低温下废铁屑对厌氧氨氧化系统的影响

考察了在低温条件下(<20℃)废铁屑及其投加方式对厌氧氨氧化反应器脱氮性能和微生物群落的影响.结果表明,当废铁屑投加量为10g/L时,直接(R2)和间接(R3)投加方式均会对厌氧氨氧化反应造成短期抑制,总氮去除率分别降低4.7%和3.4%;30d连续运行后,2组反应器总氮去除率均提升至70%左右;反应器稳定运行阶段,R2的R_s(NO₂^--N与NH₄⁺-N去除量之比)和R_p(NO₃^--N生成量与NH₄⁺-N去除量之比)为1.57和0.22, R3的R_s和R_p为1.49和0.23,比R2更接近厌氧氨氧化反应理论值.废铁屑在水中发生腐蚀,降低DO并提高pH值,且R2,R3污泥中铁含量分别为对照组的1.64倍和1.93倍,废铁屑不仅改善了厌氧氨氧菌的生境,还满足了其对铁元素的需求.高通量测序结果显示,在20~50d的运行过程中, R1,R2,R3中优势厌氧氨氧化菌属Candidatus_Kuenenia的相对丰度分别增加-1.05%,0.14%和0.96%,废铁屑的投加促进了厌氧氨氧化菌在低温下的生长,且间接投加促进效果更为显著.

Effect of iron scraps on anammox systems at low temperature

The effects of iron scraps addition and its dosing methods on the nitrogen removal performance and microbial community of anaerobic ammonia oxidation(anammox)reactors were investigated at low temperature (<20℃). The results showed that when the dosage of iron scraps was 10g/L, both the direct (R2) and indirect (R3) dosing methods caused short-term inhibition of anammox bacteria. Consequently, the total nitrogen removal effieiency reduced by 4.7% and 3.4%, respectively. The total nitrogen removal effieiency of the control group (R1), R2 and R3 all reached to about 70% after 30 days of continuous operation. During the stable operation,R_s(the ratio of NO₂^--N removal to NH₄⁺-N removal) and R_p(the ratio of NO₃^--N generation to NH₄⁺-N removal) of R2 were 1.57 and 0.22, R_s and R_p of R3 were 1.49 and 0.23, which were closer to the theoretical value of anammox than R2. The decrease of DO concentration and the increase of pH was observed likely due to the corrosion of iron scraps in the water. The iron concentration of sludge in R2 and R3 was 1.64 times and 1.93 times higher than that of in control reactor. These results suggested that the iron scraps addition not only improved the living habitats, but also supplyed iron for anammox bacteria. High-throughput sequencing results showed that during the 20~50days operation, the relative abundance of the dominant anammox bacteria Candidatus_Kuenenia in R1, R2, and R3 increased by -1.05%, 0.14%, and 0.96%, respectively. This indicated that the addition of iron scraps promoted the growth of anammox bacteria at low temperature, while the enhancment was more obvious with the indirect addition of iron scraps.