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The complexes of epigallocatechin (EGC) and 5-hydroxymethylfurfural (5-HMF) was constructed in water-soluble and ethanol-soluble systems to study the effect of EGC on the chemical structure of food harmful substance 5-HMF. The results showed that EGC and 5-HMF can be combined by non-covalent way in water-soluble and ethanol-soluble systems, and the main force was hydrogen bond. Scanning electron microscope, X-ray diffractometer and differential scanning calorimeter displayed that EGC combined with 5-HMF in the form of co-amorphous complexes. Fourier transform infrared spectroscopy, 1H-NMR spectroscopy and molecular dynamics simulation confirmed that EGC can form O-H...O hydrogen bonds with adjacent 5-HMF molecules. Thin-layer chromatography and in vitro digestive juice assay further proved that no free 5-HMF was observed after EGC and 5-HMF formed complexes. The results indicated that EGC and 5-HMF formed an EGC-5-HMF co-amorphous complexes through intermolecular hydrogen bonding, which could change the stability of free 5-HMF and EGC presents favorable potential for the control of 5-HMF in food.

Water scarcity is a worldwide problem. Recycled municipal wastewater is considered a useful alternative to the conventional types of water resources. In this study, a shallow constructed wetland (SCW) with porous filter material and Rotala rotundifolia was used for advanced municipal sewage treatment. The wetland without plant was set as the control (SCW-C). The pollutant removal performance of the system at different hydraulic retention times (HRTs) was investigated. The diversity of the microbial community was analyzed, and the fate of nutrients, mainly N and P, in the system was discussed. Results showed that SCW was efficient in pollutant removal. Effluent concentrations of chemical oxygen demand (COD), total phosphorus (TP), and ammonium nitrogen (NH

In this study, spent mushroom substrates (SMSs) were fermented anaerobically at room temperature to gain liquid SMSs (LSMSs) that were used to remove nitrogen from the piggery wastewater with a low C/N ratio in a sequencing batch reactor (SBR) and solid SMSs (SSMSs) that were utilized to adsorb Pb2+ from Pb2+-containing wastewater in a fixed-bed reactor (FBR). After LSMSs supplement, the removal efficiency of both total nitrogen (TN) and NH+4-N increased from around 50% to 60–80%. High-throughput sequencing results presented an obvious change in microbial diversity, and some functional microorganisms like Zoogloea and Hydrogenophaga predominated to promote nitrogen removal. Pb2+ did not emerge from the effluent until 240 min with the corresponding concentration being less than 3 mg/L when using 30-day SSMSs as adsorbents, and it was demonstrated to be appropriate to use the Thomas model to predict Pb2+ sorption on SSMSs. Although various functional groups played a role in binding ions, the carboxyl group was proved to contribute most to Pb2+ adsorption. These results certified that the anaerobically fermented SMSs are decidedly suitable for wastewater treatment. HIGHLIGHTS Anaerobically fermented spent mushroom substrates (AFSMS) could be recycled entirely.; AFSMSs were suitable for the treatment of piggery wastewater with a low C/N.; AFSMSs had a much higher capacity to adsorb Pb2+ than native SMSs.

The nitrite removal pathway in Acinetobacter sp. TX5 was explored through the key gene identification and the corresponding enzyme purification, after which the capability to reduce nitrite by immo...

Temperature is an extremely important factor affecting the nutrient (mainly nitrogen and phosphorus) removal of aquatic macrophytes. A novel submersed Rotala rotundifolia was separately cultivated at room and low temperatures to investigate its ability for nutrient removal. The physiological metabolism was analyzed to explore the mechanism of removing nutrients under a wide temperature range. The results showed that the removal efficiency (RE) of nutrients at low temperature was competitive with that obtained at normal temperature, demonstrating that temperature exerted no obvious influence on the nutrient removal by R. rotundifolia. The root vitality at 5 °C rose from the initial 0.26 to 1.5 mg g−1 h−1, whereas it fell by 38.66% at 10 °C, 28.74% at 20 °C and 5.15% at 30 °C. The peroxidase (POD) activity at 5 °C showed the maximum value on day 7 followed by a notable decline on day 21. All the peak values of soluble sugar and protein as well as MDA showed up at 5 °C and they were 5.5, 437.9 and 10.1 mg g−1, respectively. Chlorophyll a and b reached 8.4 and 4.4 mg g−1 on day 28, respectively, with a total chlorophyll content (a plus b) of 12.4 mg g−1 at 5 °C, all of which were higher than that at 30 °C. These results validated that R. rotundifolia could be a superior candidate suitable for in situ application.

A new Fe-C porous filter material was prepared with dredged sediment of river as raw material. The orthogonal test L9(34) and component ratio experiment of raw material were conducted to investigate the optimum technological condition. Further, the filter obtained was characterized by Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), energy dispersive X-ray spectroscope (EDS), and X-ray diffraction (XRD). Results showed that the optimal technological condition was sludge: straw: starch: iron powder: foam: iron powder 74.5∶10∶7.5∶3∶5, preheating temperature 280 ℃, preheating 15 min, sintering temperature 1080 ℃, and sintering 11 min. The BET surface area of the filter was 3.32 m2 g− 1, and average pore size was 10.05 nm. Phase composition mainly included SiO2, Fe3O4, Fe2O3 and muscovite (KAl2(Si3Al)O10(OH)2). Average effluent concentrations of total phosphorus (TP), total organic carbon (TOC), and total nitrogen (TN) of the biofilter system filled with the filter obtained were decreased to 0.08, 3.43, and 3.76 mg L− 1, separately, at hydraulic retention time 4 h. Thus, the filter prepared with dredged sediment of rive as raw material is an alternative material for polluted river water purification.

The vegetative growth and remediation potential of Rotala rotundifolia, a novel submerged aquatic plant, for eutrophic waters were investigated on different sediments, and under a range of nitrogen concentrations. Rotala Rotundifolia grew better on silt than on sand and gravel in terms of plant height, tiller number and biomass accumulation. Percent increment of biomass was enhanced at low water nitrogen (ammonium nitrogen concentration ≤10 mg/L). The maximum total nitrogen and total phosphorus removals in the overlying water were between 54% to 66% and 42% to 57%, respectively. Nitrogen contents in the sediments increased with increasing water nitrogen levels, whereas, nitrogen contents in the plant tissues showed no apparent regularity, and the greatest value was obtained at ammonium nitrogen concentration 15 mg/L. Both phosphorus contents in the sediments and tissues of plants were not affected significantly by additional nitrogen supply. Direct nitrogen uptake by plants was in the range of 16% to 39% when total phosphorus concentration was 1.0 mg/L. These results suggested that Rotala Rotundifolia can be used to effectively remove nitrogen and phosphorus in eutrophic waters.

The nitrite removal pathway in

Iron-nickel supported on modified active carbon (Fe-Ni/MAC) was prepared and characterized by XRD, SEM, XPS and EDS, followed by evaluating the practicability of Fe-Ni/MAC in treating real wastewater with a high concentration of phenol. Results showed that the optimal conditions for catalytic ozonation obtained by response surface methodology (RSM) were catalyst 10 g/L, ozone 68 mg/L, pH 9 and reaction time 90 min. Fe-Ni alloy and NiFe2O4 were demonstrated to be the dominant active species involved in catalytic reaction. The Fe-Ni/MAC catalyst can be reused six times with a satisfactory performance and little leaching of metal ions. Although some radicals like &middot, OH and &middot, O2&minus, functioned well, singlet oxygen (1O2) was regarded as the most important radical in the Fe-Ni/MAC process. Most noticeably, the fluorescence excitation emission matrices (EEMs) certified that as much as 1243 mg/L phenol in the real wastewater was completely degraded, which made Fe-Ni/MAC a fairly practical catalyst.

Temperature is an extremely important factor affecting the nutrient (mainly nitrogen and phosphorus) removal of aquatic macrophytes. A novel submersed

Rotala rotundifolia is a novel submerged macrophyte able to survive across the winter under temperature as low as 4 °C. Dynamic nutrient removal potential of R. rotundifolia was estimated using the Eco-tank system simulating natural eutrophic waters. The growth and physiological response of R. rotundifolia by cutting and division propagation to light (100%, 60%, and 20% natural light) were investigated. The results showed that R. rotundifolia was superior in removing N and P from eutrophic waters. As influent concentrations of NH4+-N and total phosphorus (TP) were 4.81–5.87 and 0.61–0.78 mg L−1, effluent concentrations of NH4+-N, total nitrogen (TN), and TP were separately 0.06–1.10, 0.40–1.59, and 0.05–0.17 mg L−1, with removal efficiencies of 93.6%, 84.6%, and 82.5% at a flow rate of 200 L d−1. The growth and morphology of the plant under two propagation patterns were influenced by light and the responses were quite different. The biomass of the plant by cutting was higher at low light conditions, and the plant allocated more biomass on above ground. However, there was no significant difference in the height. By division, the plant preferred to high light. The biomass and height were significantly higher at 100% natural light. The peroxidase (POD), superoxide dismutase (SOD) and root activities of plant by cutting showed a trend of decrease and followed by an increase with light reduction, while by division, they increased with reduced light available. Variations of chlorophyll and soluble protein of the plant by cutting and division were contrary to the changes of POD activity. These results suggest that R. rotundifolia can be used to effectively remove nitrogen and phosphorus in eutrophic waters, and high light promotes the growth of the plant by division, while suitable shade is needed for the plant by cutting.

Waste-to-energy is a promising approach for environmental sustainability. We examined the usage of watermelon rind waste coupled with nitrite-containing wastewater for electricity production in a membraneless biocathode microbial fuel cell (MB-MFC). Results showed that the maximum voltage output with internal nitrite circulation in a fed-batch mode was 294 mV, which was 1.4 and 1.3 times of that without internal circulation and in a continuous mode, respectively. Watermelon rind was quickly fermented to organic acids dominated with acetate and lactate during electricity generation. The most dominant genus in cathodic biofilm was Lactobacillus with a relative abundance of 74%, while the two dominative genera of Clostridium sensu stricto and Bacteroides in anodic biofilm had a similar abundance of approximately 18%. Three microbes cooperated well in producing electricity and converting nitrite to nitrogen gas. Additionally, we found the key genes of nirS/K, conrB and nosZ involved in nitrite reduction. Our results suggest the feasibility of harnessing electrical energy from MB-MFC with watermelon rind waste as substrates and nitrite-containing wastewater as electron acceptor.

A novel biofilm carrier (BFBC) was prepared with bamboo fiber as raw material and its characteristics, including specific surface area, hydrophilicity, and adsorption capacity were investigated. The comparison with conventional combined carrier for the removal of organics, N, and P using bio-contact oxidation reactor (BCOR) was carried out. The application of BCOR filled with BFBC in upgrading the existing activated sludge system of wastewater treatment plant was further studied. The specific surface area of BFBC was 5393 m2/m3, thoroughly saturated with water in 30 min. The BCOR filled with BFBC started up more rapidly than BCOR filled with combined carrier, and the removal efficiencies for chemical oxygen demand (COD), N, and P were significantly higher in BCOR filled with BFBC than combined carrier during start-up period. Moreover, the BCOR filled with BFBC showed higher resistance to pollutants load impact. Compared with the existing activated sludge system, the BCOR was more efficient in poll...

Dynamic remediation of river water polluted by domestic sewage using an aquatic plants bed-based Eco-tank system was investigated. Over a period of 18 days, the test demonstrated that average effluent concentrations of chemical oxygen demand (COD), ammonium nitrogen (NH4(+)-N) and total phosphorus (TP) were as low as 17.28, 0.23 and 0.03 mg/L, respectively, under the hydraulic retention time (HRT) of 8.7 d. The average removal efficiencies in terms of COD, NH4(+)-N and TP could reach 71.95, 97.96 and 97.84%, respectively. The loss of both NH4(+)-N and TP was mainly ascribed to the uptake by plants. Hydrocotyle leucocephala was effective in promoting the dissolved oxygen (DO) level, while Pistia stratiotes with numerous fibrous roots was significantly effective for the removal of organic compounds. The net photosynthetic rate, stomatal conductance, transpiration rate and biomass accumulation rate of Myriophyllum aquaticum were the highest among all tested plants. Thus, the Eco-tank system could be considered as an alternative approach for the in situ remediation of polluted river water, especially nutrient-laden river water.

An Eco-tank system of 10m was designed to simulate the natural river. It consisted of five tanks sequentially connected containing microbes, biofilm carriers and four species of floating aquatic plants. The purification performance of the system for N,N-dimethylformamide (DMF) polluted river water was evaluated by operating in continuous mode. DMF was completely removed in Tanks 1 and 2 at influent DMF concentrations between 75.42 and 161.05mg L-1. The NH4+-N concentration increased in Tank 1, followed by a gradual decrease in Tanks 2-5. Removal of NH4+-N was enhanced by aeration. The average effluent NH4+-N concentration of Tank 5 decreased to a minimum of 0.89mg L-1, corresponding to a decrease of 84.8% when compared with that before aeration. TN concentration did not decrease significantly as expected after inoculation with denitrifying bacteria. The average effluent TN concentration of the system was determined to be 4.58mg L-1, still unable to satisfy the Class V standard for surface water environmental quality. The results of this study demonstrated that the Eco-tank system is an efficient process in removing DMF, TOC, and NH4+-N from DMF polluted river water. However, if possible, alternative technologies should be adopted for controlling the effluent TN concentration.