A traditional sequencing batch reactor （SBR） and two intermittently aerated sequencing batch reactors （IASBRs） were parallelly operated for treating digested piggery wastewater. Their microbial communities were an...A traditional sequencing batch reactor （SBR） and two intermittently aerated sequencing batch reactors （IASBRs） were parallelly operated for treating digested piggery wastewater. Their microbial communities were analyzed, and the nitrogen removal performance was compared during the long term run. IASBRs demonstrated higher removal rates of total nitrogen （TN） and ammonium nitrogen （NH4＋ -N） than the SBR, and also demonstrated higher resistance against TN shock load. It was found that the more switch times between aerobic/anoxic in an IASBR, the higher the removal rates of TN and NH4＋ N. All the reactors were predominated by Thauera, Nitrosomonas and Nitrobacter, which were considered to be species of denitrifiers, ammonium oxidizing bacteria （AOB） and nitrite oxidizing bacteria （NOB）, respectively. However, the abundance and diversity was of great difference. Compared with SBR, IASBRs achieved higher abundance of denitrification related bacteria. IASBR 1# with four aerobic/anoxic switch times was detected with 25.63% of Thauera, higher than that in IASBR 2# with two aerobic/anoxic switch times （l 1.57% of Thauera）, and much higher than that in the SBR （only 6.19% of Thauera）. IASBR 2# had the highest percentage of AOB, while 1ASBR 1# had the lowest percentage. The denitrifiers abundance was significantly positive correlated with the TN removal rate. However, the NH4＋ N removal rate showed no significant correlation with the AOB abundance, but might relate to the AOB activity which was influenced by the average free ammonium （FA） concentration. Nitrobacter was the only NOB genus detectable in all reactors, and were less than 0.03%.展开更多
The volume and exposure time of nuclear radiation detectors are different in the Marine environment.This paper selects γ-rays emitted by ^(131)I,^(137)Cs and ^(208)Tl radionuclides,and uses NaI detectors of different...The volume and exposure time of nuclear radiation detectors are different in the Marine environment.This paper selects γ-rays emitted by ^(131)I,^(137)Cs and ^(208)Tl radionuclides,and uses NaI detectors of different volumes to simulate the minimum detectable activity concentration(MDAC)at different exposure time.And this paper studies the relationship between the increase multiple of crystal volume and the decrease multiple of MDAC.In this paper,based on MDAC,the existence of nuclides at different crystal volumes and different exposure times was qualitatively calculated and analyzed,which will be of guiding significance to the in situ γ spectrum measurement and long-term monitoring of seawater.展开更多
文摘A traditional sequencing batch reactor （SBR） and two intermittently aerated sequencing batch reactors （IASBRs） were parallelly operated for treating digested piggery wastewater. Their microbial communities were analyzed, and the nitrogen removal performance was compared during the long term run. IASBRs demonstrated higher removal rates of total nitrogen （TN） and ammonium nitrogen （NH4＋ -N） than the SBR, and also demonstrated higher resistance against TN shock load. It was found that the more switch times between aerobic/anoxic in an IASBR, the higher the removal rates of TN and NH4＋ N. All the reactors were predominated by Thauera, Nitrosomonas and Nitrobacter, which were considered to be species of denitrifiers, ammonium oxidizing bacteria （AOB） and nitrite oxidizing bacteria （NOB）, respectively. However, the abundance and diversity was of great difference. Compared with SBR, IASBRs achieved higher abundance of denitrification related bacteria. IASBR 1# with four aerobic/anoxic switch times was detected with 25.63% of Thauera, higher than that in IASBR 2# with two aerobic/anoxic switch times （l 1.57% of Thauera）, and much higher than that in the SBR （only 6.19% of Thauera）. IASBR 2# had the highest percentage of AOB, while 1ASBR 1# had the lowest percentage. The denitrifiers abundance was significantly positive correlated with the TN removal rate. However, the NH4＋ N removal rate showed no significant correlation with the AOB abundance, but might relate to the AOB activity which was influenced by the average free ammonium （FA） concentration. Nitrobacter was the only NOB genus detectable in all reactors, and were less than 0.03%.
基金National Defense Fundamental Research Project,JCKY2020404C004,Jiangmei ZhangNatural Science Foundation of Sichuan Province,22NSFSC2458,Jiangmei Zhang。
文摘The volume and exposure time of nuclear radiation detectors are different in the Marine environment.This paper selects γ-rays emitted by ^(131)I,^(137)Cs and ^(208)Tl radionuclides,and uses NaI detectors of different volumes to simulate the minimum detectable activity concentration(MDAC)at different exposure time.And this paper studies the relationship between the increase multiple of crystal volume and the decrease multiple of MDAC.In this paper,based on MDAC,the existence of nuclides at different crystal volumes and different exposure times was qualitatively calculated and analyzed,which will be of guiding significance to the in situ γ spectrum measurement and long-term monitoring of seawater.
