膜生物反应器技术在环境激素废水处理中的应用

本文主要介绍膜生物反应器技术在环境激素废水处理研究中的应用现状。     

环境治理中膜接触器的应用研究

膜接触器可以将膜分离与化工单元操作进行有效结合,是一种先进的高效分离器,可在不同接触的情况下实现相间传质,被广泛应用于废气治理、重金属选择吸收等环境治理中。对此,本文首先对膜接触器的分类原理及结构形式进行介绍,然后对不同膜接触器在环境治理中的应用原理进行分析,并以某废水治理项目为研究对象,对膜接触器在环境治理中的应用方式进行深入研究。     

Optimized determination of airborne tetracycline resistance genes in laboratory atmosphere

• Sampling parameters with high efficiency was determined. • Operational process to detect airborne ARGs was optimized. • Providing research basis to control airborne ARGs of a laboratory atmosphere Antibiotic resistance genes (ARGs) have been detected in various atmospheric environments. Airborne ARGs transmission presents the public health threat. However, it is very difficult to quantify airborne ARGs because of the limited availability of collectable airborne particulate matter and the low biological content of samples. In this study, an optimized protocol for collecting and detecting airborne ARGs was presented. Experimental results showed that recovery efficiency tended to increase initially and then declined over time, and a range of 550–780 copies/mm² of capture loading was recommended to ensure that the recovery efficiency is greater than 75%. As the cell walls were mechanically disrupted and nucleic acids were released, the buffer wash protects ARGs dissolution. Three ratios of buffer volume to membrane area in buffer wash were compared. The highest concentrations of airborne ARGs were detected with 1.4 µL/mm² buffer wash. Furthermore, the majority of the cells were disrupted by an ultrasonication pretreatment (5 min), allowing the efficiency ARGs detection of airborne samples. While, extending the ultrasonication can disrupt cell structures and gene sequence was broken down into fragments. Therefore, this study could provide a theoretical basis for the efficient filter collection of airborne ARGs in different environments. An optimized sampling method was proposed that the buffer wash was 1.4 µL/mm² and the ultrasonication duration was 5 min. The indoor airborne ARGs were examined in accordance with the improved protocol in two laboratories. The result demonstrated that airborne ARGs in an indoor laboratory atmosphere could pose the considerable health risk to inhabitants and we should pay attention to some complicated indoor air environment.     

Antimony toxicity in the lichen Xanthoria parietina (L.) Th. Fr.

In this paper we tested if treating the lichen Xanthoria parietina with Sb-containing solutions causes Sb bioaccumulation as well as physiological and ultrastructural changes. Total and intracellular antimony content in Sb-treated samples increased progressively with increasing concentration in the treatment solutions. Incubation of X. parietina thalli with Sb at concentrations as low as 0.1 mM caused a decrease in sample viability, measured as intensity of respiratory activity, and damage to cell membranes, expressed in terms of membrane lipid peroxidation, as well as ultrastructural changes such as plasmolysis, impairment of the thylakoid system of the alga and cytoplasmic lipid droplets. The photosynthetic system hardly responded, at least under the tested experimental conditions.     

Optimal descriptor as a translator of eclectic information into the prediction of membrane damage by means of various TiO2 nanoparticles

The increasing use of nanomaterials incorporated into consumer products leads to the need for developing approaches to establish “quantitative structure–activity relationships” (QSARs) for various nanomaterials. However, the molecular structure as rule is not available for nanomaterials at least in its classic meaning. An possible alternative of classic QSAR (based on the molecular structure) is the using of data on physicochemical features of TiO₂ nanoparticles. The damage to cellular membranes (units L⁻¹) by means of various TiO₂ nanoparticles is examined as the endpoint.     

Plant Uptake/Bioavailability of Heavy Metals from the Contaminated Soil after Treatment with Humus Soil and Hydroxyapatite

Cellulose nitrate membrane filter was used for the preconcentration-separation of Cu, Co, Cd, Pb and Cr ions. The analyte ions were collected on the membrane filter by the aid of carmine. Then membrane filter was dissolved by using nitric acid. The levels of the analytes in the final solutions were determined by flame atomic absorption spectrometry (FAAS). The analytical parameters including pH, amounts of carmine, sample volumes etc. have been optimized. No influences have been observed from the matrix ions. The detection limits for analytes were in the range of 0.08 μg/l-0.93 μg/l. The validation of the procedure was checked by the analysis of standard reference sediment (GBW 07309). The present method has been successfully applied for the FAAS determinations of analyte ions in real samples including black tea and magnesium salts.     

Separation and recovery of carbon dioxide by a membrane flash process

A novel process for carbon dioxide (CO₂) separation, which was named a membrane flash process, was developed to realize an energy-saving technology and to substitute it for a conventional regenerator. The electric energy for CO₂ recovery in a membrane flash process using aluminum oxide and diethanolamine was lower than the thermal energy of the conventional chemical absorption process. Flashing at elevated temperature by the low temperature energy significantly reduced the electric energy and required much less membrane area. This process has potentiality of low cost capture of CO₂ when the low temperature energy, which is not available for other purposes, can be utilized to elevate flashing temperature.     

分置式膜-生物反应器处理生活污水及其体积负荷的确定

分置式膜－生物反应器处理生活污水的运行结果表明,在不同的污泥龄和水力停留时间下,处理效果稳定,污泥上清液中ＣＯＤ浓度平均为１９．５ｍ ｇ／Ｌ,膜出水ＣＯＤ浓度平均为５．３ｍ ｇ／Ｌ． 对分置式－生物反应器的体积负荷进行推导表明,浓缩区的存在是该工艺处理能力较大的原因． 体积负荷由膜出水有机物浓度与污泥混合液有机物浓度之比α,浓缩区与反应器体积之比β和膜出水量与污泥混合液循环流量之比λ决定,即可以通过增加浓缩区体积和调整循环流量来控制分置式－生物反应器的处理能力．     

膜生物反应器次临界通量运行的膜污染特性研究

膜生物反应器（MBR）是将膜分离与生物反应相结合的污水处理新工艺,近年来已引起广泛的关注,但不可避免的膜污染限制其更广泛的应用。临界通量在膜污染控制中是个非常重要的概念。本试验研究平板膜生物反应器在次临界通量运行下的膜污染状况,并结合膜污染模型进一步表征膜表面的污染特性。试验结果表明。该平板膜生物反应器在次临界通量运行的情况下,膜污染可分为膜污染缓慢发展阶段（第Ⅰ阶段）和膜污染迅速发展阶段（第Ⅱ阶段）,可分别用膜孔堵塞模型和泥饼阻力模型表征膜阻力与时间的变化关系。同时,对运行后的膜阻力分布进行分析,表明泥饼阻力和孔道吸附堵塞阻力是膜污染的主要组成部分,分别占到总阻力的73％和24％,而膜本身阻力仅占3％。     

Insight into the distribution of metallic elements in membrane bioreactor: Influence of operational temperature and role of extracellular polymeric substances

The distribution of metallic elements in a submerged membrane bioreactor(MBR) was revealed at different temperatures using inductively coupled plasma-optical emission spectrometry(ICP-OES), and the role of extracellular polymeric substances(EPS) was probed by integrating scanning electron microscopy(SEM) with confocal laser scanning microscopy(CLSM) over long-term operation. More metallic elements in the influent were captured by suspended sludge and built up in the fouling layer at lower temperature. The concentration of metallic elements in the effluent was 5.60 mg/L at 10°C operational temperature, far lower than that in the influent(51.35 mg/L). The total contents of metallic elements in suspended sludge and the membrane fouling layer increased to 40.20 and 52.19 mg/g at 10°C compared to 35.14 and 32.45 mg/g at 30°C, and were dominated by the organically bound fraction. The EPS contents in suspended sludge and membrane fouling layer sharply increased to 37.88 and 101.51 mg/g at 10°C, compared to 16.87 and 30.03 mg/g at 30°C. The increase in EPS content at lower temperature was responsible for the deposition of more metallic ions. The strong bridging between EPS and metallic elements at lower temperature enhanced the compactness of the fouling layer and further decreased membrane flux. This was helpful for understanding the mechanism of membrane fouling at different operational temperatures and the role of EPS, and also of significance for the design of cleaning strategies for fouled membranes after long-term operation.