高效絮凝剂产生菌的筛选及培养条件

从活性污泥中分离出36株菌株,培养、筛选得到具有絮凝活性的菌株9株,其中有一株絮凝活性较高,命名为B-8,同时考察了培养时间、温度、pH和碳源对絮凝效果的影响。结果表明,培养时间72h,最佳温度为37℃,pH为7.0,葡萄糖为最佳碳源时,该微生物所产生的絮凝剂的絮凝效果最好,絮凝率可达95.75%。     

Removal and recovery of uranium(VI) by adsorption onto a lignocellulosic-based polymeric adsorbent containing amidoxime chelating functional group

A new adsorbent (ABS) with amidoxime functional group was prepared through graft polymerization of acrylonitrile onto banana stem (BS) using ceric ammonium nitrate (CAN)/HNO₃ initiator system, followed by treatment with hydroxylamine hydrochloride in alkaline solution. Infrared spectroscopy, surface area analyzer, thermogravimetry, and potentiometric titration were used for the characterization of the adsorbent. Effective removal of U(VI) ions was demonstrated at the pH range 4.0–6.0. The mechanism for the removal of U(VI) ions by ABS was based on complexation adsorption model. Equilibrium was achieved in approximately 3 h. The experimental kinetic data were analyzed using first-order, second-order, and Elovich kinetic models, and are well fitted with second-order kinetics. The temperature dependence indicates an exothermic process. U(VI) adsorption was found to decrease with increase of ionic strength. The Freundlich isotherm model fitted the experimental equilibrium data well. The adsorption efficiency was tested using synthetic nuclear industry effluents. The maximum adsorption capacity for U(VI) removal was found to be 80 mg g^-1 at 20°C. Adsorbed U(VI) ions were desorbed effectively, about 99% by 0.2 M HCl. Repeated adsorption/desorption cycles show the feasibility of the ABS for the removal of U(VI) ions from water and nuclear industry effluents.     

壳聚糖/膨润土复合絮凝剂处理染料废水的研究

利用壳聚糖/钠基膨润土复合絮凝剂对活性艳红X3B等11种染料模拟废水及实际印染废水进行絮凝脱色处理。考察了复合絮凝剂投加量、pH值、搅拌速率、搅拌时间等因素对模拟染料废水絮凝脱色的影响。结果表明,在染料浓度为100 mg.L-1,pH为5的条件下,复合絮凝剂投加量为1.25 g.L-1时,3种质量比的复合絮凝剂对活性艳红X3B的脱色率分别达到75%、90%和97%以上;质量比为1∶10的壳聚糖/钠基膨润土复合絮凝剂,对其它活性、还原性、分散性、水溶性等8种印染厂常用染料也具有很好的絮凝脱色作用,脱色率均可达94%以上。对印染废水处理厂进水口废水和经过A/O处理后废水的色度去除率和COD去除率分别可以达到81.05%、83.74%和53.21%、41.22%,具有一定的应用前景。     

全程自养脱氮技术处理高浓度含氮淀粉废水的工程实例

淀粉废水有机氮浓度较高,污水处理采用调节池-厌氧池-全程自养脱氮池-二沉池-混凝沉淀池处理工艺,在进水CODCr<10000mg/L,TN≤600mg/L情况下,处理后CODCr<100mg/L,NH3-N<10mg/L,完全达到预期处理效果。目前国内全程自养脱氮技术(处理超低C/N废水)大都停留在试验阶段,工程化的实例很少。     

Enzyme-Based Vinyl Polymerization

In vitro enzyme-mediated polymerization of vinyl monomers is reviewed. Oxidoreductase enzymes have been used for the polymerization of styrene, derivatives of styrene, acrylates, and acrylamide in water and water-miscible co-solvents. Kinetic and mechanistic studies revealed that a ternary system (horseradish peroxidase, H₂O₂, initiator, or -diketone) is required for efficient polymerization and the initiator controls the polymer characteristics.     

The Effect of Starch Composition on Structure of Foams Prepared by Microwave Treatment

A microwave technique was used to prepare foams from different potato starches in granular form, with varying amounts of amylose content, and water. In addition to native potato starch (PN), high amylose potato starch (HAP) and potato amylopectin (PAP) were used, as well as mixtures thereof. In all cases the native crystallinity of starch granules was lost upon microwave treatment and an amorphous material was created. An increased concentration of starch in the initial water dispersion resulted in a less dense foam structure. The potato amylopectin formed open cell foams, whereas increased amylose content, as in native potato starch, yielded a more compact structure with irregular pore shapes. The high amylose potato starch yielded a structure with hardly any porosity. Foaming experiments were done to compare pre-gelatinized and granular starches dispersed in water. The pre-gelatinisation did not affect the pore formation process. These experiments indicated that the molecular architecture of starch polymers is more important for foam formation than starch polymer organization in the granules. Studies of temperature profile and dry matter content during microwave treatment showed that water evaporates more rapidly from a high amylose starch solution than native potato starch and potato amylopectin solutions. Rheological measurements showed that the amylose solution had much lower viscosity than starch and amylopectin. This confirms that polymer – water interaction, such as in amylopectin solution, favours stabilization of bubbles formed upon boiling and evaporation of water, which yields high porosity materials.     

Accessibility of starch to enzymatic degradation in injection-molded starch-plastic composites

Most of the starch in starch-polyethylene-co-acrylic acid (EAA)-polyethylene (PE) composites prepared by injection molding was not accessible to starch-hydrolyzing enzymes. Even when these composites were treated with enzyme in the presence of Triton X-100 for 96 h, little starch hydrolysis was observed. However, when the starch-plastic material was pulverized, both the extent and the rate of starch hydrolysis increased dramatically, with about 70% hydrolysis of the starch within 18 h. Reactions carried out for up to 96 h showed that, while the enzyme was active, the reaction reached a plateau, achieving a total of 80% starch hydrolysis. Fourier transform infrared (FTIR) spectroscopy revealed that only starch, and not EAA or PE, was affected by enzyme in pulverized samples. Results indicated that while 80% of the starch in these composites was transiently inaccessible, perhaps due to EAA and PE forming an impermeable barrier to the enzyme, the other 20% remained inaccessible to enzymes. Also, the rate of starch digestion as determined by solubilized reducing sugar correlated with the particle size of the pulverized material, suggesting that a large available surface area is critical for rapid starch degradation in such composites.The mention of firms names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over the firms or similar products not mentioned. All programs and services of the U.S. Department of Agriculture are offered on a nondiscriminatory basis without regard to race, color, national origin, religion, sex, marital status, or handicap.     

一株海洋假单胞菌产生物絮凝剂去除赤潮生物的实验研究

利用一株假单胞菌(Pseudomonas sp.)的发酵液研究了该细菌产絮凝剂对东海原甲藻和裸甲藻的絮凝去除作用.结果表明,该生物絮凝剂可有效絮凝去除实验所选用两种赤潮生物,并且随絮凝剂用量的增加以及作用时间的延长,去除效果逐渐增加至最大然后基本保持恒定.有效絮凝去除赤潮生物的体积浓度为4.0%～10.0%.有效絮凝作用时间为1.5 h左右,絮凝效率与体系的pH值密切相关,pH在8.0左右絮凝效率较高.不同浓度的Ca2+、Mg2+对该絮凝剂絮凝除藻作用有一定的增效作用, Ca2+、Mg2+的最佳助凝离子浓度分别为2.0 mmol/L及4.0 mmol/L.     

MBFA9对蛋白核小球藻生长的影响研究

以蛋白核小球藻（Chlorella pyrenoidosa）实验生物,以生物量、叶绿素含量、可溶性蛋白含量及抗氧化酶活力的变化为指标,研究了不同浓度的高效微生物絮凝剂MBFA9对蛋白核小球藻的毒性效应,结果表明：低浓度短时间内MBFA9可以抑制蛋白核小球藻的生长,随着时间的延长,抑制作用减弱并最终消失;高浓度MBFA9最终可以轻微促进蛋白核小球藻生长,但SOD比活力和POD比活力稳定,表明未启动抗氧化酶系统和非酶抗性系统,对藻细胞不构成伤害。初步证明,絮凝剂MBFA9无急毒反应,是一种安全的、无毒的、对生态环境友好的微生物发酵制品。     

阳离子高分子絮凝剂的合成及其在油田的应用

利用ASP以及其他助剂组成的复合引发体系,研究了在50℃下采用水溶液自由基聚合方式,得到了溶解性能好的阳离子均聚物PDMDAAC。考察了pH值、引发剂用量和单体浓度对阳离子均聚物黏度和阳离子度的影响。研究了PDMDAAC作为絮凝荆在油田污水处理中的应用。