外文翻譯城市污水常溫處理中的新型改良egsb膨脹顆粒污泥床反應(yīng)器的發(fā)展畢業(yè)論文-資料下載頁(yè)
2025-06-20 05:08本頁(yè)面
【正文】 f mm. At 45 and 76 d,most granular sludge remained in the diameter range of mm . while a small portion of granular sludge in Regions A and B disaggregated and distributed in the diameter range of — mm .At 110 d, the diameter of granular sludge was gradually is seen that the granular sludge in the EGSBm was first disaggregated during the early period of operation, and then gradually aggregated as the anaerobic microorganisms were acclimated to the operational conditions. Hydrodynamic Characteristics When the influent flowed upward through the granular sludge bed,it would mix with(or disperse into)local ,the hydrodynamics of an ideal plugflow should take dispersion into consideration,as expressed by the following residence time distribution(RTD)model： where D/UL is the dimensionless dispersion number, D denotes the coefficient of diffusion(m2 /h),U equals Vup(m/h),and L represents the length of reactor(m). For an ideal plugflow reactor,the value of D/UL equals the contrary,for an ideal continuous stirred tank reactor(CSTR),the value of D/UL approaches the pulse tracer (.,Li+)method, the tracer concentration changes along with the experimental time under different HRT were shown in on the results of , the values of inutility volume(Vd )and D/UL at three different upflow liquid velocities were calculated and summarized in . For the EGSBc,a maximal D/UL of which corresponded to a minimal Vd of was observed at the Vup of 5 m/ the Vup decreased to 2 m/h, the D/UL value decreased,implying insuficient hydrodynamic mixing. As the Vup increased to m/h,the D/UL value also decreased, implying enhanced agrees with the previous result that the SS concentration of the EGSBc effluent increased rapidly when the Vup exceeded m/h(as shown in ). For the EGSBm, the D/UL kept increasing(or the Vd kept decreasing)with the increasing Vupvalue of % at the Vup of m/h indicated a favorable hydrodynamic condition maintained in the EGSBm. This agrees with the previous results of COD and CODfilt concentrations of the EGSBm effluent(as shown in ).As the Vup increased,the hydrodynamic mixing of the EGSBm was enhanced while the sludge washout was controlled, leading to an improved removal efficiency of organic demonstrates again that the modified recirculation of the mixed liquid in the EGSBm improved the treatment eficiency of municipal wastewater. 3 Conclusions This study showed that municipal sewage could be treated eficiently and stably with the EGSBm reactor through recirculating its mixed liquid at ambient temperatures,by contrast,effluent recycling was adopted by EGSBc. The EGSBm could achieve improved treatment efficiencies in terms of COD,CODfilt and SS in parison with the EGSBc .The washout of granular sludge from the EGSBm was much less than that from the EGSBc at high Vup values. Throughout the reactor height, anaerobic microorganisms maintained a stable microbial munity in the EGSBm regardless of the changes of wastewater quality and hydrodynamic characteristics. thus ensuring the effective degradation of organic pollutants. Though a small portion of granular sludge disaggregated after the EGSBm reactor was started up,new granular sludge gradually aggregated as the anaerobic microorganisms were acclimated to the operational conditions. The hydrodynamic analysis using the RTD model revealed that the D/UL of the EGSBm kept increasing as the Vup Vd was as low as % at the Vup of m/h which corresponded to a D/UL value of ,the maximal D/UL()for the EGSBc was found at the Vup of 5 m/ decreasing or increasing the Vup in the EGSBc would result in a decrease of the D/UL due to insuficient mixing or enhanced favorable hydrodynamic condition obtained in the EGSBm helped to achieve an enhanced treatment eficiency at high Vup valu
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