Surface properties of bacteria from activated sludge in relation to bioflocculation

Two bacterial stains were isolated from the activated sludge and identified as Leucobacter sp.and Alcaligenes faecalis by 16S rDNA sequencing.Pure cultures of these two strains,representing well or poorly settled bacteria,were used to investigate the mechanism of bioflocculation in activated sludge.Based on the analyses of the characteristics of cells hydrophobicity,ζ-potential,flocculation ability and extracellular polymeric substance (EPS) composition under different growth stages,it was found that the ratio of cell EPS protein had the highly influence on ζ-potential and hydrophobicity,which were important factors to bioflocculation.Cellulase and Proteinase K could destroy the extracellular biopolymer and resulted in a decrease in the hydrophobicity and ζ-potential.However,in our study,the flocculation characteristics exhibited differently in relation to cellulase and Proteinase K.Flocculation of cells treated with cellulase and Proteinase K decreased sharply,and then recovered quickly in cellulase treatment,while cells treated with Proteinase K showed no sign of recovery.This reveals that the presence of protein in extracellular biopolymer plays an important role to the bioflocculation of cells.     

钙化物在废弃物基活性炭制备过程中的影响

研究了以城市垃圾中3种典型的固体有机废弃物——锯木屑、纸张和塑料的热解产物（分别简称木炭、纸炭和塑料热解物）为原料,水蒸气为活化剂制备废弃物基活性炭时钙化物含量对活化过程、活性炭吸附性能（以碘值表征）及其孔结构的影响。结果表明,钙化物可加快活化反应的速度,且钙化物含量在1.5%时活化反应速度即已不再随钙化物含量的增加而增加;活性炭的吸附性能则随钙化物含量的增加而减少,同时钙化物对活性炭的孔径分布基本无影响,但降低了活性炭的比表面积、微孔孔容及中孔孔容;钙化物的2种前驱体（即CaO和Ca（OH）2）对活化过程具有相同的催化作用。     

延迟焦化装置的定量风险评估

通过长岭分公司延迟焦化装置的定量风险评估,明确了装置中的主要危险设备,量化出装置的整体风险水平,促进了企业的安全生产.     

氢化物发生原子荧光法测定地表水和饮用水中的痕量砷、汞、硒

文章研究了用SK-2002 AFS analyser氢化物发生原子荧光法测定地表水和饮用水中的砷、汞、硒的测定。在5％的酸度条件下加入5％硫脲＋5％抗坏血酸,20g／L的硼氢化钾为还原剂,调整仪器的空气和辅气流量及分析条件为文中条件,取水样中分别添加砷,汞,硒,使它们的浓度分别为2μg/L,0．4μg／L,4μg／L,连续测定12次,以砷,汞,硒的相对标准偏差分别为0．4％,1．1％,1．2％。取水样加入As,Hg,Se标准分别为2．0ng,0．6ng,4．0ng,测定的添加标准回收率分别为99．5％,97．5％,95．8％。研究结果表明,该方法操作简便,快速,灵敏,干扰少,检出限低等特点,适合于测定地表水和饮用水中砷,汞,硒的测定。     

西南喀斯特地区石漠化问题研究综述

喀斯特地区石漠化是在脆弱的生态地质背景基础上叠加了人类活动而出现的。西南地区的石漠化面积现仍约以2500km^2／a的速度进一步扩大。石漠化的生态治理工作的目的就是要在人为作用的干扰下,使这种逆向演替转变为顺向演替。石漠化治理思路设计的科学性、战略性、可行性决定了最后石漠化的治理结果。在喀斯特石漠化的治理中,要根据不同岩溶环境类型区及石漠化发育的不同程度和不同山地的立地条件,针对其特点,选择多种途径,运用恰当的恢复技术,制定出具体的开发治理措施,实行规模治理,以提高资源利用率,促进石漠化生态环境的综合治理。     

齐齐哈尔市建华区污染源普查工作的几点体会

介绍了齐齐哈尔市建华区环保局污染源普查工作,严格按照全国污染源普查办的统一要求,开展普查工作.主要工作流程有领导重视、大力宣传、统一思想、培训队伍、做好拉网清查,认真核实汇总,严格审查等工作流程.从而保证了污染源普查工作科学有序、高效优质的圆满完成.     

Effects of humic acid fractions with different polarities on photodegradation of 2, 4-D in aqueous environments

Four fractions (A, B, C, and D) of humic acids (HAs) were separated based on the polarity from weak to strong. UV-vis absorption and Fourier transform infrared spectroscopy (FTIR) analysis show that the fractions C and Dpossessedmore aromatic C=C content. The influences of HAs and their fractions on the photolysis were investigated by the photodegradation of 2,4-D solutions under simulated solar light irradiation. The degradation rate of 2,4-D was found to decrease in the presence of bulk HAs or their fractions especially at high HAs concentration. The fractions of strong polarity C and D retarded the degradation rate more than the fractions of weak polarity A and B. This could be attributed to the different absorption intensity of the four HAs fractions in the order of D ⩾ C > A > B, and the stronger π-π electron donor-acceptor interactions between the strong polar fractions and 2,4-D.     

Occurrence of phthalate esters in water and sediment of urban lakes in a subtropical city, Guangzhou, South China

Extensive use of phthalate esters (PAEs) in both industrial processes and consumer products has resulted in the ubiquitous presence of these chemicals in the environment. This study reports the first data on the concentrations of 16 phthalate esters (PAEs) in water and sediments of the urban lakes in Guangzhou City. PAEs were detected in all samples analyzed, mainly originating from urban stormwater runoff, atmospheric deposition, as well as untreated discharge of industrial wastewater and municipal sewage. The Sigma(16)PAEs concentrations in water and sediments ranged from 1.69 to 4.72 microg L(-1) and 2.27 to 74.94 microg g(-1)-dry weight (dw), with the mean concentrations of 2.91 microg L(-1) and 20.85 microg g(-1)-dw, respectively, which indicates that sediment is a significant sink for PAEs. Variability of the Sigma 16PAEs concentrations in water and sediment in the urban lakes was almost consistent. The spatial distribution of PAEs was site-specific. Of the 16 PAEs, DMP, DEP, DnBP, DiBP, DMPP, and DEHP were present in all water and sediment samples. DnBP was abundant in water (53.0-81.2%), while no single dominant congener was found in sediments. The abundances of DiBP were similar to those of DEHP, and DiBP and DEHP collectively accounted for 77.2-97.6% of the Sigma 16PAEs concentrations. Congener specific analysis confirmed that DnBP was a predictive indicator for the dissolved summation operator16 PAEs concentration (correlation coefficient r=0.968, p<0.01), and that DiBP was a predictive indicator for the sediment summation operator16 PAEs concentration (r=0.975, p<0.01). As compared to the results for other studies, the urban lakes of Guangzhou were moderately polluted by PAEs.     

Study on biosorption kinetics and thermodynamics of uranium by Citrobacter freudii

Biosorption has been developed as an effective and economic method to treat wastewater containing low concentrations of metal pollutants. In this study, a bacterium, Citrobacter freudii, was used as a biosorbent to adsorb uranium ions. The thermodynamics and kinetics of this adsorption, as well as its mechanism, were investigated. The results indicated that the biosorption rate could be better described by a pseudo 2nd-order model than a pseudo 1st-order model. The adsorption of U (VI) proceeded very rapidly in the first 30min and subsequently slowed down continuously for a long period. The biosorption isotherm of uranium by C. freudii could be described well by the Langmuir or Freundlich isotherm, and the latter was better. The thermodynamics parameters, DeltaH degrees , DeltaG degrees , and DeltaS degrees were calculated according to the results of the experiment, which showed this biosorption as being endothermic and spontaneous. The authors investigated the active sites of bacteria for biosorption and the results proved that carboxyl in the cell wall played an important role in biosorption.     

重庆市岩溶地区生态系统脆弱性分析

岩溶地区具有独特的地质地貌,在人为干扰作用影响下很容易导致当地生态系统稳定性降低,生态环境恶化,产生水土流失和石漠化等一系列生态问题。重庆市岩溶区面积占全市总面积的51％,同样面临着一系列的生态环境问题。通过分析岩溶地区生态系统的结构脆弱性、过程脆弱性、功能的脆弱性和人为胁迫脆弱的表现,发现导致生态系统脆弱的原因主要是水文、地质、植被等自然因素和人口压力以及不合理利用等人为因素,针对这些原因为生态系统恢复和重建提供合理建议。