Improvement on the modified Lowry method against interference of divalent cations in soluble protein measurement

Performances of a novel BAF with ferromanganese oxide modified biochar (FMBC) as the carriers for treating antibiotics, nitrogen and phosphorus in aquaculture wastewater

In this paper, a biological aerated filter (BAF) based on ferromanganese oxide-biochar (FMBC) was constructed to investigated the removal performance and mechanism for conventional pollutants and four kinds of antibiotic, in contrast of conventional zeolite loaded BAF (BAF-A) and bamboo biochar filled BAF (BAF-B). Results showed that the average removal efficiency of total nitrogen (TN), total phosphorus (TP) and antibiotics in a FMBC-BAF (named by BAF-C) were 52.97 ± 2.27%, 51.58 ± 1.92% and 70.36 ± 1.00% ~ 81.65 ± 0.99% respectively in running period (39-100 d), which were significantly higher than those of BAF-A and BAF-B. In the BAF-C, the expression of denitrification enzyme activities and the secretion of extracellular polymeric substance (EPS) especially polyprotein (PN) were effectively stimulated, as well as accelerated electron transfer activity (ETSA) and lower electrochemical impedance spectroscopy (EIS) were acquired. After 100 days of operation, the abundance of nitrogen, phosphorus and antibiotic removal functional bacteria like Sphingorhabdus (4.52%), Bradyrhizobium (1.98%), Hyphomicrobium (2.49%), Ferruginibacter (7.80%), unclassified_f_Blastoca tellaceae (1.84%), norank_f_JG30-KF-CM45 (6.82%), norank_f_norank_o_SBR1031 (2.43%), Nitrospira (2.58%) norank_f_Caldilineaceae (1.53%) and Micropruina (1.11%) were enriched. Mechanism hypothesis of enhanced performances of nutrients and antibiotics removal pointed that: The phosphorus was removed by adsorption and precipitation, antibiotics removal was mainly achieved through the combined action of adsorption and biodegradation, while nitrogen removal was realized by biologic nitrification and denitrification in a FMBC-BAF for aquaculture wastewater treatment.

Empowering TiO2-coated PVDF membranes stability with polyaniline and polydopamine for synergistic separation and photocatalytic enhancement in dye wastewater purification

Photocatalytic membranes are effective in removing organic dyes, but their low UV resistance poses a challenge. To address this, self-protected photocatalytic PVDF membranes were developed using polyaniline (PANI) and polydopamine (PDA), whaich are anti-oxidation polymers, as interlayers between the membrane and TiO2. PVDF membranes were first modified by a self-polymerization layer of either PANI or PDA and then coated with titanium dioxide (TiO2). The TiO2 remained firmly attached to the PANI and PDA layer, regardless of sonication and prolonged usage. The PANI and PDA layers enhanced the durability of PVDF membrane under UV/TiO2 activation. After 72 h of irradiation, PVDF-PDA-TiO2 and PVDF-PANI-TiO2 membranes exhibited no significant change. This process improved both separation and photocatalytic activity in dye wastewater treatment. The PVDF-PDA-TiO2 and PVDF-PANI-TiO2 membranes showed enhanced membrane hydrophilicity, aiding in the rejection of organic pollutants and reducing fouling. The modified membranes exhibited a significant improvement in the flux recovery rate, attributed to the synergistic effects of high hydrophilicity and photocatalytic activity. Specially, the flux recovery rate increased from 17.7% (original PVDF) to 56.3% and 37.1% for the PVDF-PDA-TiO2 membrane and PVDF-PANI-TiO2 membrane. In dye rejection tests, the PVDF‒PDA‒TiO2 membrane achieved 88% efficiency, while the PVDF‒PANI‒TiO2 reached 95.7%. Additionally, the photodegradation of Reactive Red 239 (RR239) by these membranes further improved dye removal. Despite an 11% reduction in flux, the PVDF-PDA-TiO2 membrane demonstrated greater durability and longevity. The assistance of PANI and PDA in TiO2 coating also improved COD removal (from 33 to 58-68%) and provided self-protection for photocatalytic membranes, indicating that these photocatalytic membranes can contribute to more sustainable wastewater treatment processes.

Effect of antibiotics addition on nutrient removal stability and microbial community change of the solar-powered oxidation ditch-membrane bioreactor in treating building wastewater

The solar-powered oxidation ditch-membrane bioreactors (SOD-MBR) system was developed and operated with long solid retention times (SRTs) of 80 and 160 days. The aim was to investigate the effects of using a long SRT and antibiotics in building wastewater on the stability of nutrient removal, as well as membrane fouling. An increase in the SRT from 80 days to 160 days did not significantly affect the performance of the SOD-MBR system. Ciprofloxacin and Sulfamethoxazole removal efficiencies were 94.47 ± 1.54% and 87.54 ± 24.7%. However, the presence of antibiotics resulted in lower removal efficiencies for NH4+-nitrogen and phosphorus and stimulated the production of extracellular polymeric substances (EPS), particularly proteins in L-EPS and T-EPS of the foulant. FTIR and FEEM analysis revealed that the microbial sludge primarily consisted of proteins, carbohydrates, and lipids. Furthermore, the relative abundance analysis of microbial communities identified bacteria associated with nitrogen removal in the SOD-MBR system, including Anammox, AOB (ammonia oxidizing bacteria), DNB (denitrifying bacteria), and NOB (nitrite oxidizing bacteria), with a total of 25 genera. The majority of these bacteria were stimulated by the presence of antibiotics, resulting in higher relative abundance. Finally, the SOD-MBR system achieved energy savings of 97.38% by utilizing photovoltaic (PV) technology.

Bisphenol A (BPA) exposure aggravates hepatic oxidative stress and inflammatory response under hypertensive milieu - Impact of low dose on hepatocytes and influence of MAPK and ER stress pathways

Human exposure to the hazardous chemical, Bisphenol A (BPA), is almost ubiquitous. Due to the prevalence of hypertension (CVD risk factor) in the aged human population, it is necessary to explore its adverse effect in hypertensive subjects. The current study exposed the Nω-nitro-l-arginine methyl ester (L-NAME) induced hypertensive Wistar rats to human exposure relevant low dose of BPA (50 μg/kg) for 30 days period. The liver biochemical parameters, histopathology, immunohistochemistry, gene expression (RT-qPCR), trace elements (ICP-MS), primary rat hepatocytes cell culture and metabolomic (1H NMR) assessments were performed. Results illustrate that BPA exposure potentiates/aggravates hypertension induced tissue abnormalities (hepatic fibrosis), oxidative stress, ACE activity, malfunction of the antioxidant system, lipid abnormalities and inflammatory factor (TNF-α and IL-6) expression. Also, in cells, BPA increased ROS generation, mitochondrial dysfunction and lipid peroxidation without any impact on cytotoxicity and caspase 3 and 9 activation. Notably, BPA exposure modulate lipid metabolism (cholesterol and fatty acid) in primary hepatocytes. Finally, the influence of ERK1/2, p38MAPK, ER stress and oxidative stress during relatively high dose of BPA elicited cytotoxicity was observed. Therefore, a precise hazardous risk investigation of BPA exposure in hypertensive populations is highly recommended.

Sustainable disposal of Fenton sludge and enhanced organics degradation based on dissimilatory iron reduction in the hydrolytic acidification process

Fenton sludge generated in the flocculation stage of the Fenton oxidation process contains significant amounts of ferric iron and organic pollutants, which require proper treatment. Previous studies have demonstrated that adding Fenton sludge to an anaerobic digester can decompose some of the organic pollutants in the Fenton sludge to lower its environmental risk, but iron gradually accumulates in the reactor, which weakens the sustainability of the method. In this study, Fenton sludge was introduced into a hydrolytic acidification reactor with a weak acid environment to relieve the iron accumulation as well as improve the degradation of organic matter. The results showed that the added Fenton sludge acted as an extracellular electron acceptor to induce dissimilatory iron reduction, which increased chemical oxygen demand (COD) removal and acidification efficiency by 16.1% and 19.8%, respectively, compared to the group without Fenton sludge. Along with the operation, more than 90% of the Fe(III) in Fenton sludge was reduced to Fe(II), and part of them was released to the effluent. Moreover, the Fe(II) in the effluent could be used as flocculants and Fenton reagents to further decrease the effluent COD by 29.8% and 44.5%, respectively. It provided a sustainable strategy to reuse Fenton sludge to enhance organic degradation based on the iron cycle.

Opportunities for resource recovery from Latvian municipal sewage sludge

Sewage sludge is a type of waste that has high health and environmental risks associated with its reuse. Moreover, sludge has been neglected in global circular economy targets because it is generated in considerably lower quantities than municipal solid waste. At the same time, European Union's transition towards circular economy has set the need to reduce the amount of waste and to promote the production of secondary raw materials. Many countries have developed national strategies for sludge management to reach their sustainability goals. In Latvia, the current sludge management approaches include land application, composting and anaerobic digestion which all utilize sludge as an organic fertilizer. As an alternative to current management practices, resource recovery is put forward as a solution that is in agreement with EU policy. Carbohydrates (including cellulose), proteins and lipids were selected as candidates for energy and materials recovery from sludge. For the first time, this study demonstrates a comprehensive assessment of Latvian municipal sewage sludge composition and offers the theoretical yields of secondary resources on a yearly basis. Primary, secondary, and anaerobically digested sludge from 13 wastewater treatment plants (WWTPs) in Latvia was characterized in this study. The most abundant sludge type - secondary sludge - contained 18.5% proteins, 9.8% lipids and 2.6% cellulose per TS. On a yearly basis, secondary sludge from all Latvian WWTPs could provide 2530 t proteins, corresponding to 750 t protein-based fertilizer. Primary sludge contained 23.9% proteins, 9.1% lipids and 7.1% cellulose per TS. Primary sludge could provide 763 t/a carbohydrates, including 545 t/a cellulose. The currently available secondary and digested sludge would yield 727 t bioethanol, corresponding to 4.0% of the national biofuel consumption. This work applies the concept of resource recovery to the Latvian wastewater sector and shows the potential of simultaneously addressing waste and wastewater management issues.

Enhanced Anaerobic Wastewater Treatment by a Binary Electroactive Material: Pseudocapacitance/Conductance-Mediated Microbial Interspecies Electron Transfer

Anaerobic digestion (AD) is a promising method to treat organic matter. However, AD performance was limited by the inefficient electron transfer and metabolism imbalance between acid-producing bacteria and methanogens. In this study, a novel binary electroactive material (Fe3O4@biochar) with pseudocapacitance (1.4 F/g) and conductance (10.2 μS/cm) was exploited to store-release electrons as well as enhance the direct electron transfer between acid-producing bacteria and methanogens during the AD process. The mechanism of pseudocapacitance/conductance on mediating interspecies electron transfer was deeply studied at each stage of AD. In the hydrolysis acidification stage, the pseudocapacitance of Fe3O4@biochar acting as electron acceptors proceeded NADH/NAD+ transformation of bacteria to promote ATP synthesis by 21% which supported energy for organics decomposition. In the methanogenesis stage, the conductance of Fe3O4@biochar helped the microbes establish direct interspecies electron transfer (DIET) to increase the coenzyme F420 content by 66% and then improve methane production by 13%. In the complete AD experiment, electrons generated from acid-producing bacteria were rapidly transported to methanogens via conductors. Excess electrons were buffered by the pseudocapacitor and then gradually released to methanogens which alleviated the drastic drop in pH. These findings provided a strategy to enhance the electron transfer in anaerobic treatment as well as guided the design of electroactive materials.

Spectroscopic fingerprints profiling the polysaccharide/protein/humic architecture of stratified extracellular polymeric substances (EPS) in activated sludge

Extracellular polymeric substances (EPS), with a stratified structure including tightly-bound EPS (TB-EPS), loosely-bound EPS (LB-EPS), and soluble EPS (S-EPS) surrounding the microbial cells, are known to vitally affect the physicochemical and biological functions of activated sludge in wastewater treatment. Polysaccharides (PS), proteins (PN), and humic acids (HA) are key components of EPS but their roles in constructing the multi-layer architecture are still unclear. This study explored the EPS characteristics in relation to the components using spectroscopic fingerprinting techniques. Ultraviolet-visible (UV-vis) spectra demonstrated stark difference between TB-EPS and other EPS. Fluorescence excitation-emission matrix (FEEM) and apparent quantum yield revealed further detailed differences. Fluorescence quotient analysis highlighted the dominance of TB-EPS, LB-EPS, and S-EPS in the excitation/emission wavelength (Ex/Em) region of Em = 350-400 nm, Em > 400 nm, and low-Stokes shift band (Em - Ex < 25 nm), respectively. Wavelength-wise prediction of the FEEM intensity was achieved through multiple linear regression against the chemical composition and variance partitioning analysis witnessed binary interactions of PS×HA and PS×PN in S-EPS, PN×HA and PS×PN in LB-EPS, and ternary interaction of PS×PN×HA in TB-EPS as well as the wavelength-specific fluorescence responses of these interactions. Further, X-ray photoelectron spectroscopy, infrared spectra, and circular dichroism spectra corroborated the differences in primary, secondary, and tertiary structures across the EPS layers. Ultrahigh-performance liquid chromatography-mass spectrometry detected molecular fragments confirming the multi-component hybridization among PS, PN, and HA. This study demonstrates a spectroscopic approach to sensitively fingerprint the fine structure of EPS, which has the potential for rapid monitoring of EPS and related sludge properties in wastewater treatment systems.

Carrier type affects anammox community assembly, species interactions and nitrogen conversion

The impacts of carrier type on anammox community assembly, species interactions and nitrogen conversion were studied in this work. It was found that in addition to shared species with higher abundance, different carrier types recruited rare species by imposing selection pressure. Results from co-occurrence networks revealed that carrier type strongly influenced interactions between keystone species inhabiting within anammox biofilm through potentially inducing niche differences. Overall, elastic cubic sponges would lead to closer cooperation between different populations, whereas plastic hollow cylinders would trigger fiercer competition. Meanwhile, the results based on metagenomics sequencing showed carrier type significantly affected nitrogen conversion related genes abundances, and higher reads number was detected on the elastic cubic sponges. The information obtained in this work could provide some valuable information for the selection and optimization of carrier type in the anammox process.

Sample Preparation and Protein Determination for 2D-DIGE Proteomics

Fluorescence two-dimensional difference gel electrophoresis (2D-DIGE) is a widely employed method for efficient protein separation and the determination of abundance changes in distinct proteoforms. This makes this gel-based method a key technique of comparative approaches in top-down proteomics. For the appropriate screening of proteome-wide alterations, initial preparative steps involve sample handling, homogenization, subcellular fractionation, and the determination of protein concentration, which makes the optimal application of these techniques a crucial part of a successful initiation of a new 2D-DIGE-based analysis. This chapter describes sample homogenization and a standardized protein assay for the preparation of homogenates with a known protein concentration for subsequent differential fluorescent tagging and two-dimensional gel electrophoretic separation.

Impact of combined biological hydrolysis and anaerobic digestion temperatures on the characteristics of bacterial community and digestate quality in the treatment of wastewater sludge

This work investigated the impact of temperature on the digestate water quality and bacterial community in the treatment of wastewater sludge using biological hydrolysis (BH)-anaerobic digestion (AD). The results showed that the BH 55 °C followed by AD 35 °C or 42 °C was the optimal temperature combination in terms of methane yield and digestate water quality. High-throughput sequencing revealed the key differences in bacterial communities for different BH-AD temperature combinations. Microbial source tracking showed only minor microbial migration from raw sludge and BH pre-treated sludge to the AD stage. Strong correlations between the residual sCOD, BH-AD temperature conditions, and dominant bacteria were identified. Clostridiales, Bacteroidales, Cloacimonadales, Thermotogales, and Anaerolineales were closely related to the digestate water quality and methane yield. Overall, the results showed that AD temperature exerted a dominant impact on methane yield, digestate water quality, and bacterial compositions in the BH-AD of wastewater sludge.

3D spray-coated gradient profile ceramic membranes enables improved filtration performance in aerobic submerged membrane bioreactor

Rational design of cross-sectional microstructure in ceramic membranes has shown to improve membrane filtration efficacy without affecting rejection performance. In this work, we adopted 3D spray-coating technique to generate multi-layered membrane layers on macro-porous flat-sheet ceramic supports. The thickness of each layer was controlled by spray-coating cycles, and a gradient membrane layer was rationalized by successively coating three ceramic slurries containing alumina powders of gradually refined particle sizes, followed by co-sintering. Gradient membrane layers on both sides of the various sized flat-sheet ceramic supports were fabricated. Compared to the non-gradient counterpart, the gradient membranes showed both higher pure water flux (at the same TMP) and lower membrane resistance, which clearly evidenced the benefits of gradient profile in the membrane layer. Further, their performance in aerobic membrane bioreactors (AeMBR) was comparably studied for the first time. The treatment performance was not significantly affected by the types of membranes used, while the gradient membrane showed better filtration performance (i.e., a slower rise in TMP). Although the fouling mechanisms were revealed to be similar, the fouling layer in the gradient membrane was composed of a higher percentage of smaller foulants compared to that of the non-gradient counterpart. The observed differences were closely correlated to the larger internal pore structure in the gradient membrane. The present work provides a feasible 3D spray-coating technique for the fabrication of gradient flat-sheet ceramic membranes, and clarifies the benefits in AeMBR for domestic wastewater treatment.

Activation of Peroxydisulfate by Bimetallic Nano Zero-Valent Iron for Waste-Activated Sludge Disintegration

Waste-activated sludge (WAS) disintegration using peroxydisulfate (PDS) has attracted scientific attention over the past few years. Despite several advantages offered by a sulfate radical-advanced oxidation process, there are still too many downsides of this treatment that limit its facile large-scale application. This study investigated whether modifying nano zero-valent iron (nZVI) with a second metal such as Ag and Cu enhanced the disruption of WAS. The disintegration efficiency was assessed using standard techniques, i.e., soluble chemical oxygen demand, Fourier-transform infrared spectroscopy and a scanning electron microscope. The bimetallics were shown to have an improved disintegration efficiency of > 2.5-fold compared with the untreated sample. Furthermore, nZVI/Ag was found to be more efficient than nZVI/Cu for PDS activation, which was validated by the higher ratio (3 and 2.5 for nZVI/Ag and nZVI/Cu, respectively) between the soluble extracellular polymeric substances and the bound extracellular polymeric substances (S-EPS/B-EPS). Similar conclusions were derived from a SEM analysis. The improved disintegration efficiency could be related to the enhanced electron transfer from nZVI to PDS or the intrinsic properties of silver, which was found to be one of the best activators for PDS under homogeneous conditions. We believe that this study deepens the understanding of PDS heterogeneous activation processes.

Partial Nitrification and Enhanced Biological Phosphorus Removal in a Sequencing Batch Reactor Treating High-Strength Wastewater

Complex and high levels of various pollutants in high-strength wastewaters hinder efficient and stable biological nutrient removal. In this study, the changes in pollutant removal performance and microbial community structure in a laboratory-scale anaerobic/aerobic sequencing batch reactor (SBR) treating simulated pre-fermented high-strength wastewater were investigated under different influent loading conditions. The results showed that when the influent chemical oxygen demand (COD), total nitrogen (TN), and orthophosphate (PO₄³⁻-P) concentrations in the SBR increased to 983, 56, and 20 mg/L, respectively, the COD removal efficiency was maintained above 85%, the TN removal efficiency was 64.5%, and the PO₄³⁻-P removal efficiency increased from 78.3% to 97.5%. Partial nitrification with simultaneous accumulation of ammonia (NH₄⁺-N) and nitrite (NO₂⁻-N) was observed, which may be related to the effect of high influent load on ammonia- and nitrite-oxidising bacteria. The biological phosphorus removal activity was higher when propionate was used as the carbon source instead of acetate. The relative abundance of glycogen accumulating organisms (GAOs) increased significantly with the increase in organic load, while Tetrasphaera was the consistently dominant polyphosphate accumulating organism (PAO) in the reactor. Under high organic loading conditions, there was no significant PAO–GAO competition in the reactor, thus the phosphorus removal performance was not affected.

Efficient Phosphorus Recovery from Municipal Wastewater Using Enhanced Biological Phosphorus Removal in an Anaerobic/Anoxic/Aerobic Membrane Bioreactor and Magnesium-Based Pellets

Municipal wastewater has been identified as a potential source of natural phosphorus (P) that is projected to become depleted in a few decades based on current exploitation rates. This paper focuses on combining a bench-scale anaerobic/anoxic/aerobic membrane bioreactor (MBR) and magnesium carbonate (MgCO₃)-based pellets to effectively recover P from municipal wastewater. Ethanol was introduced into the anoxic zone of the MBR system as an external carbon source to improve P release via the enhanced biological phosphorus removal (EBPR) mechanism, making it available for adsorption by the continuous-flow MgCO₃ pellet column. An increase in the concentration of P in the MBR effluent led to an increase in the P adsorption capacity of the MgCO₃ pellets. As a result, the anaerobic/anoxic/aerobic MBR system, combined with a MgCO₃ pellet column and ethanol, achieved 91.6% P recovery from municipal wastewater, resulting in a maximum P adsorption capacity of 12.8 mg P/g MgCO₃ through the continuous-flow MgCO₃ pellet column. Although the introduction of ethanol into the anoxic zone was instrumental in releasing P through the EBPR, it could potentially increase membrane fouling by increasing the concentration of extracellular polymeric substances (EPSs) in the anoxic zone.

Deciphering mono/multivalent draw solute-induced microbial ecology and membrane fouling in anaerobic osmotic membrane bioreactor

Anaerobic osmotic membrane bioreactor (AnOMBR) attracted attention due to high quality effluent production with low energy demand, and draw solute has significant effect on the system performance. However, the mutual relationship between draw solute-induced salinity accumulation and microbial community had many unknown questions to be solved. This study purpose was to construct two AnOMBR to compare the impact of draw solutes of NaCl and MgCl2 on the dynamic change of microbial ecology and membrane fouling. The result indicated that the draw solute of MgCl2 caused less salinity and more membrane biofouling than that of the draw solute NaCl. Multiple microbiological analysis methods were applied to discover keystone species related to the conductivity change and membrane fouling, especially for the MgCl2-AnOMBR system. It was found that draw solute NaCl could benefit the growth of Proteobacteria to become the most abundant phylum to affect the membrane fouling, while Mg2+ introduction could stimulate the growth of NS9, Hydrogenphilaceae and Pedosphaeraceae to potentially cause the biofouling. Furthermore, phylogenetic molecular ecological networks (pMENs) deeply analyzed the microbial structure difference under Na+ and Mg2+ introduction, and indicated that the family Lentimicrobiaceae and Candidatus_Kaiserbacteria were the keystone species in NaCl-AnOMBR, while two genus Anaerolinea and SWB02, and two families Saprospiraceae and NS9 were discovered to have key effect in MgCl2-AnOMBR due to their strong extracellular polymeric substances (EPS) production ability for survival of other microorganisms. This study was significant to give microbial targets under the impact of various draw solutes, as the reference for the engineers to further investigate how to improve the microbial structure to enhance AnOMBR performance and inhibit the membrane biofouling.

A novel anammox aggregate nourished sustainably internal heterotrophic nitrate removal pathway with endogenous carbon source

Anaerobic ammonium oxidation (anammox) is a cost-effective nitrogen removal pathway but instinctively generated nitrate limits its application. A novel anammox aggregate reduced the production of nitrate significantly with efficient removal of ammonia and nitrite in this work. The results demonstrated that the internal heterotrophic nitrate removal (IHNAR) pathway exists stably at inner of anammox aggregates, which eliminated 42.31 ± 3.85 % nitrate generated in anammox at without consuming external carbon source. The observed volatile fatty acids (VFAs) and adequate protein, polysaccharide and humic acids in the aggregates verified that the in-situ fermentation supplied sustainably endogenous carbon sources for the IHNAR. The efficient interspecies cooperation between anammox bacteria, heterotrophic denitrifiers and fermentative bacteria was identified, as the intrinsic justification for the obtained sustainability of IHNAR pathway. The findings were expected to provide theoretical guidance for promotions and applications of the anammox process with high-efficiency total nitrogen removal capabilities.

Insight investigation of the on-site activated sludge reduction induced by metabolic uncoupler: Effects of 2,6-dichlorophenol on soluble microbial products, microbial activity, and environmental impact

Metabolic uncoupling technology was one of the methods widely used to on-site control the production of excess sludge in wastewater treatment processes. However, the uncoupler effects on soluble microbial products (SMP), microbial activity, and environment impact have few been reported. This study showed that sludge yield was reduced by 33.3% at 2,6-dichlorophenol (2,6-DCP) concentrations of 10 mg/L. The addition of 2,6-DCP also reduced the content of polysaccharide and protein in SMP, and the three-dimension excitation emission matrix (3D-EEM) suggested that the fluorescence intensities of humic acid-like, fulvic acid-like, and tryptophan protein-like substances decreased, proving that 2,6-DCP addition will weaken the interaction between microorganisms and the environmental matrix. Moreover, 2,6-DCP addition will change the microbial morphology and community of activated sludge. The active or respiring bacteria portion was lessened, and sludge flocs become dispersed, but it will not affect its settling performance. Surprisingly, 2,6-DCP has certain biodegradability and could be used as an environmentally friendly metabolic uncoupler under low-concentration dosing conditions. This study systematically evaluated the effect of 2,6-DCP on sludge production, SMP contents, microbial morphology, microbial community, demonstrating the environmental impact and application feasibility in the wastewater treatment systems.

Exploration of mechanisms for calcium phosphate precipitation and accumulation in nitrifying granules by investigating the size effects of granules

Calcium phosphate could be accumulated in aerobic granules, which attracts attention recently for phosphorus removal and recovery from wastewater. In this study, partial nitrifying granules with high calcium precipitate content were sorted into different size groups for characterization and evaluation to reveal the dynamic balance of granules at stead state and relevant calcium phosphate precipitation and accumulation mechanism. It was found that light yellow small granules without calcium precipitates but high microbial activity co-existed with deep brown granules with calcium precipitate of around 91% and low microbial activity. Characterization with specific oxygen uptake rates, specific ammonium oxidation rates, calcium and phosphate removal rates from solution, EPS contents, elemental compositions by energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and scanning electron microscopy (SEM) for different size groups of granules enabled a proposal of a new hypothesized mechanism for calcium precipitation and accumulation. With this proposed mechanism, it is believed that sufficient granule retention time in reactors was critical for the accumulation of calcium precipitates followed by a slow microbial growth rate of biomass due to mass transfer resistance. The co-precipitation of calcium carbonate and calcium phosphate mainly occurred in granules with a size less than 710 µm while calcium phosphate dominant minerals were accumulated in granules larger than 710 µm. The results and conclusions in this study shed light on the mechanisms of calcium phosphate accumulation in granules, which could be used to better operate and control aerobic granular sludge with calcium phosphates for phosphorus removal and recovery.

Treatment of Effluent of Upflow Anaerobic Sludge Blanket Bioreactor for Water Reuse

The low-pressure reverse osmosis (LPRO) process is a recent development of reverse osmosis (RO) technology for the reduction in RO energy consumption and operation cost. The goal of this study was to investigate the performance of LPRO processes for the treatment and reuse of effluent discharged from brewery upflow anaerobic sludge blanket bioreactors (UASB). In this study, three different commercially available LPRO membranes were tested to evaluate the water quality that can be achieved under different operational and pretreatment conditions. It was found that the filtration performance and the effluent quality of the LPRO membranes can be considerably affected by the operation conditions and the selection of the pretreatment processes. The ultrafiltration (UF) pretreatment and the control of the operation pressure were found to be essential for mitigating LPRO membrane fouling, which could be caused by Ca2+ associated precipitates and organic gelation, in the treatment of the brewery UASB effluent. Water quality analyses showed that an integrated process of the UASB + UF + LPRO could achieve an effluent quality characterized by concentrations of 10.4–12.5 mg/L of chemical oxygen demand (COD), 1.8–2.1 mg/L of total nitrogen (TN), 1.3–1.8 mg/L of ammonia nitrogen (NH3-N) and 0.8–1.2 mg/L of total phosphorus (TP). The effluent quality and the LPRO performance could be further improved by adding a granular activated carbon (GAC) adsorption process between the UF and LPRO processes, which reduced the concentration of COD to 7–10 mg/L and those of TN, TP, NH3-N to below 1 mg/L. For the treatment of the UASB effluent tested in this study, the UF, UF + GAC (retention time 4 hrs), UF + LPRO, and UF + GAC + LPRO, respectively, achieved overall COD removal efficiencies of 89.6–93.7%, 94.5–96.7%, 99.3–99.1% and 99.3–99.4%; TN removal efficiencies of 73.0–78.2%, 89.2–97.2%, 97.1–98.2% and 94.3–99.7%; and TP removal efficiencies of 29.3–46.2%, 77.0–95.4%, 95.9–97.6z% and 98.0–98.3%. This study showed that both UASB + UF + LPRO and UASB + UF + GAC + LPRO are effective treatment processes for treating brewery wastewater toward reuse water quality standards set by the United States Environmental Protection Agency (US EPA). Therefore, the results of this study would help to answer whether a LPRO can treat the brewery UASB effluent to meet the requirements of wastewater reuse standards.

Phenotypic and Multi-Omics Characterization of Escherichia coli K-12 Adapted to Chlorhexidine Identifies the Role of MlaA and Other Cell Envelope Alterations Regulated by Stress Inducible Pathways in CHX Resistance

Chlorhexidine (CHX) is an essential medicine used as a topical antiseptic in skin and oral healthcare treatments. The widespread use of CHX has increased concerns regarding the development of antiseptic resistance in Enterobacteria and its potential impact on cross-resistance to other antimicrobials. Similar to other cationic antiseptics, resistance to CHX is believed to be driven by three membrane-based mechanisms: lipid synthesis/transport, altered porin expression, and increased efflux pump activity; however, specific gene and protein alterations associated with CHX resistance remain unclear. Here, we adapted Escherichia coli K-12 BW25113 to increasing concentrations of CHX to determine what phenotypic, morphological, genomic, transcriptomic, and proteomic changes occurred. We found that CHX-adapted E. coli isolates possessed no cross-resistance to any other antimicrobials we tested. Scanning electron microscopy imaging revealed that CHX adaptation significantly altered mean cell widths and lengths. Proteomic analyses identified changes in the abundance of porin OmpF, lipid synthesis/transporter MlaA, and efflux pump MdfA. Proteomic and transcriptomic analyses identified that CHX adaptation altered E. coli transcripts and proteins controlling acid resistance (gadE, cdaR) and antimicrobial stress-inducible pathways Mar-Sox-Rob, stringent response systems. Whole genome sequencing analyses revealed that all CHX-resistant isolates had single nucleotide variants in the retrograde lipid transporter gene mlaA as well as the yghQ gene associated with lipid A transport and synthesis. CHX resistant phenotypes were reversible only when complemented with a functional copy of the mlaA gene. Our results highlight the importance of retrograde phospholipid transport and stress response systems in CHX resistance and the consequences of prolonged CHX exposure.

Mechanism and toxicity evaluation of catalytic ozonation over Cu/Ce-Al2O3 system aiming at degradation of humic acid in real wastewater

Humic acid (HA) is the main component of organic matter in effluent from wastewater treatment. The effective removal of HA is significant. In this study, a novel catalyst was prepared using a transition metal oxide as the active component and Al2O3 as a granular carrier. The mechanism of catalytic ozonation of HA under neutral pH conditions and its efficiency were investigated. Under the chosen conditions (an ozone concentration of 2.2 mg/L, 50 mg/L HA solution, catalyst dosage of 5 g/L and initial pH of 6.49), the Cu/Ce-Al2O3 bimetallic catalyst led to 54.79% TOC removal rate after 30 min; the removal rate by ozone alone was only 20.49%. The characteristics of organic compounds determined by FT-IR and GC-MS showed that organic compounds were degraded significantly by the catalytic treatment. The addition of catalysts could effectively degrade toxic intermediates and reduce the acute toxicity produced by ozonation. Humic acid substances were largely removed and transformed into biodegradable intermediates. This study proposes a new and efficient ozonation catalyst for practical applications in advanced wastewater treatment.

Insight into the benefits of anammox bacteria living as aggregates

This work tried understanding aggregation preference of anammox bacteria from benefit-driven perspective. Aggregated anammox sludge (AGS) gained benefits in specific anammox activity (SAA) (increased by 40.47 ± 12.64%) and in toxicity resistance (enhanced by 65.41%) than scattered anammox sludge (SCS), which were verified by kinetics. The increased heme c content by 35.67 ± 5.77% and enhanced relative abundance of anammox bacteria by 9.29% supported the benefits in biological activity and improved EPS content by 1097.59 ± 43.06% (622.16 ± 61.73% for protein (PN), 2403.47 ± 162.75% for humic acid (HA) and 1145.34 ± 97.33% for polysaccharide (PS)) justified the benefits in toxicity resistance. The diverse microbial communities and organized spatial structures owned by AGS promoted interactions between species, as the intrinsic justification for obtaining the benefits. We expect our findings to provide theoretical guidance for promotions and applications of the anammox process with excellent nitrogen removal capacity and stability.

Riboswitch-Associated Guanidinium-Selective Efflux Pumps Frequently Transmitted on Proteobacterial Plasmids Increase Escherichia coli Biofilm Tolerance to Disinfectants

Members of the small multidrug resistance (SMR) efflux pump family known as SugE (recently renamed Gdx) are known for their narrow substrate selectivity to small guanidinium (Gdm+) compounds and disinfectant quaternary ammonium compounds (QACs). Gdx members have been identified on multidrug resistance plasmids in Gram-negative bacilli, but their functional role remains unclear, as few have been characterized. Here, we conducted a survey of sequenced proteobacterial plasmids that encoded one or more SugE/Gdx sequences in an effort to (i) identify the most frequently represented Gdx member(s) on these plasmids and their sequence diversity, (ii) verify if Gdx sequences possess a Gdm+ riboswitch that regulates their translation similarly to chromosomally encoded Gdx members, and (iii) determine the antimicrobial susceptibility profile of the most predominate Gdx member to various QACs and antibiotics in Escherichia coli strains BW25113 and KAM32. The results of this study determined 14 unique SugE sequences, but only one Gdx sequence, annotated as "SugE(p)," predominated among the >140 plasmids we surveyed. Enterobacterales plasmids carrying sugE(p) possessed a guanidine II riboswitch similar to the upstream region of E. coligdx Cloning and expression of sugE(p), gdx, and emrE sequences into a low-copy-number expression vector (pMS119EH) revealed significant increases in QAC resistance to a limited range of detergent-like QACs only when gdx and sugE(p) transformants were grown as biofilms. These findings suggest that sugE(p) presence on proteobacterial plasmids may be driven by species that frequently encounter Gdm+ and QAC exposure.IMPORTANCE This study characterized the function of antimicrobial-resistant phenotypes attributed to plasmid-encoded guanidinium-selective small multidrug resistance (Gdm/SugE) efflux pumps. These sequences are frequently monitored as biocide resistance markers in antimicrobial resistance surveillance studies. Our findings reveal that enterobacterial gdm sequences transmitted on plasmids possess a guanidine II riboswitch, which restricts transcript translation in the presence of guanidinium. Cloning and overexpression of this gdm sequence revealed that it confers higher resistance to quaternary ammonium compound (QAC) disinfectants (which possess guanidium moieties) when grown as biofilms. Since biofilms are commonly eradicated with QAC-containing compounds, the presence of this gene on plasmids and its biofilm-specific resistance are a growing concern for clinical and food safety prevention measures.

Formation of anaerobic granules and microbial community structure analysis in anaerobic hydrolysis denitrification reactor

An anaerobic hydrolysis denitrification (AnHD) process was developed to pretreat municipal wastewater for integrating partial nitration/anammox process. The results indicated that the carbon to nitrogen (C/N) ratio of municipal wastewater changed from 4.4 ± 0.3 to 2.2 ± 0.2 after pretreatment by AnHD process, which was favorable to the partial nitration/anammox process. The influent C/N ratio had influence on the formation of anaerobic granules. Two intrinsic factors, cyclic diguanylic acid (c-di-GMP) concentration and core bacterial community, were mainly responsible for the anaerobic granular formation. The higher c-di-GMP content increased the extracellular polymeric substances and decreased the motility of the bacteria, which was beneficial for the formation of anaerobic granules. The microbial community analysis showed that the lactic acid bacteria (Lactococcus) was the core bacteria during anaerobic hydrolysis process, while the denitrifying bacteria (Denitratisoma and unclassified Comamonadaceae) were the core bacterial community during AnHD process, which were responsible for nitrogen removal and anaerobic granular formation.

Integrating floc, aggregate and carrier to reap high-quality anammox biofilm

This work investigated the effects of integration of floc, aggregate and carrier (IFAC) on anammox biofilm quality and development mechanisms. The IFAC system harvested high-quality anammox biofilm with a reduction of 60% in the formation period, an increment of 282.14%~397.26% in mechanical stability, an enhancement of 10.18 ~ 21.56% in ecological stability and an improvement of 9.44%~46.18% in abundance of the phylum Planctomycetes. Aggregates enabled carriers to accumulate initial biomass efficiently and equipped biofilm with additional joint forces. Floc promoted accumulation of terminal biomass, enhanced ecological stability by improving community diversity and raised abundance of the phylum Planctomycetes by assisting anammox consortium settlement. A model of the development procedure of high-quality anammox biofilm was established and a strategy for pre-designing the IFAC system to reap high-quality biofilm was proposed. We expect our findings to provide theoretical guidance for designs and applications of anammox process with excellent stability.

Evaluating the performance of inorganic draw solution concentrations in an anaerobic forward osmosis membrane bioreactor for real municipal sewage treatment

Sewage can become a valuable source if its treatment is re-oriented for recovery. An anaerobic forward osmosis membrane bioreactor (AnOMBR) was developed for real municipal sewage treatment to investigate performance, biogas production, flux change and mixed liquor characteristics. The AnOMBR had a good treatment capacity with removal ratio of chemical oxygen demand, ammonia nitrogen, total nitrogen and total phosphorus more than 96%, 88%, 89% and almost 100%. Although high DS concentration increased the initial flux, it caused rapid decline and poor recoverability of FO membrane flux. Low DS concentration led to too long hydraulic retention time, thus resulting in a low reactor efficiency. Additionally, it was observed that salt, protein, polysaccharide and humic acid were all accumulated in the reactor, which was not conducive to stable long-term operation. Based on the characteristics of membrane fouling, salt accumulation and AnOMBR performance, the optimal DS of 1 M NaCl solution was selected.

Metoprolol and bisoprolol ameliorate hypertrophy of neonatal rat cardiomyocytes induced by high glucose via the PKC/NF-κB/c-fos signaling pathway

Hyperglycemia caused by diabetes mellitus could increase the risk of diabetic cardiomyopathy. However, to the best of our knowledge, the underlying mechanism of this process is still not fully explored. Thus, developing ways to prevent hyperglycemia can be beneficial for diabetic patients. The present study was designed to investigate the influence of metoprolol and bisoprolol on the cardiomyocytic hypertrophy of neonatal rat cardiomyocytes. Cardiomyocytes were cultured in two types of media: One with low glucose levels and one with high glucose levels. Cardiomyocytes cultured in high glucose were further treated with the following: A protein kinase C (PKC) inhibitor, an NF-κB inhibitor, metoprolol or bisoprolol. The pulsatile frequency, cellular diameter and surface area of cardiomyocytes were measured. Protein content and [³H]-leucine incorporation were determined, atrial natriuretic peptide (ANP), α-myosin heavy chain (α-MHC) and β-myosin heavy chain (β-MHC) mRNA levels were calculated by reverse transcription-quantitative PCR, while the expression and activation of PKC-α, PKC-β₂, NF-κB, tumor necrosis factor-α (TNF-α), and c-fos were detected by western blotting. Metoprolol or bisoprolol were also used in combination with PKC inhibitor or NF-κB inhibitor to determine whether the hypertrophic response would be attenuated to a lower extent compared with metroprolol or bisoprolol alone. Cardiomyocytes cultured in high glucose presented increased pulsatile frequency, cellular diameter, surface area, and protein content and synthesis, higher expression of ANP and β-MHC, and lower α-MHC expression. High glucose levels also upregulated the expression and activation of PKC-α, PKC-β₂, NF-κB, TNF-α and c-fos. Metoprolol and bisoprolol partly reversed the above changes, while combined use of metoprolol or bisoprolol with PKC inhibitor or NF-κB inhibitor further ameliorated the hypertrophic response mentioned above to lower levels compared with using metroprolol or bisoprolol alone. In conclusion, metoprolol and bisoprolol could prevent hypertrophy of cardiomyocytes cultured in high glucose by the inhibition of the total and phospho-PKC-α, which could further influence the PKC-α/NF-κB/c-fos signaling pathway.

Stokes Shift and Specific Fluorescence as Potential Indicators of Organic Matter Hydrophobicity and Molecular Weight in Membrane Bioreactors

Hydrophobicity and molecular weight (MW) are two fundamental properties of dissolved organic matter (DOM) in wastewater treatment systems. This study proposes fluorescence Stokes shift and specific fluorescence intensity (SFI) as novel indicators of hydrophobicity and MW. These indicators originate from the energy gap and photon efficiency of the fluorescence process and can be readily extracted from a fluorescence excitation-emission matrix (EEM). The statistical linkages between these indicators and hydrophobicity/MW were explored through investigation of DOM across 10 full-scale membrane bioreactors treating municipal wastewater. Stokes shift was found to exhibit a general rule among the hydrophobicity components in the order of hydrophilic substances (HIS) < hydrophobic acids (HOA) < hydrophobic bases (HOB). The Stokes shift of 1.2 μm^-1 is a critical border, above which the relative fluorescence correlated significantly with the HOA-related content (Pearson's r = 0.8). With regard to MW distribution (<1, 1-10, 10-100, and >100 kDa), SFI was found to be the most sensitive to the change of MW of <1 kDa proportion, especially at the excitation/emission wavelengths of 200-320/310-550 nm (r > 0.9). Hydrophobicity-related π conjugation and MW-dependent light exposure might be responsible for the correlations. These fluorescence indicators may be useful for convenient monitoring of DOM in wastewater treatment systems.

Long-term impact of heavy metals on the performance of biological wastewater treatment processes during shock-adaptation-restoration phases

The present work investigated the long-term (30 days of shock-adaptation and 60 days of restoration) impact of Cu²⁺, Hg²⁺ and Ag⁺ shock loading on the performance of biological wastewater treatment processes. Under the same inhibitory concentration (IC₁₅), Cu²⁺ had the most significant impact on the treatment efficiency. During the shock-adaptation phase, Ag⁺ led to up to 4 times of biopolymers generation compared to that of the blank one; Hg²⁺ inhibited the nitrification process but showed little influence on other parameters; Cu²⁺ and Ag⁺ inhibited the activity of sDHA completely and decreased the content of ATP significantly, as well they caused abnormal ROS generation and corresponding CAT and SOD increment. Till 60 days of restoration can the activity of enzymes be restored to the control level, which agreed well with the results of effluent quality. Cu²⁺ decreased the biodiversity of the sludge to a large extent, followed by Ag⁺ and Hg²⁺. At the phylum level, Verrucomicrobia was decreased nearly to zero after 30 days of Cu²⁺ shock. At the genera level, Zoogloea was almost vanished after 15 days of Cu²⁺ shock.

Exogenous refractory protein enhances biofilm formation by altering the quorum sensing system: A potential hazard of soluble microbial proteins from WWTP effluent

Soluble microbial refractory proteins are major components of effluent from wastewater treatment plants that utilize a biological wastewater treatment process. The remaining proteins could negatively affect downstream treatment processes by altering the bacterial quorum sensing system. In this work, we elaborated the effects of exogenous refractory protein on biofilm formation. The results showed a linear relationship between biofilm formation and experimental protein concentrations at the range typically found in effluent, 0-8.0 mg/L. Micro-observation revealed that the exogenous refractory protein stimulated extracellular polysaccharide secretion to promote biofilm maturation. Extracellular polysaccharides increased by ~200% with the addition of only 2.0 mg/L protein. In addition, exogenous refractory proteins altered the quorum sensing system gene expression and polysaccharide gene expression. This work found that exogenous protein accelerated biofilm formation by influencing the quorum sensing system, thus providing new insight into the potential harm of soluble microbial refractory products.

Digestion performance and contributions of organic and inorganic fouling in an anaerobic membrane bioreactor treating waste activated sludge

This study evaluates the performance of an anaerobic membrane bioreactor (AnMBR) digesting waste activated sludge. A digestion reactor equipped with an external hollow fiber microfiltration membrane module was operated in continuous-mode for 248 days. The system demonstrated 56% volatile solids degradation at an organic loading rate of 0.40 g-VS/(L·d) in 15 days of hydraulic retention time. The average methane content in the biogas produced was 76% which is considerably high compared to that from a typical continuously stirred tank reactor. The transmembrane pressure remained under 12 kPa without membrane cleaning during the experimental period due to low filtration flux (0.01-0.07 m/d) and cross-flow-mode filtration. Ex situ membrane cleaning revealed that physically irreversible fouling was the dominant form of membrane fouling. Inorganic and organic fouling accounted for 16% and 45% of total membrane fouling, respectively.

Acceleration of saturated porous media clogging and silicon dissolution due to low concentrations of Al(III) in the recharge of reclaimed water

The recharge of reclaimed water is an effective strategy for addressing the issues of water quality deterioration and groundwater level decline simultaneously. Residual Al coagulants are normally remained in the recovered water at low concentrations, and may induce clogging problems during the recharging process. However, this issue has been ignored in the past. In this study, we investigated the mechanisms of Al(III)-induced aquifer bio-clogging, the role of Al(III) in quartz sand media (SiO₂) dissolution and re-precipitation in the series of aquifer columns. We determined that Al(III) resulted in serious clogging in ∼140 h at low concentrations that satisfied the national drinking water standard of China. The corresponding hydraulic conductivity decreased by more than ∼90% in the bacteria-containing aquifer, which was ∼30% greater than that for the bacteria-free trials. The enhanced Al(III)-related clogging was caused by modifying quartz sand to form Si-O-Al(OH)n and improving microbes attachment. Microbes retention kinetic coefficients (k) of the Al recharged simulated aquifer could increase by 3.0-8.3 times. The Al(III) also enhanced biomass production and clogging by binding to microbial extracellular polymeric substances. In turn, the greater amount of biomass accelerated the Si dissolution and re-precipitation, this may potentially damage the stability of aquifer structure. The results showed that reclaimed water treated with Al coagulation should be employed with caution for recharging.

Insight into the characteristics, removal, and toxicity of effluent organic matter from a pharmaceutical wastewater treatment plant during catalytic ozonation

Changes in the characteristics, removal efficiency, and toxicity of pharmaceutical effluent organic matter (EfOM) after catalytic ozonation were investigated in this study. After a 90-min treatment with a catalytic ozonation process (COP) in the presence of MnO₂ ceramsite, the total organic carbon (TOC), UV₂₅₄, colority, protein, and humic acid removal rates were 13.24%, 60.83%, 85.42%, 29.36% and 74.19%, respectively. The polysaccharide content increased by 12.73 mg/L during the COP for reaction times between 0 and ~50 min and decreased by 6.97 mg/L between 50 and ~90 min. Furthermore, 64.44% of the total colority was detected in the hydrophobic organic matter (HOM) fraction, and after the COP, and 88.69% of the colority in the HOM was eliminated. Meanwhile, only 59.18% of the colority in the hydrophilic organic matter (HIM) fraction was removed. GC-MS analysis showed that 38 organic pollutant species were completely removed, 8 were partially removed, and 7 were generated. After 90 min of COP treatment, the pharmaceutical EfOM toxicity was effectively reduced based on the higher incubation and lower mortality rates.

Performance and membrane fouling of a step-fed submerged membrane sequencing batch reactor treating swine biogas digestion slurry

To identify the performance of step-fed submerged membrane sequencing batch reactor (SMSBR) treating swine biogas digestion slurry and to explore the correlation between microbial metabolites and membrane fouling within this novel reactor, a lab-scale step-fed SMSBR was operated under nitrogen loading rate of 0.026, 0.052 and 0.062 g NH₄⁺-N (gVSS·d)^-1. Results show that the total removal efficiencies for NH₄⁺-N, total nitrogen and chemical oxygen demand in the reactor (>94%, >89% and >97%, respectively) were high during the whole experiment. However, the cycle removal efficiency of NH₄⁺-N decreased significantly when the nitrogen loading rate was increased to 0.062 g NH₄⁺-N (gVSS·d)^-1. The total removal efficiency of total phosphorus in the step-fed SMSBR was generally higher than 75%, though large fluctuations were observed during the experiments. In addition, the concentrations of microbial metabolites, i.e., soluble microbial products (SMP) and extracellular polymeric substances (EPS) from activated sludge increased as nitrogen loading rate increased, both showing quadratic equation correlations with viscosity of the mixed liquid in the step-fed SMSBR (both R² > 0.90). EPS content was higher than SMP content, while protein (PN) was detected as the main component in both SMP and EPS. EPS PN was found to be well correlated with transmembrane pressure, membrane flux and the total membrane fouling resistance. Furthermore, the three-dimensional excitation-emission matrix fluorescence spectroscopy results suggested the tryptophan-like protein as one of the main contributors to the membrane fouling. Overall, this study showed that the step-fed SMSBR could be used to treat swine digestion slurry at nitrogen loading rate of 0.052 g NH₄⁺-N (gVSS·d)^-1, and the control strategy of membrane fouling should be developed based on reducing the tryptophan-like PN in EPS.

Fluidized-bed Fenton coupled with ceramic membrane separation for advanced treatment of flax wastewater

Fluidized-bed Fenton coupled with ceramic membrane separation to treat the flax secondary effluent was investigated. The operating variables, including initial pH, dosage of H₂O₂ and Fe⁰, air flow rate, TMP and pore size, were optimized. The distributions of DOMs in the treatment process were analyzed. Under the optimum condition (600mgL^-1H₂O₂, 1.4gL^-1 Fe⁰, pH=3, 300Lh^-1 air flow rate and 15psi TMP), the highest TOC and color removal efficiencies were 84% and 94% in the coupled reactor with 100nm ceramic membrane, reducing 39% of total iron with similar removal efficiency compared with Fluidized-bed Fenton. Experimental results showed that the ceramic membrane could intercept catalyst particles (average particle size >100nm), 10.4% macromolecules organic matter (AMW>20000Da) and 12.53% hydrophobic humic-like component. EEM-PARAFAC identified four humic-like (M1-M4) and one protein-like components (M5), and the fluorescence intensities of M1-M5 in the secondary effluent were 63.27, 63.05, 33.41, 16.71 and 0.72 QSE, respectively. After the coupled treatment, the removal efficiencies of M1(81%), M2(86%) were higher than M3, M4(63%, 61%). Pearson correlation analysis suggested that M1, M2 and M3 were the major contributors to the cake layer, and M4, M5 might more easily lead to pore blockages.

Inhibition of DPP-4 Activity and Neuronal Atrophy with Genistein Attenuates Neurological Deficits Induced by Transient Global Cerebral Ischemia and Reperfusion in Streptozotocin-Induced Diabetic Mice

Genistein, an isoflavonoid phytoestrogen, has been known for its potential pharmacological properties especially for neuroprotection and treating diabetes. The present study aims to determine the neuroprotective efficacy of genistein against global cerebral ischemia-reperfusion-induced neuronal injury in streptozotocin-induced diabetic mice and explore the underlying mechanisms. Streptozotocin-induced diabetic mice were subjected to transient cerebral ischemia by occluding both common carotid arteries for 30 min followed by 24 h reperfusion to induce neuronal injury. Effect of genistein (2.5, 5.0, and 10.0 mg/kg, i.p., o.d.) treatment on ischemia-reperfusion-induced neuronal injury in diabetic mice was evaluated in terms of cerebral infarct size, oxidative damage, mitochondrial activity in terms of neuronal apoptosis and cellular viability, dipeptidyl peptidase-4 activity and active glucagon-like peptide-1 concentration, and neurological functions measured as short-term memory and motor performance. Genistein administration following transient cerebral ischemia significantly (p ˂ 0.0001) counteracted cognitive impairment and re-established (p ˂ 0.001) motor performance in diabetic mice. Ischemia-reperfusion increased the infarct size, genistein administration prevented the increase in cerebral infarct size (p ˂ 0.0001) and significantly suppressed (p ˂ 0.001) the increase in cerebral oxidative stress in transient cerebral ischemia-reperfusion subjected diabetic mice. Genistein treatment significantly (p ˂ 0.001) reduced neuronal apoptosis and increased cellular viability (p ˂ 0.0001), almost completely suppressed (p ˂ 0.0001) the circulating dipeptidyl peptidase-4 activity, and enhanced (p ˂ 0.0001) glucagon-like peptide-1 concentration in diabetic mice with cerebral ischemia-reperfusion. This study suggests that genistein has potent neuroprotective activity against global cerebral ischemia-reperfusion-induced neuronal injury and consequent neurological deficits in streptozotocin-induced diabetic mice.

Effects of 17β-estradiol and 2-methoxyestradiol on the oxidative stress-hypoxia inducible factor-1 pathway in hypoxic pulmonary hypertensive rats

The present study aimed to investigate the effects of 17β-estradiol (E2) and 2-methoxyestradiol (2ME) on the oxidative stress-hypoxia inducible factor-1 (OS-HIF-1) pathway in hypoxic pulmonary hypertensive rats. Female Sprague-Dawley rats were divided randomly into 4 groups, as follows: i) Control (Group A); ii) ovariectomy (OVX) + hypoxia (Group B); iii) OVX + hypoxia + E2 injection (Group C); and iv) 2ME injection (Group D). The rats were maintained under hypoxic conditions for 8 weeks, and mean pulmonary artery pressure (mPAP) and pulmonary arteriole morphology were measured. The reactive oxygen species, superoxide dismutase (SOD), manganese superoxide dismutase (MnSOD), and copper-zinc superoxide dismutase (Cu/ZnSOD) levels in serum were also measured. MnSOD and HIF-1α expression levels in lung tissue were determined by western blotting and reverse transcription-quantitative polymerase chain reaction. The mPAP and arterial remodeling index were significantly elevated following chronic hypoxia exposure; however, experimental data revealed a reduced response in E2 and 2ME intervention rats. Compared with Group A, Group B had significantly elevated oxidative stress levels, as illustrated by increased serum ROS levels, decreased serum SOD and MnSOD levels and decreased MnSOD mRNA and protein expression levels in lung tissue. Furthermore, HIF-1α mRNA and protein expression in Group B was significantly elevated compared with Group A. E2 and 2ME intervention significantly attenuated the aforementioned parameter changes, suggesting that E2 and 2ME partially ameliorate hypoxic pulmonary hypertension. The underlying mechanism of this may be associated with the increase in MnSOD activity and expression and reduction in ROS level, which reduces the levels of transcription and translation of HIF-1α.

The effectiveness of coagulation for water reclamation from a wastewater treatment plant that has a long hydraulic and sludge retention times: A case study

Coagulation is a feasible process to reclaim municipal wastewater, however, the role of coagulation in removing effluent organic matter (EfOM) from underutilized wastewater treatment plants (WWTPs) has not been fully explored. We identified the characteristics of the EfOM from a typical underutilized WWTP (i.e., the ratio of actual capacity to design capacity is 50%-70%), and investigated the performance of coagulation on suspended solids (SS) and dissolved organic matter (DOM) removal. The effluent could even satisfy the highest national standard of China (Class 1 A) for WWTP effluent, as evaluated by the traditional parameters such as SS and chemical oxygen demand (COD). However, the DOM in the EfOM we studied contained considerable biomass-associated products (BAPs), which were dominated by proteins with a molecular weight of approximately 150 kDa. In addition, protein also dominated the DOM after coagulation. Fulvic acid and humic-like acid organics were poorly removed by either AlCl3 or polyaluminum chloride (PAC) coagulation, even with a dosage as high as 24 mg Al L(-1). Biodegradability was very poor, as the ratio of biological oxygen demand (BOD5) to COD was less than 0.17. After coagulation the typical BAPs, protein and polysaccharide, remained as high as 1.6 mg L(-1) and 1.2 mg L(-1) respectively. In this study we found coagulation was ineffective for removal of recalcitrant BAPs.

Changes in microtubule-associated protein tau during peripheral nerve injury and regeneration

Tau, a primary component of microtubule-associated protein, promotes microtubule assembly and/or disassembly and maintains the stability of the microtubule structure. Although the importance of tau in neurodegenerative diseases has been well demonstrated, whether tau is involved in peripheral nerve regeneration remains unknown. In the current study, we obtained sciatic nerve tissue from adult rats 0, 1, 4, 7, and 14 days after sciatic nerve crush and examined tau mRNA and protein expression levels and the location of tau in the sciatic nerve following peripheral nerve injury. The results from our quantitative reverse transcription polymerase chain reaction analysis showed that compared with the uninjured control sciatic nerve, mRNA expression levels for both tau and tau tubulin kinase 1, a serine/threonine kinase that regulates tau phosphorylation, were decreased following peripheral nerve injury. Our western blot assay results suggested that the protein expression levels of tau and phosphorylated tau initially decreased 1 day post nerve injury but then gradually increased. The results of our immunohistochemical labeling showed that the location of tau protein was not altered by nerve injury. Thus, these results showed that the expression of tau was changed following sciatic nerve crush, suggesting that tau may be involved in peripheral nerve repair and regeneration.