Microbial growth and transport in porous media under denitrification conditions: experiments and simulations

Soil column experiments were conducted to study bacterial growth and transport in porous media under denitrifying conditions. The study used a denitrifying microbial consortium isolated from aquifer sediments sampled at the U.S. Department of Energy's Hanford site. One-dimensional, packed-column transport studies were conducted under two substrate loading conditions. A detailed numerical model was developed to predict the measured effluent cell and substrate concentration profiles. First-order attachment and detachment models described the interphase exchange processes between suspended and attached biomass. Insignificantly different detachment coefficient values of 0.32 and 0.43 day⁻¹, respectively, were estimated for the high and low nitrate loading conditions (48 and 5 mg l⁻¹ NO₃, respectively). Comparison of these values with those calculated from published data for aerobically growing organisms shows that the denitrifying consortium had lower detachment rate coefficients. This suggests that, similar to detachment rates in reactor-grown biofilms, detachment in porous media may increase with microbial growth rate. However, available literature data are not sufficient to confirm a specific analytical model for predicting this growth dependence.     

Drinking water biotic safety of particles and bacteria attached to fines in activated carbon process

In this paper, the drinking water biotic safety of particles and bacteria attached to fines in activated carbon process was investigated by actual treatment process and advanced treatment pilot trial with granular activated carbon. In the experiment, the particles were detected by IBR particle calculating instrument, the activated carbon fines were counted on the basis of the most probable number (MPN) with a microscope, the total number of bacteria was analyzed between the conventional agar culture medium and the one with R2A, and the bacteria attached to activated carbon fines was resolved by the homogenization technique. The experimental results showed that the average total number of particles was 205 CNT/mL in the activated carbon effluent during a filter cycle, of which the number of particles with sizes > 2 μm was 77 CNT/mL more than the present particle control criterion of the American drinking water product standard (50 CNT/mL). The backwash of low density and long duration lowered particle number in the effluent. The MPN of activated carbon fines in the effluent was between 400 and 600 CNT/L, which accounted for less than 5‰ of the total particles from activated carbon filtration for a poor relative level (R ² = 0.34). The microorganisms in activated carbon effluent consisted mostly of heterotrophic bacillus and the total bacteria number was five times as high as that of the inflow, i.e. the effluent from sand filter. The actual bacteria number may be truly indicated by the detection technique with R2A culture medium compared with the traditional agar cultivation. The inactivation efficiency of bacteria attached to activated carbon fines was less than 40% under 1.1 mg/L of chlorine contacting for 40 min. Results showed that the particles and bacteria attached to activated carbon fines may influence drinking water biotic safety, and that the effective control measures need to be further investigated.     

光合细菌和螺旋藻对啤酒废水的净化与利用研究

应用ＰＳＢ将啤酒废水中的有机质降解处理为无机质，用甲壳质絮凝沉降除去ＰＳＢ后加入螺旋藻进行培养．小型动态模拟实验结果表明ＰＳＢ和螺旋藻不仅能高效地净化啤酒废水，对ＣＯＤ和ＮＨ＋４Ｎ的去除率达１００％，而且能回收数量可观（７８１ｍｇ（干重）／（Ｌ·ｄ）），营养价值高（蛋白质含量为４９３ｇ／１００ｇ（干重））的螺旋藻，还研究了ｐＨ、溶解氧、光照、光合细菌密度等因子对ＰＳＢ去除废水有机质的影响．     

高效原油降解菌筛选驯化实验研究

由含油废水原有微生物种群中分离出纯种菌株，通过纯种菌株的单一菌种降解性能实验，混合菌株垢正交性能实验，筛选出7种高效原油降解菌（包括芽孢杆菌属，黄杆菌属，黄单胞菌属，和假单胞菌属），其中芽孢杆菌属降解原油能力最强，对于18．4mg/L的含油废水，降解去除率高达94％－95％，实验还表明，单种菌株降解原油的能力比混合菌株要好。     

磁场对固定化紫色非硫光合细菌脱氢酶影响的研究

研究磁场作用对固定化紫色非硫光合细菌（ＰＳＢ）脱氢酶活力的影响，选出可产生最佳磁生物效应的磁场值，并证明磁场作用一定累积效应，实验结果表明在最佳磁场作用下，最适温度为３０－４０℃，最适ｐＨ值为８，脱氢酶活力可提高３０％左右，有良好热稳定性和ｐＨ稳定性。在４℃冰箱保存４５至２１０ｄ，磁场对脱氢酶活力影响基本稳定，可保持提高２０％。磁场对菌液中加某些金属离子（Ｆｅ＾２＋、Ｍｎ＾２＋、Ｚｎ＾２＋）ｂｎ     

硫酸盐,亚硫酸盐,硫代硫酸盐对甲烷菌协同抑制作用的研究

本研究用二次回归正交设计法进行试验设计,研究了硫酸盐、亚硫酸盐、和硫代硫酸盐对甲烷菌的协同抑制作用。对试验结果分析得出了协同抑制作用动力学方程式,并发现硫酸盐、亚硫酸盐、和硫代硫酸盐对甲烷菌协同抑制作用具有可加性。     

耐铜细菌的筛选及其吸附条件优化

从电镀厂废水污泥中分离到一株高耐铜的菌株 ,它能耐受Cu2 + 的最高浓度为 560mg/L ,通过形态学观察及生理生化特性测定 ,初步鉴定为铜绿假单胞菌 (Pseudomonasaeruginosa) ,并通过正交试验确定该菌吸附Cu2 + 的最佳条件为pH 5 .0 ,接触反应时间为 0 .5h ,摇床转速为 50r/min ,菌量为 1 0 0mg。在最佳条件下 ,该菌对Cu2 + 的吸附量可达 1 4 .68mg/g。     

从武汉印染厂废水淤泥中分离出的趋磁细菌的生长与磁小体形成过程

对从武汉印染厂污泥中分离出的趋磁细菌YN-1,分别进行了5 d,10 d,20 d,25 d和30 d的纯培养与透射电镜的观察,并对30 d释放出的磁小体进行了能谱分析.结果表明:培养5 d的趋磁细菌,其体内的细胞质相对均匀,可见到铁质在细胞内输送的痕迹.随后细胞质变为不均匀,菌体内泡状物和磁小体增多;20 d后菌体膜出现自溶,可见磁小体从破裂的菌膜排出体外的现象,25 d后可见到具有鞭毛、细胞质分布均匀的“营养体”.培养30 d,菌膜基本自溶,除见有营养体外,残存大量的细胞膜碎片和磁小体,对它们的能谱分析显示,磁小体的主要无机成分为Fe.由此判断,25 d可能为该菌在培养条件下的趋磁细菌生长与磁小体形成周期.图3表1参15     

中度嗜盐菌Halomonas sp.BYS-1耐盐相关DNA片段的克隆

通过固体亚硝基胍诱变获得了Halom onassp.BYS-1的盐敏感突变株BYS-1M.以pBBR1MCS-2为载体在E.coliDH5α中构建了BYS-1的基因文库.以文库菌E.coliDH5α(pBBR-X)为供体菌、E.coliWD803(pRK2013)为辅助菌、BYS-1M为受体菌进行三亲接合,筛选到了恢复耐盐性能的接合子HR-23,提取接合子HR-23的重组质粒pHR23,酶切确定其插入的耐盐相关DNA片段大小分为5.4 kb.该片段为Halom onassp.BYS-1耐盐相关基因的克隆奠定了基础.图5表1参14     

产冷适应复合酶菌株Pseudomonas sp.NJ197的选育、发酵条件及酶学性质

从南极普利兹湾深海沉积物中筛选到一株同时产多种冷适应酶的菌株NJ197,细菌学形态鉴定及16S rDNA序列分析表明,该菌株属于假单胞菌属(Pseudomonas).生长特性研究表明,该菌株属于耐冷菌,其最适生长温度为5~15℃.NJ197菌株能利用多种单一的碳、氮源产酶,最适产酶温度为20℃,最高产酶温度为30℃.粗酶液经硫酸铵盐析、DEAE cellulose-52柱层析初步分离纯化后进行酶学性质的研究.该菌株所分泌复合酶中脂肪酶和淀粉酶的活力最高,它们的最适作用温度分别为30℃和35℃,最适pH值分别为9.0和9.5,对热敏感,是典型的碱性冷适应复合酶.Ca2 、Mn2 、Cu2 、Co2 、Fe3 对该复合酶有较为明显的激活作用,而Zn2 、Hg2 、Rb2 、Cd2 、EDTA则能抑制酶活.其中脂肪酶能在高浓度的SDS、CHAPS等变性剂中表现出较好的稳定性.图5表2参21