温度冲击对低强度超声波促进短程硝化的影响

Effect of Temperature Shock on Partial Nitrification Enhanced by Low Intensity Ultrasound

采用低强度超声波辐照污泥,考察了 SBR内亚硝酸盐积累率(NAR)、氮素转化、比耗氧速率(SOUR)、污泥性能的变化,探究温度冲击对低强度超声波促进短程硝化的影响。结果表明,温度由18℃升高至28℃后,对照组的短程硝化消失,超声组的NAR仍保持在90%以上,实现了稳定的短程硝化。对照组和超声组的SOURmb分别为3.76,3.80 mgO2/(gMLSS·h),但超声组的SOURnob为3.95 mgO2/(gMLSS·h),显著低于对照组的7.90 mgO2/(gMLSS·h)。对照组的污泥容积指数(SVI)由200 mL/g持续升高至500 ml/g以上,发生了污泥膨胀,而超声组的SVI值一直保持在200 mL/g左右。通过扫描电镜发现,超声波辐照增加了污泥中的短杆菌和球菌数量,促进了氨氧化菌(AOB)活性,同时有效抑制了亚硝酸盐氧化菌(NOB)活性。因此,可通过低强度超声波辐照提高短程硝化的抗温度冲击性能,以保证短程硝化的稳定运行。

The sludge was irradiated by low intensity ultrasound. Variations of nitrite accumulation rate ( NAR), nitrogen transformation, specific oxygen uptake rate ( SOUR) and sludge properties were investigated, and the effect of temperature shock on partial nitrification ( PN) enhanced by low intensity ultrasound was explored. The results showed that PN in the control group was disappeared after the temperature increased from 18℃ to 28℃. However, the NAR of the ultrasound group remained above 90%, indicating a stable PN was achieved. The SOURaob of the control group and the ultrasound group were 3. 76 mgO2/(gMLSS·h) and 3. 80 mgO2/( gMLSS·h), respectively, while the SOURnob of the ultrasound group was 3. 95 mgO2/( gMLSS·h), which was significantly lower than that of the control group [7. 90 mgO2/( gMLSS·h)]. The sludge volume index ( SVI) of the control group increased from 200 mL/g to more than 500 mL/g, indicating sludge bulking occurred. By contrast, the SVI value of the ultrasound group was maintained at about 200 mL/g. Scanning electron microscopy ( SEM) showed that ultrasonic irradiation increased the number of Brevibacterium and cocci of the sludge, and the activity of ammonia oxidizing bacteria ( AOB) was improved and that of nitrite oxidizing bacteria ( NOB ) was effectively inhibited. Therefore, temperature shock resistance of PN could be improved by low intensity ultrasonic irradiation, and stable PN was maintained.