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Lu Ao Wenjun Liu Yang Qiao Cuiping Li Xiaomao Wang 《Frontiers of Environmental Science & Engineering》2018,12(6):9
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Coagulation of colloidal material in surface waters: the role of natural organic matter 总被引:1,自引:0,他引:1
Organic matter has a great influence over the fate of inorganic colloids in surface waters. The chemical nature and structure of natural organic matter (NOM) will be an important factor in determining whether colloids will be stabilised or destabilised by NOM. Under environmentally relevant conditions, the ubiquitous fulvic acids are likely to be responsible for coating and imparting a negative charge to colloids. If the adsorbed polyelectrolyte coating produces an increase in absolute surface potential, it will act to stabilise colloids in the water column. On the other hand, colloidal organic carbon, especially chain-like structures, has been shown to be involved in the aggregation of inorganic colloids through the formation of bridges. It is highly probable that both adsorption and bridging flocculation are occurring simultaneously in the natural aquatic environment. The importance of each process depends directly on the nature and concentration of organic matter in the system and indirectly on the productivity of the lake, its hydrological pathways, temporal variations, temperature, etc. The present paper reports such results and emphasises the need to discriminate the different kinds of NOM. 相似文献
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The combined fouling during ultrafiltration(UF) of surface water pretreated to different extents was investigated to disclose the roles of polysaccharides, proteins, and inorganic particles in UF membrane fouling. Both reversible and irreversible fouling decreased with enhanced pretreatment(biologically active carbon(BAC) treatment and sand filtration). The sand filter effluent fouled the membrane very slowly. The UF membrane removed turbidity to less than 0.1 nephelometric turbidity unit(NTU), reduced polysaccharides by 25.4%–29.9%, but rejected few proteins. Both polysaccharides and inorganic particles were detected on the fouled membranes, but inorganic particles could be effectively removed by backwashing. The increase of turbidity in the sand filter effluent to 3.05 NTU did not significantly increase the fouling rate, but an increase in the turbidity in the BAC effluent to6.11 NTU increased the fouling rate by more than 100%. The results demonstrated that the polysaccharide, not the protein, constituents of biopolymers were responsible for membrane fouling. Membrane fouling was closely associated with a small fraction of polysaccharides in the feed water. Inorganic particles exacerbated membrane fouling only when the concentration of fouling–inducing polysaccharides in the feed water was relatively high. The combined fouling was largely reversible, and polysaccharides were the predominant substances responsible for irreversible fouling. 相似文献
4.
Apart from conventional uses of polysaccharide materials, such as food, clothing, paper packaging and construction, new polysaccharide
products and materials have been developed. This paper reviews life cycle assessment (LCA) studies in order to gain insight
of the environmental profiles of polysaccharide products (e.g. viscose or natural fibre polymer composites) in comparison
with their conventional counterparts (e.g. cotton or petrochemical polymers). The application areas covered are textiles,
engineering materials and packing. It is found that for each stage of the life cycle (production, use phase and waste management)
polysaccharide-based end products show better environmental profiles than their conventional counterparts in terms of non-renewable
energy use (NREU) and greenhouse gas (GHG) emissions. Cotton is an exception, with high environmental impacts that are related
to the use of fertilisers, herbicides, pesticides and high water consumption. The available literature for man-made cellulose
fibres shows that they allow to reduce NREU and GHG emissions in the fibre production phase. No study has been found for the
fabric production and the use phase of man-made cellulose textiles.
相似文献
Martin K. PatelEmail: |
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黄精多糖对果蝇寿命的影响 总被引:30,自引:1,他引:30
水提法从黄精属的一种(Pdygonatum sp.)分离得到一种含糖为96.25%的黄精多糖(Polygonatum polysaccharide,简称PP)。PP经UV-240紫外分光光度计扫描,其特征吸收率为200nm,无蛋白质(280nm)和核酸(260mn)的特征吸收峰。浓度分别为0.05%、0.5%、2%的PP哺养果蝇(60d)的实验结果表明:三种浓度组两性果蝇的平均寿命和最高寿命均明显 相似文献
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Naoko Takada-Oikawa Norihisa Katoh Toshio Oshida Sukeo Kawanabe Toshikazu Kaise 《Journal of Material Cycles and Waste Management》2000,2(2):138-142
A potting experiment was carried out to determine the effects of soil amendments containing polysaccharides and earthworms
on a land application system for the purification of animal waste water. The following soil amendments were used: purified
Konjak powder (KP, powder containing glucomannan made from the root system of devil's tongue, Amorphophalus rivieri Dur.), crystallized cellulose (CC), and a mixture of the two (MX). These soil amendments were added to the pots, and then
Chrysanthemum corondria were planted in the earthworm pots (A pots), the nonearthworm pots (B pots), and the control pots (C pots); the first two
plots received primary-treated animal waste water, and the other one received tap water. The following items were then measured:
pH, electrical conductivity, chemical oxygen demand (CODMn), total nitrogen (TN), total phosphorus, the volume of drained water from each pots, the height and dry matter weight of
plants, and the water permeability into the soil. The MX-A pots, i.e., the pots containing both soil amendments and earthworms,
gave good results, especially for water permeability, plant growth, the purification of CODMn, and TN. These results suggest that the presence of soil amendments and earthworms may enhance the improvement of water quality
in land application systems using vegetation.
Received: December 9, 1998 / Accepted: February 8, 2000 相似文献
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黄精多糖对老龄大鼠衰老生理生化指标的影响 总被引:28,自引:1,他引:28
以水提法从黄精(Polygonatumsp)中得到的粗多糖成分(PP)进行了老龄大鼠的衰老生理生化指标测定试验.两种剂量的PP灌喂老龄大鼠1mo后,测定其12项衰老生理生化指标:胸腺指数和脾脏指数,外周血淋巴细胞ANAE活性,红细胞、视网膜、晶体核、晶体皮质的SOD活性,心脏、血浆中过氧化脂质含量,肝脏、肾脏中脂褐质含量及脑中B型单胺氧化酶活性.结果表明:除胸腺指数、血浆中过氧化脂质含量无显著性变化外,其他10项指标均有明显的改善作用;试验结果经统计学处理有显著性差异. 相似文献
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Shan Chen Jiayuan Li Wenbo Feng Mingzhe Yuan Wei Zhang Houtao Xu Xiaoyan Zheng Liqing Wang 《环境科学学报(英文版)》2020,32(11):141-148
Sulfonamides (SAs) are common antimicrobial drugs, which are frequently detected in surface water systems, and are difficult to degrade, posing a potential threat to the aquatic environment. However, little is known about the potential adverse effects of SAs on non-target organisms (e.g., microalgae) in the aquatic ecosystem. In this study, the effect of SAs (sulfadiazine (SD), sulfamerazine (SM1), and sulfamethazine (SM2) at 1, 5, 20, and 50 mg/L concentrations, respectively) on the freshwater microalga Dictyosphaerium sp. was investigated, with respect to changes of biomass and chlorophyll a content and induction of extracellular polymer substances (EPS), including protein and polysaccharide contents. At the same time, the residue of SAs was determined. The results showed that Dictyosphaerium sp. was tolerant to the three SAs, and the chlorophyll a content in Dictyosphaerium sp. significantly decreased on day 7, followed by a “compensation phenomena”. The increase in protein and polysaccharide contents played a defensive role in Dictyosphaerium sp. against antibiotic stress, and there was a strong positive correlation between polysaccharide contents and antibiotic concentrations. Dictyosphaerium sp. exhibited 35%–45%, 30%–42%, and 26%–51% removal of SD, SM1, and SM2, respectively. This study is helpful to understand the changes of EPS in the defense process of microalgae under the action of antibiotics, and provides a new insight for the ecological removal of antibiotic pollution in natural surface water system. 相似文献
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