Advanced treatment of municipal wastewater by nanofiltration： Operational optimization and membrane fouling analysis

Municipal sewage from an oxidation ditch was treated for reuse by nanofiltration（NF） in this study. The NF performance was optimized, and its fouling characteristics after different operational durations（i.e., 48 and 169 hr） were analyzed to investigate the applicability of nanofiltration for water reuse. The optimum performance was achieved when transmembrane pressure = 12 bar, p H = 4 and flow rate = 8 L/min using a GE membrane. The permeate water quality could satisfy the requirements of water reclamation for different uses and local standards for water reuse in Beijing. Flux decline in the fouling experiments could be divided into a rapid flux decline and a quasi-steady state. The boundary flux theory was used to predict the evolution of permeate flux. The expected operational duration based on the 169-hr experiment was 392.6 hr which is 175% longer than that of the 48-hr one. High molecular weight（MW） protein-like substances were suggested to be the dominant foulants after an extended period based on the MW distribution and the fluorescence characteristics. The analyses of infrared spectra and extracellular polymeric substances revealed that the roles of both humic- and polysaccharide-like substances were diminished, while that of protein-like substances were strengthened in the contribution of membrane fouling with time prolonged. Inorganic salts were found to have marginally influence on membrane fouling. Additionally, alkali washing was more efficient at removing organic foulants in the long term, and a combination of water flushing and alkali washing was appropriate for NF fouling control in municipal sewage treatment.

Analysis of clinical features and prognosis of anti-glomerular basement membrane antibody positive patients with anti-neutrophil cytoplasmic antibodies

Objective To investigate the characteristics and outcome of glomerulonephritis in patients with both antineutrophil cytoplasmic antibody and anti-glomerular basement membrane antibody.Methods The sera of 23 antiGBM glomerulonephritis patients were collected and were tested for ANCA respectively.Characteristics and outcome of patients with coexisting anti-GBM antibody

Potentiometric determination of mefenamic acid in pharmaceutical formulation by membrane sensor based on ion-pair with basic dye

The characteristics, performance and application of membrane sensors based on ion-pair Brilliant Green mefenamate are described. The sensor＇s response to the mefenamate ion has the sensitivity of （86.0 ± 2.0） mV/pC over the range of 9 × 10 s-I × 10 2 mol/L and the detection limit of 4.5 ×10 s mol/L at pH 8.5-12. The sensor is easily assembled at a relatively low cost and has fast response time （5-10 s）. The proposed sensor displayed good selectivity for mefenamate ion in the presence of different substances. It was used to determine mefenamic acid in pharmaceuticals.

Identifying the major fluorescent components responsible for ultrafiltration membrane fouling in different water sources

Three-dimensional fluorescence excitation–emission matrix（EEM） coupled with parallel factor analysis（PARAFAC） was performed for a total of 18 water samples taken from three water sources（two lakes and one wastewater treatment plant（WWTP） secondary effluent）,with the purpose of identifying the major ultrafiltration（UF） membrane foulants in different water sources. Three fluorescent components（C1, C2 and C3） were identified,which represented terrestrially derived humic-like substances（C1）, microbially derived humic-like substances（C2）, and protein-like substances（C3）. The correlations between the different fluorescent components and UF membrane fouling were analyzed. It was shown that for the WWTP secondary effluent, all three components（C1, C2 and C3） made a considerable contribution to the irreversible and total fouling of the UF membrane.However, for the two lakes, only the C3 exhibited a strong correlation with membrane fouling, indicating that the protein-like substances were the major membrane foulants in the lake waters. Significant attachment of C1, C2 and C3 to the UF membrane was also confirmed by mass balance analyses for the WWTP secondary effluent; while the attachment of C1 and C2 was shown to be negligible for the two lakes. The results may provide basic formation for developing suitable fouling control strategies for sustainable UF processes.

Mixed Matrix Membranes of Polysulfone/Polyimide Reinforced with Modified Zeolite Based Filler: Preparation, Properties and Application

In this work, polysulfone/polyimide（PSf/PI） mixed matrix membranes were fabricated by reinforcement of modified zeolite（MZ） particles through solution casting method for investigation of antibacterial activity against two gram negative bacteria（Salmonella typhi, Klebsella pneumonia） and two gram positive bacteria（Staphylococcus aureus, Bacillus subtilis）. The modified zeolite particles were incorporated to PSf and PI matrix and the influence of these particles on thermal, mechanical and structural properties was evaluated. The morphological evolution was investigated through scanning electron microscopy（SEM） and transmission electron microscopy（TEM） analysis, which revealed good compatibility between organic polymer matrix and inorganic filler. Mechanical stability was investigated by tensile testing while thermal analysis was evaluated by thermogravimetric analysis（TGA） and differential scanning calorimetry（DSC）. This revealed improvement in thermal properties with increasing filler concentration from 1 wt% to 10 wt%. Structural analysis was successfully done using X-ray diffraction analysis（XRD） and Fourier transform infrared（FTIR） spectroscopy. Solvent content of fabricated mixed matrix membranes was observed to decrease while moving from more hydrophilic to less hydrophilic solvent. However, addition of filler content enhanced the porosity of fabricated membranes. The synthesized mixed matrix membranes exhibited good antibacterial activity and the highest activity was shown by PSf/PI/MZ mixed matrix membrane. Therefore, the combination effect of PSf, PI and MZ sufficiently enhanced the antibacterial activity of mixed matrix membranes.

Molecular characteristics of the omp A gene of serotype B Chlamydia trachomatis in Qinghai Tibetan primary school students

To study the molecular characteristics of Chlamydia trachomatis, the major outer membrane protein gene(omp A) of C. trachomatis from primary school students with trachoma residing in the Qinghai Tibetan area was sequenced and compared with the same serotype in Gen Bank. In Jianshetang Primary School and Galeng Central Primary School in the Galeng Tibetan Township of Qinghai Haidong Sala Autonomous County, scraped samples were collected from the upper tarsal conjunctiva and lower conjunctival sac of both eyes of 45 students with trachoma, stored at 4°C, and transported to Beijing Tongren Hospital by air within 24 h. The samples were screened for C. trachomatis by real-time PCR. The omp A gene from the C. trachomatis-positive samples was amplified by nested PCR. The serotype was confirmed by National Center for Biotechnology Information(NCBI) BLAST search and homology analysis. The entire omp A gene sequence was compared with the corresponding gene sequences of serotype B strains available in Gen Bank. Of the 45 students aged 6–13 years with trachoma, 26 C. trachomatis-positive students were identified by the initial real-time PCR screening(average age,(9.09±1.63) years; sex ratio, 1.0), accounting for 57.78%(26/45). The cycle threshold values for real-time PCR were 16.79–37.77. Half(13/26) of C. trachomatis-positive students had a bacterial copy number of >105. The compliance rate of the omp A gene sequences with the C. trachomatis serotype B strains in Gen Bank was up to 99%. Two novel genetic mutations were found when the omp A gene was compared with those of the 11 serotype B strains in Gen Bank. The two non-synonymous mutations were located at(i) position 271 in the second constant domain, an adenine(A) to guanine(G) substitution(ACT?GCT), changing the amino acid at position 91 from threonine to alanine(Thr?Ala) in all 26 strains; and(ii) position 887 in the fourth variable domain, a cytosine(C) to thymine(T) substitution(GCA?GTA), changing the amino acid at residue 296 from alanine to valine(Ala?Val) in four of the 26 strains. Six mutations were identified relative to ATCC VR-573. The strains could be divided into two gene clusters according to the mutation at nucleotide position 887: CQZ-1(China Qinghai Tibetan-1) and CQZ-2(China Qinghai Tibetan-2). We thus detected two novel serotype B mutant strains of C. trachomatis among study subjects with trachoma.