| N2O is an important greenhouse gas, which is250times the greenhouse effect of CO2, CH4is20to30times. N2O are trace gases in the atmosphere, but the N2O concentration in the atmosphere for each doubling of global warming will lead to0.3℃. And, N2O in the stratosphere is very stable, its long life of more than120years, it produces nitrogen oxides by photolysis can damage the ozone layer. And biological denitrification potential is artificially generated N2O sources of its annual emissions of about0.3×1012～3×1012kg, this amount can not be ignored. In addition, energy-saving micro-expansion theory advent, not only can solve the problem of sludge bulking, but also energy saving. But also for N2O study provides a new direction. According to the survey, released the sewage treatment process N2O exacerbated the rate of global warming, has been a serious threat to the survival of mankind; sludge bulking problem long plagued sewage treatment plants, two aspects of the problem has become particularly urgent and important.In this study, low dissolved oxygen SBR reactor, successfully cultured micro-bulking granular sludge. Aerobic granular sludge micro-bulking radial surface villi, but pressed for structural relaxation of sludge, with a mesh shape, sludge volume index between150-250mL/g. Reactor startup process:COD removal from68%to87%growth; ammonia removal from42%to75%growth; effluent nitrate and nitrite concentration is less than1mg/L, is typical of simultaneous nitrification and denitrification system. Stable micro-bulking aerobic granular sludge system:COD removal efficiency was90.99%, compared with an increase of not expanded granular sludge1.54percentage points, slightly expanded granular sludge removal had no significant effect on COD. However, the performance of micro-bulking granular sludge denitrification significant change, ammonia removal efficiency of68.29percent, down nine percentage points higher than not expanded granular sludge. Meanwhile, AOB nitrification rate is33.46×10-3mg N/(g MLSS-min), not expanded granular sludge nitrification rate is1.16times the micro-swelling granular sludge.Micro-bulking granular sludge production significantly affect N2O, micro expanded granular sludge N2O generation of2.42mg/m, is not expansive1.26times the amount of N2O production of granular sludge. Micro-bulking granular sludge N2O emission is1.14mg/m3an increase of0.28mg/m3N2O than not expanded granular sludge generation. Micro-bulking granular sludge dissolved N2O generation of1.28mg/m3, generation than not expanded granular sludge dissolved N2O increased0.22mg/m3. Micro-bulking granular sludge great influence on N2O release rate, slightly expanded granular sludge N2O release rate of3.63×10-3mg/(L·min) rose to4.72×10-3mg/(L·min). Micro expanded granular sludge is not expanded granular sludge N2O release rate1.30times.Temperature had no significant effect on COD removal, removal of most of the more than90%. Influence of temperature on ammonia removal significantly, the temperature rose from21℃, respectively, to26℃,31℃, the nitrification rate of22.47×10-3mg/(g-min), respectively, rose to27.47×10-3mg/(g-min),38.95×10-3mg/(g-min). Nitrification rate change directly affects the denitrification performance, resulting in a temperature rise of21℃another minute to26℃,31℃, the ammonia removal efficiency increased from42.97%to50.14%, respectively, and68.29%. Ammonia removal reached the maximum21.03mg/L at31℃. ΔρN/COD26degrees Celsius when the utilization of carbon sources of nitrogen reached a peak value of0.054mg N/mg COD. Temperature to produce significant effects on the amount of N2O at different temperatures (21℃,26℃,31℃) under, N2O release rates are3.70×10-3mg/(L-min);3.89×10-3mg/(L-min);4.72×103mg/(L-min),31℃when N2O emissions0.96mg/m3were21℃,1.43times at26℃,1.37times. Dissolve31℃tense N2O production capacity of1.46mg/m3were21℃,2.86times26℃at1.60times. Thus, at21℃N2O produced the least amount of time, more conducive to energy conservation. |
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