Microbial dynamics reveal the adaptation strategies of ecological niche in distinct anammox consortia under mainstream conditions.

The feasibility of anammox-based processes for nitrogen-contained wastewater treatment has been verified with different anammox bacteria, however, the ecological niche of anammox bacteria under mainstream conditions is still elusive. In this study, six sludge samples collected from different habitats were utilized to culture anammox bacteria under mainstream conditions, and two distinct anammox genera (Ca. Kuenenia and Ca. Brocadia) with a relative abundance of 6.31% (C1) and 3.09% (C3), respectively, were identified. Notably, the microbial dynamics revealed that anammox bacteria (AMX), ammonia-oxidizing bacteria (AOB), nitrite-oxidizing bacteria (NOB), Chloroflexi bacteria (CFX), and heterotrophic denitrification bacteria (HDB) were the core members in anammox consortia. However, Ca. Kuenenia and Ca. Brocadia occupied different ecological niches in anammox consortia. The dissolved oxygen and microbial structures of the anammox-continuous stirred tank reactor systems were the main factors to affect their niche differentiation. Meanwhile, comammox might exist in the systems and occupy the ecological niche of AOB in nitrogen cycling. The network analysis suggested that Ignavibacterium could be the associated bacteria in Ca. Kuenenia-dominated consortia, while Ca. Nitrotoga was that in the Ca. Brocadia-dominated consortia. Our findings reveal a valuable reference for the observation of distinct anammox genera under mainstream conditions, which provides theoretical guidance for the engineering application of mainstream anammox-based processes.

The organics-mediated microbial dynamics and mixotrophic metabolisms in anammox consortia under micro-aerobic conditions.

The engineering applications of mainstream anaerobic ammonium oxidation (anammox) have raised increasing attention due to its energy-efficient, however, the organics-mediated microbial dynamics and mixotrophic metabolisms in anammox consortia under micro-aerobic conditions are still elusive. Here, the response of the anammox process to sodium acetate and glucose at a C/N ratio ranging from 0 to 0.5 was investigated under micro-aerobic conditions, respectively. Results showed that the additional glucose could promote the nitrogen removal efficiency (NRE) and nitrogen removal rate (NRR) of anammox processes at a low C/N ratio (0.3), representing 84.00% and 0.53 N kg·m-3·d-1. The introduced organics could regulate the diversity of the microbial community and simplify the microbial relationship in anammox consortia. Anammox could not benefit from the introduced sodium acetate, while glucose could effectively enhance the anammox activity and microbial interactions in anammox consortia. Glucose might also stimulate the mixotrophic mechanism of Ca. Kuenenia, further promotes the proliferation of anammox sludge under micro-aerobic conditions. This study reveals that glucose could positively mediate microbial interactions and mixotrophic metabolism in anammox consortia under micro-aerobic conditions, which raises a new horizon for the proliferation of anammox sludge for mainstream engineering applications.

Degradation of Diphenyl Ether in Sphingobium phenoxybenzoativorans SC_3 Is Initiated by a Novel Ring Cleavage Dioxygenase.

Sphingobium phenoxybenzoativorans SC_3 degrades and utilizes diphenyl ether (DE) or 2-carboxy-DE as its sole carbon and energy source. In this study, we report the degradation of DE and 2-carboxy-DE initiated by a novel ring cleavage angular dioxygenase (diphenyl ether dioxygenase [Dpe]) in the strain. Dpe functions at the angular carbon and its adjacent carbon (C-1a, C-2) of a benzene ring in DE (or the 2-carboxybenzene ring in 2-carboxy-DE) and cleaves the C-1a-C-2 bond (decarboxylation occurs simultaneously for 2-carboxy-DE), yielding 2,4-hexadienal phenyl ester, which is subsequently hydrolyzed to muconic acid semialdehyde and phenol. Dpe is a type IV Rieske non-heme iron oxygenase (RHO) and consists of three components: a hetero-oligomer oxygenase, a [2Fe-2S]-type ferredoxin, and a glutathione reductase (GR)-type reductase. Genetic analyses revealed that dpeA1A2 plays an essential role in the degradation and utilization of DE and 2-carboxy-DE in S. phenoxybenzoativorans SC_3. Enzymatic study showed that transformation of 1 molecule of DE needs two molecules of oxygen and two molecules of NADH, supporting the assumption that the cleavage of DE catalyzed by Dpe is a continuous two-step dioxygenation process: DE is dioxygenated at C-1a and C-2 to form a hemiacetal-like intermediate, which is further deoxygenated, resulting in the cleavage of the C-1a-C-2 bond to form one molecule of 2,4-hexadienal phenyl ester and two molecules of H2O. This study extends our knowledge of the mode and mechanism of ring cleavage of aromatic compounds.IMPORTANCE Benzene ring cleavage, catalyzed by dioxygenase, is the key and speed-limiting step in the aerobic degradation of aromatic compounds. As previously reported, in the ring cleavage of DEs, the benzene ring needs to be first dihydroxylated at a lateral position and subsequently dehydrogenated and opened through extradiol cleavage. This process requires three enzymes (two dioxygenases and one dehydrogenase). In this study, we identified a novel angular dioxygenase (Dpe) in S. phenoxybenzoativorans SC_3. Under Dpe-mediated catalysis, the benzene ring of DE is dioxygenated at the angular position (C-1a, C-2), resulting in the cleavage of the C-1a-C-2 bond to generate a novel product, 2,4-hexadienal phenyl ester. This process needs only one angular dioxygenase, Dpe. Thus, the ring cleavage catalyzed by Dpe represents a novel mechanism of benzene ring cleavage.

Quantifying instability in neurological disorders EEG based on phase space DTM function.

Classifying individuals with neurological disorders and healthy subjects using EEG is a crucial area of research. The current feature extraction approach focuses on the frequency domain features in each of the EEG frequency bands and functional brain networks. In recent years, researchers have discovered and extensively studied stability differences in the electroencephalograms (EEG) of patients with neurological disorders. Based on this, this paper proposes a feature descriptor to characterize EEG instability. The proposed method starts by forming a signal point cloud through Phase Space Reconstruction (PSR). Subsequently, a pseudo-metric space is constructed, and pseudo-distances are calculated based on the consistent measure of the point cloud. Finally, Distance to Measure (DTM) Function are generated to replace the distance function in the original metric space. We calculated the relative distances in the point cloud by measuring signal similarity and, based on this, summarized the point cloud structures formed by EEG with different stabilities after PSR. This process demonstrated that Multivariate Kernel Density Estimation (MKDE) based on a Gaussian kernel can effectively separate the mappings of different stable components within the signal in the phase space. The two average DTM values are then proposed as feature descriptors for EEG instability.In the validation phase, the proposed feature descriptor is tested on three typical neurological disorders: epilepsy, Alzheimer's disease, and Parkinson's disease, using the Bonn dataset, CHB-MIT, the Florida State University dataset, and the Iowa State University dataset. DTM values are used as feature inputs for four different machine learning classifiers, and The results show that the best classification accuracy of the proposed method reaches 98.00 %, 96.25 %, 96.71 % and 95.34 % respectively, outperforming commonly used nonlinear descriptors. Finally, the proposed method is tested and analyzed using noisy signals, demonstrating its robustness compared to other methods.

Deciphering the core bacterial community structure and function and their response to environmental factors in activated sludge from pharmaceutical wastewater treatment plants.

Pharmaceutical wastewater is recognized for its heightened concentrations of organic pollutants, and biological treatment stands out as an effective technology to remove these organic pollution. Therefore, a comprehensive exploration of core bacterial community compositions, functions, and their responses to environmental factors in pharmaceutical wastewater treatment plants (PWWTPs) is important for understanding the removal mechanism of these organic pollutants. This study comprehensively investigated 36 activated sludge (AS) samples from 15 PWWTPs in China. The results revealed that Proteobacteria (45.41%) was the dominant phylum in AS samples, followed by Bacteroidetes (19.54%) and Chloroflexi (4.13%). While the dominant genera were similar in both aerobic and anaerobic treatment processes, their relative abundances exhibited significant variations. Genera like HA73, Kosmotoga, and Desulfovibrio were more abundant during anaerobic treatment, while Rhodoplanes, Bdellovibrio, and Hyphomicrobium dominated during aerobic treatment. 13 and 10 core operational taxonomic units (OTUs) were identified in aerobic and anaerobic sludge, respectively. Further analysis revealed that core OTUs belonging to genera Kosmotoga, Desulfovibrio, Thauera, Hyphomicrobium, and Chelativorans, were associated with key functions, including sulfur metabolism, methane metabolism, amino acid metabolism, carbohydrate metabolism, toluene degradation, and nitrogen metabolism. Furthermore, this study highlighted the crucial roles of environmental factors, such as COD, NH4+-N, SO42-, and TP, in shaping both the structure and core functions of bacterial communities within AS of PWWTPs. Notably, these factors indirectly affect functional attributes by modulating the bacterial community composition and structure in pharmaceutical wastewater. These findings provide valuable insights for optimizing the efficiency of biochemical treatment processes in PWWTPs.

Activation of persulfate with natural organic acids (ascorbic acid/catechin hydrate) for naproxen degradation in water and soil: Mechanism, pathway, and toxicity assessment.

In this study, we investigated the effects of different natural organic acids (NOAs), L-ascorbic acid (AA) and (+)-catechin hydrate (CAT), on the activation of persulfate (PDS) for the oxidation of naproxen (NAP) in water and soil. We found that only AA-activated PDS process had a significant degradation efficiency of NAP in water. High AA concentration (500 µM) inhibited the degradation of NAP, whereas high levels of PDS (7.5 mM) and acidic conditions (pH=3-7) were beneficial for NAP degradation. In soil, both CAT and AA promoted PDS activation and NAP degradation. Low soil organic matter and high Fe/Mn-mineral contents were favorable for NAP degradation by AA-activated PDS. Column experiments confirmed that NAP was readily transported and degraded under porous medium conditions using AA-activated PDS. Moreover, we revealed that SO4•- and HO• were the dominant reactive species for NAP degradation by AA-activated PDS. Intermediate products of NAP in the AA-activated PDS process were analyzed and the reactive sites of NAP were predicted. E. coli growth tests verified that the intermediate products in the AA-activated PDS process were less toxic than NAP. Our results highlight the high potential of NOAs-activated PDS process for the remediation of NAP-contaminated water and soil.

Succession of microbial communities reveals the inevitability of anammox core in the development of anammox processes.

The lack of anammox seeds is regarded as the bottleneck of anammox-based processes. Although the interactions in anammox consortia have attracted increasing attention, little is known about the influence of inoculated sludge populations on the growth of anammox bacteria. In this study, four sludge of distinct communities mixed with anammox sludge (the relative abundance of Ca. Kuenenia was 1.96 %) were used as the seeds, respectively for the start-up of anammox processes. Notably, all these mixed microbial communities tend to form a similar microbial community, defined as the anammox core, containing anammox-bacteria (22.9 ± 5.9 %), ammonia-oxidizing-bacteria (0.8 ± 0.7 %), nitrite-oxidizing-bacteria (0.2 ± 0.2 %), Chloroflexi-bacteria (0.7 ± 0.4 %), and heterotrophic-denitrification-bacteria (0.3 ± 0.2 %). It also elucidated that the communities of Nitrosomonas-dominated sludge were the closest to the anammox core, and achieved the highest nitrogen-removal rate of 0.73 kg-N m-3 d-1. This study sheds light on the solution to the shortage of anammox seeds in the full-scale wastewater treatment application.

Co/N co-doped porous carbon as a catalyst for the degradation of RhB by efficient activation of peroxymonosulfate.

We report on the preparation of Co/N-NPCx/y with porous structure and excellent activation properties. The synthesis involves the preparation of Zn/Co-ZIFx and the carbonization of Zn/Co-ZIFx at a high temperature in an inert atmosphere. The volatilization of zinc during carbonization results in a porous structure, which is beneficial to the migration of pollutants. The sizes, specific surface areas, and pore size distribution of Co/N-NPCx/y can be achieved by tuning Zn/Co ratio. The calcination temperatures mainly affect the crystalline phase, crystallinity, and magnetic properties of the as-prepared materials. The effects of the as-prepared materials properties and activation conditions on the Rhodamine B (RhB) degradation by PMS activation were investigated. Overall, it exhibited superior catalytic activity in PMS activation, as evidenced by almost complete removal of RhB (0.020 mM, 100 mL) by using 5 mg/L Co/N-NPC0.5/900 and 1.250 mM PMS within 30 min. Furthermore, it confirmed the participation of SO4•-, •OH, and 1O2 in the catalytic reaction, and both SO4•- and 1O2 were the main reactive oxygen species that play a major role.

Coupling continuous poly(3-hydroxybutyrate) synthesis with piperazine-contained wastewater treatment: Fermentation performance and microbial contamination deciphering.

Open poly(3-hydroxybutyrate) (PHB) fermentation is of great potential, and batch PHB synthesis with piperazine as the nitrogen switch has been realized. However, it is vital to explore the feasibility of continuous PHB fermentation with piperazine-contained wastewater remediation collaboratively. Here, an aerobic membrane bioreactor was constructed for consecutive PHB synthesis. The removal efficiency of piperazine decreased from 100 % to 82.6 % after three cycles, meanwhile, the PHB concentration was 0.39 g·L-1, 0.18 g·L-1, and undetected for each cycle. Microbial community analysis showed that Proteobacteria, Actinobacteriota, and Bacteroidota were the main contaminating microbes. Furthermore, three metagenome-assembled genomes related to Flavobacterium collumnare, Herbaspirillum aquaticum, and Microbacterium enclense were identified as the dominant contaminating strains. These microbes obtained nitrogenous substrates transformed by Paracoccus sp. TOH, such as amino acids and dissolved organic matter, as nutrient for accumulation. This study verified the practicability of coupling continuous PHB synthesis with industrial wastewater treatment and revealed the derivation mechanism of contaminating species, which could provide a reference for the targeted nitrogen release gene knockout of functional PHB fermentation chassis.

Microbial interactions play a keystone role in rapid anaerobic ammonium oxidation sludge proliferation and biofilm formation.

Two mature anaerobic ammonium oxidation (anammox) consortia with high/low relative abundance of anammox bacteria were inoculated for the rapid sludge proliferation and biofilm formation in this study, named up-flow anaerobic sludge blanket reactor (UASB1) (high) and UASB2 (low), respectively. Results showed that the nitrogen removal efficiency of UASB2 reached 90.94% after the 120-day operation, which was 13% higher than that of UASB1. Moreover, its biomass amounts were 22.18% (biofilm) and 40.96% (flocs) higher than that of UASB1, respectively. Ca. Kuenenia possessed relative abundances of 29.32% (flocs), 27.42% (biofilm) and 31.56% (flocs), 35.20% (biofilm) in the UASB1 and UASB2, respectively. The relative abundances of genes involved in anammox transformation (hzs, nir) and carbon metabolism (fdh, lgA/B/C, acs) were higher in the UASB2, indicating that Ca. Kuenenia might produce acetate and glycogen to enhance microbial interactions. These findings emphasized the importance of microbial interactions in anammox sludge proliferation and biofilm formation.

Biosynthesis of poly(3-hydroxybutyrate) by N,N-dimethylformamide degrading strain Paracoccus sp. PXZ: A strategy for resource utilization of pollutants.

N,N-dimethylformamide is a toxic chemical solvent, which widely exists in industrial wastewater. Nevertheless, the relevant methods merely achieved non-hazardous treatment of N,N-dimethylformamide. In this study, one efficient N,N-dimethylformamide degrading strain was isolated and developed for pollutant removal coupling with poly(3-hydroxybutyrate) (PHB) accumulation. The functional host was characterized as Paracoccus sp. PXZ, which could consume N,N-dimethylformamide as the nutrient substrate for cell reproduction. Whole-genome sequencing analysis confirmed that PXZ simultaneously possesses the essential genes for poly(3-hydroxybutyrate) synthesis. Subsequently, the approaches of nutrient supplementation and various physicochemical variables to strengthen poly(3-hydroxybutyrate) production were investigated. The optimal biopolymer concentration was 2.74 g·L-1 with a poly(3-hydroxybutyrate) proportion of 61%, showing a yield of 0.29 g-PHB·g-1-fructose. Furthermore, N,N-dimethylformamide served as the special nitrogen matter that could realize a similar poly(3-hydroxybutyrate) accumulation. This study provided a fermentation technology coupling with N,N-dimethylformamide degradation, offering a new strategy for resource utilization of specific pollutants and wastewater treatment.

Poly(3-hydroxybutyrate) biosynthesis under non-sterile conditions: Piperazine as nitrogen substrate control switch.

Poly(3-hydroxybutyrate) (PHB), as a kind of bioplastics for sustainable development, can be synthesized by various microorganisms, however, the high cost of its microbial fermentation is a challenge for its large-scale application. In this study, piperazine degrading strain, Paracoccus sp. TOH, was developed as an excellent chassis for open PHB fermentation with piperazine as controlling element. Whole-genome analysis showed that TOH possesses multi-substrate metabolic pathways to synthesize PHB. Next, TOH could achieve a maximum PHB concentration of 2.42 g L-1, representing a yield of 0.36 g-PHB g-1-glycerol when C/N ratio was set as 60:1 with 10 g L-1 glycerol as substrate. Furthermore, TOH could even synthesize 0.39 g-PHB g-1-glycerol under non-sterile conditions when piperazine was fed with a suitable rate of 1 mg L-1 h-1. 16S rRNA gene sequencing analysis showed that microbial contamination could be effectively inhibited through the regulation of piperazine under non-sterile conditions and TOH dominated the microbial community with a relative abundance of 72.3% at the end of the operational period. This study offers an inspired open PHB fermentation system with piperazine as the control switch, which will realize the goal of efficient industrial biotechnology as well as industrial wastewater treatment.

Evaluation of potassium ferrate activated biochar for the simultaneous adsorption of copper and sulfadiazine: Competitive versus synergistic.

Combined pollution caused by organic pollutants and heavy metals pose a significant challenge to the adsorption process. In this study, iron-modified biochar (Fe-BC) was prepared by using ferrate (K2FeO4) and wheat stalk as the precursors for the adsorption of copper (Cu2+) and sulfadiazine (SDZ), especially under combined pollution scenarios. Iron modification not only enlarged the surface area but also loaded iron oxide nanoparticles on biochar surface. Accordingly, Fe-BC exhibited better adsorption capability of Cu2+ and SDZ than the pristine biochar (BC). The corresponding maximum adsorption capacities of Fe-BC700 were 46.85 mg g-1 and 45.43 mg g-1 towards Cu2+ and SDZ, respectively. Interestingly, the adsorption was elevated in binary-pollutants system, suggesting a synergistic effect, which was probably attributed to the mutual bridging effects and complexation between Cu2+ and SDZ. The loaded iron oxide particles could serve as a physical barrier to separate the adsorptions of Cu2+ and SDZ and thus inhibited the competitive adsorption. Meanwhile, theoretical calculation demonstrated that sulfonamide group was the most probable binding site. Columns packed with Fe-BC700 showed better performances for Cu2+ and SDZ removal in binary system (635.73 BV for Cu2+ and 4846.26 BV for SDZ) than in single systems (571.60 BV for Cu2+ and 3572.06 BV for SDZ), which was consistent with batch adsorption experiments. These results demonstrated the potential application of Fe-BC700 for simultaneous adsorption of Cu2+ and SDZ and provided a cost-effective way for the remediation of organic and inorganic pollutants.

Bioconversion of waste activated sludge hydrolysate into polyhydroxyalkanoates using Paracoccus sp. TOH: Volatile fatty acids generation and fermentation strategy.

The expensive carbon matrix is a bottleneck restricting the industrialization of polyhydroxyalkanoates (PHAs). Volatile fatty acids (VFAs) derived from waste activated sludge via anaerobic fermentation might be alternative carbon matters for PHAs synthesis. In this study, the effect of enzymes on VFAs yields and the feasibility of the produced VFAs for PHAs fermentation by Paracoccus sp. TOH were investigated. The optimum cumulative VFAs concentration reached 4076.6 mg-COD·L-1 in the lysozyme treatment system. Correspondingly, the highest poly(3-hydroxybuturate-co-3-hydroxyvalerate) (PHBV) concentration (119.1 mg·L-1) containing 20.3 mol% 3-hydroxyvalerate was obtained. It proved that Paracoccus sp. TOH possesses the capability for PHBV accumulation. The functional hydrolytic-acidogenic microorganisms, such as Clostridium sensu stricto and Bacteroides sp. were accumulated. The functional genes encoding hydrolysis, carbohydrates metabolism, VFAs generation were enriched. This study offered a possible strategy for VFAs production and verified the feasibility of sludge hydrolysate as a high-quality carbon substrate for PHAs fermentation.

Nitrogen contribution and microbial community of size-fractionated anammox sludge in continuous stirred-tank reactors.

In this study, the microbial diversity of size-fractionated anammox sludge in a well-mixed system and their contribution to nitrogen transformation were investigated. Results showed that small granules (0.2-1.0 mm) contributed to the major part of the nitrogen removal rate (56 %) due to its largest mixed liquor volatile suspended solids (1240 ± 80 mg·L-1). However, large granules (>1.0 mm) possessed the highest relative abundances of Ca. Kuenenia stuttgartiensis and specific anammox activity, representing 49.34 % and 24.45 ± 0.01 mg-N·g-1-mixed liquor volatile suspended solids·h-1, respectively. The microbial diversity decreased as the increase of granular size, resulting in microbial community shifting to a simpler model. Metagenomic analysis showed that fine sludge might be the potential major for NO/N2O production in the mature well-mixed system under inorganic conditions. This study provides guidance for the evaluation of nitrogen contribution by anammox size-fractionated sludge and the inhibition of the potential NO/N2O emission in anammox processes.

Biodegradation of benazolin-ethyl by strain Methyloversatilis sp. cd-1 isolated from activated sludge.

Benazolin-ethyl has been used on a wide range of weeds present in various crops since 1964. Because benazolin-ethyl is a potential hazard to the environment and human health, it is important to remove this herbicide from the environment. However, to the best of our knowledge, no report is available in the literature regarding the microbial degradation of benazolin-ethyl by bacteria. In this study, one strain named cd-1, which is capable of degrading benazolin-ethyl, was isolated from benazolin-ethyl wastewater treatment pool. The isolate was identified as Methyloversatilis sp. according to its morphological, physiological, biochemical properties, and 16S rRNA gene sequences analysis. This strain utilizes benazolin-ethyl as the sole carbon source. and degrades 100 mg l⁻¹ benazolin-ethyl to non-detectable level within 48 h. Three metabolites were identified as benazolin, 7-chloro-3-methylbenzo[d]thiazol-2(3H)-one, and 2-chloro-6-(methyleneamino)benzenethiol based on the MS/MS and GC/MS analyses. The first step involved in the degradation of benazolin-ethyl was the cleavage of the ester bond to form benazolin. Benazolin was subsequently subjected to demethylation for decomposition into 7-chloro-3-methylbenzo[d]thiazol-2(3H)-one and methanol. The last step was to form 2-chloro-6-(methyleneamino)benzenethiol.

Degradation of bromoxynil octanoate by strain Acinetobacter sp. XB2 isolated from contaminated soil.

Bromoxynil octanoate (BOO), the most widespread herbicide applied to maize, is potentially toxic to both animals and humans. In this article, a highly effective BOO-degrading bacterial strain, XB2, was isolated from the soil of a herbicide factory. The strain was identified as an Acinetobacter sp. based on its 16S rRNA gene sequence analysis, morphological, physiological, and biochemical properties. This strain could use BOO as its sole carbon source and could degrade 100 mg l(-1) BOO to non-detectable levels in 72 h (h). The optimal pH and temperature for strain XB2's growth and degradation of BOO in MSM are 7.0 and 30°C, respectively. We propose the following pathway of BOO degradation by strain XB2: the first step is the scission of the ester bond to form bromoxynil, bromoxynil then transformed to 3,5-dibromo-4-hydroxybenzoic acid due to the hydrolysis of nitriles, and debromination finally results in the formation of 3-bromo-4-hydroxybenzoic acid. Inoculating BOO-treated soil samples with strain XB2 resulted in a higher rate of BOO degradation than in non-inoculated soil, regardless of whether the soil had previously been sterilized.

Characterization of fluoroglycofen ethyl degradation by strain Mycobacterium phocaicum MBWY-1.

A fluoroglycofen ethyl-degrading bacterium, MBWY-1, was isolated from the soil of an herbicide factory. This isolated strain was identified as Mycobacterium phocaicum based on analysis of its 16S rRNA gene sequence and its morphological, physiological, and biochemical properties. The strain was able to utilize fluoroglycofen ethyl as its sole source of carbon for growth and could degrade 100 mg l(-1) of fluoroglycofen ethyl to a non-detectable level within 72 h. The optimum temperature and pH for fluoroglycofen ethyl degradation by strain MBWY-1 were 30°C and 7.0, respectively. Five metabolites produced during the degradation of fluoroglycofen ethyl and were identified by mass spectrometry as {5-[2-chloro-4-(trifluoromethyl) phenoxy]-2-nitrophenylacyl} hydroxyacetic acid, acifluorfen, 5-[2-chloro-4-(trifluoromethyl) phenoxy]-2-nitrobenzoate, 5-[2-chloro-4-(trifluoromethyl) phenoxy]-2-hydroxyl, and 3-chloro-4-hydroxyl benzotrifluoride. Identification of the metabolites allowed to propose the degradation pathway of fluoroglycofen ethyl by strain MBWY-1. The inoculation of strain MBWY-1 into soil treated with fluoroglycofen ethyl resulted in a higher fluoroglycofen ethyl degradation rate than in uninoculated soil regardless of whether the soil was sterilized or nonsterilized.

Ferrous-activated persulfate oxidation of triclosan in soil and groundwater: The roles of natural mineral and organic matter.

Contamination of antimicrobial agents such as Triclosan (TCS) in soil and groundwater possess high risk to human health and ecological systems. Present study systematically studied the degradation of TCS in soil and groundwater by Fe2+ activated persulfate (Fe2+/PS) oxidation process and special attention was paid on revealing the influence of remediation process on soil physicochemical and microbial characteristics. Experimental results demonstrated that TCS was readily degraded in soil upon Fe2+/PS oxidation system. Higher Fe2+/PS concentration and lower pH value may promote the TCS degradation. Besides added Fe2+, the naturally present Fe (III)-O and dissolved Fe from iron containing minerals may also activate PS for TCS degradation. SO4•-, HO•, R• and 1O2 were identified to be involved in the reaction system while addition of Fe2+-chelating agents, e.g., oxalic acid and ethylene diamine tetraacetic acid (EDTA) may slightly promote the degradation. Low concentration of Cl- facilitated TCS degradation and high concentration of Cl- slowed down the degradation. The presence of HCO3- may inhibit the degradation. Fe2+/PS oxidation process may partly reduce the soil organic matter content and diversely affect the composition of various C functional groups on soil. It also induced the breakdown of large soil aggregates and reduced the soil porosity, especially at macroporosity region. Phospholipid Fatty Acid test indicated that soil microbial community structure has been altered and the actinomycetes, fungi and Gram-negative bacteria decreased largely. The feasibility of remediation of TCS using Fe2+/PS oxidation in various natural groundwater samples was evaluated. Finally, five degradation intermediates of TCS by Fe2+/PS oxidation in soil were enriched by solid phase extraction and were identified by liquid chromatography-triple quadrupole mass spectrometry for proposing detailed transformation pathways.

Degradation of Atrazine, Simazine and Ametryn in an arable soil using thermal-activated persulfate oxidation process: Optimization, kinetics, and degradation pathway.

This study examined the feasibility of applying thermal-activated persulfate (PS) oxidation for remediation of soil co-contaminated with s-triazine herbicides including Atrazine (ATZ), Simazine (SIM) and Ametryn (AME). Homogeneous activation using heating method (50 °C) was selected. Results showed that thermal-activated PS oxidation process may successfully degrade ATZ in soil and degradation efficiency was increased along the arising activation temperature. Higher PS dosages and depressed initial pH were beneficial for degradation while increasing initial ATZ concentration may hamper the degradation. The oxidation process may lead to changes of surface functional groups on soil. The presence of Cl-, HCO3- and H2PO4- at both of low and high concentrations may inhibit the degradation of ATZ. Soil depths may apparently influence the ATZ degradation which followed 0-10 < 10-30 < 30-60 cm mainly depending on the soil organic matter (SOM) contents. Thermal-activated PS may effectively degrade ATZ, SIM and AME under co-contaminated condition and the more favorable of ethyl group towards SO4- than isopropyl and methylation groups was detected. Both of SO4- and HO were identified to be responsible for degradation. Finally, degradation intermediates of ATZ, SIM and AME were identified by LC-Q-TOF-MS and detailed transformation pathways for three pesticides were proposed, respectively.