and motion was studied,and the velocity of algae's floating up has been measured,so as to discover the mechanism of restraining algae's growth by the Water-lifting Aerator.The characteristic of pollutants' releasing from sediment have been discovered.Aiming at the design of the Water-lifting Aerator,models of structure optimization,water flow velocity and oxygenation capacity have been built up.The fields of flow velocity,dissolved oxygen and temperature around Water-lifting Aerator have been modeled by CFD model.The Water-lifting Aerator which has functions of lifting water and oxygenation was developed by tests.The subassemblies of the Water-lifting Aerator were determined.The two functions of lifting water and oxygenate were achieved by the Water-lifting Aerator.The ascending cylinder is designed as telescopic structure,so that it can adjust its length automatically with the variation of water level to enhance the effect of mixing water.A combined water quality improvement technology of Water-lifting Aerator and bio-contact oxidation process has been developed also.The component and the combining mode of the combined technology were determined.The Water-lifting Aeration technology and its combined technology can mix upper layer water and lower layer water to restrain algae's growth,and increase dissolved oxygen to control pollutants' releasing from sediment,so as to resolve the problems of eutrophication and inner pollutent source in water soruce.The application qualification,method and affect area for the Water-lifting Aerator to restrain alga's growth were studied.The hydraulic requirement for the Water-lifting Aerator to restrain alga's growth is that the down flow velocity is more than 1.65cm/min,and the required water depth for Water-lifting Aerator to restrain alga's growth is more than 10m.The area where algae growth is controlled by Water-lifting Aerator was determined by CFD modeling.The Water-lifting Aeration technology was applied to restrain alga's growth in the raw water preliminary sedimentation tank of Jie-Yuan water plant of Tian-Jin city.The Water-lifting Aerators made alga decreased for 14%in the preliminary sedimentation tank, and for 26.5%in the area impacted by Water-lifting Aerators.A greater effect would be obtained by theoretical analysis in deeper and longer staying time water.The application qualification,method and affect area for the Water-lifting Aerator to control pollutants' releasing from sediment were studied.The application qualification for the Water- lifting Aerator to control nitrogen and organic materials releasing from sediment is that the dissolved oxygen on the interface of sediment and water must be more than 2mg/L, and more than 1mg/L for controlling phosphorus,iron and manganese releasing.The area where the pollutants releasing from sediment will be controlled is determined by modeling distribution field of dissolved oxygen around the Water-lifting Aerator.The Water-lifting Aeration technology had been applied to control pollutants releasing from sediments in Fen-He reservoir which is a part of water transmission project from Huang-He reviver in Shan-Xi province.Compare with that in the same time of last year,the pollutants released from sediment were decreased by the Water-lifting Aerator technology for 95%,the effect of water quality improvement is great.