固定化反硝化菌去除水中硝酸盐氮的研究

目的：研究固定化反硝化菌的反硝化特性及影响因素。方法：将活性污泥置上流式厌氧污泥床（UASB）反应器中驯化培养后,反硝化细菌数量增加约60倍,反硝化能力有较大提高。驯化污泥采用聚乙烯醇（PVA）作为包埋载体,添加适量活性炭粉末及海藻酸钠包埋固定后,做成固定化小球,用于处理不同条件下含一定浓度硝酸盐氮的水样。结果：固定化细菌能利用外加有机物（甲醇）作为碳源进行反硝化作用,脱氮率与碳源的量有关。在一定范围内随着碳源量的增加,反硝化作用的启动及平均反硝化速率加快。当水样温度及pH值分别在5－35℃及6．0－9．0之间变化时,固定化反硝化菌能保持较高的活性,6h内脱氮率达到90％。当碳氮比（C／N）为3．5,水力停留时间（HRT）为4h时,脱氮率可达95．9％。结论：当外加有机碳源充足时,固定化反硝化菌能有效去除水中的硝酸盐氮,且对水温及pH值的适应范围较宽。     

不同碳源对固定化反硝化菌脱氮的影响

为寻找较为经济、高效的有机碳源 ,分别外加葡萄糖、蔗糖、甲醇和乙酸 ,以研究它们对固定化反硝化菌脱氮的影响。结果表明 ,固定化反硝化菌能有效利用上述碳源 ,进行反硝化作用。其中采用葡萄糖、蔗糖和乙酸的反硝化速率较快。HRT为 6h时 ,脱氮率达 96%以上。若碳源较丰富 ,反硝化过程中的氨化作用并不明显 ,被转化成氨氮的硝态氮低于被还原总量的 5 %。采用固定化反硝化菌处理COD NO-3-N较低 ,且不外加碳源 ,起始浓度分别为 45 2和 2 4 6mg L的实际水样 ,分别经过 60h和 3 2h后 ,脱氮率达 90 %以上。固定化细菌能利用水中部分的有机物进行反硝化作用     

固定化反硝化菌对富营养化水体脱氮的试验研究

目的 研究固定化反硝化菌对富营养化水体中硝酸盐氮的还原能力，以及对水体中有机物的降解情况，探索富营养化水体原位生物脱氮的新途径。方法 采用PVA作包埋剂，将反硝化菌包埋固定后制成小球，并将其投入模拟富营养化水环境中进行脱氮和有机污染物的降解试验。结果 经过40d的处理后，原水中的亚硝化菌和硝化菌能将水样中的氨氮转化成硝酸盐氮，转化率约为57.5％，但原水中的反硝化细菌作用较微弱，对照水样中总无机氮的去除率约为6．7％。固定化反硝化菌能利用原水中的部分有机物作碳源，进行反硝化作用。模拟水样中NO3^-—N的去除率分别为66．1％(高浓度环境)和25．3％(低浓度环境)；总无机氮(TIN)的去除率分别为62．9％(高浓度环境)和38．8％(低浓度环境)；COD去除率分别为29．5％(高浓度环境)和21．9％(低浓度环境)。结论 向富营养化模拟水环境中投加固定化反硝化菌，可起到原位修复的作用。     

生活污水中反硝化细菌的分离及其营养盐的去除性能研究

目的分离、筛选去除营养盐的高效菌,并研究其生长特性和除污性能。方法采用富集培养、硅胶平板分离的方法,经过多次分离纯化,得到一纯反硝化菌株,并研究了其反硝化强度和生长规律。将分离纯化的反硝化细菌富集培养后进行除污试验,探讨其不同浓度的除污效果。结果筛选的菌株具有一定的脱氮除磷能力,反硝化强度为63.21%,通过对该菌株在培养过程中光密度的测定,进一步研究了生长规律:在2～5天,活菌数迅速提高,处于对数生长期,在5～7天,处于稳定期。利用不同投加量的反硝化细菌对生活污水进行处理,当投加量为100mg/L时,处理效果最好,总氮(TN)、总磷(TP)的去除率最大可达76.2%、93.8%。结论从生活污水沉积物中分离出的反硝化菌株具有较好的脱氮除磷效果,为富营养化水体的脱氮除磷性能和相关污水的生物处理提供了微生物基础。     

生物反应器填埋场原位脱氮技术分析

以生物反应器填埋场原位脱氮原理为出发点,从操作参数以及处理方式2个方面进行分析,提出通过提高氧气含量、减少H2S气体、采用先低再高的回灌频率以及适宜温度、pH等操作参数的优化,为填埋场脱氮过程提供适宜环境条件;在处理方式上改变填埋场填埋结构,发展好氧、准好氧和混合型生物反应器填埋场,或联合多种异位硝化处理方法,利用填埋垃圾自身较强的反硝化能力,有效实现原位硝化反硝化和异位硝化原位反硝化作用,实现填埋场高效脱氮。     

其它

992078 聚乙烯醇(PVA)固定化反硝化菌的脱氮特性/袁林江…//中国环境科学.-1998,18(2).-189～191 采用PVA包埋反硝化菌,研究了其脱氮特性并与未包埋菌进行了对比。结果表明,相对于未包埋反硝化菌,包埋菌进行废水脱氮时的最适宜pH值及温度未变,为pH=8和30℃,但在外界环境超出最适范围     

上流式厌氧污泥床去除饮用水中硝酸盐氮的研究

在室温、COD∶N∶P =2 0 0∶5∶1、NO-3 N浓度从 5mg L逐渐增加至 10 0mg L、水力停留时间从 11 1h缩短至 4 7h的条件下 ,活性污泥在上流式厌氧污泥床中经过 7周时间即可完成反硝化细菌的驯化培养过程。此时反硝化细菌数量可较驯化前增加约 6 0倍 ,产甲烷速率提高约 10倍 ,脱氮率达 99%。还详细研究了C N(原子计 )及pH值对反硝化的影响 ,当C N≥ 1 0时 ,反硝化效率差别无显著性。水样经脱氮处理后无需调节pH值。     

同时好氧厌氧法处理垃圾压缩站废水

分析了垃圾压缩站废水的水质情况,在此基础上根据同时硝化反硝化和厌氧氨氧化机理,用专利产品SOA（Simultaneous Oxic and Anaerobic）生物反应器对垃圾压缩站废水进行脱氮处理。通过试验,出水氨氮平均值在8．2mg／L,硝酸盐氮在13mg／L,氨氮去除率在83％,同时也验证了同时硝化反硝化所需的条件。     

固定化反硝化菌涂层电极及模拟脱氮装置的研制

目的　制备活性炭纤维 (AFC)涂层电极 ,研究电解产氢的自养反硝化法去除地下水中的硝酸盐氮。方法　采用挂膜培养以及PVA包埋的方法 ,将异养反硝化菌固定在ACF电极表面 ,制成ACF涂层电极。结果　涂层电极中的异养反硝化菌经过驯化后 ,可用于去除模拟水样中的NO- 3 N。在生物电化学反应器中 ,当NO-3 N初始浓度为 30 7mg L ,电流强度为 1 0mA时 ,水样经过 1 2小时的处理后 ,脱氮率达到 38 4 % ,生物电化学反应器的容积负荷为 2 3 6gNO-3 N (m3·d) ,涂层电极的面积负荷为 0 92gNO-3 N (m2 ·d)。在同等条件下 ,ACF电极微电解以及涂层电极内源性反硝化作用的脱氮率分别为 3 7%和 2 8%。在涂层电极上进行的反硝化作用中 ,内源性反硝化作用约占 7%。结论　活性炭纤维比表面积大、表面粗糙 ,适合反硝化菌附着生长。包埋了反硝化细菌的PVA凝胶能牢固地粘附在活性炭纤维表面 ,可制成PVA凝胶涂层电极。涂层电极中的异养反硝化菌经过驯化培养后 ,能够利用氢作为电子供体进行反硝化作用     

首次截获来自美国的不合格进境环保微生物菌剂

目的通对美国进境的环保微生物菌剂恶臭假单胞菌进行鉴定。方法从该样品中分离、纯化得到菌株,进行形态学、生理生化测定,并提取其基因组DNA,进行16SrDNA扩增、基因测序等,分析该菌是否是恶臭假单胞菌。结果综合形态学、生理生化特征,16SrDNA扩增片段序列分析及在数据库NCBI上比对结果,分析该样品中不含有恶臭假单胞菌,与申报进境的商品不符。结论首次截获从美国进境的不合格环保微生物菌剂恶臭假单胞菌。     

反硝化菌涂层电极脱氮的主要影响因素

目的　探讨涂层电极脱氮模拟装置的最佳工作条件 ,提高反应器的脱氮效率。方法　在不同电流强度、氧化还原电位、水力停留时间 (HRT)及水温条件下 ,测定反应器的脱氮率。结果　在 0～ 15mA范围内 ,反应器的脱氮率随电流强度的增大而提高。在 15mA ,反应器有最大脱氮率 ,达到 5 7 3%。此时 ,反应器的容积负荷为NO-3 N 34 4g (m3·d)。HRT在 12h内 ,平均脱氮速率为NO-3 N 0 183mg h。当水温在 5～ 35℃内变化时 ,对脱氮率有一定影响。反应开始 1h后 ,脱氮装置中溶解氧和氧化还原电位迅速下降 ,分别降至1 0 8mg L和 - 4 0mV。结论　涂层电极脱氮装置能快速建立反硝菌所需的厌氧环境。极间电压和电流密度控制在 2 5V和 0 0 83mA cm2 为宜。随着反应的进行 ,反应器中pH值的下降以及NO- 2 N的积累将抑制脱氮反应 ,HRT以 12h为宜     

Changes in Microbial Populations and Enzyme Activities During Nitrogen Biodegradation of Domestic Sewage Treatment in the Subsurface Wastewater Infiltration System (SWIS)

During the process of domestic sewage treatment in the Subsurface Wastewater Infiltration System (SWIS), changes in the microbial populations (nitrifying and denitrifying bacteria) and enzyme activities (urease, nitrate reductase and nitrite reductase) involved in the nitrogen removal process were evaluated over a 2-year period. The results showed nitrifying bacteria number declined with depths increasing, while denitrifying bacteria increased, both of which increased nearer the inlet. The depth for nitrate reductase activity from high to low in sequence was 0.3, 0.5, 0.7, 0.9 and 1.1 m. For nitrite reductase, the sequence was 0.5, 0.3, 0.7, 0.9 and 1.1 m. Urease and nitrite reductase activities were in positive correlation with the total nitrogen removal efficiency, with correlation coefficients 0.8662 and 0.9140, respectively and could be alternative to monitor the nitrogen biodegradation process in SWIS.     

Acetate Enhances the Specific Consumption Rate of Toluene Under Denitrifying Conditions

Toluene is usually present in the environment as a contaminant along with other carbon sources which may influence its removal. In this work we studied the effect of a readily consumable carbon source such as acetate on toluene mineralization under denitrifying conditions. Continuous and batch cultures with stabilized denitrifying sludge were carried out. An upflow anaerobic sludge blanket reactor (UASB) was fed with several ratios of acetate-C/toluene-C loading rates (mg C/L-day: 100/0, 75/25, 50/50, and 0/100). Batch assays with different acetate-C/toluene-C ratios (10/70, 30/50, 50/30, and 65/20 mg C/L) were also done. As the acetate loading rate decreased in the culture, the carbon and nitrate consumption efficiency decreased by 40% and 34%, respectively. HCO₃ ⁻ and N₂ yields also decreased by 43%. Analysis of the denitrifying community using the denaturing gradient gel electrophoresis technique indicated that there was no clear relationship between its population profile and the metabolic pattern. In batch assays, when the acetate concentration was higher than that of toluene (65 mg acetate-C/L vs 20 mg toluene-C/L), the specific consumption rate of toluene (q_T) was two times higher than in assays with 20 mg toluene-C/L as the sole electron source (0.006 mg C/mg volatile suspended solids-day). It is proposed that acetate can act by enhancing the growth of microbial populations and as a biochemical enhancer. The results show that acetate addition can be useful to improve the consumption rate of toluene in contaminated water.     

Insights into the Composition of a Co-Culture of 10 Probiotic Strains (OMNi BiOTiC® AAD10) and Effects of Its Postbiotic Culture Supernatant

Background: We aimed to gain insights in a co-culture of 10 bacteria and their postbiotic supernatant. Methods: Abundances and gene expression were monitored by shotgun analysis. The supernatant was characterized by liquid chromatography mass spectroscopy (LC-MS) and gas chromatography mass spectroscopy (GC-MS). Supernatant was harvested after 48 h (S48) and 196 h (S196). Susceptibility testing included nine bacteria and C. albicans. Bagg albino (BALBc) mice were fed with supernatant or culture medium. Fecal samples were obtained for 16S analysis. Results: A time-dependent decrease of the relative abundances and gene expression of L. salivarius, L. paracasei, E. faecium and B. longum/lactis and an increase of L. plantarum were observed. Substances in LC-MS were predominantly allocated to groups amino acids/peptides/metabolites and nucleotides/metabolites, relating to gene expression. Fumaric, panthotenic, 9,3-methyl-2-oxovaleric, malic and aspartic acid, cytidine monophosphate, orotidine, phosphoserine, creatine, tryptophan correlated to culture time. Supernatant had no effect against anaerobic bacteria. S48 was reactive against S. epidermidis, L. monocytogenes, P. aeruginosae, E. faecium and C. albicans. S196 against S. epidermidis and Str. agalactiae. In vivo S48/S196 had no effect on alpha/beta diversity. Linear discriminant analysis effect size (LEfSe) and analysis of composition of microbiomes (ANCOM) revealed an increase of Anaeroplasma and Faecalibacterium prausnitzii. Conclusions: The postbiotic supernatant had positive antibacterial and antifungal effects in vitro and promoted the growth of distinct bacteria in vivo.     

Distribution of bacteria in the rumen contents of dairy cows given a diet supplemented with soya-bean oil

1. Liquid-associated bacteria (LAB) were harvested from the liquid phase (LAB1) and from the solid phase of rumen contents after washing and manual shaking (LAB2). Solid-adherent bacteria (SAB) were recovered after washing and pummelling the total particles (SAB1). The distribution and the chemical composition of these three bacterial compartments were investigated in four dairy cows fitted with rumen fistulas. The animals received successively a diet consisting of one part hay and one part barley-based concentrate (diet C) and the same diet containing free soya-bean oil (79 g/kg dry matter (DM); diet So). 2. The efficiency of removal of SAB1 from total particles of rumen digesta collected 1 h after feeding, was calculated from the diaminopimelic acid content in particles and of the corresponding detached bacteria. It was 24% on diet C and 18% on diet So (P less than 0.05), using a combination of homogenizing and 'stomaching' treatments in saline (9 g sodium choloride/1) (reference treatment). For diets C and So respectively it was lowered by Tween in saline solution (1 g/l; 22.7 and 17.8%, not significant), but was increased when using a previous chilling (6 h at 4 degrees) of homogenized particles before stomaching in saline (28.8 and 24.7%, P less than 0.05) and in Tween 80 in saline (1 g/l; 26.6 and 20.8%, P less than 0.05). 3. The extent of removal of SAB1 from the solid fraction of rumen digesta by the reference treatment decreased with decreasing particle size; it was at the highest for particles retained on 4 and 2 mm sieves (62.1-82.1%) and still elevated for particles retained on 0.8, 0.4 and 0.1 mm sieves (41.3-57.9%). It was very much reduced for particles smaller than 0.1 mm (11.7-14.5%), suggesting the occurrence of favourable conditions for the adhesion of SAB firmly resistant to removal (SAB2). 4. The concentration of total SAB (SAB1 + SAB2) in particles collected 1 h after feeding was lower (P less than 0.05) in diet C (190 g/kg DM) than in diet So (234 g/kg DM). Values averaged 595-645 g/kg DM for particles smaller than 0.1 mm, but only 61 and 81-98 g/kg DM for particles retained on 4 and 0.4 mm sieves, and on a 0.1 mm sieve respectively.(ABSTRACT TRUNCATED AT 400 WORDS)     

Selective growth of mucolytic bacteria including Clostridium perfringens in a neonatal piglet model of total parenteral nutrition

BACKGROUND: Compromised barrier function and intestinal inflammation are common complications of total parenteral nutrition (TPN). OBJECTIVE: We tested the hypothesis that the lack of enteral nutrients in TPN might select commensal or pathogenic bacteria that use mucus as a substrate, thereby weakening the protection provided by the intestinal mucus layer. DESIGN: Ileal microbiota profiles of piglets fed by total enteral nutrition (TEN; n = 6) or TPN (n = 5) were compared with the use of 16S ribosomal DNA polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis and with a PCR-based method developed to specifically measure Clostridium perfringens concentrations. Ileal bacteria from TEN and TPN piglets were also examined for their ability to grow on mucin or sulfated monosaccharides. RESULTS: Bacterial community structure was equally complex in the ileum of TEN and TPN piglets, but profiles clustered according to mode of nutrition. Sixty-two percent of total mucus-associated bacteria (100 colonies tested) in TPN compared with 33% of mucus-associated bacteria (100 colonies tested) in TEN ileal samples grew on mucin. Bacteria capable of using sulfated monosaccharides were also enriched in TPN samples. C. perfringens, an opportunistic pathogen, was specifically enriched in the TPN ileum (P < 0.05). These results were corroborated by cultivation-based studies that showed rapid growth of C. perfringens on mucin-based substrates. CONCLUSIONS: Mucolytic potential is widespread among intestinal bacteria. Mucolytic bacteria in general and C. perfringens in particular were selected when enteral nutrients were withheld in this TPN piglet model. Similar enrichment processes may occur in humans nourished by TPN and may thereby contribute to intestinal dysfunction.     

Genotoxic and hepatic biotransformation responses induced by the overflow of pulp mill and secondary-treated effluents on Anguilla anguilla L

Pulp and paper mill effluent compounds pollute the aquatic environment and are responsible for increased biochemical alterations and genotoxicity in aquatic organisms such as fish. Adult eels (Anguilla anguilla L) were exposed during 8, 16, 24, and 72 h to the following conditions: (1) aerated, filtered, and dechlorinated tap water (C); (2) 2.5% (v/v) sewage water previously treated with activated sludge (T); (3) bleached kraft pulp and paper mill effluent collected at the river Vouga, close to an ancient sewage outlet (Portucel), diluted in tap water [25% (E25) and 50% (E50)]; and (4) bleached kraft pulp and paper mill effluent sediment [water-soluble fraction (S)]. Liver biotransformation induced by the above conditions was measured as ethoxyresorufin-O-deethylase (EROD), cytochrome P450 (P450) (Phase I), and glutathione-S-transferase (GST) (Phase II). Genotoxicity was also determined as blood/liver DNA strand breaks and erythrocytic nuclear abnormalities (ENA) induced on European eel (A. anguilla L). Liver EROD activity was significantly increased in eels at 8 and 16 h exposure to E25, as well as at 16, 24, and 72 h exposure to E50. S exposure induced liver EROD activity only at 24h. A significant decrease in liver P450 was observed at 72 h exposure to T, whereas a significant P450 increase at 16 h was followed by a significant decrease at 24h exposure to E25. Another P450 significant increase was noticed at 72 h exposure to S. Liver GST activity (Phase II) demonstrated a significant increase at 72 h exposure to E50 and to S. A significant decrease in blood DNA integrity was observed at 72 h exposure to T and at 24 and 72 h to S. Blood DNA integrity significantly decreased at 16 and 24 h exposure to E25, as well as at 8, 16, and 24 h exposure to E50. Liver DNA integrity significantly decreased at 72 h exposure to T and at 16 h exposure to S. Moreover, liver DNA integrity was significantly decreased at 24h exposure to E25 and E50, and 72 h to E50. A. anguilla L. increased ENA frequency was detected in T at 16, 24, and 72 h, whereas in E25 and S it was observed at 8, 16, and 24 h. Furthermore, E50 ENA frequency increased at 24 h exposure.