微囊藻毒素的处理方法研究进展

微囊藻毒素是在藻类细胞内合成的毒素,细胞死亡后释放出来并表现出毒性.本文主要综述了水体中藻毒素目前常用的各种物理、化学、生物以及低温等离子体灭活技术等方法的国内外研究现状,介绍了影响去除的因素、机理以及存在的问题和未来研究发展的方向.     

湖泊富营养化危害机理研究

介绍了湖泊富营养化集中产生危害的原因和机理,包括水华产生的藻毒素类物质造成动物死亡、菲斯达杀鱼藻导致鱼类死亡、产生毒素的肉毒杆菌导致鸟类死亡、自由漂浮植物异常繁殖的影响。概述了这些水环境问题的处理措施。     

饮用水处理中藻毒素污染及其工艺控制特性研究

有毒藻类在富营养化水源水中大量繁殖形成极富危害的藻毒素污染。藻毒素在水环境的迁移转化受光照、温度、有机物、水生生物等因素的共同影响。好氧条件下 ,已驯化的微生物对水中藻毒素的降解较为迅速。水处理的单元工艺 (混凝、沉淀、砂滤、加氯等 )及其组合的常规工艺对藻毒素的去除率较低 ,而常规工艺 +活性炭过滤、臭氧 +常规工艺两种工艺能 10 0 %地去除水中的藻毒素。不破坏藻细胞而能够大量降低其数量的预处理 +臭氧 +常规工艺 +活性炭工艺应能够取得最佳的解毒效果。     

水源水中藻类及藻毒素控制试验研究

研究了氯、高锰酸钾、臭氧等单独预氧化及与混凝沉淀联合作用时,水源水中藻类及藻毒素含量的变化规律,发现预氧化对藻类的去除作用有限,混凝沉淀对藻毒素的去除作用也有限,而两者的联合作用可提高对藻类和藻毒素的去除效果;在合适的投加量下,藻类去除率在80%以上,藻毒素的去除率近90%,可有效减轻后续处理工艺的负荷,保障饮用水的安全。     

富营养化水体中蓝藻毒素的研究进展

众多研究表明,蓝藻毒素的释放对水体产生不利影响,它不仅对水生植物、水生动物等生物体会有负面影响,同时也会对人类的健康产生危害,解决由此产生的污染问题已迫在眉睫.近年来频繁发生的水体富营养化所产生的蓝藻毒素严重影响饮水用水安全.随着人们对水安全的重视和蓝藻毒素研究的不断深入,藻毒素快速、高灵敏分析检测已成为研究的热点.对目前国内外的藻毒素的致毒解毒机理和检测技术进行综述,并对这些方法的优缺点进行分析,以期寻找或建立一套灵敏度高、简单易行且快速的藻毒素检测系统.     

富营养化原水中蓝藻及其毒素的生物降解技术研究

本文主要研究以生物接触氧化作为预处理工序的富营养化原水的实用处理方法 ,以有效去除蓝藻及其藻毒素。考察了生物反应器内流态、构型对处理效果的影响 ,确定了最佳的工艺参数和处理效率 ,并初步探讨了藻类和藻毒素的降解机理。同时与传统自来水厂常规工艺处理富营养化原水中藻类及其藻毒素的处理效果相比较 ,讨论了生物预处理工艺保障水厂供水水质的积极作用。主要研究成果如下 :(1)对水厂常规工艺出水取样检测发现 ,ＮＨ3 -Ｎ ,ＮＯ2 --Ｎ ,ＣＯＤＭｎ等常规指标的去除效率普遍不高 ,藻类和藻毒素的去除效率也不理想。(2 )三阶生物接触氧…     

饮用水源中藻毒素污染控制研究

藻毒素给传统净水工艺带来了诸多不利影响,增加了水处理难度。通过对国内外饮用水源藻毒素去除技术的分析,揭示了各种技术去除效果、局限性,对藻毒素研究前景进行了展望。提出综合控制办法:水污染综合治理、采用臭氧活性炭工艺和生物调控法相结合。     

藻毒素的生物降解研究进展

近年来蓝藻水华污染产生的有毒代谢产物藻毒素对水生生态系统和人类健康构成严重的威胁。生物降解技术尤其是生物滤池由于运行维护费用低并且不产生有毒副产物,已广泛应用于去除藻毒素。然而,水处理过程中可能存在的生物降解多种藻毒素效果的信息少有收集,这在越来越多不同种类的藻毒素能同时在水源地中检测出来的情况下更加重要。综述了目前所有藻毒素生物降解性的相关研究进展,分析了影响藻毒素生物降解的因素,并探讨了目前藻毒素生物降解技术如何在水处理过程中应用优化去除藻毒素效果,为运用生物降解方法控制或去除各种藻毒素提供理论指导。     

利用超滤法去除藻类的试验研究

以藻、微囊藻毒素(Microcystin,MCYST)为研究对象,考察了超滤在不同的水温透膜压力、藻含量、膜污染程度下对藻的去除效果,同时研究了超滤对池塘水中囊藻毒素的去除情况,初步探讨了超滤除藻技术应用于水厂生产实际的可能性.     

压力强化混凝沉淀过滤除藻工艺中藻毒素去除研究

为了探究压力强化混凝沉淀过滤除藻工艺中藻毒素的去除效果,试验对比研究了预加压和预氧化后的含藻水,经混凝沉淀、粉末活性炭吸附后的藻毒素去除效果,考察了不同粉末活性炭投加点及投加量对藻毒素去除效果的影响。结果表明,含藻水加压后混凝沉淀,藻类和浊度物质去除效果最优,蓝藻去除率达到96.2%,浊度降至0.49NTU。含藻水在加压和高锰酸钾预氧化后,水中藻毒素浓度未增加,而次氯酸钠预氧化后水中藻毒素浓度最大增幅为215.78%;对于加压水样,在混凝剂投加前30min或投加后7min投加粉末活性炭效果较好,粉末活性炭投加量为5~20 mg/L时,沉淀水藻毒素平均去除率分别达54.13%和53.57%,而与混凝剂同时投加则效果不佳。对次氯酸钠预氧化的水样,粉末活性炭与混凝剂同时投加时效果最好,沉淀水藻毒素平均去除率15.84%。     

超声波技术预防性抑制蓝藻水华的研究

指出传统的蓝藻水华治理方法中存在的问题:大规模地杀灭蓝藻,造成大量藻细胞破裂,细胞内藻毒素等有害分泌物释放到水中,引发二次污染。介绍蓝藻水华的预防性调控方法,即在水体形成水华前,通过抑制蓝藻细胞生长,将其藻类生物量始终控制在一定水平以下,避免蓝藻水华的暴发。综述了超声参数对除藻抑藻效果的影响,以及超声对藻细胞生理系统的影响,探讨超声除藻抑藻的机理,并针对以往研究存在的不足,对后续研究重点进行了展望。     

Cyanobacterial blooms in the central basin of Lake Erie: Potentials for cyanotoxins and environmental drivers

Lake Erie western basin (WB) cyanobacterial blooms are a yearly summer occurrence; however, blooms have also been reported in the offshore waters of the central basin (CB), and very little is known about what drives these blooms or their potential for cyanobacterial toxins. Cyanobacteria Index was quantified using MODIS and MERIS data for the CB between 2003 and 2017, and water samples were collected between 2013 and 2017. The goals were to 1) quantify cyanobacteria, 2) determine environmental drivers of CB blooms, and 3) determine the potential for cyanobacterial toxins in the CB. Dolichospermum (Anabaena) occurred in the CB during July before the onset of the WB bloom, and then in August and September, the cyanobacteria community shifted towards Microcystis. The largest Dolichospermum blooms (2003, 2012, 2013, and 2015) were associated with reduced water clarity (Secchi disk depth?<?4?m), whereas large CB Microcystis blooms (2011 and 2015) were associated with large WB blooms. Dolichospermum blooms occurred in high nitrate concentrations (>20?μmol/L) and high nitrogen-to?phosphorus ratios (>100), which indicate nutrient concentrations or ratios did not select for Dolichospermum. Additionally, the sxtA gene, but not mcyE or microcystins, were detected in the CB during July 2016 and 2017. The mcyE gene and microcystins were detected in the CB during August 2016 and 2017. The results indicate the CB's potential for cyanotoxins shifts from saxitoxins to microcystins throughout the summer. Continued monitoring of cyanobacteria and multiple cyanobacterial toxins is recommended to ensure safe drinking water for CB coastal communities.     

Correlating 2-MIB and microcystin concentrations with environmental parameters in two reservoirs in South Taiwan.

Cyanobacteria are present in many drinking water reservoirs in Taiwan, and some of them may produce off-flavour compounds and natural toxins. To investigate the correlation among two groups of cyanobacterial metabolites, microcystins and 2-methylisoborneol (2-MIB), and other environmental parameters, approximately 22 water quality and meteorological parameters were monitored for two source waters (Moo-Tan and Tseng-Wen reservoirs) in south Taiwan from August 2003 to April 2005. Monitoring results showed that the two groups of cyanobacterial metabolites were present in the source waters. Concentrations of 2-30 ng/L of 2-MIB was observed for the two reservoirs, while that of the total concentrations of the five microcystin congeners measured were between 30 and 340 ng/L. The concentration of both 2-MIB and microcystins showed higher concentrations in warmer seasons. A stepwise regression technique was employed to correlate 2-MIB and microcystins concentrations with all the corresponding water quality and meteorological parameters. Correlations among 2-MIB concentration, microcystin concentration, water temperature and air temperature were found in the water samples collected from both reservoirs. The correlations may provide a simple means for the water utility to anticipate the two groups of cyanobacterial metabolites in the two source waters.     

Support Vector Machines and Multilayer Perceptron Networks Used to Evaluate the Cyanotoxins Presence from Experimental Cyanobacteria Concentrations in the Trasona Reservoir (Northern Spain)

Cyanobacteria also known as blue-green algae can be found in almost every conceivable environment. Cyanobacteria blooms occur frequently and globally in water bodies and they are a major concern in terms of their effects on other species such as plants, fish and other microorganisms, but especially by the possible acute and chronic effects on human health due to the potential danger from cyanobacterial toxins produced by some of them in recreational or drinking waters. Consequently, anticipation of cyanotoxins presence is a matter of importance to prevent risks. The aim of this study is to build a cyanotoxin diagnostic model by using support vector machines and multilayer perceptron networks from cyanobacterial concentrations determined experimentally in the Trasona reservoir (recreational reservoir used as a high performance training centre of canoeing in the Northern Spain). The results of the present study are two-fold. In the first place, the significance of each biological and physical-chemical variables on the cyanotoxins presence in the reservoir is presented through the model. Secondly, a predictive model able to forecast the possible presence of cyanotoxins is obtained. The agreement of the model with experimental data confirmed its good performance. Finally, conclusions of this innovative research work are exposed.     

Dolichospermum blooms in Lake Superior: DNA-based approach provides insight to the past,present and future of blooms

Cyanobacterial blooms are increasing in frequency, duration, and severity globally in freshwater ecosystems. The Laurentian Great Lakes are prone to toxin-producing cyanobacterial blooms and have experienced annually recurring blooms. Because of its oligotrophic nature, Lake Superior has been relatively free of bloom occurrences. However, in recent years, Dolichospermum blooms have occurred with increasing frequency, especially in the western arm. During a Dolichospermum bloom in 2018, opportunistic samples were collected from the offshore bloom and investigated with shotgun metagenomics. We identified a near-complete Dolichospermum genome that is highly similar to genomes from cultures recovered in Lakes Erie and Ontario. The genomes from the Laurentian Great Lakes are typified by their putative ability to produce a suite of secondary metabolites like anabaenopeptin, but not toxins like microcystin. Additionally, we recovered a Dolichospermum lemmermannii 16S rRNA gene from the bloom and using datasets collected from the epilimnion and sediments in Lake Superior show this organism is ubiquitous and that several strains may exist. While there is much to learn about Lake Superior cyanobacterial bloom development and triggers, understanding this organism is endemic to the region, what its genome is capable of and that specific strains may have provenance within the lake provides a distinct ecological basis for understanding and working towards a predictive framework for future blooms.     

Analytical techniques for monitoring harmful cyanobacteria in lakes

The toxins of cyanobacteria include potent neurotoxins and hepatotoxins. Deaths after exposure by ingestion of cyanobacterial cells and toxins from freshwater sources have been reported. The hepatotoxins are cyclic peptides, which comprise microcystins (MC) and nodularin (NOD), and they cause poisonings with an established syndrome of human and animal illnesses. The identification and determination of these hepatotoxic peptides are challenges for analytical chemists. Methods based on solid phase extraction and size exclusion chromatography are available for the clean up of raw extracts. Both principles are also used for the enrichment of MC from low contaminated sample material. The separation of MC is achieved by high‐pressure liquid chromatography methods with ultraviolet (UV) detection or mass spectrometric detection. The unambiguous identification of MC not available as standards is possible by mass spectrometry (MS) or, under optimal conditions, by UV spectrometry using diode array detection. To date, 60 different MC and four NOD have been described, but new compounds are frequently identified. Therefore, powerful tools for the elucidation of the structure of unknown MC are an important need. In addition to classical methods for structure elucidation (e.g. nuclear magnetic resonance spectrometry), microwave‐assisted hydrolysis of cyclic peptides followed by enantio‐selective determination of the amino acid profiles can be used. More recently, MS with collision‐activated dissociation has become an important tool for obtaining structure information. The present paper discusses the advantages and disadvantages of the various analytical techniques used for monitoring of cyanobacteria in lakes, optimized or developed at the Institute of Nutrition, Jena, Germany. A pathway for handling MC‐containing samples with regard to different analytical tasks (i.e. the identification and elucidation of structure followed by qualitative and quantitative determination) is proposed.     

Technological and hygienic consequences of reservoirs eutrophication in the Czech Republic

More than one half of drinking water demand in the Czech Republic is covered by surface water resources. The most frequent problems of the water treatment and supply are caused by the eutrophication of reservoirs. Biological parameters of drinking water quality based upon the microscopic analysis are included in local standards and commonly used in water works laboratories. Several new methods and criteria have been elaborated: microscopic evaluation of the separation efficiency of water treatment, categorization of microorganisms according to their separability, a screening bioassay for the assessment of biological stability of the water in course of the treatment and distribution, biological indicators of the eutrophication degree of reservoirs and their tributaries. A set of supplementary biological methods and criteria for special cases was published. Algal toxins have been detected not only in cyanobacterial water blooms in reservoirs but also in periphyton layers growing m different units of water works treatment trains. Two examples of the integrated system approach to the water supply from eutrophicated reservoirs inclusive of proposed preventive and remedial measures are selected from a recently finished extensive research project. Improvement actions in the resources protection, water works design and operation, laboratory control system and legislation are recommended.     

蓝藻藻泥固结特性的试验研究

蓝藻藻泥的脱水减量处理已成为湖泊治理的一个新的问题,脱水的本质是藻泥的固结排水过程。因此通过藻泥的固结试验研究其固结特性,对于提高藻泥的脱水效率具有重要意义。通过对固结仪进行改进,对1种蓝藻藻泥和1种湖泊淤泥进行试验,研究藻泥的固结特性及区别。结果表明:藻泥的固结排水时间很长,孔压消散非常慢;藻泥的固结系数及渗透系数非常小,并随着固结压力的增加而减小的非常明显;通过分析认为藻泥中的生物质细胞体是造成固结时间长、水分排出缓慢的主要原因。     

Models for identifying significant environmental factors associated with cyanobacterial bloom occurrence and for predicting cyanobacterial blooms

Compared with microscopic indices such as biomass, inverted satellite images can reflect cyanobacterial blooms from a macroscopic perspective, can provide planar information for blooms, and can more definitely reflect the occurrence of visible cyanobacterial blooms. We therefore adopted inverted images (from MODIS imagery) to judge whether cyanobacterial blooms had occurred in a water area at a given time. We constructed two probit models for identifying significant environmental factors related to cyanobacterial bloom occurrence and for short-term forecasts of bloom occurrence. The models used the index of cyanobacterial bloom occurrence as the dependent variable and the predicted variable, respectively, and used three categories (water quality, hydrology, and weather) of monitoring variables as the independent variables (or predictive variables). We used the Hill Dagong water area of Lake Tai in China as a case study of the new methods. The results produced by the identification model are consistent with the general conclusions in this research field indicating the validity of the model. The mean relative error of the forecast model is 13.5%, which is close to or lower than that of two previous models. Compared with the previous models, our forecast model also has advantages in terms of spatial and temporal precision. The new models have both practical applicability and the ability to be generalized and can, therefore, be easily adapted for the prevention, control, and prediction of cyanobacterial blooms in other bodies of water.