Underwater light source changes microecosystem constructed by Vallisneria spinulosa Yan for water restoration: Efficiency of water purification, characteristics of growth, and rhizosphere.

Submerged macrophytes are effective in ecological restoration of water bodies polluted by nitrogen and phosphorus, and its restoration capacity depends on underwater illumination condition. This study explored the influencing mechanism of illumination on Vallisneria spinulosa Yan (V. spinulosa Yan) for water restoration. Addition of underwater light source increased the total nitrogen, ammonia nitrogen, total phosphorus, and phosphate removal loads of the V. spinulosa Yan growth system by 61.5, 39.2, 8.5, and 5.0 mg m-2 d-1, respectively. Meanwhile, the growth of V. spinulosa Yan was obviously promoted, even with high water turbidity. Although the biological nitrogen removal processes were inhibited by adding underwater light source, the growth of V. spinulosa Yan can be significantly improved, thus enhancing the efficiency of water purification via the absorption of nitrogen and phosphorus by V. spinulosa Yan. This study provides a theoretical foundation and technical support for application of submerged macrophytes in ecological water restoration.

Subtle magnesium liberation of self-fabricated functional filler actuates highly efficient phosphorus removal from source-separated urine by SBBR.

Domestic wastewater source-separated treatment has attracted wide attention due to the efficiency improvement of sewage treatment systems, energy saving, resource reuse, and the construction and operation cost saving of pipeline networks. Nonetheless, the excess source-separated urine still demands further harmless treatment. Sequencing batch biofilm reactor (SBBR), a new type of composite biofilm reactor developed by filling different fillers into the sequential batch reactor (SBR) reactor, has higher pollutant removal performance and simpler operation and maintenance. However, the phosphorus removal ability of the SBBR filling with conventional fillers is still limited and needs further improvement. In this study, we developed two new fillers, the self-fabricated filler A and B (SFA/SFB), and compared their source-separated urine treatment performance. Long-term treatment experimental results demonstrated that the SBBR systems with different fillers had good removal performance on the COD and TN in the influent, and the removal rate increased with the increasing HRT. However, only the SBBR system with the SFA showed excellent PO43--P and TP removal performance, with the removal rates being 83.7 ± 11.9% and 77.3 ± 13.7% when the HRT was 1 d. Microbial community analysis results indicated that no special bacteria with strong phosphorus removal ability were present on the surface of the SFA. Adsorption experimental results suggested that the SFA had better adsorption performance for phosphorus than the SFB, but it could not always have stronger phosphorus adsorption and removal performance during long-term operation due to the adsorption saturation. Through a series of characterizations such as SEM, XRD, and BET, it was found that the SFA had a looser structure due to the use of different binder and production processes, and the magnesium in the SFA gradually released and reacted with PO43- and NH4+ in the source-separated urine to form dittmarite and struvite, thus achieving efficient phosphorus removal. This study provides a feasible manner for the efficient treatment of source-separated urine using the SBBR system with self-fabricated fillers.

Seasonal purification efficiency, greenhouse gas emissions and microbial community characteristics of a field-scale surface-flow constructed wetland treating agricultural runoff.

Controlling nonpoint source pollution (NPSP) is very important for protecting the water environment, and surface-flow constructed wetlands (SFCWs) have been widely established to mitigate NPSP loads. In this study, the pollutant removal efficiencies, greenhouse gas (GHG) emissions, and chemical and microbial community properties of the sediment in a large-scale SFCW established beside a plateau lake (Qilu Lake) in southwestern China to treat agricultural runoff were evaluated over a year. The SFCW performed best in terms of nitrogen removal in autumn (average efficiency of 63.5% at influent concentrations of 9.3-35.4 mg L-1) and demonstrated comparable efficiency in other seasons (23.7-40.0%). The removal rates of total phosphorus (TP) and chemical oxygen demand (COD) were limited (18.6% and 12.4% at influent concentrations of 1.1 and 45.5 mg L-1 on average, respectively). The SFCW was a hotspot of CH4 emissions, with an average flux of 31.6 mg m-2·h-1; moreover, CH4 emissions contributed the most to the global warming potential (GWP) of the SFCW. Higher CH4 and N2O fluxes were detected in winter and in the front-end section of the SFCW with high pollutant concentrations, and plant presence increased CH4 emissions. Significant positive relationships between nutrient and heavy metal contents in the SFCW sediment were detected. The microbial community compositions were similar in autumn and winter, with Thiobacillus, Lysobacter, Acinetobacter and Pseudomonas dominating, and this distribution pattern was clearly distinct from those in spring and summer, with high proportions of Spirochaeta_2 and Denitratisoma. The microbial co-occurrence network in spring was more complex with stronger positive correlations than those in winter and autumn, while it was more stable in autumn with more keystone taxa. Optimization of the construction, operation and management of SFCWs treating NPSP in lake watersheds is necessary to promote their environmental benefits.

Symmetry-Breaking Manipulated Channel Ergodicity in Intramolecular Singlet Fission Uncovered Statistically by Molecular Dynamics Samplings.

Persistent structure dynamics of chromophores in a solvent has a pivotal influence on singlet fission (SF) phenomena through breaking structure symmetry and tuning electronic properties. However, clarifying how the dynamic factors manipulate the SF dynamics faces major challenges. Here, we for the first time propose a dynamic symmetry-breaking strategy for manipulating intramolecular SF and unveil channel-ergodic characters by constructing transient configuration space of an individual solvated monomer in a chromophore-in-solvent ensemble by sampling its dynamics trajectory. Dynamic symmetry-breaking leads an SF ensemble to find possible SF channels (i.e., subensembles), characterized by a broad energy population of a charge-transfer state and its coupling with a locally excited state, and the populated multichannels featuring distinct probability distributions determine the dominant SF mechanism and also reveal channel conversion and ergodic behavior, agreeing highly with experimental observations. This work emphasizes the vital role of the inherent structure dynamics of a chromophore in solvent in manipulating such photophysics characteristics by evaluating their symmetry-breaking properties statistically.

Prenatal diagnosis of Treacher Collins syndrome: A case report and literature review.

Treacher Collins syndrome (TCS) should be suspected if the triad of micrognathia, glossoptosis, and posterior cleft palate, and deformed external ears are observed during prenatal ultrasonography, excepting Pierre Robin sequence. Visualization of the fetal zygomatic bone and down-slanting palpebral fissures are conducive to differentiation. Molecular genetics testing can establish a definite diagnosis. A 28-year-old pregnant Chinese woman was referred for systematic ultrasound examination at 24 weeks. Two-dimensional and three-dimensional ultrasound showed polyhydramnios, micrognathia, absence of nasal bone, microtia, secondary cleft palate, mandibular hypoplasia, glossoptosis, and normal limbs and vertebrae. Pierre Robin sequence was misdiagnosed with the triad of micrognathia, glossoptosis, and posterior cleft palate. Final diagnosis of TCS was confirmed by whole-exome sequencing. Visualization of the fetal zygomatic bone and down-slanting palpebral fissures can facilitate a differential diagnosis between Pierre Robin sequence and TCS, with the triad of micrognathia, glossoptosis, and posterior cleft palate.

Identification of microbial consortia for sustainable disposal of constructed wetland reed litter wastes.

Reed is a typical emerged plant in constructed wetlands (CWs). Its litters were used as raw materials for preparing Fe-C ceramic-filler (Fe-C-CF). The physical and chemical properties of Fe-C-CF were studied under different conditions, including the mass ration of Fe to carbon (Fe/C ratio), sintering temperature, and time, to determine the optimum preparing conditions. Meanwhile, the denitrification performance and CO2 emission flux of the surface flow constructed wetland (SFCW) systems were investigated when using Fe-C-CF as the matrix. The optimum preparing conditions for Fe-C-CF were Fe/C ratio of 1:1, sintering temperature and time of 500 °C and 20 min, respectively. The SFCW system with Fe-C-CF obtained a higher total nitrogen (TN), nitrate nitrogen (NO3--N), and ammonia nitrogen (NH3-N) removal efficiencies than the control SFCW system without Fe-C-CF. Compared with the heterotrophic denitrification process, the SFCW system with Fe-C-CF decreased CO2 emission by 67.9 g m-2 per year. The results of microbial community analysis indicated that addition of Fe-C-CF increased the diversity and abundance of microbial communities in the SFCW systems. The dominant genus of the SFCW system with Fe-C-CF was Bacillus, while Uliginosibacterium was the dominant genus in the system without the filler.

Shaddock peels derived multilayer biochar with embedded CoO@Co nanoparticles for peroxymonosulfate based wastewater treatment.

The utilization of bio-wastes, such as shaddock peels, is of great significance for sustainable development. Combined with the potential of peroxymonosulfate (PMS) based advanced oxidation process (AOP) in wastewater treatment, a highly efficient functional catalyst, derived from shaddock peels biochar (SPC) and embedded with CoO@Co nanoparticles, i.e. Co-SPC-x(y), was prepared using a facile impregnation-calcination method and used for refractory organics degradation with PMS. The decoration amount of Co and annealing temperature were optimized, and the effects of various reaction factors were investigated. The results indicated that the optimized sample of Co-SPC-10 (900) consisted of multilayer biochar with curly edges and highly dispersed CoO@Co nanoparticles in the range of 20-200 nm, which is in cubic metallic Co and CoO. Moreover, it also possessed a specific surface area of 248.6 m2/g, and exhibited excellent PMS activation ability with ∼100% chlortetracycline hydrochloride (CTC) removal ratio within only 12 min of operation. The Co-SPC-10 (900)/PMS system showed relatively high tolerance for HPO42-, NO3- and SO42-, while the Cl- and HA had considerable effects on it. Mechanism exploration results revealed that both radical and non-radical pathways existed in the Co-SPC-10 (900)/PMS system, in which the multilayered biochar functioned as an electron transfer carrier to facilitate the continuous cycle of Co2+/Co3+ in the CoO@Co nanoparticles by reacting with the absorbed CTC and PMS, resulting in the production of •OH, SO4•-, O2•- and 1O2. Additionally, the Co-SPC-10 (900) also showed good stability and catalytic oxidation performance for various refractory organics.

Embedding Co in perovskite MoO3 for superior catalytic oxidation of refractory organic pollutants with peroxymonosulfate.

A cobalt (Co)-doped perovskite molybdenum trioxide (α-MoO3) catalyst (Co-MO) was synthesized by a facile pyrolysis strategy and used for degrading various organic contaminants via peroxymonosulfate (PMS) activation. The doped Co was inserted in the inter space between the octahedron [MoO6], facilitating the growth of the α-MoO3 crystal on the [010] direction. This unique structure accelerated the activation of PMS as the Co-MO could function as a carrier for electron transfer to facilitate the Co(II)/Co(III) cycle in the Co-MO/PMS system. As a result, the Co-MO/PMS system showed noticeable activity for removing 100% bisphenol A (BPA) under a broad conditions within 30 min. The radical quenching test and electron paramagnetic resonance analysis revealed that singlet oxygen (1O2) was the main active species for BPA degradation in the Co-MO/PMS system, while free radicals, such as O2•-, SO4•- and •OH, were also produced as the intermediate species. Furthermore, the carrier mechanism may enable the Co-MO/PMS system maintain relatively high performance during repeat use, and also excellent adaptability was revealed by the well function in various water matrices and high activity in degrading various refractory organic pollutants. Our findings pave a useful avenue for the rational design of novel cobalt-doped catalysts with high catalytic performance toward wide environmental applications.

A comprehensive review on mixotrophic denitrification processes for biological nitrogen removal.

Biological denitrification is the most widely used method for nitrogen removal in water treatment. Compared with heterotrophic and autotrophic denitrification, mixotrophic denitrification is later studied and used. Because mixotrophic denitrification can overcome some shortcomings of heterotrophic and autotrophic denitrification, such as a high carbon source demand for heterotrophic denitrification and a long start-up time for autotrophic denitrification. It has attracted extensive attention of researchers and is increasingly used in biological nitrogen removal processes. However, so far, a comprehensive review is lacking. This paper aims to review the current research status of mixotrophic denitrification and provide guidance for future research in this field. It is shown that mixotrophic denitrification processes can be divided into three main kinds based on different kinds of electron donors, mainly including sulfur-, hydrogen-, and iron-based reducing substances. Among them, sulfur-based mixotrophic denitrification is the most widely studied. The most concerned influencing factors of mixotrophic denitrification processes are hydraulic retention times (HRT) and ratio of chemical oxygen demand (COD) to total inorganic nitrogen (C/N). The dominant functional bacteria of sulfur-based mixotrophic denitrification system are Thiobacillus, Azoarcus, Pseudomonas, and Thauera. At present, mixotrophic denitrification processes are mainly applied for nitrogen removal in drinking water, groundwater, and wastewater treatment. Finally, challenges and future research directions are discussed.

Improve follicular thyroid carcinoma diagnosis using computer aided diagnosis system on ultrasound images.

Objective: We aim to leverage deep learning to develop a computer aided diagnosis (CAD) system toward helping radiologists in the diagnosis of follicular thyroid carcinoma (FTC) on thyroid ultrasonography. Methods: A dataset of 1159 images, consisting of 351 images from 138 FTC patients and 808 images from 274 benign follicular-pattern nodule patients, was divided into a balanced and unbalanced dataset, and used to train and test the CAD system based on a transfer learning of a residual network. Six radiologists participated in the experiments to verify whether and how much the proposed CAD system helps to improve their performance. Results: On the balanced dataset, the CAD system achieved 0.892 of area under the ROC (AUC). The accuracy, recall, precision, and F1-score of the CAD method were 84.66%, 84.66%, 84.77%, 84.65%, while those of the junior and senior radiologists were 56.82%, 56.82%, 56.95%, 56.62% and 64.20%, 64.20%, 64.35%, 64.11% respectively. With the help of CAD, the metrics of the junior and senior radiologists improved to 62.81%, 62.81%, 62.85%, 62.79% and 73.86%, 73.86%, 74.00%, 73.83%. The results almost repeated on the unbalanced dataset. The results show the proposed CAD approach can not only achieve better performance than radiologists, but also significantly improve the radiologists' diagnosis of FTC. Conclusions: The performances of the CAD system indicate it is a reliable reference for preoperative diagnosis of FTC, and might assist the development of a fast, accessible screening method for FTC.

Enhancement of cottonseed oil refining wastewater treatment by zero valent iron under sunlight irradiation and O2 bubbling.

This study is the first to apply a zero-valent iron (ZVI) system in the treatment of cottonseed oil (CTO) refining wastewater. The results indicated that the ZVI system can effectively degrade and mineralize CTO in the wastewater, whereas sunlight irradiation and O2 bubbling can considerably enhance CTO degradation, removing 93.5% of CTO and 69.0% of chemical oxygen demand within 180 min. In addition, a low concentration (0.1 mM) of SO42- and Cl- in the wastewater improved CTO degradation, whereas a high concentration (>1 mM) of these anions considerably inhibited the degradation process. However, NO3- at all concentrations hindered CTO degradation. Furthermore, OH and O2- were the main active species for CTO degradation in the ZVI system under dark conditions. However, in addition to these two species, photogenerated hole (h+) played a key role in CTO degradation under sunlight irradiation. This observation might be derived from the photocatalytic effect due to photoexcitation of the iron corrosion product, γ-FeOOH. Our findings show that the ZVI system assisted by sunlight irradiation and O2 bubbling is feasible for CTO-refining wastewater treatment and can guide the real wastewater treatment project.

Isolation and thermo-acclimation of thermophilic bacteria in hyperthermophilic fermentation system.

Hyperthermophilic microorganisms play a key role in the hyper-thermophilic composting (HTC) technique. However, little information is available about the hyperthermophilic microorganisms prevalent in HTC systems, except for the Calditerricola satsumensis, Calditerricola yamamurae, and Thermaerobacter. To obtain effective hyper-thermophilic microorganisms, a continuous thermo-acclimation of the suitable thermophilic microorganisms was demonstrated in this study. Bacillus thermoamylovorans with high-temperature endurance (70 °C) were newly isolated from sludge composting, and an adequate slow heating rate (2 °C per cycle) was applied to further improve its thermostability. Finally, a strain with a maximum growth temperature of 80 °C was obtained. Moreover, structural and hydrophobic changes in cell proteins, the special amino acid content ratio, and the membrane permeability of the thermophilic bacterium after thermo-acclimation were evaluated for improved thermostability. In addition, the acclimated hyperthermophilic bacterium was further inoculated into the HTC system, and an excellent performance with a maximum operating temperature of 82 °C was observed.

Optimisation of enzymatic saccharification of wheat straw pre-treated with sodium hydroxide.

To enhance the reducing sugar yield in enzymatic hydrolysis, various factors (NaOH concentration, solid content and pre-treatment time) that affect the pre-treatment process were investigated and evaluated based on the reducing sugar yield of the subsequent enzymatic hydrolysis. The enzymatic hydrolysis was based on the cellulase from Trichoderma reesi ATCC 26921, the optimum NaOH pre-treatment conditions were an NaOH concentration of 1.0% (w/w), a solid content of 5.0% (w/v) and a pre-treatment time of 60 min. Various parameters that affect the enzymatic hydrolysis of wheat straw, including the solid content, enzyme loading, pH and hydrolysis time, were investigated and optimized through a Box-Behnken design and response surface methodology. The predicted optimum conditions for enzymatic hydrolysis were a solid content of 8.0% (w/v), an enzyme loading of 35 FPU/g substrate, a temperature of 50 °C, a pH of 5.3 and a hydrolysis time of 96 h. The experimental result showed that the maximum reducing sugar yield was 60.73% (53.35% higher than the wheat straw without NaOH pre-treatment), which is in accordance with the predicted conditions.

Web-Based Ultrasonic Nomogram Predicts Preoperative Central Lymph Node Metastasis of cN0 Papillary Thyroid Microcarcinoma.

Background: Many clinicians are facing the dilemma about whether they should apply the active surveillance (AS) strategy for managing Clinically Node-negative (cN0) PTMC patients in daily clinical practice. This research plans to construct a dynamic nomogram based on network, connected with ultrasound characteristics and clinical data, to predict the risk of central lymph node metastasis (CLNM) in cN0 PTMC patients before surgery. Methods: A retrospective analysis of 659 patients with cN0 PTMC who had underwent thyroid surgery and central compartment neck dissection. Patients were randomly (2:1) divided into the development cohort (439 patients) and validation cohort (220 patients). The group least absolute shrinkage and selection operator (Group Lasso) regression method was used to select the ultrasonic features for CLNM prediction in the development cohort. These features and clinical data were screened by the multivariable regression analysis, and the CLNM prediction model and web-based calculator were established. Receiver operating characteristic, calibration curve, Clinical impact curve and decision curve analysis (DCA) were used to weigh the performance of the prediction model in the validation set. Results: Multivariable regression analysis showed that age, tumor size, multifocality, the number of contact surface, and real-time elastography were risk factors that could predict CLNM. The area under the curve of the prediction model in the development and validation sets were 0.78 and 0.77, respectively, with good discrimination and calibration. A web-based dynamic calculator was built. DCA proved that the prediction model had excellent net benefits and clinical practicability. Conclusions: The web-based dynamic nomogram incorporating US and clinical features was able to forecast the risk of preoperative CLNM in cN0 PTMC patients, and has good predictive performance. As a new observational indicator, NCS can provide additional predictive information.

Ultrasound Real-Time Tissue Elastography Improves the Diagnostic Performance of the ACR Thyroid Imaging Reporting and Data System in Differentiating Malignant from Benign Thyroid Nodules: A Summary of 1525 Thyroid Nodules.

BACKGROUND: To explore the correlation between the ultrasound elasticity score (ES) of real-time tissue elastography (RTE) and the malignant risk stratification of the Thyroid Imaging Reporting and Data System (TI-RADS) and to evaluate the added value of RTE to TI-RADS in differentiating malignant nodules from benign ones. METHODS: A total of 1,498 patients (885 women and 613 men; mean age of 43.5 ± 12.4 years) with 1,525 confirmed thyroid nodules (D = maximum diameter, D ≤ 2.5 cm) confirmed by fine-needle aspiration (FNA) and/or surgery were included. The nodules were divided into four groups based on their sizes (D ≤ 0.5 cm, 0.5 < D ≤ 1.0 cm, 1.0 < D ≤ 2.0 cm, and 2.0 < D ≤ 2.5 cm). We assigned an ES of RTE and malignant risk stratification of the TI-RADS category to each nodule. The correlation between the ES of RTE and the malignant risk stratification of TI-RADS category was analyzed by the Spearman's rank correlation. The diagnostic performances of RTE, TI-RADS, and their combination were compared by the receiver operator characteristic (ROC) analysis. RESULTS: The ES of RTE and the malignant risk stratification of TI-RADS showed a strong correlation in the size intervals of 0.5 < D ≤ 1.0 cm, 1.0 < D ≤ 2.0 cm, and 2.0 < D ≤ 2.5 cm (r = 0.768, 0.711, and 0.743, respectively). The diagnostic performance of their combination for each size interval was always better than RTE or TI-RADS alone (for all, P < 0.001). CONCLUSIONS: Overall, The ES of RTE was strongly correlated with the malignant risk stratification of TI-RADS. The diagnostic performance of the combination of RTE and TI-RADS outperformed RTE or TI-RADS alone. Therefore, RTE may be an adjunctive tool to the current TI-RADS system for differentiating malignant from benign thyroid nodules.

Intermittent operating characteristics of an ecological soil system with two-stage water distribution for wastewater treatment.

Ecological soil systems (ESSs) are usually used to remove nitrogen from wastewater. Due to the poor denitrification performance of traditional ecological soil systems (ESSs), this study proposes a two-stage water distribution system to improve the nitrogen removal. The effects of different distribution ratios on the system treatment effect were studied in an intermittent operation mode. After determining the optimal distribution ratio and intermittent operation conditions, the dynamics of system inflow, outflow, and nitrogen removal were monitored. Theoretical analysis of the denitrification mechanism was carried out. The results showed that the optimum water distribution ratio was 2: 1, and a mean total nitrogen removal rate of 60.42% was achieved, which is 23.09% greater than that is typically achieved by the single-section ecological system. Under optimum distribution ratio conditions, the system also demonstrated effective removal of chemical oxygen demand (COD), total phosphorus (TP) and ammonia nitrogen (NH4+-N), allowing the effluent to satisfy China's urban sewage treatment plant level B emission standards.

The influence of phosphorus on the autotrophic and mixotrophic denitrification.

Autotrophic and mixotrophic denitrification, two approaches of biological denitrification, have drawn more and more attention among the techniques to remove nitrogen from the aquatic environment. This study investigated the influence of phosphorus on the denitrification performance and bacterial community structure in the autotrophic and mixotrophic denitrification reactors. The activity test was applied to evaluate the variation of denitrification activity of autotrophic and mixotrophic sludge before and after phosphorus addition. High-throughput sequencing was used to analyze the change of bacterial community structure. The results showed that NO3--N removal efficiency of autotrophic and mixotrophic denitrification process increased by 40 and 35%, respectively, after phosphorus addition. The sludge denitrification activity of autotrophic and mixotrophic sludge was enhanced significantly. And phosphorus addition could greatly improve the proportion of denitrifying bacteria in both autotrophic (from 11.83 to 64.31%) and mixotrophic denitrifying sludge (from 13.59 to 45.12%). Overall, phosphorus addition could greatly improve the autotrophic and mixotrophic denitrification ability in the phosphorus deficient surface water.

Pre-treatment of pyridine wastewater by new cathodic-anodic-electrolysis packing.

A novel cathodic-anodic-electrolysis packing (CAEP) used in the treatment of pyridine wastewater was researched, which mainly consisted of 4,4'-diamino-2,2'-disulfonic acid (DSD acid) industrial iron sludge. The physical properties and morphology of the packing were studied. The CAEP was used in a column reactor during the pretreatment of pyridine wastewater. The influence of pH, hydraulic retention time (HRT), the air-liquid ratio (A/L) and the initial concentration of pyridine were investigated by measuring the removal of total organic carbon (TOC) and pyridine. The characterization results showed that the bulk density, grain density, water absorption percentage and specific surface area were 921kg/m3, 1086kg/m3, 25% and 29.89m2/g, respectively; the removal of TOC and pyridine could reach 50% and 58% at the optimal experimental conditions (pH=3, HRT=8hr, A/L=2). Notably, the surface of the packing was renewed constantly during the running of the filter, and the handling capacity was stable after running for three months.

Nitrogen removal by thiosulfate-driven denitrification and plant uptake in enhanced floating treatment wetland.

This study investigated the potential of thiosulfate-driven autotrophic enhanced floating treatment wetland (AEFTW) in removing nitrogen from the secondary effluent at the relatively short hydraulic retention times and low S/N ratios. Simultaneous autotrophic and heterotrophic denitrification was observed in AEFTW. The peak TN removal rate (15.3gm-2d-1) exceeded most of the reported floating treatment wetlands. Based on the kinetic model results, low mean temperature coefficient and high k20 verified that the excellent performance in AEFTW diminished the microbial dependence on temperature. Nitrogen removal performance of enhanced floating treatment wetland (EFTW) and floating treatment wetland (FTW) were similar and highly sensitive to temperature. The interaction of sulfur transformation on the nitrogen, carbon uptake of plants was studied. Thiosulfate addition significantly raised sulfur content in the shoots and further enhanced the uptake of nitrogen and carbon, and increased the plant biomass at the same time. Higher composition of autotrophic and heterotrophic denitrifiers in AEFTW interpreted the occurrence of mixotrophic denitrification during summer. Thiosulfate induced mutual promotion of nitrogen removal by plant uptake and microbial denitrification in AEFTW.

Decomposition characteristics of three different kinds of aquatic macrophytes and their potential application as carbon resource in constructed wetland.

Decomposition of aquatic macrophytes usually generates significant influence on aquatic environment. Study on the aquatic macrophytes decomposition may help reusing the aquatic macrophytes litters, as well as controlling the water pollution caused by the decomposition process. This study verified that the decomposition processes of three different kinds of aquatic macrophytes (water hyacinth, hydrilla and cattail) could exert significant influences on water quality of the receiving water, including the change extent of pH, dissolved oxygen (DO), the contents of carbon, nitrogen and phosphorus, etc. The influence of decomposition on water quality and the concentrations of the released chemical materials both followed the order of water hyacinth > hydrilla > cattail. Greater influence was obtained with higher dosage of plant litter addition. The influence also varied with sediment addition. Moreover, nitrogen released from the decomposition of water hyacinth and hydrilla were mainly NH3-N and organic nitrogen while those from cattail litter included organic nitrogen and NO3--N. After the decomposition, the average carbon to nitrogen ratio (C/N) in the receiving water was about 2.6 (water hyacinth), 5.3 (hydrilla) and 20.3 (cattail). Therefore, cattail litter might be a potential plant carbon source for denitrification in ecological system of a constructed wetland.