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Artificial sweeteners discharged into aquatic environments have raised concern because of their ubiquitous occurrence and potential biological effect. And some of them, such as sucralose (SUC) and acesulfame (ACE), have been identified as emerging contaminants. Wastewater treatment plants (WWTPs) are considered as important sources and sinks of artificial sweeteners discharged into the environment. In this study, the occurrence and removal of four representative artificial sweeteners in 12 WWTPs located in different provinces of China were investigated. The results showed that artificial sweeteners were detected widely in the investigated WWTPs. The median concentrations of the four target artificial sweeteners were detected in influents at levels of 0.03-3.85 μg L

In this study, the spatiotemporal variation in the occurrence of 19 endocrine-disrupting chemicals (EDCs) spanning four seasons in wastewater treatment plants (WWTPs) located in 17 Chinese cities was investigated. Removal efficiencies for selected EDCs in 17 WWTPs over four seasons were analyzed. Contributions of conventional and advanced process segments to the removal efficiency of EDCs were explored, which compared the removal efficacies of a variety of secondary and advanced processes for EDCs. Results showed that EDCs were extensively detected in WWTPs, with bisphenol A (BPA), dehydroepiandrosterone (DHRD), androstenedione (ADD), and pregnanediol (PD) being dominant in excess sludge and wastewater. Seasonally, the greatest seasonal differences were observed in the influent, with the concentrations of 12 EDCs varying significantly between seasons. Spatially, concentrations of BPA, DHRD, testosterone (TTR), and estriol (E3) in the influent significantly varied between the northern and southern WWTPs. Fourteen EDCs were removed steadily among the four seasons, while most EDCs had considerable removal differences between WWTPs. Contribution of the conventional process segment to the removal of individual EDCs was higher than that of the advanced process segment in WWTPs. Quantitative meta-analysis indicated that the anaerobic-anoxic-anaerobic (AAO) process in the various secondary processes had the highest removal of the target EDCs. Mass balance analysis further suggested that biodegradation in the aerobic tank of the AAO process was the major pathway for most EDCs removal. This study systematically depicts the spatiotemporal distribution of EDCs in WWTPs located across China and deepens the comprehension of EDCs removal in Chinese WWTPs from a treatment process perspective.

Progesterone (P4) and norgestrel (NGT) are two steroid progestogens that can pose adverse effects on aquatic organisms at ng/L levels. Despite increasing concern on their occurrence and removal in wastewater, their fate in the wastewater treatment process has not been well documented. This study identified the transformation products (TPs) of P4 and NGT in anaerobic/anoxic/oxic (A/A/O) process. Potential functional genes involved in biotransformation of P4 and NGT were explored. The elimination or formation behavior of P4, NGT and convinced TPs along various units of A/A/O process was revealed through the mass flow. Results showed that 12 and 13 TPs were identified in the P4 and NGT groups respectively, wherein 10 identical TPs and C-19 structures transformation pathways were observed in both groups. Six genes were found that may be involved in dehydrogenation and isomerization reactions in the pathways. Mass flow indicated that P4 and NGT were mainly eliminated in anaerobic and anoxic units, while convinced TPs mainly formed in anaerobic and anoxic units and were then eliminated in aerobic unit. Further, the ecological risks of the effluent should not be ignored as residual compounds including P4 or NGT and their TPs in the effluent still posed adverse effects on zebrafish transcript levels.

The characteristics of dissolved organic matter (DOM) can significantly affect the degradation of target compounds by the advanced oxidation processes. In this study, the effects of the different hydrophobicity/hydrophilicity fractions, molecular weight (MW) fractions, fluorescence components and molecular components of DOM extracted from municipal wastewater on the degradation of 4 pharmaceutically active compounds (PhACs), including carbamazepine, clofibric acid, atenolol and erythromycin by the UV/H

This study investigated the overall occurrence and spatiotemporal variation of 19 progestogens in 608 samples collected from 17 wastewater treatment plants (WWTPs) distributed across China during four seasons. The aqueous removal efficiencies of progestogens were calculated and the efficacies of process segments, secondary and advanced processes, and process units in the removal of progestogens were explored. The results indicated that progestogens were widely detected in investigating WWTPs, with the progesterone, dydrogesterone, dienogest, ethisterone, and norethindrone were always dominant in the influent, secondary effluent, final effluent, and excess sludge. Seasonally, the influent exhibited more variability than the other matrices, that 10 progestogens concentrations varied significantly during the four seasons. Spatially, the influent concentrations of progestogens were generally higher in northern WWTPs than that in southern WWTPs during spring and summer. Eight progestogens were stably removed by the WWTPs across seasons, and most progestogens varied considerably in removal in different WWTPs. The conventional process segment was the dominant contributor to progestogen removal. The anaerobic-anoxic-oxic process and a combined process consisting of densadeg and cloth media filter and ultraviolet disinfection showed the highest removal of progestogens among various secondary and advanced treatment processes, respectively. Mass balance analysis showed that most progestogens were effectively eliminated in the aerobic unit, with biodegradation being the primary removal pathway. This study presents the first picture of the spatiotemporal dynamics of the distribution of progestogens in WWTPs of China and provides valuable information for better understanding of the occurrence and removal of progestogens in WWTPs.

Understanding the degradation of dissolved organic matter (DOM) is vital for optimizing DOM control. However, the microbe-mediated DOM transformation during wastewater treatment remains poorly characterized. Here, microbes and DOM along full-scale biotreatment processes were simultaneously characterized using comparative genomics and high-resolution mass spectrometry-based reactomics. Biotreatments significantly increased DOM's aromaticity and unsaturation due to the overproduced lignin and polyphenol analogs. DOM was diversified by over five times in richness, with thousands of nitrogenous and sulfur-containing compounds generated through microbe-mediated oxidoreduction, functional group transfer, and C-N and C-S bond formation. Network analysis demonstrated microbial division of labor in DOM transformation. However, their roles were determined by their functional traits rather than taxa. Specifically, network and module hubs exhibited rapid growth potentials and broad substrate affinities but were deficient in xenobiotics-metabolism-associated genes. They were mainly correlated to liable DOM consumption and its transformation to recalcitrant compounds. In contrast, connectors and peripherals were potential degraders of recalcitrant DOM but slow in growth. They showed specialized associations with fewer DOM molecules and probably fed on metabolites of hub microbes. Thus, developing technologies (e.g., carriers) to selectively enrich peripheral degraders and consequently decouple the liable and recalcitrant DOM transformation processes may advance DOM removal.

Progestagens discharged from municipal wastewater treatment plants (WWTPs) have increasingly gained attention due to their potential risks to the aquatic organisms. However, limited information is available on the occurrence and removal of various progestagens in WWTPs in different cities of China. This work investigated the occurrence and removal of 11 progestagens in 21 WWTPs from 19 Chinese cities. Results showed that progestagens are widely distributed in the investigated WWTPs, with higher influent concentrations of total progestagens in northern WWTPs. The concentration of progestagens in WWTP influent were closely correlated with influent quality, service population and daily service volume of the WWTPs. Additionally, progesterone (PGT) and dydrogesterone (DDT) were two predominant progestagens in influent, effluent and excess sludge. Up to 5 of 11 progestagens showed high aqueous removal efficiencies (median removal efficiency >90%), whereas megestrol acetate (MTA), chlormadinone acetate (CMA), drospirenone (DSP) and levonorgestrel (LNG) had a removal efficiency of below 50%. Specially, the behaviors of progestagens along the anaerobic-anoxic-oxic of a WWTP were further explored and the aerobic tank is the main contributor to the removal of progestagens. Finally, in the effluent of these 21 WWTPs, daily mass loadings of the total progestagens ranged from 0.51 to 10.4 g d−1. Notably, LNG exhibited high potential risk to the fish base on risk quotient.

The objective of this study was to establish a quantitative response to biofilm aging from perspectives of metabolic activity and microbial community applied in distinct wastewater. Biofilms developed on soft, integrated and suspended biocarriers in three full-scale aerobic bioreactors under stable operations from municipal and industrial wastewater treatment plants, were tracked for more than 11 weeks for biofilm aging study. Results showed the first evidence of biofilm aging in full-scale aerobic bioreactors by adenylate energy charge (AEC) that biofilm needed to be reactivated when AEC was less than 0.6. Biofilm aged more easily on soft and integrated biocarriers and high salinity, high organic contents and high suspended sludge concentration accelerated the aging process of biofilm. Caldilinea and Acinetobacter predominated in aging biofilm on suspended biocarriers. This study offered a novel evaluation methodology of biofilm aging and was believed to provide important reference for biofilm regulation in biofilm-based wastewater treatment process.

The frequent detection of artificial sweeteners (ASs) in wastewater and surface water gives rise to concerns about their removal, Acesulfame (ACE) and sucralose (SUC) are two ASs that are difficult to remove. The ultraviolet/persulfate (UV/PS) advanced oxidation technology (AOT) is being considered as an effective process for the degradation of micropollutants in wastewater. However, the study of the degradation of ASs in real wastewater by the UV/PS is minimal. This study investigated the kinetics and modeling of ACE and SUC degradation in wastewater by the UV/PS process. Both ACE and SUC could be degraded effectively using this process. The degradation of ACE was mainly attributed to UV photolysis (51%), HO∙ (26%) and SO4∙- (16%), while that of SUC was mainly attributed to HO∙ (68%) and SO4∙- (27%). The second-order rate constants of ASs with SO4∙- were significantly lower than that with HO∙. Three major transformation products (TPs) of ACE and four major TPs of SUC were identified. Additionally, the effects and mechanisms of the water matrices, such as HCO3−, Cl−, NO3− and natural organic matter (NOM), on ASs degradation were investigated through response surface methodology (RSM). NOM and Cl− significantly inhibited the degradation of ACE in the UV/PS system, whereas NOM and HCO3− played a main inhibition role on the degradation of SUC. A water matrices parameter model for predicting ASs degradation in real wastewater was established by RSM for the first time, and the removal of ACE and SUC was well predicted by the model.

Deficiency of researches on biotic community-driven biofilm activity makes biofilm regulation lack of quantitative response for decades. Based on three full-scale aerobic bioreactors in wastewater treatment plants, this study for the first time linked microbial respiratory activity with phospholipid fatty acid (PLFA) of biofilm developed on fixed and suspended carriers. Results showed that C16:00, C18:00, C16:1, ω7c, C18:1, ω7c, C12:00 and C18:1ω9c were top six biomarkers of PLFA among different sources of samples and Gram-negative bacteria (G−) was more abundant than Gram-positive bacteria (G+) with average G−/G+ of 2.98. It’s interesting to find defective revealing of PLFA-based biofilm activity by specific oxygen uptake rate (SOUR). Further modeling indicated that C16:00 achieved the optimal quantitative response to STOUR with the best model of composite, growth, or exponential curve (R2 = 0.416, p = 0.005). This research was promising to provide important reference for biofilm regulation and accurate control of biofilm-based process.

Advanced nitrogen removal of effluent discharged from secondary treatment systems can avoid eutrophication. However, the lack of biodegradable organics limits biodenitrification. Packed bed reactors filled with carriers with different micromagnetic field (MMF) strengths were used to perform tertiary denitrification. The results showed that MMF significantly improved the denitrification performance, especially at low C/N ratios. Total nitrogen (TN) removal was increased by 4.12% with 0.6 mT MMF when C/N = 4 and increased by 7.06% and 8.06% with 0.3 mT and 0.9 mT MMFs when C/N = 3, respectively. Zooglea, Flavobacterium, and Denitratisoma contributed to the advanced denitrification performance under MMF. In addition, 0.6 mT MMF enhanced nitrogen metabolism and ABC transporter protein and two-component system activities of microorganisms under C/N = 4; 0.3 mT and 0.9 mT MMFs increased nitrogen, carbohydrate, and amino acid metabolism and ABC transporter protein activities under C/N = 3. These findings indicate that MMF has great potential for advanced denitrification from secondary effluent.

This study aimed to explore whether the “window” effect of static magnetic field (SMF) on nitrous oxide (N2O) emission from the biological nitrogen removal process at low temperature existed and reveal its biological mechanism at the gene level. Four sequencing batch reactors (SBRs) with SMFs of 0, 10, 45, and 75 mT were operated continuously for 110 days at 10 °C and the lowest N2O-Gas cumulative emission (5.50 mg N/day) and N2O conversion rate (4.28 %) in 45 mT SMF-SBR verified the existence of the “window” effect. In 45 mT SMF-SBR, nearly all enzymatic activities related to N2O reduction and corresponding functional gene abundances improved significantly. Metagenomic high-throughput sequencing analysis revealed that Alicycliphilus denitricans, Paracoccus denitrificans, Rhodopseudomonas palustris, Pseudomonas stutzeri, and Dechloromonas aromatica, as species related to N2O reduction, could be separately enriched by applying suitable SMF intensity. Gene functions annotation based on KEGG and CAZy databases indicated that SMF not only accelerated the rate of free ammonia into ammonia-oxidizing bacteria and electrons delivered to the corresponding denitrification reductases, but also enhanced the degradation of complex organic matter into smaller molecules, and thus reducing the production of N2O via nitrifier denitrification and incomplete denitrification pathways at 10 °C. These findings provided a guideline and presented a blueprint of ecophysiology for the future application of magnetic field to the reduction of N2O emission in wastewater treatment plants in the cold region.

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.

Dissolved organic matter (DOM) mediates the microbial transformation of micropollutants, including norgestrel (NGT) in natural waters. However, little is known of the effect of complex and variable wastewater-derived DOM composition on NGT degradation during wastewater treatment. In this study, the relationship between the compositions of initial DOM and NGT removal efficiencies of 17 wastewater treatment plants (WWTPs) in spring and summer were analyzed. The different molecular composition of DOM was selected in the lab to further explore its effect on NGT degradation by activated sludge. Results indicated that the DOM composition was a substantial driver of NGT removal in WWTPs. The discrepancies in the initial DOM composition contributed to the differences in the kinetics of NGT degradation by activated sludge. The larger rapid decay phase rates of NGT are usually accompanied by a large proportion of labile substances in DOM. High-throughput sequencing and ultrahigh-resolution mass spectrometry were used to further analyze the evolution of bacterial communities and DOM molecular composition were combined with network analysis to reveal the intrinsic relationship that how DOM composition affected NGT degradation by regulating core microbes. Eighty-nine core OTUs were significantly associated with NGT degradation, and 73 occurred in the rapid decay phase, implying that NGT degradation was mainly regulated by the initial composition of DOM. Nine major transformation products were identified in different groups with widely varying concentrations or relative abundances of these transformation products. This work provides valuable insights into the effects of wastewater-derived DOM composition on NGT degradation by activated sludge and innovatively explores the influence mechanisms from the bacterial community and molecular characterization perspectives.

Activated sludge process with anaerobic side-stream reactors (SR) in the sludge recirculation can achieve in-situ sludge reduction, but sludge reduction efficiency is limited with the low hydraulic retention time (HRT) of SR. An anoxic/aerobic (AO) process, AO coupled with anaerobic SR and AO coupled with alternating aerobic/anaerobic side-stream reactor (AO-OASR) were operated to investigate enhancing effects of alternative aerobic and anaerobic condition (AltOA) in SR on sludge reduction and pollutants removal performance. The AltOA was firstly proposed into SR with a low HRT during the long-term continuous operation. The results showed that AO-OASR presented a lower effluent COD concentration (29.6%) with no adverse effect on nitrogen removal, compared to AO, owing to the intensified refractory carbon reuse in the mainstream aerobic tank. The sludge yield in AO-OASR (0.240 g SS/g COD) was 39.7% lower than that in AO. The OASR accelerated sludge lysis and particle organic matter hydrolysis due to the weakened network strength of flocs, leading to an enhanced increase (17.3 mg/L) of dissolved organic matter (DOM), especially for the fraction of molecular weight (MW) 25 kDa. The OASR reduced the adenosine triphosphate (ATP) content for heterotrophic anabolism in the mainstream reactor by 42.9%, compared to the ASR. MW 25 kDa of DOM caused the disturbance of oxidative phosphorylation with a decreasing ATP synthase activity under high-level electronic transport system, leading to ATP dissipation. The cooperation interaction of predator (norank_Chitinophagales), hydrolytic/fermentative bacteria (unclassified_Bacteroidia and Delftia), and slow grower (Trichococcus) played a key role in improving the sludge reduction and carbon reuse in AO-OASR. The results provided an efficient and cost-saving technology for sludge reduction with modified SR under low HRT, which is meaningful to overcome the present bottleneck of deficient reduction efficiency for application in wastewater treatment plants.

In this study, the effect of Fe

The adverse effect of pharmaceuticals on ecosystem and human health raises great interest for the removal of pharmaceuticals in wastewater treatment plants (WWTPs). Enhanced removal of pharmaceuticals by ammonia oxidizers (AOs) has been observed during nitrification. This review provides a comprehensive summary on the removal of pharmaceuticals by AOs—ammonia oxidizing bacteria (AOB), ammonia oxidizing archaea (AOA), and complete ammonia oxidizer (comammox) during nitrification in pure ammonia oxidizing culture and mixed microbes systems. The superior removal of pharmaceuticals by AOs in conditions with nitrifying activity compared with the conditions without nitrifying activity was proposed. The contribution of AOs on pharmaceuticals removal in pure and mixed microbe systems was discussed and activated sludge modeling was suggested as the proper measure on assessing the contribution of AOs on the removal of pharmaceuticals in mixed microbe culture. Three transformation processes and the involved reaction types of pharmaceuticals transformation during nitrification were reviewed. The present paper provides a systematical summary on pharmaceuticals removal by different AOs across pure and mixed microbes culture during nitrification, which opens up the opportunity to optimize the wastewater biological treatment systems for enhanced removal of pharmaceuticals. • The superior removal of pharmaceuticals by ammonia oxidizers (AOs) was summarized. • The removal contribution of pharmaceuticals attributed by AOs was elucidated. • The transformation processes and reaction types of pharmaceuticals were discussed.

Pharmaceutically active compounds (PhACs) have been frequently detected in aquatic environment and raised concerns because of their environmental persistence and potential ecological risk, especially carbamazepine (CBZ), erythromycin (ERY), atenolol (ATL) and clofibric acid (CA). The UV/H

Nanoplastics (NPs) and microplastics (MPs) are a heterogeneous class of pollutants with diverse sizes in aquatic environments. To evaluate the hazardous effects of N/MPs with different sizes, the accumulation, oxidative stress, cytochrome P450 (CYP) enzymes, neurotoxicity, and metabolomics changes were investigated in the red tilapia exposed to three sizes of polystyrene (PS) N/MPs (0.3, 5, and 70 − 90 μm). After 14-d exposures, the largest particles (70 − 90 μm) showed the highest accumulation levels in most cases. Exposures to PS-MPs (5 and 70 − 90 μm) caused a more severe oxidative stress in red tilapia than PS-NPs. The activity of CYP3A-related enzyme was obviously inhibited by PS-NPs, whereas the CYP enzymes in the liver may not be sensitive to MP exposures. In the brain, only 5 μm PS-MPs significantly inhibited the acetylcholinesterase activity. After exposures, the treatments with 0.3, 5, and 70 − 90 μm N/MPs resulted in 31, 40, and 23 significantly differentially expressed metabolites, respectively, in which the pathway of tyrosine metabolism was significantly affected by all the three PS-N/MP exposures. Overall, the PS particles within the μm size posed more severe stress to red tilapia. Our results suggest that the toxicity of N/MPs may not show a simply monotonic negative correlation with their sizes.

Chemical high-risk pollutants (HRPs) in wastewater have received growing concerns in recent years for their persistent input and potential threat to ecological environment and human health. Heavy metals, persistent organic pollutants (POPs), pharmaceutical and personal care products (PPCPs), endocrine disrupting chemicals (EDCs), and disinfection by-products (DBPs) are the most frequently detectable chemical HRPs in wastewater. Understanding the environmental behavior and transformation characteristic of chemical HRPs is important to their removal and risk reduction in environment. In this chapter, according to the different types of chemical HRPs in municipal wastewater and industrial wastewater, the source of different chemical HRPs are introduced at first. Then, the occurrence and contamination levels of chemical HRPs are summarized item by item. Furthermore, the migration and transformation processes of chemical HRPs and the major factors are described in detail. This information contributes not only to further understand the fate of chemical HRPs but also to control the HRPs in wastewater.

Progesterone (PGT) is not completely removed in conventional treatment plants, and the processing results may have adverse effects on aquatic organisms. In this study, an effective PGT-degradation bacterium, Rhodococcus sp. HYW, was newly isolated from the pharmaceutical plant and was used to augment degradation of PGT. When grown in a mineral medium (MM) containing a trace amount of PGT (500 μg/L) as the sole carbon and energy source, the results show that 99% of PGT was degraded within 1 h and followed the first-order reaction kinetics. Bioaugmentation of PGT-contaminated activated sludge greatly enhanced the PGT degradation rate (∼91%) and its derivatives degradation rate were also greatly improved (>83%). The process of PGT degradation in non-bioaugmented PGT-contaminated activated sludge (NBS) and bioaugmentation activated sludge with the bacterial consortium(BS) also conforms to the first-order kinetic model. Furthermore, 12 and 11 biodegradation products for PGT in the NBS and BS were identified using HPLC-LTQ-Orbitrap XL™, respectively. Based on these biodegradation products, two degradation pathways for PGT in NBS and BS were proposed, respectively. Comparing the degradation kinetics and metabolites, it was found that BS degrades PGT more rapidly and can further convert PGT to a small molecular acid. Finally, to reveal the probable cause for the differences in the PGT degradation efficiency and products in the NBS and BS.

This paper investigated the influences of different dissolved oxygen (DO) concentration (0.71–1.32, 2.13–3.02 and 4.31–5.16 mg/L) on cell membrane characteristics and microbial population distribution of moving biofilm reactors. Two representative reactors, i.e., moving bed biofilm reactors and integrated fixed-film activated sludge were operated. Results indicated that both DO concentration of 0.71–1.32 mg/L and 4.31–5.16 mg/L could increase membrane lipid mobile fraction (49.4%-67.4%) of the microbes, however, through prompting the synthesis of branched fatty acids and unsaturated fatty acids, respectively. For the biofilms, the abundance of Bacteroidetes decreased and Actinobacteria increased with the increase of DO levels. The lowest EfOM content and the highest microbial diversities (1.14–1.52) was observed at DO of 2.13–3.02 mg/L. Redundancy analysis showed that changes of DO levels could alter cell membrane properties and bacterial community structures, and subsequently significantly influenced effluent organic matter composition of moving biofilm reactors.

Phosphite (P+III) is of emerging chemical interest due to its importance within the global phosphorus cycle. Yet, to date, precise/accurate measurements of P+III are still lacking due to the inherent analytical challenges linked to its instability/ease of oxidation and ultra-trace concentration. Here, we present the first in-situ sampling and speciation analysis method, for dissolved P+III, using the diffusive-gradients-in-thin-films (DGT) technique, combined with capillary-column-configured-dual-ion-chromatography (CC-DIC). Method optimization of the DGT elution regime, to simultaneously maximize desorption efficiency and CC-DIC sensitivity, along with the characterization of diffusion coefficients for P+III, were undertaken before full method validation. Laboratory-performance testing confirmed DGT-P+III acquisition to be independent of pH (3.0–10.0) and ionic strength (0–500 mM). The capacity for P+III was 45.8 μg cm−2, while neither P+V (up to 10 mg L−1) nor As+V (up to 1 mg L−1) impacted the DGT-P+III measurement. This novel method's functionality stems from the herein confirmed speciation preservation and double pre-concentration of P+III, resulting in quantification limits as low as 7.44 ng L−1 for a 3-day deployment. Applications of this method in various terrestrial/aquatic environments were demonstrated and simultaneous profiles of P+III and P+V across a sediment-water interface were captured at mm resolution in two contrasting redox-mesocosm systems.

Startup of biofilm process triggered by initial adhesion of bacteria is difficult in high ammonia nitrogen wastewater treatment. In this study, the influence of two commonly used N-acyl homoserine lactones (AHLs), N-Hexanoyl-l-homoserine lactone (C6-HSL) and N-Octanoyl-l-homoserine lactone (C8-HSL), on the adhesion of soluble macromolecules and bacteria in four types of high ammonia nitrogen wastewater to surfaces of model biocarriers (i.e. polystyrene, polyamide and polyethylene terephthalate) was investigated by using a quartz crystal microbalance with dissipation (QCM-D) monitoring technology. Results showed that the adhesion was enhanced by the addition of exogenous AHLs and there was more microbial retention attributed by C8-HSL. Greater deposition amount was generally found on PS and better enhanced performances of the adhesion were found on PA surface. Furthermore, viscoelastic film formed under synchronous high-low salinity and organic content and dominant bacteria of real wastewater determined the role of exogenous AHLs. The method of adding moderate amount of exogenous AHLs into bioreactors has important implications for accelerating the startup process treating high ammonia nitrogen wastewater by biofilm process.

Start-up of biofilm process initiated by the deposition of soluble matters on biocarriers is a very important yet time-consuming procedure. However, rapid start-up methods especially in the enhancement of soluble matters deposition have been rarely addressed. In this study, a quartz crystal microbalance with dissipation monitoring (QCM-D) was applied to investigate the influences of calcium ion and rhamnolipid (RL) on the deposition of soluble matters from real and synthetic industrial wastewaters with different configurations of organics (bovine serum albumin and sodium alginate) and ionic strength on the model biocarriers polystyrene and polyamide. Results showed that deposition was effectively promoted by the addition of Ca2+ and along with the increase in Ca2+ content. However, RL enhanced the deposition effectively only in hyperhaline wastewater through breaking hydration repulsion and decreased the deposition in low-salinity wastewater, and its influence to the deposited layer property exhibited characteristics of negative feedback. The combined use of Ca2+ and RL had a better enhancement effect than that of separate use and the mechanism involved can not be soundly explained only by Derjaguin−Landau−Verwey−Overbeek (DLVO) theory. The strategy of mediating the deposition of soluble matters on different biocarriers by adding Ca2+ and RL has important implications for regulating biofilm formation to accelerate the start-up process in attached-growth bioreactors.

Biofilm development plays an important role in facilitating wastewater treatment. The ultrasonic time domain reflectometry (UTDR) is presented for the first time as a tool to assess the initial biofilms development process on bio-carriers. The experiments were carried out with bio samples gathered from practical municipal wastewater and industrial wastewater, respectively. The in-situ and non-invasive UTDR technique was applied to visualize and evaluate the biofilm development process on slices through using the 2D and 3D wavelet analysis by a false color scale. Especially, the distinguished biofilms thickness was observed during the initial biofilm development process via a differential signal, and the relatively dense degree of biofilm were also obtained at the same time. The UTDR measurement could distinguish the initial adherence, reversible adhesion and irreversible adhesion during the initial biofilm formation process. In addition, the UTDR response correlates well with the off-line measurements of the biofilm thickness via an atomic force microscope and optical coherence tomography, suggesting that UTDR-based characterization is a useful tool for in-situ investigating the dynamic processes of predefined biofilm development used for wastewater treatment.

Activated sludge process with anaerobic side-stream reactors (SR) in the sludge recirculation line can achieve in-situ sludge reduction. But sludge reduction efficiency (SRE) is limited with low cell lysis and particle organic matter hydrolysis rates under short hydraulic retention time of SR for practical application. This study firstly inserted alternating micro-aerobic/anaerobic conditions (AMAC) and packing carriers into SR with low hydraulic retention time for improving SRE. The effects of AMAC and packing carriers on sludge rheology properties, molecular characteristics of dissolved organic matter (DOM) and microbial communities were investigated. Results showed that AMAC coupled packing carriers achieved SRE by 51.09% with efficient effluent pollutant removal. AMAC specialized inactive particle organic matter hydrolysis and active cell lysis in the micro-aerobic and anaerobic SR, respectively. Packing carriers intensified this function division effect. This effect weakened colloidal entanglement of flocs. It intensified the cell lysis in mainstream aerobic tank, causing the accumulation of refractory lignins in DOM. The higher utilization of released bioavailable DOM decreased microbial activity. Overall, the improved SRE favored the declined DOM bioavailability by inserting AMAC and packing carriers in SR. The sludge reduction-related bacteria like slow growing (Dechloromonas), predatory (Norank_Saprospiraceae), and hydrolytic/fermentative bacteria (Chelatococcus, Pseudomonas, Tolumonas, and Unclassified_Bacteroidia) were involved in decreasing DOM bioavailability. This study advanced our knowledge about the effects of AMAC and packing carriers on in-situ sludge reduction systems. This research also showed how AMAC and packing carriers enhanced the sludge lysis/hydrolysis for sludge reduction.

Wastewater treatment plants (WWTPs) are the main sources of emerging contaminants (ECs) in aquatic environment. However, the standards for limiting emerging pollutants in effluent are extremely lacking. We investigated the occurrence and removal of emerging pollutants in 16 WWTPs in China using non-target analysis. 568 substances screened out were divided into 9 kinds including 167 pharmaceuticals, 113 natural substances, 85 pesticides, 86 endogenous substances, 64 chemical raw materials, 14 personal care products, 17 food additives, 6 hormones and 16 others. And they were divided into 5 fates. Pesticides and pharmaceutical compounds seemed to be the most notable categories, the kinds detected in each sample is the largest compared with other compounds. Besides, the average removal rate of pesticides and pharmaceuticals in all WWTPs were the lowest, at 9.54% and 23.77%, respectively. Priority pollutants were screened by considering distribution of pollutants with different fates. Pollutants with the same fate especially "consistent" in different WWTPs had attracted attention. 4 potential priority pollutants including metoprolol, carbamazepine, 10, 11-dihydro-10, 11-dihydroxycarbamazepine and irbesartan were proposed. And it was found that the 4 compounds, "consistent suspects" and "consistent non-targets" had similar rankings of removal rate in 16 WWTPs, which can reflect the performance of different WWTPs.

The compositional characteristics of dissolved organic matter (DOM) in pharmaceutical wastewater effluent can affect the further improvement and application of the ozone treatment process. The present study investigated the changes of chemical structures, molecular weight (MW) distribution, hydrophobicity/hydrophilicity distribution, fluorescence properties and the molecular composition of DOM in pharmaceutical wastewater effluent during ozonation. Besides, the toxicity change of pharmaceutical wastewater effluent during ozonation was estimated. The results show that ozone is prone to attack high MW fractions, which contributes the most to the UV254 value and could improve the biodegradability of refractory DOM in pharmaceutical wastewater effluent. Hydrophobic acid contained the most aromatic and unsaturated bonded organic matter, and was more readily oxidized under ozonation. In fluorescent components, ozonation significantly decreased humic-like acid compounds, and hydrophobic humic-like compounds exhibited the highest removal through parallel factor analysis. At the molecular level, the main organics removed by ozone were compounds with high H/C and low O/C, especially compounds where H/C >1.5. The CHO, CHON and CHOS compounds exhibited high removal under ozonation in formula classes. Lignin compounds, condensed aromatics compounds, and unsaturated hydrocarbons were effectively removed by ozone in compound classes. After ozonation, the number of lipid and sugar compounds increased. In addition, O/Cwa (the intensity-weighted average parameters of O/C) and NOSCwa (nominal oxidation state of carbon) were significantly positively correlated with acute toxicity on the luminescence. With the increase of ozone dose, the acute toxicity of pharmaceutical wastewater effluent after ozonation first decreased and then increased.

The efficiency of advanced oxidation processes (AOPs) for disposing of non-steroidal anti-inflammatory drugs (NSAIDs) has been widely studied, but the environmental fates and effects of the NSAIDs and their degradation products (DPs) are poorly understood. In this study, the efficiency of ultraviolet light/Na

This study aims to investigate the effect of a magnetic field on nitrous oxide (N2O) emission from a sequencing batch reactor treating low-strength domestic wastewater at low temperature (10°C). After running for 124 days in parallel, results indicated that the conversion rate of N2O for a magnetic field-sequencing batch reactor (MF-SBR) decreased by 34.3% compared to that of a conventional SBR (C-SBR). Meanwhile, the removal efficiencies for total nitrogen (TN) and ammonia nitrogen (NH4-N) of the MF-SBR were 22.4% and 39.5% higher than those of the C-SBR. High-throughput sequencing revealed that the abundances of AOB (Nitrosomonas), NOB (Nitrospira) and denitrifiers (Zoogloea), which could reduce N2O to N2, were promoted significantly in the MF-SBR. Enzyme activities (Nir) and gene abundances (nosZ nirS and nirK) for denitrification in the MF-SBR were also notably higher compared to C-SBR. Our study shows that application of a magnetic field is a useful approach for inhibiting the generation of N2O and promoting the nitrogen removal efficiency by affecting the microbial characteristics of sludge in an SBR treating domestic wastewater at low temperature.

This study aimed to investigate the effects and biological mechanism of external static magnetic fields (SMFs) on enhancing nitrogen removal at different influent ammonium nitrogen (NH4+) concentrations. Four sequential batch reactors (SBRs) with SMFs of 0, 15, 30, and 50 mT were operated continuously for 196 days, during which the influent NH4+-N concentration increased stepwise as 50, 100, 350, and 600 mg L−1. The results showed that 50 mT had optimum effects on enhancing nitrogen removal, especially at high NH4+-N concentrations (350 and 600 mg L−1). The biological mechanism by which SMF influences nitrogen removal varies depending on the NH4+ concentration. At low NH4+-N concentrations (50 and 100 mg L−1), a field of 50 mT increased key enzyme activities and corresponding functional gene abundances. Additionally, it further improved functional bacterial abundances, which involved nitrifying and denitrifying bacteria at high NH4+ concentrations. These findings could provide guidance for the selection of optimum SMF intensity at different influent NH4+ concentrations.

Pharmaceutically active compounds (PhACs) have been frequently detected in aquatic environment and raised concerns because of their environmental persistence and potential ecological risk, especially carbamazepine (CBZ), erythromycin (ERY), atenolol (ATL) and clofibric acid (CA). The UV/H2O2 advanced oxidation process was considered as an effective process to remove pharmaceuticals in wastewater. Because of the diverse structure of pharmaceuticals and the various wastewater matrices, this study established two models to predict the degradation of 4 PhACs in wastewater by UV/H2O2. Besides, the degradation pathway and toxicity of 4 PhACs by UV/H2O2 were explored. The degradation of 4 PhACs by UV/H2O2 followed the pseudo first-order kinetics pattern. The degradation rate of pharmaceuticals decreased as CBZ > ATL > CA > ERY. A kinetic model combining the steady state concentrations of HO∙ successfully predicted the degradation process of pharmaceuticals in 14 secondary municipal wastewater effluents. Also, a water matrix prediction model by response surface methodology (RSM) was established to estimate the degradation of pharmaceuticals well. A detailed and systematic comparison of two models in the objectives of models, predicting target contaminants, types of wastewater and parameters of models was made. In addition, the tentative transformation pathways of 4 PhACs by UV/H2O2 were proposed. 4 PhACs after UV/H2O2 treatment enhanced the toxicity, and prolongation of treatment time can reduce the toxicity on the luminescence.

The present study used red tilapia (Oreochromis niloticusas) as the model fish to compare the interactive effects between aged and virgin microplastics (MPs) with the antibiotic sulfamethoxazole (SMX) and the β-blocker propranolol (PRP). To this end, the ultraviolet irradiation was used to simulate the MP aging in the environment. The accumulations of MPs and pharmaceuticals, and changes in enzyme activities and genes expressions in tilapia were also evaluated. Some physical properties of MPs changed during the aging process, reflected by 0.27- and 0.16-fold increases in the specific surface area and average pore volume, respectively. And more carbonyl formation was observed on the surface of aged MPs. Compared to the 14-d coexposure with virgin MPs, the MP aging increased the accumulation of PRP by 82.3% in the brain, whereas decreased the concentration of SMX by 46.1% in the gills. The stress on tilapia caused by the MPs and PRP was alleviated by the aging process, largely related to the lower neurotoxicity and reduced lipid peroxidation damages. However, the coexposure to aged MPs and SMX would result in higher inhibitions of cytochrome P450 enzymes activities. The results of the transcriptomics showed that the MP aging mainly influenced the expression of genes related to the metabolic process, immune system process, and the genetic information process in tilapia under the coexposure to MPs and pharmaceuticals. Collectively, our results suggest that the MP aging could induce complex changes in the interactive effects between MPs and pharmaceuticals on aquatic organisms.

In this study, the effect of Fe3+ on the start-up of Anammox process was investigated. Four EGSB reactors were operated with the addition of 0 (R1), 0.04 (R2), 0.08 (R3) and 0.14 (R4) mmol/L Fe3+, respectively. The results showed that Fe3+ remarkably improved the nitrogen loading rate (NLR) and operation efficiency of the reactor. After 180 days, the influent NH4+-N concentration in the four reactors was 201.4, 301.8, 343.2, 380.2 mg N/L, and the NLR was 589.3, 877.6, 993.0, 1105.8 mg N/(L·d), respectively. And the nitrogen removal rate (NRR) in R2, R3 and R4 was respectively 1.54, 1.73 and 1.94 times of that in R1. High throughput sequencing revealed that Fe3+ could promote the enrichment of Anammox bacteria Candidatus Brocadia. Moreover, the analysis by qPCR indicated that the abundance of Anammox 16S rRNA gene and the functional gene hzsB increased, which showed a positive correlation with the concentration of Fe3+.

In situ activity recovery of aging biofilm in the biological aerated filter (BAF) is an important but underappreciated problem. Lab-scaled BAFs were established in this study and three kinds of surfactants containing sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS) and rhamnolipid were employed. Multiple indicators including effluent qualities, dissolved organic matters, biofilm physiology and morphology characteristics were investigated to explore the mechanisms. Results showed that removal rates of effluent COD in test groups significantly recovered to the level before aging. Compared with the control, effluent in SDBS and rhamnolipid-treated groups obtained more protein-like and humic-like substances, respectively. Furthermore, great live cell ratio, smooth surface and low adhesion force of biofilm were observed after rhamnolipid treatment, which was in consistent with good effluent qualities in the same group. This is the first report of applying rhamnolipid for in situ activity recovery of aging biofilm in bioreactors.

Bioavailable dissolved organic nitrogen (ABDON) can support algal growth and consume oxygen in surface waters. In this study, the variations of ABDON and DON bioavailability in municipal wastewater effluents after coagulation were evaluated by algal bioassay. Surprisingly, the bioavailability of DON increased from 45 to 81% (mean 62%) to 50 to 96% (mean 79%) after coagulation and the concentration of ABDON were not significantly different before and after coagulation ( p > 0.05, t -test). Correlations of carbon characteristics of DON, specific DON compounds, different fractions of DON, and DON bioavailability were assessed. Spearman’s correlation analysis showed DON bioavailability correlated strongly with hydrophobicity-based DON fractions ( r = 0.67, p r = −0.60, p