The Application Of The Combined Filtration Process In Advanced Wastewater Treatment

The raw water is the secondary effluent treatmented by the SBR, the article mainly focuses on four parts about the combined process: three start-up methods for slow sand filter; the effect of the combined process treatment for the depth sewage; the comparion of the two different groups of slow sand filter; through analysis, comparing the combined process and the conventional process.There are three start-up methods of SSF: Incubation with effluent of wastewater primary sedimentation tank following incremental flowrate, constant flowrate(0.3m/h) and incremental flowrate(0.1m/h-0.2m/h-0.3m/h). All results showed that, three startup times are around in the 32d, so the recommended slow sand filter start-up method is to start up with norminal flowrate.Compare two different slow sand filters (the filter bed is 0.15m, 1m), the result shows that:the removal rates of turbidity chromaticity and COD of the SSFs are closer, respectively above 87%, 39.82%, 27.57%; the removal rates of NH3-N, TN and TP are low.The combined process treats the secondary effluent, and the result shows that the combined process has a strong anti-load capacity, and the outlet quality is stability. The raw water quality heavily impacts the running cycle. The influent turbidity chromaticity COD and NH3-N are respectively 47.82NUT, 77.25°, 91.86mg/L and 60.11 mg/L, the removal rates of turbidity chromaticity COD and NH3-N are better, respectively 95.88%, 58.38%, 46.96 % and 27.6 %, but the removal effect of TP and TN are badly. The removal rates of NH3-N and COD of the BAF are better, respectively 24.74%, 25.76%; the removal rates of turbidity chromaticity and COD of the SSF are better, respectively 87.55%, 39.82%, 27.57%.Simulation of recycling plants with the combined process (BAF-SSF-UV disinfection) and the conventional process (coagulation-sedimentation-filtration-UV disinfection), the scale is 50000m3/d, comparing the two plants. Through the costs analysis, the results show that the project cost and the annual operation cost of the combined process are higher than of the conventional process, the project costs are respectively 38324800 RMB, 14373350RMB, the annual operation costs are respectively 9066900 RMB, 5713700 RMB. The effluent water quality of the combined process is better than the conventional process. The combined process is superior to the conventional process by multi-objective weight and evaluation of ordinal.By the LCA, the result shows that the construction materials of the recycling plants are mainly concrete and reinforcing steel materials, the impact of building energy consumption, energy consumption during the removal phase, the environmental impact of CO₂ and P of the conventional process is lower than of the combined process; the running energy consumptions are respectively 249 10⁹kJ, 580.2 10⁹ kJ, total energy consumptions are respectively 328.667 10⁹ kJ, 603.8710⁹ kJ; the impact on the environment of N and sludge of the combined process is lower than the conventional process.