Research On The Technology Of Aeration And Electrolysis For N And P Removal Applying On Livestock Wastewater Treatment

With encouragement to enlarge livestock yielding in most countryside, our country's livestock industry has developed well and recently become more industrial, intensive and regional. For livestock industry, due to the large amount and high concentration of wastewater that is discharged from intensive livestock farm, livestock wastewater has gradually become one of most important pollution sources in most districts and watersheds and also has caused severe environmental pollution and much drainage of valuable N and P resource every year. This dissertation intensively researches on the electrolysis technology for N and P removal of livestock wastewater from intensive livestock farm, on the basis of which aeration treatment will be analyzed. The technology can overcome the bottleneck of traditional treatment that has a less efficiency on removal of high concentration of N and P in wastewater, with the advantages of simple apparatus, small occupation of land, easy maintenance, short HRT and high removal effects compared with biotechnology.Through an experimental research on removal of N and P from high concentrated N and P wastewater, this dissertation obtained the optimized index of operational parameters. Furthermore, the process Integration of artificial and real wastewater experiments justified the feasibility of application of the aeration and electrolysis technology to livestock wastewater treatment. In addition, the dissertation made a detailed study on pollutant concentration changes and their interaction in the process of N and P removal, and the changes of main operational parameters in the process Integration.The research results showed that:1. The process for N removal lasted 180mins. RuO2 -IrO2 -TiO2/Ti electrode (anode) +iron electrode (cathode) had been chosen. The optimal pH range was from 6 to 10. The process of N and P removal electrolysis conformed to zero order reaction, and the reaction rate had no connection with the initial concentration of N and P. The optimal current density was 85mA/cm2. The optimal initial concentration of Cl- was 8000mg.L-1. Aeration could improve the removal rate of NH3-N and the optimal aeration condition was that pH was 10, reaction time was 60min, and vapor liquid ratio was 240:1.2. The process for P removal lasted 60mins. Iron electrode (anode) +RuO2 -IrO2 - TiO2/Ti electrode (cathode) had been chosen. The optimal current density was 25mA/cm2. Aeration could improve the removal rate of P. Aeration had the functions of improving electrode passivation and lowering energy consumption, and the optimal aeration condition was that reaction time was 60mins, and vapor liquid ratio was 90:1.3. Artificial wastewater experiment, which realized the switch between N and P removal electrolysis, justified the feasibility of the electrolysis technology. However, acid that was generated in N removal process was more than alkalinity, which caused that the time of N removal electrolysis was so limited that effluent quality of NH3-N could not meet the discharge standard. In the total reaction time of 173mins, the removal rate of NH3-N and phosphate were 59.91% and over 99.5% respectively.4. Real wastewater experiment lasted about 136mins in all. The organic pollutions could make up the alkalinity of wastewater and extend N removal electrolysis time. The removal rate of NH3-N, phosphate and COD were 92.48%, 99.5% and 35.99% respectively. For the whole reaction process, phosphate could be completely removed, and NH3-N could be mostly removed, while COD could be partly removed.