Investigation On The Effect Of Reparing Landscape Water By Integrated Technology Of Solar Mixing-oxygenation With Ecological Floating Island

Compared with the single traditional mixing,oxygenation and ecological floating island technologies,the integrated remediation technology of solar mixing-oxygenation with ecological floating island is a green water purification technology with less investment,low energy consumption,high efficiency and without secondary pollution.Using the combination of theoretical analysis,pilot experiment and field test,the mixing and oxygenation performance of a new mechanical mixing and vacuum oxygenator was first systematically studied.Then,the integrated device of mixing-oxygenation with ecological floating island was designed,and the performance of remediating a simulated V-level landscape water.Finally,a demonstration project using the integrated technology of mixing-oxygenation with ecological floating island driven by solar energy was constructed in a residential quarter,Xi'an,and the performance of remediating the landscape water was tested.The key research results are as follows.?1?A new Vacuum-type mixing-oxygenator was developed.Under the motor speeds of 200¹400 r·min^-1,the circulated flow rates increased linearly with the motor speeds.A dynamic model of the radial outflow was developed from the model of air-bubble flow,the energy loss coefficient and entrainment coefficient were optimized with the measured flow velocity data,and the radial outflow velocity distributions were successfully predicted with the developed model under different motor speeds.The effective mixing radii were studied under different motor speeds,and the installation intervals of the mixing-oxygenator under different motor speeds were properly determined.Under the motor speeds of 400¹200 r·min^-1,the oxygenation rate,the total oxygen transfer coefficient and the oxygen transfer efficiency increased with the motor speed,and the mixing-oxygenation performance was improved with the increase of motor speed.?2?An integrated experimental device of mixing-oxygenation with ecological floating island was developed,the area ratio of the floating island to the whole water body was about 10%,and the filling rate of the biocarrier was one thousandth.The mixing-oxygenator can provide sufficient oxygen for the breeding and growth of the microorganisms in the filling area.Under the action of microorganisms in the filling area,the polluted landscape water was well improved together with the mixing-oxygenation.The removal rates of TN,TP,NO₃^--N,NH₄⁺-N and BOD₅ were82.4%,92%,91%,85%and 85%,respectivel.?3?A demonstration project of landscape water remediation was constructed in a residential quarter,Xi'an,using the integrated technology of mixing-oxygenation with artificial floating island based on solar energy.The water area was 245 square meters.The solar power supply system consists of three solar panels?size is 1650mm x 990mm and 260W?,providing power to the entire system.The area of ecological floating island was 5332mm x 5332mm,accounting for 9.8%of the water area.The aquatic plants were Hyacinth,Canna,and Lilypad,and the combined planting methods were used in the field test.The effectiveness of water purification with this integrated device was investigated on site,and the results showed that the average removal rates of nitrite nitrogen and nitrate nitrogen were about 72%and 24%;the ammonia nitrogen and total phosphorus concentrations fluctuated greatly after rainfall and Hyacinth harvest.However,once Crassipes grew well,the removal rates of ammonia nitrogen and total phosphorus could reach 70%and 50%respectively.The concentrations of algae and chlorophyll also decreased with the decreases of ammonia nitrogen and total phosphorus concentrations.The integrated device of mixing-oxygenation with ecological floating island has great practical application potential in urban polluted water restoration.