水处理絮凝剂研究与应用进展

水处理絮凝剂的发展经历了从最初的传统絮凝剂,到无机高分子絮凝剂,再到有机高分子絮凝剂;从简单的天然有机高分子絮凝剂,到合成的有机高分子絮凝剂,再到基于生态安全性的天然改性有机高分子絮凝剂;从单纯的无机或有机高分子絮凝剂,到有机 无机复合絮凝剂;从化学絮凝剂,再到具有生态安全性能的生物絮凝剂.为了促进水处理絮凝剂的迅速发展和实际应用,本文综述了水处理絮凝剂在国内外的研究进展与应用现状,重点对化学和微生物两大类絮凝剂分别阐述了其特点以及在水处理中的应用情况,并对其发展方向进行了分析和评价;尤其是针对目前我国絮凝剂研究与开发应用中的不足,对今后的研究工作提出了一些建议和设想.     

水华微囊藻混凝沉降去除过程中铝盐回收及循环使用

以水华微囊藻(Microcystis flos-aquae)为研究对象,对用聚合氯化铝和阳离子聚丙烯酰胺收获后的生物质进行酸洗处理回收铝盐并进行多次循环使用,以降低混凝沉降工艺中吨水处理成本.研究结果表明,总铝盐回收效率随酸洗次数增加而增大随后达到最大,而在较高的盐酸浓度或较高的液-固比条件下可最快达到较高的铝盐回收效...     

微生物絮凝剂及其产生菌的研究新进展

介绍了近几年来国内外微生物絮凝剂及其产生菌的一些发展概况,列举了近几年一些研究较深入的胞外生物高聚物絮凝剂的物质属性和化学组成.重点讨论了胞外生物高聚物絮凝剂的成分分析、絮凝机理以及影响絮凝活性的因素,详细综述了絮凝剂产生菌的遗传学和代谢机理方面的研究进展,文章最后提出微生物絮凝剂的发展趋势和研究方向.     

生物絮凝剂的最新研究进展及其应用*

从絮凝剂的来源和分子组成两方面对生物絮凝剂进行了系统分类,综述了生物絮凝剂产生菌的筛选模型以及生物絮凝剂在水处理和发酵工业中的应用,详细阐述了目前国内外提出的几种不同的生物絮凝剂絮凝机理,进而在此基础上剖析了目前生物絮凝剂研究工作中仍然存在的问题,并提出生物絮凝剂今后的主要研究方向。     

中性环境中铝盐絮凝剂对典型作物的生态毒性效应

采用种子发芽和根伸长抑制的陆生生态毒理方法,在中性条件(pH=7.0)下对铝盐絮凝剂(AlCl₃)的生态毒性效应进行了研究.结果表明,AlCl₃溶液在pH=7.0时,与其酸性条件(pH=4.0)相比对萝卜、白菜和小麦等受试作物种子发芽和根伸长均表现出抑制作用,且发芽抑制率和根伸长抑制率与铝浓度均呈极显著相关(P＜0.01).尽管在酸性条件下AlCl₃对白菜和小麦根伸长抑制效应比相同浓度中性条件更为强烈,但对萝卜根伸长的抑制程度在相同铝浓度条件下则是pH=7.0时明显大于pH=4.0时,在低浓度时萝卜发芽抑制率也是中性条件明显高于酸性条件.同时,铝盐在中性条件下对萝卜、白菜的发芽和根伸长产生明显抑制效应的起始浓度低于酸性条件(＜2.0 mg·L^-1).     

新合成复合絮凝剂HECES絮凝性能研究

以元机铝盐和天然高分子玉米淀粉为原料,合成一种生态安全型复合高效絮凝剂HECES．结果表明,在一定范围里适当提高淀粉／铝盐比例,有利于HECES絮凝性能的提高;处理模拟废水时,3．0mg·L^-1的HECES相当于4．5mg·L^-2PAC和1．0mg·L^-1PAM复合投加效果;对生活污水、市政污水的最佳投加量分别为8．0mg·L^-1和4．0mg·L^-1,相当于PAC用量的50％和40％,浊度去除率高达95％和99％．研究还证实絮凝效果与模拟浊度废水的浓度、供试污水的组成成分有关,HECES对高浓度废水处理效果更佳．HECES在PH＝4．0-9.5范围内絮凝效果最佳。其生态安全特点体现在投加量少,具有较大生态毒性的游离态铝离子残留量低。     

生物絮凝剂的最新研究进展及其应用

从絮凝剂的来源和分子组成两方面对生物絮凝剂进行了系统分类,综述了生物絮凝剂产生菌的筛选模型以及生物絮凝剂在水处理和发酵工业中的应用,详细阐述了目前国内外提出的几种不同的生物絮凝剂絮凝机理,进而在此基础上剖析了目前生物絮凝剂研究工作中仍然存在的问题,并提出生物絮凝剂今后的主要研究方向。     

西湖引水工程絮凝剂余铝对菹草生长及水质的影响

为分析杭州西湖引水工程絮凝剂残余铝盐对水质和沉水植物的影响,研究采用室外模拟试验,考察了连续投加不同浓度梯度的明矾(KAlSO412H2O)絮凝剂对菹草(Potamogeton crispus)的生理影响和对水质的影响。试验设置了4个处理: 对照组、低剂量组(35050) g/L、中剂量组(65070) g/L、高剂量组(1100150) g/L。结果表明: (1)低、中剂量投加对水中铝盐含量无显著影响,高剂量投加导致水中铝盐含量显著上升; (2)水中铝盐含量呈先升高后降低的趋势,pH随铝盐含量升高而降低,总磷(TP)随之有所下降,各处理组水中总氮(TN)、浮游植物密度、浊度均明显下降; (3)3个剂量组菹草各生化指标较对照组几乎无显著变化,试验浓度的铝盐投加对菹草的生长没有造成明显损害,在菹草耐受范围内,建议在西湖引水工程入水口附近[水中铝盐含量约(25050) g/L]可选用菹草进行植被恢复。     

绿色化学理念在高中化学实验教学中渗入思考

众所周知,化学实验中,经常会产生一些对环境极其有害的物质,"绿色化学",在化学学习和应用中坚持人与自然和谐平等的原则,提出新的化学发展理念和发展方法,有利于提高化学研究,并减少对环境的危害,本文拟从绿色化学理念在高中化学实验教学中的应用和开展结果分析,探索绿色化学理念的重要性。     

黄孢原毛平革菌产絮凝剂营养条件优化

微生物絮凝剂与传统化学絮凝剂相比,安全无毒、无二次污染,具有开发潜力.黄孢原毛平革菌(Phanerochaete chrysosporium)能产生微生物絮凝剂,但目前缺少对其产絮凝剂营养条件的优化.使用高岭土并利用单因素法研究碳源、氮源、碳氮比、接种量对Phanerochaete chrysosporium产絮凝剂的...     

Interaction of lactic acid bacteria with metal ions: opportunities for improving food safety and quality

Certain species of lactic acid bacteria (LAB), as well as other microorganisms, can bind metal ions to their cells surface or transport and store them inside the cell. Due to this fact, over the past few years interactions of metal ions with LAB have been intensively investigated in order to develop the usage of these bacteria in new biotechnology processes in addition to their health and probiotic aspects. Preliminary studies in model aqueous solutions yielded LAB with high absorption potential for toxic and essential metal ions, which can be used for improving food safety and quality. This paper provides an overview of results obtained by LAB application in toxic metal ions removing from drinking water, food and human body, as well as production of functional foods and nutraceutics. The biosorption abilities of LAB towards metal ions are emphasized. The binding mechanisms, as well as the parameters influencing the passive and active uptake are analyzed.     

Recovery of poly(3-hydroxybutyrate) from coagulated Ralstonia eutropha using a chemical digestion method

For economic recovery of poly(3-hydroxybutyrate) (PHB) from culture broths of Ralstonia eutropha containing PHB, Al-based and Fe-based coagulants were used in the pretreatment step. The coagulated cells were then separated by centrifugation, and PHB was extracted by chemical digestion with a sodium hypochlorite/chloroform dispersion solution. The practical upper limits of dosage were found to be 1, 500 mg-Al/L and 1,000 mg-Fe/L, respectively, for Al- and Fe-based coagulants. When the harvested cells were treated with a 50% sodium hypochlorite/chloroform dispersion solution, PHB recovery and purity were 90-94% and 98-99%, respectively. The influence of the use of coagulants on the PHB recovery process was found to be insignificant. Despite the residual Al and Fe in the recovered PHB (less than 450 mg-Al/kg-PHB and 750 mg-Fe/kg-PHB, respectively), no detectable amounts of Al and Fe were leached from films made of the recovered PHB under acidic conditions. The use of Fe-based coagulants is less recommended because the Fe impurity can cause an unwanted colorization problem in the final product.     

微生物絮凝剂水处理的影响因素及其工艺研究进展

本文对近年来微生物絮凝剂的发展进行了概述,在介绍微生物絮凝剂化学性质的基础上,讨论了与絮凝活性相关的絮凝剂投加量、投加顺序,待处理水体性质和水力条件等因素。重点论述了单一微生物絮凝剂水处理工艺、微生物絮凝剂和助凝剂复配水处理工艺、复合微生物絮凝剂水处理工艺和物理、化学方法和微生物絮凝剂联合水处理工艺。讨论发现结合现有研究成果,开发新的微生物絮凝剂水处理工艺具有重要的工业应用价值。     

Separation of Alcaligenes eutrophus cells containing Poly(3-hydroxybutyrate) from fermentation broth with pretreatment using Al- and Fe-based coagulants

Alcaligenes eutrophus containing intracellular poly(3-hydroxybutyrate) was recovered from fermentation broth by centrifugation and filtration after pretreatment with Al- and Fe-based coagulants. Coagulation efficiency was largely affected by pH, and the optimum pH's for cell recovery were about 4.6-5.6 for the Al-based coagulants and about 5-8 for the Fe-based coagulants. Ammonium ions that combined with metals to form complex compounds increased the coagulant requirement, and the additional requirement of coagulant was found to be proportional to the ammonium concentration. In addition, various ligands in addition to ammonium ions contained in the culture medium interfered with the coagulation reaction and increased the coagulant requirement also. The coagulant requirement increased with the cell concentration regardless of coagulant type. The polymeric coagulants such as PACS, Hi-PAX, and Ferix-3 were more effective than nonpolymeric coagulants of aluminum sulfate and ferrous sulfate. The optimum dosages of the coagulants tested were determined over a broad range of cell concentration of 20.5-210 g/L. It was observed that the energy requirement for centrifugation could be greatly reduced with cell coagulation.     

Non-toxic nanoparticles from phytochemicals: preparation and biomedical application

Nanoparticles (NPs) have various applications in biomedicine and drug delivery carriers and also are widely used in cosmetics. However, the preparation of biocompatible and non-toxic nanomaterials is a very important issue as most of the starting materials are synthesized using toxic chemical reagents. This review introduces the preparation of biocompatible NPs in a range of their concentrations using phytochemicals for biomedicine and biotechnology. Phytochemicals are natural products that are extracted from plants, vegetables, and fruits. Phytochemicals serve as reducing agents and stabilizers during NP synthesis to convert metal ions to metal NPs in water. Possible applications of such nanomaterials in biomedical sciences are also described in this review.     

综述与专论: 河鲀毒素的检测技术与应用

河鲀毒素（tetrodotoxin， TTX）是毒性极强的小分子生物碱类毒素，包括中国在内的亚洲沿海国家因误食TTX污染食品而中毒的事件时有发生，其发病迅速且无特效解毒剂，对环境安全、食品安全与社会安全造成极大的威胁。通过检测食品与环境中的TTX含量可以实现TTX的风险预警，可有效防范TTX中毒事件的发生。本文梳理了4类TTX的检测技术，分析比较了传统的生物检测法、化学检测法、免疫检测法之间的优势、不足与实际应用进展，介绍了基于适配体技术的新型检测技术的兴起、发展与广阔的应用前景，对生物安全领域中TTX风险的管理与控制有现实意义。     

Application of whole cell rhodococcal biocatalysts in acrylic polymer manufacture

Rhodococci are ubiquitous in nature and their ability to metabolise a wide range of chemicals, many of which are toxic, has given rise to an increasing number of studies into their diverse use as biocatalysts. Indeed rhodococci have been shown to be especially good at degrading aromatic and aliphatic nitriles and amides and thus they are very useful for waste clean up where these toxic chemicals are present.The use of biocatalysts in the chemical industry has in the main been for the manufacture of high-value fine chemicals, such as pharmaceutical intermediates, though investigations into the use of nitrile hydratase, amidase and nitrilase to convert acrylonitrile into the higher value products acrylamide and acrylic acid have been carried out for a number of years. Acrylamide and acrylic acid are manufactured by chemical processes in vast tonnages annually and they are used to produce polymers for applications such as superabsorbents, dispersants and flocculants. Rhodococci are chosen for use as biocatalysts on an industrial scale for the production of acrylamide and acrylic acid due to their ease of growth to high biomass yields, high specific enzyme activities obtainable, their EFB class 1 status and robustness of the whole cells within chemical reaction systems.Several isolates belonging to the genus Rhodococcus have been shown in our studies to be among the best candidates for acrylic acid preparation from acrylonitrile due to their stability and tolerance to high concentrations of this reactive and disruptive substrate. A critical part of the selection procedure for the best candidates during the screening programme was high purity product with very low residual substrate concentrations, even in the presence of high product concentrations. Additionally the nitrile and amide substrate scavenging ability which enables rhodococci to survive very successfully in the environment leads to the formation of biocatalysts which are suitable for the removal of low concentrations of acrylonitrile and acrylamide in waste streams and for the removal of impurities in manufacturing processes.     

Recent advances in polysaccharide bio-based flocculants

Natural polysaccharides, derived from biomass feedstocks, marine resources, and microorganisms, have been attracting considerable attention as benign and environmentally friendly substitutes for synthetic polymeric products. Besides many other applications, these biopolymers are rapidly emerging as viable alternatives to harmful synthetic flocculating agents for the removal of contaminants from water and wastewater. In recent years, a great deal of effort has been devoted to improve the production and performance of polysaccharide bio-based flocculants. In this review, current trends in preparation and chemical modification of polysaccharide bio-based flocculants and their flocculation performance are discussed. Aspects including mechanisms of flocculation, biosynthesis, classification, purification and characterization, chemical modification, the effect of physicochemical factors on flocculating activity, and recent applications of polysaccharide bio-based flocculants are summarized and presented.     

微藻源生物刺激剂的制备及在设施农业中的应用

化肥和农药的过量使用导致的农业面源污染已经成为我国环境污染的重要组成部分,对农业绿色高效安全生产及设施农业带来了巨大挑战。寻找新型的传统化肥替代品、提高化肥使用效率及保护生态环境是亟待解决的重大问题。生物刺激剂是具有调控植物生长作用的成分和(或)微生物的统称,用于农业生产,可改善土壤理化性质与群落微生物,能促进作物的代谢与生长,增强对营养物质的吸收和利用,提升作物抗逆能力及提高作物产量与产品品质。微藻体内具有结构新颖、功能独特的天然活性物质,是制备新型生物刺激剂的理想来源。微藻用于环境治理的同时,可获得足量的微藻生物质来制备生物刺激剂,从而达到治理环境、降低成本及提质增效的目的。就微藻源生物刺激剂的定义及功能、微藻全细胞和天然活性物质生物刺激剂的制备、应用效果及对植物和土壤的作用原理进行综述,以期为微藻源强效生物刺激剂的规模化制备及农业生产应用奠定理论基础和提供生产实践指导。