一种测定活性污泥中高等微生物活性的方法

采用机械破碎方式灭活活性污泥中高等微生物,并通过测定破碎前后泥样耗氧速率(OUR)之差别间接计算高等微生物的活性作用.实验结果表明,以分散机破碎活性污泥,高等微生物均可被有效地破碎灭活,且再培养138h后不再恢复.与此同时,对酵母菌破碎实验显示,机械破碎并未对其数量、形态以及活性产生太大影响,这表明机械破碎亦不会对个体尺寸比酵母菌更小的细菌构成任何影响.为使破碎前后活性污泥絮凝体形态基本一致,将破碎后的泥样经离心处理,以尽可能使絮凝体恢复如初(以SVI衡量).通过比较破碎前后泥样的OUR并计算可知,高等微生物活性相对于活性污泥总活性约占12%～14%.     

农村水资源短缺：现状、趋势及其对作物种植结构的影响——基于全国10个省调查数据的实证分析

论文利用全国10个省面板数据对中国农村水资源短缺的现状、趋势及对作物种植结构的影响做实证分析。研究发现,无论是对水资源短缺进行总体判断,还是从灌溉水源、供水可靠性和地下水位变动趋势等其它方面进行分析,水资源短缺状况都不容忽视,而且这一趋势在加重。水资源越短缺,农民就越可能倾向于种植对灌溉依赖程度低、需水量小的作物,尤其是豆类作物。     

氯对模拟管壁生物膜的氧化特性研究

以载片上培养的大肠杆菌生物膜为对象,研究了氯对模拟管壁生物膜中大肠杆菌的灭活效果,同时考察氯氧化生物膜后水中生物可同化有机碳(AOC)、生物可利用磷(MAP)和细菌生长潜能(BRP)的变化情况.结果表明,氯可以有效灭活悬浮态的大肠杆菌,而对生物膜中的大肠杆菌的灭活效率远低于悬浮菌;在相同CT值下,较高浓度的氯对悬浮态和生物膜中大肠杆菌的灭活效果要高于低浓度的氯.氯对生物膜的氧化作用会使生物膜中物质溶出,增加了水中AOC和MAP浓度,如当氯的浓度为1.0 mg/Ｌ(CT值为100 mg·min/L)时,水中AOC由20.78 μg/L增加到120.17 μg/L,MAP含量由0.11 μg/L增加到0.17 μg/L;氯的氧化作用会增加水的细菌生长潜能（BRP）,BRP随着CT值的增加而增加,如当氯投量为1.0 mg/Ｌ(CT值为100　mg·min/L)时,BRP可达到1.10×10⁷ CFU/mL.     

A2/O工艺中好氧污泥絮体的分形结构与理化特征分析

采用图像法和沉降柱法分别研究了A²/O工艺中好氧污泥絮体的形貌、粒度分布、低维分形维数和沉降速率、有效密度、空隙率以及质量分形维数,并尝试探讨了上述相关性质与这些污泥宏观操作性质(沉降、压缩、脱水和稳定性)相关的各种理化指标以及胞外高分子物质(EPS)的含量之间的变化关系.结果表明,污泥絮体呈现不规则的形貌,表面具有空隙.其有效密度一般随着其粒径的增加而降低,而空隙率和沉降速率却呈现与有效密度相反的变化趋势,这些均表明了污泥絮体的分形结构的存在.2次所采集的污泥絮体的中位直径分别为248.81、 332.86 μm,有效密度的平均值分别为0.004 0、 0.007 2 g·cm^-3,自由沉降速率的平均值分别为2.67、 4.79　mm·s^-1,空隙率的平均值分别为0.94、 0.89,一维分形维数分别为1.03、 1.19,二维分形维数分别为1.64、 1.84,采用基于Logan经验公式的有效密度-最大直径的双对数关系确定的质量分形维数分别为1.74、 2.29.尽管第2次所采集的污泥絮体较为密实,但其表面粗糙程度却比第1次的低.此外,研究中发现絮凝能力较高或负电荷较高的A²/O好氧污泥絮体具有高的SVI和ZSV值;分形维数较低的污泥具有高的剪切敏感性和低絮体强度,相应的污泥稳定性低;EPS总量高的污泥脱水性能差,EPS中蛋白质含量高的污泥其表面电荷也较高.     

城市污水处理系统中氨氧化细菌种群结构研究

利用PCR-DGGE(变性梯度凝胶电泳)技术对北京7个城市污水厂中10个处理系统的氨氧化细菌(AOB)种群结构进行了调查研究,发现城市污水厂的AOB种群多样性不高,除了硝化效果不好的一个污水厂外,其他9个污水处理系统中均检测到AOB的存在.切胶测序结果表明主要属于Nitrosomomu oligotropha/aestuarii-like cluster.     

基于GIS与群落调查的北京市野生北柴胡资源量测算

以2007年北京市地全区236个群落调查样方数据和典型区域300株野生北柴胡采样数据为基础,采用模型模拟、样方调查、GIS与数理统计等方法,对野生北柴胡分布与资源产量进行研究。结果表明：①北京市野生北柴胡在植物群落中的种群密度介于0～6000株/hm²之间,产量密度范围介于0～683kg/km²之间,密度最大的生境为海拔1 800m左右的山顶杂草草甸;②不同生境下根生物量（Y）与植株地上形态特征株高（x₁）,叶片数（x₂）和分枝数（x₃）显著相关;③北京地区北柴胡资源分布面积为752 937hm²,资源总量约为410t;④北京市野生北柴胡资源的水平分布特征表现为,东部怀柔、密云和平谷等地产量密度低,西部和中部地区密度较高,从垂直变化规律看,北柴胡分布的主要区域集中在海拔100～2 000m的范围内,随着海拔高度的增加,产量密度表现出先增加后减少的总体趋势。     

胞外酶对堆肥中微生物群落演替的影响

研究了添加黄孢原毛平革菌胞外酶对农业废物堆肥中木质纤维素降解及微生物群落演替的影响.结果表明,堆肥初期,胞外酶对微生物生长具有抑制作用,且随堆肥时间的延长逐渐减弱;堆肥后期,胞外酶可提高微生物群落的多样性和均匀性,并促进木质素和半纤维素的大量降解.醌指纹数据显示,胞外酶并未引起新的优势醌的出现,进入高温期后,以MK-7为主要醌类的微生物作为优势菌群,且这种优势一直存在;堆肥后期胞外酶对甲基萘醌影响较大,可促进长链甲基萘醌的出现.主成分分析表明,胞外酶对醌种类演替的影响主要作用在3d和40d,这与非相似性指数结果一致,并使真菌在整个体系中影响力加大.     

Influence of temperature on the characteristics of aerobic granulation in sequencing batch airlift reactors

Aerobic granular sludge was cultivated in sequencing batch airlift reactors(SBAR) at 25,30,and 35°C,respectively.The effect of temperature on the granules characteristics was analyzed and the microbial community structures of the granules were probed using scanning electron microscope(SEM) and polymerase chain reaction-denaturing gradient gel electrophoresis(PCR-DGGE).The results showed that 30°C is optimum for matured granule cultivation,where the granules had a more compact structure,better settling abili...     

Phosphorus utilization and microbial community in response to lead/iron addition to a waterlogged soil

Constructed wetlands have emerged as a viable option for helping to solve a wide range of water quality problems. However, heavy metals adsorbed by substrates would decrease the growth of plants, impair the functions of wetlands and eventually result in a failure of contaminant removal. Typha latifolia L., tolerant to heavy metals, has been widely used for phytoremediation of Pb/Zn mine tailings under waterlogged conditions. This study examined e ects of iron as ferrous sulfate (100 and 500 mg/kg) and lead as lead nitrate (0, 100, 500 and 1000 mg/kg) on phosphorus utilization and microbial community structure in a constructed wetland. Wetland plants (T. latifolia) were grown for 8 weeks in rhizobags filled with a paddy soil under waterlogged conditions. The results showed that both the amount of iron plaque on the roots and phosphorus adsorbed on the plaque decreased with the amount of lead addition. When the ratio of added iron to lead was 1:1, phosphorus utilized by plants was the maximum. Total amount of phospholipids fatty acids (PLFAs) was 23%–59% higher in the rhizosphere soil than in bulk soil. The relative abundance of Gram-negative bacteria, aerobic bacteria, and methane oxidizing bacteria was also higher in the rhizosphere soil than in bulk soil, but opposite was observed for other bacteria and fungi. Based on cluster analysis, microbial communities were mostly controlled by the addition of ferrous sulfate and lead nitrate in rhizosphere and bulk soil, respectively.     

Biofilm structure and its influence on clogging in drip irrigation emitters distributing reclaimed wastewater

Using reclaimed wastewater for crop irrigation is a practical alternative to discharge wastewater treatment plant effluents into surface waters.However,biofouling has been identified as a major contributor to emitter clogging in drip irrigation systems distributing reclaimed wastewater.Little is known about the biofilm structure and its influence on clogging in the drip emitter flow path.This study was first to investigate the microbial characteristics of mature biofilms present in the emitters and the effect of flow path structures on the biofilm microbial communities.The analysis of biofilm matrix structure using a scanning electron microscopy (SEM) revealed that particles in the matrix of the biofilm coupled extracellular polysaccharides (EPS) and formed sediment in the emitter flow path.Analysis of biofilm mass including protein,polysaccharide and phospholipid fatty acids (PLFAs) showed that emitter flow path style influenced biofilm community structure and diversity.The correlations of biofilm biomass and discharge reduction after 360 h irrigation were computed and suggest that PFLAs provide the best correlation coefficient.Comparatively,the emitter with the unsymmetrical dentate structure and shorter flow path (Emitter C) had the best anti-clogging capability.By optimizing the dentate structure,the internal flow pattern within the flow path could be enhanced as an important method to control the biofilm within emitter flow path.This study established electron microscope techniques and biochemical microbial analysis methods that may provide a framework for future emitter biofilm studies.