超声波参数对短程硝化的影响

Effect of Ultrasound Parameters on Partial Nitrification

在SBR连续运行过程中,采用20 k Hz的超声波,在不同声能密度与辐照时间下处理浓缩污泥,考察超声波参数对短程硝化的影响。结果表明,低强度超声波可有效促进氨氧化细菌(AOB)活性并抑制亚硝酸盐氧化细菌(NOB)活性。适宜的超声波声能密度为0.05 W/m L,辐照时间为20 min,能量为23 k J/g VSS。在此条件下,SBR的NH_4^+-N去除负荷为2.54 mg/(g VSS·h),亚硝酸盐积累率(NAR)为59.6%,在过度曝气条件下仍可维持短程硝化状态。同时AOB活性达到最大值8.06 mg O_2/(g VSS·h),比未超声组提高了近114%。胞外聚合物(EPS)、蛋白质与多糖浓度分别提高了62.0%、200.3%与30.1%,超声波可加快细胞新陈代谢进而促进胞外聚合物分泌。因此,合适能量的超声波是维持短程硝化的有效措施。

In order to investigate the efl＇ect of uhrasound parameters on partial nitrification, six se- quencing batch reactors（SBRs） were obtained. Condensed sludge in SBRs was treated by uhrasound with density from 0.05 W/mL to 0.4 W/mL and irradiation time ranging from 10 min to 90 min at a frequency of 20 kHz. Results showed that bioactivity of ammonia-oxidizing bacteria （AOB） was enhanced by ultra- sound, while that of nitrite-oxidizing bacteria （NOB） was suppressed simuhanenusly. The optimal ultra- sonic density and irradiation time for stimulating partial nitrification were 0.05 W/mL and 20 Min respec- tively, under which ultrasonic energy was 23 kJ/gVSS. Under the optimal condition, NH4 - N removal load in SBR was 2.54 mg/（gVSS · h） and NO2- -N accumulation rate （NAR） reached 59.6%, which indicated that even with excessive aeration operation partial nitrification could be maintained by uhra-sound with suitable parameters. AOB bioactivity reached the maximun of 8.06 mgO2/（ gVSS · h） at ul- trasonic energy of 23 kJ/gVSS, which was increased by 114% compared with the control. Under the same condition, sludge extracellular polymeric substances （ EPS）, protein and polysaccharide concentra- tions were increased by 62.0%, 200.3% and 30.1% compared with the control, which revealed that ul- trasound irradiation could accelerate cell metabolism then enhance EPS yield. Ultrasound with appropriate energy is a feasible strategy to retain partial nitrification.