紫外光预氧化下高岭土复合聚合氯化铝混凝去除水体中颤藻

采用紫外光预氧化复合高岭土,通过混凝去除给水中的颤藻。结果表明,紫外光的预氧化可破坏藻细胞的结构,抑制其生长。最佳复配条件:紫外光照射时间4 min,高岭土投加量45 mg.L-1,PAC投加量4.5 mg.L-1,静置沉淀时间20 min。在此条件下,浊度和叶绿素a去除率分别达到91.2%和94.6%,残留铝含量为0.13 mg.L-1。     

K_2FeO_4预氧化复合絮凝处理颤藻和腐殖酸混合水

采用K2FeO4预氧化复合高岭土和聚合氯化铝(PAC)混凝处理了含颤藻和腐殖酸的混合水,并探讨了对处理后水中残留铝含量及其形态分布的影响。结果表明:投加4.0 mg·L-1K2FeO4预氧化就能使混合水样的浊度、腐殖酸和藻类的去除率分别达到94.05%、91.67%和90.78%,明显优于相同条件下单纯的PAC处理效果;水样的pH值对K2FeO4预氧化有显著的影响,在pH=6.5时效果最好;K2FeO4预氧化影响处理后水中残留铝的含量和形态,在最佳条件下总铝浓度降低了51.8%,特别是对人体毒害作用最大的溶解态铝降低了43.9%。     

Desiccation and recolonization of phytobenthos in a regulated desert river: Colorado River at Lees Ferry,Arizona, USA

We tested the recolonization of the phytobenthic community in the tailwaters of Glen Canyon Dam following long- and short-term experimentally induced desiccation. The response of Cladophora glomerata, Oscillatoria spp., miscellaneous phytobenthos species and periphyton was studied over 18 weeks using three treatments: (1) undisturbed control cobbles from the submerged zone; (2) cobbles desiccated and replaced into the submerged zone; and (3) cobbles desiccated and replaced into the varial zone. Periphyton density and compositional response resulting from these treatments were also examined. Desiccation treatments were significantly different in biomass from controls throughout the study. The biomass of desiccated and replaced river cobbles averaged <30% of the controls for C. glomerata and periphyton during the 18-week recolonization period. In contrast, the biomass of the control Oscillatoria and miscellaneous phytobenthos species averaged only 3 and 50% of that in the desiccation treatments, respectively. Cladophora, the dominant alga, comprised 77% of the phytobenthic biomass. A significant positive relationship between discharge, Cladophora and periphyton biomass was present in all treatments, while there was a negative relationship with discharge for Oscillatoria and miscellaneous phytobenthos species. There was a significant inverse correlation, as well as a pattern of separate biomass dominance, between C. glomerata and Oscillatoria. Cladophora was the dominant phytobenthos species on cobbles below the baseflow and Oscillatoria was dominant on cobbles in the varial zone. In general, the Cladophora biomass decreased under intermittent drying conditions, while Oscillatoria declined under permanently wet conditions. Diatom composition was not significantly different between treatments; however, their density was lower on desiccated cobbles. Diatom density on desiccated cobbles in the submerged and varial zones averaged 69 and 42% of that of the controls, respectively. Recovery and maintenance of benthic resources are hindered by fluctuating flow regimes driven by electricity and irrigation requirements. Repeated desiccation of the phytobenthos has major effects on the bottom-up interactions in the Colorado River ecosystem. © 1998 John Wiley & Sons, Ltd.     

预氧化与化学混凝联合去除颤藻的研究进展

日趋严重的水体富营养化早已成为全球性的环境问题,藻类及其副产物给传统除藻工艺带来了很多不利影响,增加了水处理难度。本文对国内预氧化与化学混凝联合去除颤藻的研究和应用动态进行了概括总结,并系统分析各技术去除效果、局限性,展望了颤藻去除技术发展前景。同时也提出了存在的一些问题,便于今后的研究和应用中进一步改进和完善。     

Hydrogen evolution in relation to PS I-reducible substrates in the cyanobacterium Oscillatoria chalybea assayed by means of mass spectrometry

None of the PS I-reducible molecules (nitrate, NAD or NADP) decreased H₂ evolution in Oscillatoria chalybea; indicating that their reduction would not compete with proton reduction. Seemingly, CO₂ reduction does not compete as well. Only nitrite was accompanied with a strong and consistent inhibition most probably due to a specific characteristic of the chemical rather than substrate competition. Such nitrite-induced inhibition could not be attributed to a lack in photosynthetic electrons since nitrite inhibited neither PS I nor PS II activity. ATP enhanced hydrogen evolution (about 50%) while NH₄Cl in an uncoupling concentration was inhibitory; although in hydrogenases (other than nitrogenases) ATP is not directly involved (discussed).     

Treatment of Mine Water by a Microbial Mat: Bench-scale Experiments

Abstract.   We investigated the treatment of acid mine drainage (AMD) by a blue-green algae-microbial consortium and substrate (containing powdered goat manure, wood chips, and soil) in 1 m³ bench scale biological treatment test cells. The microbial mat resulted from the interaction of bacteria and filamentous blue-green algae (predominantly Oscillatoria spp). The experiments were carried out for different water column heights, and were evaluated for 24, 48, 72, 96, and 168 hours of retention. Within 24 hours of retention, the pH increased from 2.93 to 6.78 as net alkalinity went from -125 mg/L to 197 mg/L as CaCO₃. Turbidity decreased by 33–54%, sulphate decreased by 23–29%, and hardness decreased by 19 to 26%. We also observed that: 95% of the Fe, 79–97% of the Cu, 84–86% of the Zn, 88% of the Pb, 59–83% of the Co, 22–62% of the Ni, and 28–45% of the Mn were removed. A blue-green algae/microbial mat consortium may be a cost–effective treatment technique for removing metals from AMD.     

K2FeO4预氧化对颤藻和腐殖酸复合絮凝相互作用的研究

采用K2FeO4预氧化复合高岭土和聚合氯化铝(PAC)混凝处理含藻和腐殖酸的混合水.结果表明,当藻浓度不变时,在一定范围内,随着腐殖酸浓度的升高,浊度、腐殖酸及藻去除率均逐渐下降.当腐殖酸浓度固定时,随着藻液浓度的升高,腐殖酸和藻去除率逐渐上升,而浊度去除率基本不变.同时考察了矿物高岭土投加量及目数、K2FeO4预氧化时间、不同污染物浓度比例对K2FeO4预氧化处理混合水效果的影响,当高岭土投加量为8 mg/L、粒径为140目时,浊度和腐殖酸、藻类的去除率分别为91.0%,80.9%和88.2%,投加量过大或目数过大,沉降性能变差,起不到良好的助凝作用.     

Cyanobacterial (Blue-Green Algal) Toxins and their Significance in UK and European Waters

The cyanobacteria (blue-green algae) which commonly produce mass developments in fresh and saline waters are capable of producing toxins. These compounds have been responsible for the deaths of animals, birds and fish in many countries, and have been linked with several forms of human illness through skin contact and ingestion. Evidence has accumulated over the past decade that cyanobacterial toxins occur commonly in European waters which contain cyanobacterial mass growths. This paper summarizes the recent published occurrence and types of cyanobacterial toxins found in European waters with reference to poisoning incidents.
Cyanobacterial blooms were particularly abundant in the warm dry summer of 1989 in the UK. The deaths of sheep and dogs and the cases of human illness that were ascribed to cyanobacterial toxins were followed by a more intensive and wider investigation into the extent of cyanobacterial toxicity in UK waters than had hitherto been undertaken. Of the cyanobacterial blooms sampled from over 90 freshwaters, approximately two-thirds were toxic (lethal) according to mouse bioassay. Short-term and long-term needs for the recognition, quantification and management of problems which can be caused by potentially toxigenic cyanobacteria in water-bodies used for recreation, aquaculture and potable supply are briefly discussed.     

高锰酸钾预氧化对颤藻活性及其混凝效果的影响

采用不同浓度的KMnO4对颤藻预氧化后,再接种到培养液中进行培养,根据达到对数生长期的时间,考察了KMnO4预氧化对颤藻活性的影响。通过显微镜观察了藻细胞的破裂情况,同时采用聚合氯化铝(PAC)以及高岭土与PAC复合对KMnO4预氧化水体进行混凝处理。结果表明,在KMnO4达到130 mg.L-1时才能完全杀灭水体中的颤藻,低于该浓度时,不同浓度KMnO4对颤藻活性的抑制时间不同;在投加量为2 mg.L-1以下时,预氧化没有破坏颤藻的细胞结构。模拟含藻水在KMnO4预氧化后,采用高岭土与PAC复合混凝,浊度和叶绿素a的去除率分别达到96.9%和98.3%,藻毒素降低了63.6%。