Cure of Filament-Caused MBR Fouling in the Presence of Antibiotics: Taking Ciprofloxacin Exposure As an Example

Pharmaceuticals and personal care products (PPCPs) are ubiquitous in wastewater streams, but little is known regarding their roles in membrane fouling during the operation of membrane bioreactors (MBRs). This study attempted to understand the role of ciprofloxacin exposure in control of filamentous bulking as well as membrane fouling mitigation. Compared with the control MBR, results show that the ciprofloxacin could selectively inhibit and kill filaments present in the mixed liquor, and, as a consequence, the sludge settleability improved significantly. The addition of ciprofloxacin had little influence on organic removals and nitrification, but had an adverse effect on denitrification. In addition, the sludge flocs exposure to ciprofloxacin still kept in compact structure; specifically, granular sludge was finally formed possibly due to the increase of polysaccharides in extracellular polymeric substances (EPS). Characterization by nuclear magnetic resonance (NMR) corroborated the enrichment of polysaccharides in the EPS exposure to ciprofloxacin. On the other hand, because of the release of EPS and the decay of filaments, soluble microbial products (SMP), particularly soluble polysaccharides, increased significantly in the MBR exposure to ciprofloxacin. Despite this, the results of this study show that the presence of trace contaminants in wastewater streams may play some positive roles in MBR fouling control

Microbial Transformation of Structural and Functional Makeup of Human-Impacted Riverine Dissolved Organic Matter

The aim of this study was to reveal the biotransformation of human-impacted riverine dissolved organic matter (DOM) using well-controlled bioassay tests, with a focus on the biodegradation of the structural and functional makeup. Results of three-dimensional fluorescence excitation–emission matrix with parallel factor analysis (EEM-PARAFAC) showed that humic substances derived from human activities (i.e., anthropogenic humic-like substances) were of higher biodegradation potentials than terrestrial and microbial humic-like substances. In addition, the biodegradation finally led to an increase of the percentage contribution of fluorescent DOM to the total DOM. Characterization by nuclear magnetic resonance (NMR) spectroscopy indicated that large amounts of the structural components of the DOM were removed within 3 h of biodegradation. Characterization by X-ray photoelectron spectroscopy (XPS) further revealed that the riverine DOM contained various functional groups that underwent different biotransformation mechanisms. The XPS data also indicated the appearance of newly generated, oxygen-rich functional groups upon biodegradation and the disappearance of nitrogen-containing groups as a result of hydrolysis and nitrification of organic and/or ammonium nitrogen

Removal of sulfadiazine and tetracycline in membrane bioreactors: linking pathway to microbial community shift

<p>In this study, the removal pathway of sulfadiazine (SDZ) and tetracycline (TC) and their roles in shaping microbial community were separately explored in two lab-scale membrane bioreactors (MBRs) operating in parallel with one control MBR. Results show that the MBR system eliminated more than 90% of TC in the feed, whereas removal efficiency of SDZ decreased from 100% to 40% with increasing SDZ concentrations (1-1000 μg/L). Based on batch tests, biodegradation and adsorption was the main removal route for SDZ and TC, following pseudo-first-order kinetic and pseudo-second-order kinetic model with a rate constant of 1.21 L/(g MLSS·d) and 1.91 h^-1, respectively, in the acclimated sludge. As expected, the acclimated sludge possessed a higher removal potential for the antibiotics compared with unacclimated sludge. Notably, high-throughput sequencing revealed that the most abundant phylum <i>Proteobacteria</i> was resistant to TC (1-1000 μg/L), but was suppressed by SDZ (100-1000 μg/L). Members of the phylum TM7 were likely responsible for SDZ degradation. Overall, TC exhibited a stronger inhibitory effect on bacterial species and significantly reduced the biodiversity compared with SDZ, which could be strongly related to the persistent toxicity of TC to microbes resulting from its high adsorption potential on activated sludge.</p

Location of study areas in the map of China.

<p>The urban study areas were selected from Gansu, Shandong and Fujian provinces; the rural study areas were selected from Jilin, Anhui and Chongqing provinces. According to geographical regions of China, Fujian and Chongqing are in the southern, Shandong and Anhui are in the middle, Gansu and Jilin are in the northern. </p

MUI and TSH relationship in 4 groups of population.

<p>The MUI was divided into 6 groups (<100, 100-199.9, 200-299.9, 300-399.9, 400-499.9 and >500 µg/L). The TSH value was spotted to decrease and subsequently increase with an elevation in MUI, and formed a “U curve” relationship in children, adults and pregnant women except in lactating women. The R² was 0.6176, 0.8091 and 0.9965 in children, adults and pregnant women respectively.</p

MUI of the six study areas in the 4 groups of population.

<p>Of the 6 provinces, MUI in children was above the requirement except Jilin province; MUI in adults was above the requirement except Fujian province; And, MUI in lactating women was above the requirement except Fujian and Chongqing provinces. MUI was adequate in pregnant women of the six provinces. </p

Engineering Antifouling Nanofiltration Membranes Using Amino-Quinone Networks–Phytic Acid <i>Pseudo</i> Zwitterionic Clusters for Water Treatment

Nanofiltration (NF) shows great potential for water treatment and recycling. Nevertheless, severe membrane fouling significantly decreased lifetime and performance of NF membranes, impeding NF applications for clean water production. Herein, novel antifouling NF membranes with a pseudo zwitterionic separation layer were designed using layer-by-layer (LBL) assembly of amino-quinone networks (AQNs) and hydrophilic phytic acid (PhA) (AQN-PhA). The AQNs were formed by 5-hydroxy-1,4-naphthoquinone (HNQ) and polyethylenimine (PEI) via Michael addition and Schiff base reaction. The modification conditions of the AQN-PhA system were systematically investigated for an optimum membrane performance. The optimized conditions were found to be a PEI molecular weight of 600 Da, HNQ/PEI ratio at 1:2, an AQN coating time of 10 min, and pH of PhA at 5. The optimized membrane (i.e., AQN-PhA-5-2L) showed improved hydrophilicity along with a pure water permeability of 9.0 L·m–2·h–1·bar–1 and a molecular weight cut-off of 766 Da. It exhibited excellent fouling resistance with approximately 94% flux recovery ratio against a synthetic wastewater during a long-term filtration, which was superior in comparison with a benchmark commercial polyamide NF membrane. This study provides an idea for simple, feasible, and scalable zwitterionic modification in the future design of antifouling NF membranes

Associations between thyroid diseases and different iodine nutrition status and other potential risk factors.

<p>*<i>p</i><0.05.</p><p>**<i>p</i><0.01.</p><p>Associations between thyroid diseases and different iodine nutrition status and other potential risk factors.</p

Demographic characteristics of the participants in the three different iodine nutrition groups.

<p>16 missing.</p>▴<p>13 missing.</p>★<p>22 missing.</p>△<p>29 missing.</p><p>Demographic characteristics of the participants in the three different iodine nutrition groups.</p

A summary of the samples collected and the iodine nutrition status of the survey sites.

<p>A summary of the samples collected and the iodine nutrition status of the survey sites.</p