变功率微波法制备壳聚糖絮凝剂的研究

研究了变功率下微波加热对甲壳素脱乙酰化反应和粘度的影响。结果表明:在4 80W下反应4min、然后在16 0W下反应6min的最佳功率组合下,可制得脱乙酰度77.3%、粘度4 6mPa·s的壳聚糖产品;与恒功率微波法相比,变功率微波法制备壳聚糖的脱乙酰度稍低,但粘度高出31% ,反应时间缩短三分之一,能耗降低6 0 %     

微生物絮凝剂及其絮凝微生物的研究进展

介绍了近几年来国内外微生物絮凝剂和絮凝微生物的一些发展概况,列举了近几年发现的一些微生物絮凝剂的物质属性和组成,重点讨论了胞外絮凝剂和絮凝酵母的絮凝机理,详细综述了絮凝微生物的遗传学方面的研究进展,分析讨论微生物絮凝剂的应用概况,提出微生物絮凝剂的发展趋势和研究方向。     

微生物絮凝剂产生菌的筛选和发酵条件研究

设计了微生物絮凝剂产生菌菌种筛选模型,并从土壤和活性污泥中筛选到５１株絮凝剂产生菌,经复筛获得两株絮凝活性较高的菌株,分别定名为Ｎｏｃａｒｄｉａ,ＪＩＭ－８９和ＪＩＭ－１２７。对两株菌的发酵条件,特别是培养基组成,进行了初步研究。两株菌所产生的絮凝剂,对大肠杆菌悬液２０ｍｉｎ的絮凝活性在１０００ｕ／ｍｌ,最高可达１２４８ｕ／ｍｌ。     

微生物絮凝剂在养殖废水处理中的应用

微生物絮凝剂作为一种新型的絮凝剂,因其安全、高效等特性,正逐渐成为目前水产养殖废水处理研究的热点。主要从微生物絮凝剂的概念、絮凝机理、特点、研究现状、应用实例等方面,分析了微生物絮凝剂作为水质改良剂在水产养殖中的应用前景,并就今后的研究趋势作了展望。     

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.     

Global research trends on bioflocculant potentials in wastewater remediation from 1990 to 2019 using a bibliometric approach

The preference of biofloculants over chemical flocculants in water and wastewater remediation systems has gained wider attention due to their biodegradability, innocuousness, safety to human and environmental friendliness. The present study aimed to evaluate research outputs on bioflocculant potentials in wastewater remediation from 1990 to 2019 using bibliometric analyses. To the best of our knowledge, this is the first bibliometric report in bioflocculant research. The subject bibliometric dataset was extracted from the Web of Science Core Collection (WoSCC) and Scopus using the Boolean, ‘bioflocculant* and waste*’ and analysed for indicators such as a yearly trend, productivity (authors, articles, country, institution and journal source), conceptual framework and collaboration network. We found 119 documents with 347 authors from 78 journal sources on the subject, an annual growth rate of 12·1%, and average citations/document of 15·08. Guo J. and Wang Y. were the top researchers with 15 and 12 outputs respectively. China (42%) and South Africa (9·24%) ranked the top two dominant countries in the field. The top journals were Bioresource Technology (9 papers, 506 citations), Applied Microbiology and Biotechnology (5 papers, 268 citations), whereas, the top institution was Chengdu University of Information and Technology (n = 9 documents) followed by Sichuan Univ. Sci. & Engn, China (n = 8 documents). This study found that lack of intercountry collaboration and research funding adversely affects research participants in the field.     

高絮凝活性霉菌的筛选及其在制革废水中的应用

采用常规分离方法,以高岭土悬液絮凝能力为指标,从活性污泥中筛选霉菌,并对其基本特性和处理制革废水的可行性进行研究。结果获得2株絮凝活性高的霉菌,经初步鉴定为米曲霉(Aspergillus oryzae)和黑曲霉(Aspergillus niger)。对处理制革废水,色度、氨氮、化学需氧量(COD)和铬的去除都有明显效果,宜作为制革废水生物处理的絮凝剂。     

Optimization of flocculation conditions for kaolin suspension using the composite flocculant of MBFGA1 and PAC by response surface methodology

The response surface methodology (RSM) was employed to study the treatment of kaolin suspension by the composite flocculant of MBFGA1 and PAC. And the two quadratic models of the five factors were established with the flocculating rate and floc size as the target responses. The optimal flocculating conditions are MBFGA1 99.75 mg/L, PAC 121 mg/L, pH 7.3, CaCl₂ 27 mg/L and the top speed of stir 163 rpm, respectively. That was obtained from the compromised results of two desirable responses, flocculating rate as 100% and floc size as 0.7 mm which were deduced from the frequency of responses. By means of Zeta potential measurement and experiment of flocculating process, it could be concluded that PAC has more capability on changing the potential of colloid and MBFGA1 is good at absorption and bridge effect. The composite of two kinds of predominance makes a significant sense on enhancing flocculating rate, reducing flocculent costs and decreasing secondary pollution.     

Structural Analysis of an Extracellular Polysaccharide Bioflocculant of Klebsiella pneumoniae

The glycoside composition and sequence of an extracellular polysaccharide flocculant of Klebsiella pneumoniae H12 was analyzed. GC and HPLC analysis of the acid-hydrolysate identified its constituent monosaccharides as D-Glc, D-Man, D-Gal, and D-GlcA in an approximate molar ratio of 3.9:1.0:2.3:3.6. To analyze the glycoside sequence, the polysaccharide was partially hydrolyzed by acid and enzyme treatment. GC, HPLC, TLC, MALDI-TOF/MS, and 1H- and 13C- NMR spectroscopy characterized the obtained oligosaccharides.

The results clarified the partial structure of H12 polysaccharide as a linear polymer of a unit of pentasaccharide with a side chain of one D-GlcA to D-Glc moiety (see below). Although the existence of other sequences or other constituent glycosides could not be fully excluded, H12 polysaccharide must be a novel types as such a complicated unit for a polymer has not so far been reported. The partial structure of a H12 polysaccharide flocculant is also discussed in this report.

→4)- α-D-Glcp-(1→2)-α-D-Manp-(1→3)-4,6-Pyr-β-D- 3 Galp-(1→4)-β-D-Galp-(1→ ↓

1 β-D-GlcpA     

壳聚糖絮凝蛹虫草菌丝体多糖工艺优化及其失活动力学分析

利用响应面法对蛹虫草诱变菌株CSYB-2菌丝体多糖的制备工艺进行优化,结果显示在壳聚糖用量1.4mL/g、絮凝温度55℃、絮凝时间70min条件下,多糖保留率为(82.05±0.21)%。在壳聚糖絮凝诱变菌株CSYB-2菌丝体多糖浸提液的絮凝工艺基础上,通过构建壳聚糖失活动力学模型,探究絮凝剂（壳聚糖）在絮凝过程中的动力学规律和失活机理。结果表明壳聚糖的失活动力学符合一级反应的失活动力学方程,在考察溶液澄清率（絮凝率）在不同时间、温度下变化规律的基础上推算出失活速率常数、活化能等动力学函数值,为研究絮凝作用中絮凝剂失活的机理提供理论支持。