| The difficulty conditions in the continuous flow of low-operation load, low- efficiency of nitration and nitrogen removal, as well as large area occupied,the Sequencing batch Constructed Wetland (SCW) is developed by a change of feed mode in CW and extra setting the idle time for Strengthening reaeration, efficiency for nitrogen removal of SCW is 48 times compared with the conventional CW. Obtained the Key Parameters in high efficiency for nitrogen removal of SCW based on the systematic study for nitrogen removal efficiency effect of several factors, such as HRT, IT and feed mode. In addition, discussed the nitrogen removal mechanism about SCW by testing. Put forward the"ASBBR-SCW"combined process for guarantee the treatment efficiency of SCW and further reduce the area occupied. Using ASBBR for the pretreatment process of SCW, studied the treatment efficiency effect of load and running condition. Meanwhile, obtained the Key Parameters in municipal sewage treatment by combined process, and analyzed the combined process adaptability in municipal sewage treatment. In addition, discussed the performance of blocking inhibition and self-repair. The main research conclusions are as following:The study on effect of treatment efficiency by HRT and IT show that: in high nitrogen municipal sewage treatment, the nitrogen removal efficiency significantly increased by HRT Prolonged., the best HRT meeting the objective of nitrogen removal is 12h. Idle time could significantly affect the residue of internal carbon source which is essential to denitrification, the best idle time meeting the objective of nitrogen removal is 4h. The effluent concentration about COD, NH3-N and TN is 38mg/L, 10mg/L and 13mg/L, removal rate is 88, 84 and 80 percent, effluent concentration about COD and TN meeting the primary standard A, and NH3-N meeting close to the primary standard B, on condition of 2632℃, influent concentration about COD, NH3-N and TN is 270mg/L, 60mg/L and 63mg/L, by using the condition:"inlet-12h's reaction-drainage-4h's emptying idle" in the two-stage SCW. Removal loading is 65.6gCOD/(m3·d), 3.8gNH3-N/(m3·d) and 13.8gTN/(m3·d). The nitrogen removal efficiency is 48 times compared with the Bainikeng, Shatian and Shiyan CW. At this time, unit volume sewage treatment need the site of SCW is 3.8m2.The effect of influent modes to the treatment efficiency of SCW shows that: During the reactions of SCW by using intermittent influent or continuous influent had no significant effect on the the removal of COD and NH3-N, however, the removal of TN is significantly affected. Using intermittent influent during the reaction can enhance the total removal rate of COD and TN in SCW by four percent and 27 percent respectively, but the removal rate of NH3-N in the first-stage SCW dropped 7 percent, two-stage SCW 3 percent.The efficiency study of combined process of ASBBR-SCW shows that: as a pretreatment reactor, ASBBR gathers regulation, sedimentation and biological degradation in integral whole. The removal rate was 64 percent at temperature of 28 to 31℃, HRT of 24h, COD influent concentration of 320mg/L, COD effluent concentration of 118mg/L. Meanwhile, by using the condition "inlet-4h's reaction-drainage-4h's emptying idle " in the two-stage SCW, the removal load of COD and NH3-N were respectively 93gCOD/(m3·d) and 35gNH3-N/(m3·d), the effluent concentration were 48mg/L and 18mg/L, respectively, the total removal rate of 76% and 75% when the site area of SCW pretreatment is only 1.6 m2.After more than one year, the internal sludge concentration of SCW had not increased significantly with the passage of running time . The water acceptance of SCW is basically stable, with an average decline rate only 0.05L/(m3·m). In the emptying and idle period, through strengthening atmospheric reaeration enables the proliferation of biological sludge and oxidation--decomposition amount reaching a balanced state, which was beneficial to control the proliferation rate of sludge and effectively improve the constructed wetland clogging. |
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