好氧活性污泥胞外聚合物的影响因素研究

研究了4种活性污泥处理工艺和两种污泥培养基质对好氧活性污泥胞外聚合物(EPS)的影响,包括对EPS总量和组分的影响。EPS的提取总量以TOC来表示,并以DNA的浓度来衡量提取过程中细胞裂解的程度。结果发现,处理工艺不同,导致EPS的含量和组成不相同,主要体现在蛋白质和多糖含量比的不同;淀粉基质培养的污泥的EPS总量平均值比葡萄糖基质培养的污泥的EPS总量平均值略高一些,它们都比实际污水处理厂污泥的EPS含量高。     

Sorption of 1-naphthol by plant cuticular fractions

The contribution of aliphatic-rich plant biopolymer to sorption of hydrophobic organic compounds is significantly important because of their preservation and accumulation in the soil environment,but sorption mechanism is still not fully understood.In this study, sorption of 1-naphthol by plant cuticular fractions was examined to better understand the contributions of respective fraction.Toward this end,cuticular materials were isolated from the fruits of tomato by chemical method.The tomato cuticle sheet consisted of waxes (6.5 wt%),cuticular monomer (69.5 wt%),and polysaccharide (24.0 wt%).Isotherms of l-naphthol to the cuticular fractions were nonlinear (N value (0.82-0.90)) at the whole tested concentration ranges.The KodKow ratios for bulk cuticle (TC1),dewaxed cuticle (TC2),cutin (TC4),and desugared cuticle (TC5) were larger than unity,suggested that tomato bulk cuticle and cutin are much powerful solption medium.Sorption capability of cutin (TC4) was 2.4 times higher than the nonsaponifiable fraction (TC3).The 1-naphthol interactions with tomato cuticular materials were governed by both hydrophobic-type interactions and polar (H-bonding) interactions. Removal of the wax and polysaccharide materials from the bulk tomato cuticle caused a significant increase in the sorption ability of the cuticular material.There was a linear negative trend between K_(oc) values and the amount of polysaccharides or fraction's polarities ((N O)/C);while a linear positive relationship between K_(oc) values and the content of cutin monomer (linear R~2=0.993) was observed for present in the cuticular fractions.Predominant sorbent of the hydrophobic organic compounds (HOCs) in the plant cuticular fraction was the cutin monomer,contributing to 91.7% of the total sorption of tomato bulk cuticle.     

Electrosynthesis of κ-Carrageenan Complexes with Gelatin

Electrosynthesis at pH 9, 12, and 11 of -carrageenan–gelatin complexes from electrolytes containing the components at proportions varying from 1:5 to 5:1 provided complexes in the composition varying in a range from 1:10 to 1:1.8. Components were bound mainly electrostatically, although partial insolubility of complexes in 7 M aqueous urea pointed to a part of the complexes bound covalently. None of the performed tests except solubility could confirm formation of covalent complexes. The complexation of -carrageenan to gelatin significantly increased the thermal stability of carrageenan, whereas the thermal stability of gelatin increased rather insignificantly.     

好氧颗粒污泥胞外聚合物（EPS）的生化性研究

将人工培养的好氧颗粒污泥进行饥饿试验,研究EPS的可生化性.结果表明,好氧颗粒污泥EPS是由40%可生物降解EPS和60%不可生物降解EPS组成的,其中可生物降解EPS可作为颗粒污泥自身的能源,而不可生物降解EPS则不行,但其对颗粒污泥的立体结构有巨大作用.将从新鲜好氧颗粒污泥中提取的EPS投加到好氧颗粒污泥和活性污泥中,提取的EPS均可被两者作为碳源利用,且活性污泥对EPS的利用速率是好氧颗粒污泥的1.5倍;而从饥饿好氧颗粒中提取的EPS作为两者碳源时,均没有明显的利用效果,说明不可生物降解的EPS不能作为两者的能源.     

污泥EPS高值、高效提取与回收技术发展趋势

污泥有机质（特别是胞外聚合物,EPS）高值产品回收将会推动污水/污泥资源化.然而,EPS典型提取方法效率较低、回收产物成分复杂,限制了EPS目标物质的高效提取、降低了回收物的潜在高值应用.为此,探究高值、高效EPS提取/回收技术极为重要.这就需要改变目前典型的"笼统"EPS提取方法,将"胞外多糖"和"胞外蛋白"这样的模糊提取物（实为"有机物混合物"）转变为单目标物质（如类藻酸盐物质、酸溶性EPS、硫酸盐多糖、淀粉样蛋白质以及透明质酸等）或多目标物质（依靠物理、化学性质差异分离、提纯）,实现产物的定向提取并保证其纯度,从而使回收产物获得高值利用.另一方面,把握进水水质、营养物负荷以及运行环境对污泥EPS形成的影响亦十分重要;同时,需要鉴定易形成EPS的优势菌并掌握其生理、生化特征,这对通过污水处理运行而"原位"增加EPS污泥本底含量具有非常重要的意义.此外,还需要针对高值组分进一步发展优化提取方法（如添加表面活性剂等）,以实现回收物高效提取与高值回收利用.     

Synchronous removal of CuO nanoparticles and Cu2+ by polyaluminum chloride-Enteromorpha polysaccharides: Effect of Al species and pH

Copper oxide nanomaterials have been extensively applied and can have serious impacts when discharged into the aquatic environment, especially when complexed with humic acid (HA) to form composite contaminants. As an innovative recycled coagulant aid, Enteromorpha polysaccharides (Ep) were associated with polyaluminum chloride (PACl) (denoted as PACl-Ep) to simultaneously remove CuO nanoparticles, Cu²⁺ and HA in this study. The influence of different Al species coagulants (AlCl₃, PACl_b and PACl_c) and water pH on coagulation performance, floc properties and reaction mechanisms was investigated in detail. Results showed that in the three PACl-Ep systems, PACl_b-Ep gave the highest removal efficiencies for turbidity and Cu²⁺, and the best UV₂₅₄ removal effect was reached by using PACl_c-Ep. Higher contents of Al_b and Al_c contributed to great coagulation performance because of their stronger bridging and sweeping effects. For all the Al species coagulants, alkalescent conditions were more conducive to removing Cu and HA compared to acidic conditions. Additionally, smaller and more agminated flocs with great recovery ability were formed by PACl_b-Ep and PACl_c-Ep systems (bridging and enmeshment effects cooperated with the chelated reticular structure formed by the Ep and Al species). Similarly, due to the increased hydrolysis and hydroxide precipitates, flocs formed under the condition of alkalescence were smaller, denser and stronger compared with weakly acidic conditions.     

Chemical Valorization of Forest and Agricultural By-Products. Obtention,Chemical Characteristics,and Mechanical Behavior of a Novel Family of Hydrophobic Films

Abstract

Esterification of hemicelluloses of the xylan family was performed in order to produce hydrophobic films. Acylation reactions were carried out with lauroyl chloride in the N,N-dimethylacetamide/lithium chloride homogeneous system using 4-dimethylaminopyridine as activator and were induced by microwave irradiation. In the experimental conditions used, 108 and 172% mass ratios were obtained for the dodecyl-grafted xylan and heteroxylan, respectively. The degrees of substitution (DS) were 1.3 (maximum 2) for xylan and 1.2 (maximum 2.1) for heteroxylan. These products were further characterized by FT-IR spectroscopy. The mechanical and thermomechanical behavior of this new family of hydrophobic films were analyzed and compared to those obtained from cellulose with a similar DS by the means of tensile tests. Our results indicate that the dodecyl-grafted xylan film presents the best rigidity—resistance to traction ratio.     

Performance of sequential anaerobic/aerobic digestion applied to municipal sewage sludge

A promising alternative to conventional single phase processing, the use of sequential anaerobic-aerobic digestion, was extensively investigated on municipal sewage sludge from a full scale wastewater treatment plant. The objective of the work was to evaluate sequential digestion performance by testing the characteristics of the digested sludge in terms of volatile solids (VS), Chemical Oxygen Demand (COD) and nitrogen reduction, biogas production, dewaterability and the content of proteins and polysaccharides. VS removal efficiencies of 32% in the anaerobic phase and 17% in the aerobic one were obtained, and similar COD removal efficiencies (29% anaerobic and 21% aerobic) were also observed. The aerobic stage was also efficient in nitrogen removal providing a decrease of the nitrogen content in the supernatant attributable to nitrification and simultaneous denitrification. Moreover, in the aerobic phase an additional marked removal of proteins and polysaccharides produced in the anaerobic phase was achieved. The sludge dewaterability was evaluated by determining the Optimal Polymer Dose (OPD) and the Capillary Suction Time (CST) and a significant positive effect due to the aerobic stage was observed. Biogas production was close to the upper limit of the range of values reported in the literature in spite of the low anaerobic sludge retention time of 15 days. From a preliminary analysis it was found that the energy demand of the aerobic phase was significantly lower than the recovered energy in the anaerobic phase and the associated additional cost was negligible in comparison to the saving derived from the reduced amount of sludge to be disposed.     

Endogenous nitric oxide mediates alleviation of cadmium toxicity induced by calcium in rice seedlings

The effect of calcium chloride (CaCl₂) on rice seedling growth under cadmium chloride (CdCl₂) stress, as well as the possible role of endogenous nitric oxide (NO) in this process, was studied. The growth of rice seedlings was seriously inhibited by CdCl₂, and the inhibition was significantly mitigated by CaCl₂. However, hemoglobin (Hb) and 2-(4-carboxyphenyl)-4, 4,5,5-tetramethylimidazolinel- oxyl-3-oxide (cPTIO) weakened the promotion effect of CaCl₂. The results of NO fluorescence localization suggest that growth accelerated by CaCl₂ might be associated with elevated NO levels. The content of Cd, protein thiols (PBT), and nonprotein thiols (NPT) in cell walls, cell organelles, and soluble fractions, respectively, of rice seedlings decreased considerably in the presence of CaCl₂, whereas the content of pectin, hemicellulose 1 (HC1), and hemicellulose 2 (HC2) increased significantly. Elimination of endogenous NO in Cd+Ca treatment could promote the transportation of Cd²⁺ to cell organelles and soluble fractions and increase the content of NPT and PBT in leaves. In addition, transportation of Cd²⁺ to cell organelles and soluble fractions was retarded in roots, the content of NPT increased, and the content of PBT decreased. With elimination of endogenous NO in Cd+Ca treatment, the content of pectin, HC1, and HC2 decreased significantly. Thus, Ca may alleviate Cd toxicity via endogenous NO with variation in the levels of NPT, PBT, and matrix polysaccharides.     

胶网藻对水体中恩诺沙星的毒性响应及去除作用

恩诺沙星是医药及水产养殖业广泛使用的喹诺酮类抗生素,是我国地表水中残留量较多的抗生素种类之一;然而有关该抗生素对水体中浮游植物毒理作用以及后者对其去除作用的研究还鲜见报道.本研究以绿藻门的胶网藻(Dictyosphaerium sp.)为对象,通过12 d室内培养实验,分析在不同浓度(0、 5、 25、 50和100 mg·L^-1)恩诺沙星暴露的条件下,胶网藻的生长、光合作用活力和胞外多糖的响应变化及其对不同浓度恩诺沙星的去除效率.结果表明,各处理组中胶网藻的生物量和光合色素含量均随培养时间的增加而升高,但与对照组相比,恩诺沙星对胶网藻的生长和光合色素积累均产生显著抑制作用(P<0.01).通过拟合分析,计算出恩诺沙星对胶网藻96 h半数致死浓度(LC₅₀)为(241.29±7.33) mg·L^-1,表明胶网藻能够适应高浓度的恩诺沙星胁迫.同时发现,当恩诺沙星浓度<5 mg·L^-1时,能够促进胶网藻的最大光合速率(F_v/F_m),但浓度>5...