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•The effect of carbon-to-nitrogen ratios in mDON generation dynamics was considered.•The simulation of mDON generation in four-denitrification was accurate (R2 = 0.909–0.986).•mDON ...formed in real wastewater was provided a reasonable prediction (1.16–1.63 mg/L).•Production of new nitrogenous molecules confirmed the model applicability.•High carbon-to-nitrogen ratios are of benefit to reduce effluent-associated ecological risk.
Quantifying microorganism-derived dissolved organic nitrogen (mDON) formed from microbial activities is a prerequisite for reducing effluent nitrogen. In this work, a new model based on activated sludge model for nitrogen (ASMN) is proposed for determining mDON formation together with its dynamics in post-denitrification under different carbon-to-nitrogen (C/N) ratios of 3, 4, 5, and 6. This model incorporates mDON as a separate component among four-step denitrification and introduces three new mDON-related parameters (i.e., fH,mDON, KH,mDON, and KI4SS) to develop mDON production and utilization equations. The model was calibrated and established with data from an experiment using synthetic wastewater, demonstrating its capability of accurately simulating mDON generation (R2 = 0.909–0.986). Accordingly, the simulated results successfully captured the experimental trends, suggesting that higher C/N ratios were preferred for mitigating mDON generation. The model applicability was further tested by predicting mDON generation in real wastewater, producing reasonable predicted results of formed mDON (1.16–1.63 mg/L). These predicted results were also indirectly confirmed by newly produced nitrogenous molecules (i.e., lipid-, carbohydrates-, and protein/amino sugars-like molecules). Overall, this work offers a tool to quantify mDON which benefits controlling mDON toward minimizing the adverse impacts of effluent organic nitrogen on receiving waters.
Depression is a common comorbidity in Parkinson's Disease (PD) and treatment of depression can significantly support PD management. Zishen pingchan granules (ZPG), a traditional Chinese herbal ...formula, may help ameliorate depressive symptoms in PD patients. However, the molecular mechanisms underlying the effects of ZPG remain unclear. This study aimed to investigate the impact of ZPG on serum levels of brain-derived neurotrophic factor (BDNF), interleukin-1β (IL-1β), interleukin-6 (IL-6), C-reactive protein (CRP), and tumor necrosis factor-α (TNF-α) in PD patients with depression.
Eighty PD patients treated with pramipexole but still experiencing mild to moderate depression symptoms were randomly allocated to a group receiving 12-week ZPG treatment (n = 40) or placebo (n = 40). The Hamilton Depression Scale 17 items (HAM-D-17) was utilized to evaluate changes in depressive symptoms from baseline over 12 weeks, while the Unified Parkinson's Disease Rating Scales (UPDRS) part 3 was employed to assess changes in motor symptoms over the same duration. Serum levels of BDNF, IL-1β, IL-6, CRP, and TNF-α were measured at baseline and post-treatment.
Seventy-one participants completed the study. Following treatment, both groups showed significantly reduced HAMD scores. The placebo group demonstrated a decrease in BDNF levels, while the ZPG group showed an increase in IL-6 levels post-treatment. In the examination of the group-time interaction, the ZPG group exhibited a greater decrease in HAMD scores and increase in IL-6 levels compared to the placebo group. Conversely, the placebo group showed a greater decrease in BDNF levels compared to the ZPG group. However, no significant group differences were observed in UPDRS part 3 change scores or serum levels of IL-1β, CRP, or TNF-α change from baseline.
ZPG may potentially ameliorate depressive symptoms in PD patients, with the potential mechanism involving mitigation of reductions in serum BDNF level and an increase in IL-6 level.
•Zishen pingchan granules (ZPG) may potentially alleviate depressive symptoms in PD patients.•ZPG has the potential to mitigate reductions in serum BDNF levels.•ZPG may lead to an increase in serum IL-6 levels.•The antidepressant effects of ZPG may be due to its ability to prevent decreases in BDNF levels and increase IL-6 levels.
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•A total of 4 different AHLs were detected in all anaerobic granular sludge.•C8-HSL and C10-HSL were the potentially universal AHLs in anaerobic granular system.•C8-HSL and C10-HSL ...might play an important role in the regulation of EPS production.•12 Microorganisms probably participated in the synthesis of EPS.
Although AHL-mediated quorum sensing (QS) signaling has been proved to be ecologically important in biofilm formation and aerobic granulation process, the biological role of AHL in anaerobic granule has not been experimentally investigated. In this paper, we explored the AHL level in 10 full-scale industrial anaerobic granular bioreactors and detected a total of 4 kinds of AHLs. C8-HSL and C10-HSL were indicated to be the potentially universal QS signal molecules in anaerobic granules and involved in extracellular polymeric substance (EPS) production and granulation process. The add-back experiments further supported the hypothesis that C8-HSL and C10-HSL might play an important role in facilitating anaerobic granulation through regulation of EPS synthesis. 12 Microorganisms might be regulated by AHL to play an important role in EPS production. This study provides a foundation for exploring the function of AHL in anaerobic granular systems, which may shed light on advanced AHL-based anaerobic granulation strategy.
Herein, we report a strategically novel method for the efficient construction of indole skeletons using 2-phenylisoxazol-5-ones as the starting material. This reaction proceeds via Brønsted ...acid-promoted α-iminyl cation generation by N–O bond cleavage and a subsequent intramolecular cyclization to afford 1H-indole-3-carboxylic acid, which further undergoes decarboxylation to yield the final product. Control experiments show that N–O bond cleavage and intramolecular cyclization proceed so fast that the 1H-indole-3-carboxylic acid could be isolated in high yields even after 5–10 min. The substrate scope of this transformation is broad, and the desired products are obtained in moderate to good yields. The transition-metal-free reaction condition, CO2 as the sole byproduct, and good practicability add to the synthetic potential of this transformation in the pharmaceutical and flavor industries.
•Effluent DON and NDMA precursors significantly increased at low DO (p<0.05).•Proteins-like DON contributed to 73.6% positive NDMA precursors-DON relationships.•Increased proteins-like DON was ...related to the accumulation of microbe-derived DON.•Low-DO effects on NDMA formation were delivered by DO-microbe-DON-NDMA links.•Good side and bad side of low-DO strategies should be simultaneously considered.
The presence of dissolved organic nitrogen (DON) in biological nutrient removal (BNR) effluent has led to increased concern about its adverse effects on wastewater discharge and reuse applications. Previous studies have demonstrated efficient biological inorganic nitrogen removal in BNR under low dissolved oxygen (DO) conditions; however, information on DON is scarce. This study investigated low-DO effects on DON and N-nitrosodimethylamine (NDMA) precursor concentrations in BNR effluents. Identical BNR reactors consisting of an external real-time DO intelligent control system were operated at three different DO concentrations (0.3, 1.0, and 4.0 mgO2/L). Surprisingly, significantly higher values of effluent DON (p<0.05, t-test) and NDMA precursors (p<0.01, t-test) were observed at lower DO levels. Ultrahigh-resolution mass spectrometry analysis showed that molecules produced by microbes at low-DO levels exhibited high proteins/amino sugars-like and low normal oxidation state of carbon characteristics, which possibly acted critical roles in NDMA formation. Furthermore, path analysis by partial least-squares path modeling suggested that NDMA formation potential had strong associations with microbe-DON network stability of microbe-DON co-occurrence interactions (r=0.979, p<0.01). These results highlight the necessity of reconsidering the feasibility of BNR systems operating at low-DO concentrations considering the adverse effects of DON on wastewater discharge and reuse applications.
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Ni/SBA-15 catalysts with various promoters (V, Ce, and Zr) were prepared by an ultrasonic coimpregnation method and used in CO methanation. The addition of promoters played a significant role in ...improving the catalytic activity of the Ni/SBA-15 catalyst. This improvement could be explained by changes in the valences of the V and Ce promoter species through an oxidation-reduction shift cycle process (M
x
+
↔ M
y
+
, M = V, Ce), which could trigger electron transfer. This transfer enhanced the electron density of active Ni species and promoted CO dissociation. The Zr promoter could produce oxygen vacancies during calcination and reduction, thereby increasing the ability of CO to adsorb and dissociate. In addition, the formation of a Si-O-M bond (M = Zr, Ce, V) increased the interaction between the active species and support, which facilitated CO methanation. Under 1.0 MPa and a WHSV of 15 000 mL g
−1
h
−1
, 10Ni-5V/SBA-15 exhibited the best catalytic performance (99.9% CO conversion; 95.5% CH
4
selectivity).
The addition of promoter species to 10Ni/SBA-15 catalysts is of significant importance for the CO methanation reaction.
Previous research has focused on dissolved organic carbon (DOC) as a surrogate for soluble microbial products (SMPs) and found that temperature has a significant influence on the production of ...SMP-based DOC (SDOC) during biological processes. Little is known about the SMP-based dissolved organic nitrogen (SDON), although some nitrogenous organic matter has been identified as an important part of SMPs. This study investigated the effect of temperature (8 °C, 15 °C and 25 °C) on the characterization of SMPs in an activated sludge system with special emphasis on SDON. Results showed the positive effect of reduced temperature on SDON production. Fluorescence spectroscopy and ultrahigh-resolution mass spectrometry showed the produced SDON at 8 °C and 15 °C exhibits more lability than at 25 °C. This was also supported by the algal bioassay, indicating the SDON produced at low temperature is highly bioavailable and prone to stimulate algae and microorganisms. In addition, principal component analysis demonstrated that the effect of temperature on the chemical characterization of SDON is different from that of SDOC. Overall, this study highlights the importance of SDON control during biological processes at a low temperature to reduce the potential impact of effluent SMPs on receiving waters or wastewater reuse.
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•The effect of temperature on the characterization of SDON was investigated.•Results showed the positive effect of reduced temperature on SDON production.•SDON produced at low temperature was highly bioavailable.•The effect of temperature on the characterization of SDON was different from that of SDOC.
Biofilm start-up is a critical and time-consuming process in moving bed biofilm reactors (MBBRs), with the procedure beginning with bacteria being statically bound on surfaces. Studies addressing ...this critical process have mainly focused on constructing models based on single strains, although consideration of the unstable adhesion process of structured bacterial communities remains underexplored. In this study, impedance based real-time cell analysis (RTCA) was employed to quantitatively characterize the unstable adhesion process of structured bacterial communities collected from the aerobic tanks of eight full-scale wastewater treatment plants (WWTPs). The unstable adhesion time ranged from 8.85 ± 1.53 h to 17.06 ± 0.64 h, indicating significant differences in bacterial colonization properties. Using principal components analysis (PCA), Na+, K+ and proteins were found to significantly influence the biofilm unstable adhesion process. Furthermore, the differences in unstable adhesion times were closely related to the abundance of the most abundant operational taxonomic units (OTUs). The dominant OTUs mainly belonged to Aeromonadaceae and Enterobacteriaceae, with 73% found to be negatively corelated with unstable adhesion time. Furthermore, bacterial assembly during the initial adhesion phase was driven by bacterial interactions and key OTUs (exhibiting maximum connectivity in phylogenetic molecular ecological networks (pMENs)). Analysis of pMENs indicated that bacterial cooperation was a dominant factor in the initial adhesion, which may involve bacterial co-colonization, co-aggregation and communication. Considering keystone taxa were not identified, OTUs with max connectivity in pMENs were considered as key species. Although these key species play important roles in the connection of networks, their relative abundances were low and no significant relationships were observed with the unstable adhesion time. Overall, unstable adhesion in MBBRs is regulated by the dominant bacterial species and the alleviation of environmental variables by repulsive forces, providing potential strategies of dosing quorum sensing signals and key cations at the initial adhesion phase in reactors, to facilitate initial biofilm formation.
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•The unstable adhesion time of biofilms were identified via on-line RTCA.•High concentrations of Na+ and K+ were conducive to the formation of firm adhesion.•Differences in unstable adhesion time were well explained by the 5 most abundant taxa.•Bacterial communities possess high complexity during the initial adhesion phase.
There is debating over the question of whether the large-scale 'Grain for Green' program on the Loess Plateau of China threatens regional food security. Self-sufficiency index and cropland pressure ...index were used to assess food security on the Loess Plateau after the implementation of revegetation program. The results showed that the 'Grain for Green' program initially had a considerable impact on regional food security, where grain yield fell from 1999 to 2001, resulting in a lower grain self-sufficiency and increased farmland stress. Subsequently, grain yield in this region increased due to the elevated agricultural material input and increased construction of terraces and check dams. The grain self-sufficiency index would have increased to 96.55% if there were improvements to the agricultural conditions, such as fertilization and irrigation, which would have resulted in an increase in the crop yield per unit of 20%. However, the grain self-sufficiency increased to 105.25% via the construction of terraces and check dams. Thus, the government should further expand the 'Grain for Green' program in coordination with improvements to the agricultural production conditions and the construction of terraces and check dams on the Loess Plateau.
Wastewater-derived dissolved organic nitrogen (DON) should be minimized by municipal wastewater treatment plants (MWWTPs) to reduce its potential impact on receiving waters. Solids retention time ...(SRT) is a key control parameter for the activated sludge (AS) process; however, knowledge of its impact on effluent DON is limited. This study investigated the effect of SRT on the bioavailability, fluorescent components, and molecular characteristics of effluent DON in the AS process. Four lab-scale AS reactors were operated in parallel at different SRTs (5, 13, 26, and 40 days) for treatment of primary treated wastewater collected from an MWWTP. Results showed the positive effect of prolonged SRT on DON removal. AS reactors during longer SRTs, however, cannot sequester the bioavailable DON (ABDON) and occasionally contribute to greater amounts of ABDON in the effluents. Consequently, effluent DON bioavailability increased with SRT (R 2 = 0.619, p < 0.05, ANOVA). Analysis of effluent DON fluorescent components and molecular characteristics indicated that the high effluent DON bioavailability observed at long SRTs is contributed by the production of microbially derived nitrogenous organics. The results presented herein indicate that operating an AS process with a longer SRT cannot control the DON forms that readily stimulate algal growth.
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