Autotrophic biological nitrogen removal from saline wastewater under low DO

BACKGROUND: This study was conducted to investigate the feasibility and performance of nitrogen removal through the complete autotrophic nitrogen removal over nitrite (CANON) process for saline wastewater in a continuous reactor, and to characterize microorganisms in the sludge from the reactor using DNA‐based techniques. RESULTS: The nitrogen removal experiment in the reactor was operated over five phases for 286 days treating a synthetic sewage of 1.2% salinity at 21–25 °C. At dissolved oxygen (DO) concentrations of 0.5–1.0 mg L^?1 and in the presence of glucose, NO₂^? was accumulated, indicating the activity of ammonia‐oxidizing bacteria (AOB). At DO concentration of 0.5 mg L^?1 without organic substrate, the anaerobic ammonium oxidation (Anammox) process was the major pathway responsible for nitrogen removal, with a total nitrogen removal of 70% and an ammonium conversion efficiency of 96%. A maximum ammonium removal rate of 0.57 kg‐N m^?3 d^?1 was achieved during the experimental period. The concentrations of AOB and Anammox bacteria were monitored over the operation of reactor using quantitative real‐time polymerase chain reaction (qRT‐PCR). CONCLUSION: In this study, autotrophic nitrogen removal process was achieved under salinity condition in a one‐reactor system. An over 100 fold increase of AOB was found due to the increased supply of ammonium at the beginning, then AOB concentration decreased temporarily in correspondence with the decreased DO, and the AOB resumed their concentration at the last phase. The Anammox bacteria abundance was about 150 fold higher than that at the beginning, indicating the successful enrichment of Anammox bacteria in the reactor. Copyright © 2010 Society of Chemical Industry     

Assessment of the antioxidant capacity of a fermented grain food product,Antioxidant Biofactor (AOB), by using pyranine and pyrogallol red as a combined probe

The role of antioxidants contained in foods, beverages, and supplements against oxidative stress has received much attention. The capacity of antioxidants has been assessed by various methods. In this study, the antioxidant capacity of a complex mixture of fermented grains has been assessed by using two probes, pyranine and pyrogallol red (PGR). A supplement commercialised as Antioxidant Biofactor, AOB, was used as a substrate. The extracts from AOB obtained with water and dimethylsulphoxide (DMSO) inhibited the free radical-induced consumption of pyranine and PGR in a concentration-dependent manner. They also suppressed the free radical-induced oxidation of human plasma. It was estimated that 1 g of AOB contained, as Trolox equivalent, roughly 0.13 and 0.24 mmol (2.5 and 4.7 wt%) antioxidants, which could be extracted by water and DMSO, respectively. This study shows that the combination of the above two probes is useful for assessing the total content and activity of antioxidants contained in complex mixtures.     

游离氨对活性污泥系统中硝化性能和硝化群落结构的影响

建立了4个平行的SBR处理合成废水,游离氨（FA）浓度分别为0.5、5、10、15 mg/L,命名为S_0.5、S₅、S₁₀和S₁₅,4个系统的脱氮性能在整个实验过程中均很好（平均值为98.7%）,利用FA对亚硝酸氧化细菌（NOB）的抑制作用,结合过程控制,成功在S₁₀和S₁₅系统中实现短程硝化。在建立短程硝化途径的过程中,S₁₀的NAR在第79天迅速达到90.3%,S₁₅的NAR在139天迅速达到90.5%。在S₁₀的80~250 d和S₁₅的140~250 d中,平均NAR分别稳定在98.8%和98.2%左右。用16S rRNA基因的高通量测序技术分析样本中硝化细菌的相对丰度和结构,结果表明,AOB和NOB丰度的变化与试验结果一致。FA不仅可以显著影响AOB和NOB的相对丰度,而且还可以抑制NOB活性。此外,还发现较低的AOB含量在FA浓度为15 mg/L时具有较高的氨底物微生物利用能力。     

Integration of anammox into the aerobic granular sludge process for main stream wastewater treatment at ambient temperatures

Anaerobic ammonium oxidation, nitrification and removal of COD was studied at ambient temperature (18 °C ± 3) in an anoxic/aerobic granular sludge reactor during 390 days. The reactor was operated in a sequencing fed batch mode and was fed with acetate and ammonium containing medium with a COD/N ratio of 0.5 [g COD/gN]. During influent addition, the medium was mixed with recycled effluent which contained nitrate in order to allow acetate oxidation and nitrate reduction by anammox bacteria. In the remainder of the operational cycle the reactor was aerated and controlled at a dissolved oxygen concentration of 1.5 mg O₂/l in order to establish simultaneous nitritation and Anammox. Fluorescent in-situ hybridization (FISH) revealed that the dominant Anammox bacterial population shifted toward Candidatus “Brocadia fulgida” which is known to be capable of organotrophic nitrate reduction. The reactor achieved stable volumetric removal rates of 900 [g N₂-N/m³/day] and 600 [g COD/m³/day]. During the total experimental period Anammox bacteria remained dominant and the sludge production was 5 fold lower than what was expected by heterotrophic growth suggesting that consumed acetate was not used by heterotrophs. These observations show that Anammox bacteria can effectively compete for COD at ambient temperatures and can remove effectively nitrate with a limited amount of acetate. This study indicates a potential successful route toward application of Anammox in granular sludge reactors on municipal wastewater with a limited amount of COD.     

外部微扰反馈对Bragg声光双稳系统混沌的控制

针对Bragg路声光双稳系统的混沌态，提出了利用外部微扰反馈的方法对其进行控制。数值分析表明，适当选择反馈强度可将原本混沌的系统控制到各种不同的周期轨道上，同时计算了噪声对系统状态演化的影响。结果表明，系统对小幅度噪声具有一定抗干扰能力。     

氯、亚氯酸盐控制氯胺消毒管网硝化作用效果

采用2台串联环状生物膜培养反应器(biofilm annular reactor,BAR)模拟氯胺消毒给水管网系统,通过对余氯、NH4+-N、NO2--N、NO3--N、DO、异养菌(heterotropic,HPC)及亚硝化菌(amnoniu-oxidizing bacteria,AOB)等指标进行检测,共同评价氯和亚氯酸盐2种消毒剂对氯胺消毒管网中硝化作用的控制效果.试验结果表明,出厂水再投氯消毒可造成NH4+-N降解,使得NO2--N和NO3--N产生积累;再投亚氯酸盐更易提高管网中余氯和DO的质量浓度,使得NO2--N和NO3--N质量浓度降低,可有效地控制硝化作用;与投加氯消毒时相比,投加0.6 mg/L亚氯酸盐时,第1台BAR中悬浮和生物膜中HPC分别平均降低了2.58 log和2.86 log,悬浮及生物膜中AOB降低约1 log,亚氯酸盐能对AOB起到控制灭活效果而等量氯对其几乎没有灭活效果.因此,在控制管网硝化作用方面,亚氯酸盐与氯胺联用的消毒效果优于氯与氯胺.     

氯、二氧化氯对氯胺消毒管网硝化作用控制效果对比

采用2台串联BAR模拟给水管网系统,通过对余氯、NH4+-N、N02-N、NO3--N、DO、HPC及AOB等指标检测,评价氯和二氧化氯2种消毒剂对氯胺消毒管网中硝化作用的控制效果.研究结果表明:二氧化氯比等量氯更易提高管网中余氯质量浓度和DO质量浓度;氯消毒阶段NH4+-N降解,NO2--N和NO3--N积累,而投加二氧化氯后可有效控制硝化作用;与投加氯消毒相比,投加等质量浓度(0.6 mg/L)二氧化氯时,第1台BAR中悬浮和生物膜中HPC分别降低了2.54 log和1.63 log,悬浮及生物膜中AOB降低约1 log;二氧化氯能对AOB起到控制灭活效果而等量氯对其几乎没有灭活效果,在控制供水管网硝化作用方面,二氧化氯与氯胺联用的消毒效果优于氯与氯胺.     

酱腌菜保鲜的初步研究

本文探讨了在空气和隔绝氧条件下，异抗坏血酸、AOB抗氧保鲜液及其混合液的抗氧化褐变和防霉能力，比较了室温（25℃）和加热（40℃）情况下异抗坏血酸和AOB保鲜液对酱腌菜的保鲜效果和组织状态变化，并分析了发生褐变的原因。实验结果表明：真空保藏时，2％异抗坏血酸液在室温和加热（40℃）条件下都能明显加速酱腌菜褐变，但抑制霉菌效果较好；在有氧情况下，异抗坏血酸没有抑菌效果。而在无论有无氧的情况下，2％AOB保鲜液对酱腌菜的抗氧化报变和防霉性都甚佳，能大大延长酱腌菜保鲜期。酱腌菜组织状态劣变随着其褐变程度的增加而加剧。     

纳米银颗粒对膜生物反应器运行性能及硝化细菌丰度的影响

考察了0.10 mg/L纳米银对膜生物反应器(MBR)运行、氨氧化菌(AOB)和亚硝酸盐氧化细菌(NOB)丰度的影响。运行试验结果表明,在投放纳米银前后,处理系统对化学需氧量(COD)平均去除率为95.4%和94.1%,处理水中的总氮(TN)以硝态氮为主,硝态氮平均质量浓度前后分别为12.5 mg/L和13.2 mg/L,因此,在纳米银颗粒影响下,MBR仍能达到普通MBR的处理效果。实时定量聚合酶链反应(QPCR)结果表明:在整个运行周期内,AOB与NOB菌群的基因数量都处于107数量级,且硝化螺旋菌Nitrospira为优势NOB;结合银离子的变化规律可知,纳米银大部分富集到污泥中,但硝化菌群的丰度没有受到长期投放纳米银颗粒的影响。     

Process optimization by decoupled control of key microbial populations: distribution of activity and abundance of polyphosphate-accumulating organisms and nitrifying populations in a full-scale IFAS-EBPR plant

This study investigated the abundance and distribution of key functional microbial populations and their activities in a full-scale integrated fixed film activated sludge-enhanced biological phosphorus removal (IFAS-EBPR) process. Polyphosphate accumulating organisms (PAOs) including Accumulibacter and EBPR activities were predominately associated with the mixed liquor (>90%) whereas nitrifying populations and nitrification activity resided mostly (>70%) on the carrier media. Ammonia oxidizer bacteria (AOB) were members of the Nitrosomonas europaea/eutropha/halophila and the Nitrosomonas oligotropha lineages, while nitrite oxidizer bacteria (NOB) belonged to the Nitrospira genus. Addition of the carrier media in the hybrid activated sludge system increased the nitrification capacity and stability; this effect was much greater in the first IFAS stage than in the second one where the residual ammonia concentration becomes limiting. Our results show that IFAS-EBPR systems enable decoupling of solid residence time (SRT) control for nitrifiers and PAOs that require or prefer conflicting SRT values (e.g. >15 days required for nitrifiers and <5 days preferred for PAOs). Allowing the slow-growing nitrifiers to attach to the carrier media and the faster-growing phosphorus (P)-removing organisms (and other heterotrophs, e.g. denitrifiers) to be in the suspended mixed liquor (ML), the EBPR-IFAS system facilitates separate SRT controls and overall optimization for both N and P removal processes.