筛选制备微生物菌剂降解剩余污泥

活性污泥法处理污水工艺伴随大量剩余污泥的产生,有效减量污泥是污水处理厂可持续运营的关键。为了实现高效环保的降解剩余污泥,对筛选芽孢杆菌制备微生物菌剂进行了研究。提出以产酶芽孢杆菌为出发菌株,通过测定菌株对污泥混合液悬浮固体浓度（mixed liquid suspended solids,MLSS）的直接减量效果以及菌株在限制性培养基内的传代稳定性和对污泥有机质及总氮（total nitrogen,TN）的去除率,得到3株污泥高效降解菌株10001、11009和R10。实验结合扫描电镜（scanning electron microscope,SEM）优化了其菌剂的制备工艺,菌剂复配比例,最适应用pH和最佳处理时长。确定选取喷雾干燥工艺制备微生物菌剂,当10001、11009和R10菌剂添加量分别为0.45%、0.80%和0.55%（质量体积比）,剩余污泥pH为7.0时,经过72 h降解处理,达到剩余污泥最佳降解效果即有机质去除率达25.4%,总氮去除率达48.8%。扫描电镜分析结果显示菌剂的失效时间约为7 d。     

溶液中Fe2+强化Fe0还原NO3-的机制

通过不同条件下Fe0还原NO3-的研究发现,在中性条件下溶液中Fe2+明显强化了Fe0对NO3-的还原,最终还原产物以NH4+-N为主,而反应过程中Fe2+消耗与NO3-还原量存在明显的正相关性。在Fe2+初始浓度为1~8 mmol·L-1条件下,6 g·L-1的Fe0对初始浓度为100 mg·L-1 NO3-的还原符合零级反应动力学过程,结合电化学和X射线衍射分析,证明Fe2+通过沉积到Fe0表面,加速了电子传递过程,促进Fe0表面活性,从而强化了Fe0对NO3-的还原。     

改性矿化垃圾对渗滤液生化出水中COD和氨氮的吸附

用矿化垃圾作为吸附剂吸附处理生化后的垃圾渗滤液,利用单因素变量法研究了改性温度、pH、吸附剂投加量和反应时间对吸附效果的影响,并采用红外光谱和电镜扫描对矿化垃圾进行表征。结果表明:矿化垃圾改性温度为700℃,水样pH值为9,吸附剂用量为60 g/L,反应时间为10 h时,COD和氨氮去除率分别达到58.38%和79.77%,平衡吸附量分别为11.68 mg/g和1.58 mg/g;动力学数据拟合COD和氨氮吸附过程均符合拟二级动力学方程即吸附速率被化学吸附所控制;等温方程拟合表明,矿化垃圾对COD和氨氮的吸附分别属于多层吸附和单层吸附;红外光谱分析结果显示,吸附过程中OH、CO和C-O 3种基团起主要作用;电镜扫描结果显示,矿化垃圾改性前、后和吸附前、后内部结构均发生变化。     

电子受体冲击条件下低有机质剩余污泥的高温厌氧水解酸化性能

剩余污泥水解酸化是其后续能源资源化的重要前提保障技术。针对低有机质剩余污泥,在55 ℃高温运行条件下,研究了电子受体冲击对剩余污泥水解酸化运行性能的影响,重点考察了水解酸化过程中水解、酸化效果和氮磷营养元素的释放。结果表明：采用短时曝气冲击模式能够有效提高厌氧水解酸化过程中污泥的去除率,短时曝气和对照组条件下污泥挥发性悬浮固体去除率分别为40%和31%。电子受体冲击条件下增加了溶解性化学需氧量(重铬酸钾法)的产率,尤其是蛋白质产率。引入电子受体冲击主要改善固体物质的降解效率,并不影响酸化的代谢模式,酸化产生的挥发性脂肪酸主要以丁酸型为主。氨氮释放、三维荧光和分子量分布均表明蛋白质类物质的差异主要在于水解阶段产生溶解性蛋白质浓度不同,而不是酸化阶段造成的差异。电子受体冲击尤其是短时曝气冲击是强化污泥水解酸化的有效技术途径。     

Heavy Metals in Moss and Bark From Urban Area of Florence: A New Cleaness Procedure for Removing Superficial Particulate Matter

Hypnum cupressiforme epiphytic moss and tree bark (elm and holm oak) samples have been collected in three sites of the city of Florence in the period 1995-1998. Lead, zinc, copper, and cadmium were determined by differential pulse anodic stripping voltammetry (DPASV) in about 200 samples collected at different heights above ground. A new clean-up procedure by nitrogen jet has been followed and its efficiency has been also verified by electron microscopy (SEM and ESEM techniques). Lead median contents in moss and bark samples fall within the ranges of 0.052-0.86 and 0.20-1.30 μmoles g^-1 (dry weight), resulting values for moss and bark are proportional to the vehicular traffic density. the increasing use of lead-free gasoline has not been followed by a decrease of lead moss concentration.     

New tabletop SEM-EDS-based approach for cost-efficient monitoring of airborne particulate matter

Recent developments in scanning electron microscopy (SEM) have produced tabletop instruments capable of reasonable imaging resolution at less cost compared to conventional equipment. Combining the SEM with energy dispersive spectroscopy (EDS) allows the possibility of elemental analysis through detection of X-rays emitted from interaction between individual particles and the SEM electron beam, revealing their atomic composition. It’s well known that exposure to inhalable particulate matter (PM) poses health risks and routine monitoring of the chemical content of these has been realized. Exposure information is of a general character but by combining the chemical build-up of monitored particles and knowledge of their inherent health effects will allow better risk assessment. An analysis technique using a tabletop SEM with EDS is demonstrated on particles collected onto nucleopore filters from urban, industrial and rural areas. Detailed characterization of the instruments analysis capabilities as applied to PM are described.     

Topographical imaging as a means of monitoring biodegradation of poly(hydroxyalkanoate) films

Poly(hydroxyalkanoates) (PHAs) are a class of bacterially-derived polymers that are naturally biodegradable through the action of extracellular depolymerase enzymes secreted by a number of different bacteria and fungi. In this paper we describe the development of topographical imaging protocols (by both scanning electron microscopy; SEM, and confocal microscopy; CM) as a means of monitoring the biodegradation of solution cast films of poly(3-hydroxybutanoate-co-3-hydroxyhexanoate) (P3HB/3HHx) and medium-chain-length (mcl-) PHA. Pseudomonas lemoignei and Comamonas P37C were used as sources for PHA depolymerase enzymes as these bacteria are known to degrade at least one of the polymers in question. SEM revealed the bacterial colonization of the film surfaces while CM permitted the comparative assessment of the roughness of the film surfaces upon exposure to the two bacterial strains. By dividing the total surface area of the film (A′) by the total area of the scan (A) it was possible to monitor biodegradation by observing differences in the topography of the film surface. Prior to inoculation, P3HB/3HHx films had an A′/A ratio of 1.06. A 24-h incubation with P. lemoignei increased the A′/A ratio to 1.47 while a 48- and 120-h incubation with Comamonas resulted in A′/A ratios of 1.16 and 1.33, respectively. These increases in the A′/A ratios over time demonstrated an increase in the irregularity of the film surface, indicative of PHA polymer breakdown. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.     

利用反硝化过程处理有机废水

试验以甲醇配水作为污水，研究利用外加硝酸盐的反硝化技术去除难以复氧的低溶解氧水中的有机物的可行性。结果表明：达到最佳去除效果时，外加硝酸盐与有机污染物的Ｎ／Ｃ为１．４，停留时间为１６ｈ时有机物去除率可达８６％，１５℃以上时去除率受温度影响不大。     

己酸菌富集及其利用餐厨垃圾产己酸的研究

采用批式发酵的方式,考察3种不同电子供体(乙醇、乳酸、乙醇和乳酸)对己酸菌的富集情况,进而选取产己酸最优的混合菌,探究在不外加电子供体情况下,餐厨垃圾厌氧发酵产己酸的性能.结果表明:当以乙醇和乳酸共同作为电子供体时,己酸浓度可达(2303.06±499.56) mgCOD/L,产己酸效果最佳,并显著富集到了3种碳链延长菌:Clostridium_sensu_stricto_12(16.04%±0.16%),Caproiciproducens(28.78%±0.15%),Oscillibacter(2.32%±0.03%);将产己酸最优的混合菌接种于餐厨垃圾进行厌氧发酵,己酸浓度最高可达(8657.36±996.21) mg COD/L,己酸产率为(230.05±26.47) mg COD/gVS,己酸选择度为27.74%±3.19%.以上结果验证了以乙醇和乳酸共同作为电子供体时对己酸菌具有明显的富集作用,富集到的混合菌可有效用于餐厨垃圾的产己酸发酵,为餐厨垃圾的资源化利用提供了理论支撑.     

沉积物电缆细菌研究进展

目前,在沉积物中发现一种丝状多细胞微生物-电缆细菌,该菌属于变形菌门的脱硫球茎菌科（Desulfobulbaceae）.电缆细菌通过远距离电子传输将沉积物表面的氧还原与深处缺氧层的硫化物氧化电耦合进行完整的氧化还原反应,调节氧分子和硫化物迁移转化.电缆细菌有3种连接方式,表层存在脊段结构进行电子运输,并在富含硫酸盐和季节性周期变化的自然环境中广泛存在.这种新型的多细胞合作方式对沉积物的生物地球化学循环产生显著影响,促进沉积物硫化区铁锰的溶解,并抑制硫和磷等元素的释放.此外,电缆细菌参与硫化物和烃类污染物的降解,为污染沉积物生物修复领域提供新的研究方向.本文对电缆细菌的发现、生理代谢、栖息环境以及生物地球化学循环的影响等研究进行了综述.