| Aiming at the problem of high concentration nitrate removal in photovoltaic wastewater,intermittent denitrification was used to treat photovoltaic wastewater in this experiment.Set up a continuous flow denitrification unit as a comparison,proving the efficiency of intermittent denitrification treatment of high nitrate wastewater;Use High-throughput sequencing technology to compare the changes and differences of microbial community structure between the two groups before the acclimation from the acclimation to the highest nitrate nitrogen concentration,identify the dominant genus,and explain the efficiency of intermittent denitrification treatment of high nitrate wastewater from microbial perspective;The batch denitrification effluent combined with the continuous flow AO process for advanced treatment,so that the treated effluent index meets the emission standards stipulated in the "Electronic Industry Pollutant Emission Standard",determining a set of photovoltaic wastewater treatment process.The main findings are as follows:(1)The intermittent denitrification device with the same three-stage carbon source addition has better and more stable treatment effect on the high nitrate wastewater than the continuous flow denitrification device.When the concentration of nitrate in influent is about 300mg/L,the total removal rate of nitrate and nitrite in the intermittent reactor is 5.76%higher than that of the continuous flow reactor;When the concentration of nitrate in influent is about 600mg/L,the total removal rate of nitrate and nitrite in the intermittent reactor is 17.89%higher than that of the continuous flow reactor;When the concentration of nitrate in influent is about 900mg/L,the total removal rate of nitrate and nitrite in the intermittent reactor is 24.98%higher than that of the continuous flow reactor;When the concentration of nitrate in influent is about 1200mg/L,the total removal rate of nitrate and nitrite in the intermittent reactor is 26.3%higher than that of the continuous flow reactor;When the concentration of nitrate in influent is about 1500mg/L,the total removal rate of nitrate and nitrite in the intermittent reactor is 28.83%higher than that of the continuous flow reactor.(2)The intermittent denitrification device with the same three-stage carbon source addition has lower nitrite accumulation rate than the continuous flow denitrification device for the treatment of high nitrate wastewater.When the concentration of nitrate in influent is about 300mg/L,the nitrite accumulation rate in the effluent of the intermittent reactor is 1.91%lower than that of the continuous flow reactor;When the concentration of nitrate in influent is about 600mg/L,the nitrite accumulation rate in the effluent of the intermittent reactor is 2.55%lower than that of the continuous flow reactor;When the concentration of nitrate in influent is about 900mg/L,the nitrite accumulation rate in the effluent of the intermittent reactor is 3.17%lower than that of the continuous flow reactor;When the concentration of nitrate in influent is about 1200mg/L,the nitrite accumulation rate in the effluent of the intermittent reactor is 4.8%lower than that of the continuous flow reactor;When the concentration of nitrate in influent is about 1500mg/L,the nitrite accumulation rate in the effluent of the intermittent reactor is 6.31%lower than that of the continuous flow reactor.(3)The optimum C/N for the treatment of high nitrate wastewater by intermittent denitrification is 3.5,the optimal hydraulic retention time is 10h,the treatment effect of the same three-stage carbon source is better than that of the first and second stages.Under the best working conditions,the total removal rate of nitrate and nitrite is always above 85%when the high nitrate wastewater is treated by the intermittent denitrification device,and the utilization rate of external carbon sources is always above 77%.And the utilization rate of external carbon source is always above 77%,which not only removes nitrate efficiently but also avoids excessive COD of effluent.(4)The high efficiency of intermittent denitrification treatment of high nitrate wastewater is mainly reflected in the dominant bacteria community.The domesticated sludge is taken from the domestic sewage treatment plant,and the microbial community is rich in diversity.With the progress of denitrification reaction,the unadapted microbial is gradually eliminated,the adaptive microbial gradually grows into the dominant microbial in the treatment of high nitrate wastewater by intermittent denitrification.In the intermittent denitrification system,the proportion of Proteobacteria in the first dominant microbial is as high as 83.2%,while that in the continuous flow denitrification system is 58.56%,and other dominant microbial before acclimation gradually reduce or even disappear.The reason for the analysis is:Intermittent denitrification system influent nitrate concentration and organic matter concentration are in dynamic changes,which can better screen the dominant microbial in the system;In addition,the intermittent denitrification system needs to be periodically suspended to separate the mud water due to the intermittent operation,so that the sludge maintains good flocculation.(5)The photovoltaic wastewater treatment process is as follows:intermittent denitrification combined with continuous flow AO process.Intermittent denitrification combined with continuous flow AO process has good depth processing effect for photovoltaic wastewater,the final effluent COD,NH4+-N,TN meet the emission standards.For the 300mg/L nitrate concentration wastewater,intermittent denitrification combined with continuous flow AO process to treat effluent meets the straight emission standard stipulated in the "Electrical Industry Pollutant Emission Standards".For the 600mg/L,900mg/L,1200mg/L,1500mg/L nitrate concentration wastewater,batch denitrification combined with continuous flow AO process to treat effluent meets the indirect emission standard stipulated in the "Electronic Industry Pollutant Emission Standard". |
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