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Water ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 206
Author(s):  
Yicheng Wang ◽  
Yingkun Wang ◽  
Xi Lu ◽  
Wenquan Sun ◽  
Yanhua Xu ◽  
...  

An Mn/Ce@red mud (RM) catalyst was prepared from RM via a doping–calcination method. Scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy were used to characterize the surface morphology, crystal morphology, and elemental composition of the Mn/Ce@RM catalyst, respectively. In addition, preparation and catalytic ozonation conditions were optimized, and the mechanism of catalytic ozonation was discussed. Lastly, a fuzzy analytic hierarchy process (FAHP) was adopted to evaluate the degradation of coal chemical biochemical tail water. The best preparation conditions for the Mn/Ce@RM catalyst were found to be as follows: (1) active component loading of 3%, (2) Mn/Ce doping ratio of 2:1, (3) calcination temperature of 550 °C, (4) calcination time of 240 min, and (5) fly ash floating bead doping of 10%. The chemical oxygen demand (COD) removal rate was 76.58% under this preparation condition. The characterization results suggested that the pore structure of the optimized Mn/Ce@RM catalyst was significantly improved. Mn and Ce were successfully loaded on the catalyst in the form of MnO2 and CeO2. The best operating conditions in the study were as follows: (1) reaction time of 80 min, (2) initial pH of 9, (3) ozone dosage of 2.0 g/h, (4) catalyst dosage of 62.5 g/L, and (5) COD removal rate of 84.96%. Mechanism analysis results showed that hydroxyl radicals (•OH) played a leading role in degrading organics in the biochemical tail water, and adsorption of RM and direct oxidation of ozone played a secondary role. FAHP was established on the basis of environmental impact, economic benefit, and energy consumption. Comprehensive evaluation by FAHP demonstrated that D3 (with an ozone dosage of 2.0 g/H, a catalyst dosage of 62.5 g/L, initial pH of 9, reaction time of 80 min, and a COD removal rate of 84.96%) was the best operating condition.


2021 ◽  
Vol 14 (22) ◽  
Author(s):  
Hanxi Wang ◽  
Jianling Xu ◽  
Lianxi Sheng

2021 ◽  
Author(s):  
Regan Nicholaus ◽  
Betina Lukwambe ◽  
Wen Yang ◽  
Zhongming Zheng

Constructed-wetlands, Biofilms, and sedimentation are potential aquaculture tail-water treatments however their roles on the distribution of benthic microbial community and the way they affect the interaction between microbial community and inorganic nutrient fluxes have not been fully explored. This study applied 16S rRNA high-throughput sequencing technology to investigate the microbial community distribution and their link with nutrient fluxes in an aquaculture tail- water bioremediation system . Results showed that bacterial community compositions were significantly different in constructed-wetland and biofilm treatments (p<0.05) relative to sedimentation. The composition of the 16S rRNA genes among all the treatments was enriched with Proteobacteria, Bacteroidetes, Firmicutes, and Flavobacteria . NMDS analysis showed that the bacterial composition in constructed-wetland and biofilm samples clustered separately compared to those in sedimentation. The Functional-Annotation-of-Prokaryotic-Taxa analysis indicated that the proportions of sediment-microbial-functional groups (aerobic-chemoheterophy, chemoheterotrophy, and nitrate-ammonification combined) in the constructed-wetland treatment were 47%, 32% in biofilm and 13% in sedimentation system. Benthic-nutrient fluxes for phosphate, ammonium, nitrite, nitrate and sediment oxygen consumption differed markedly among the treatments ( p<0.05 ). Canonical correspondence analysis indicated constructed-wetland had the strongest association between biogeochemical contents and the bacterial community relative to other treatments. This study suggests that the microbial community distributions and their interactions nutrient fluxes were most improved in the constructed-wetland followed by the area under biofilm and sedimentation treatment.


2021 ◽  
Vol 10 (8) ◽  
pp. 494
Author(s):  
Bruna Almeida ◽  
Pedro Cabral

The spatially explicit assessment of freshwater is key to introduce the ecosystem services (ES) concept into decision-making processes. Many tools are being developed to model water balance and to analyze the effects of meteorological conditions on water ES behaviors at multiple spatial scales. The current study uses the InVEST Annual Water Yield Model (WYM) to assess water availability in watersheds of the mainland of Portugal. The methodology included sensitivity analysis to test different parameters of the model and validation using the European Environment Agency (EEA) database on the quantity of Europe’s water resources. To evaluate the models’ sensitivity, Pearson’s correlation coefficients and statistical methods were calculated for each simulation. Results at the national level show a correlation coefficient of 0.803 with statistical significance for 0.01 one-tail. Water yield was underestimated by 56.5 mm/ha/year in the North of the country and overestimated by 58.1 mm/ha/year in the South. This difference was explained through the spatial-temporal assessment of the main climatic variables used as input. This study contributes to a methodology to assess the level of confidence in the WYM outputs and can be used to support the trustworthiness of water availability studies, using open-access data and software.


Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4313
Author(s):  
Bronisław Jańczuk ◽  
Katarzyna Szymczyk ◽  
Anna Zdziennicka

Measurements were made of the surface tension of the aqueous solutions of p-(1,1,3,3-tetramethylbutyl) phenoxypoly(ethylene glycols) having 10 oxyethylene groups in the molecule (Triton X-100, TX100) and cetyltrimethylammonium bromide (CTAB) with Zonyl FSN-100 (FC6EO14, FC1) as well as with Zonyl FSO-100 (FC5EO10, FC2) ternary mixtures. The obtained results were compared to those provided by the Fainerman and Miller equation and to the values of the solution surface tension calculated, based on the contribution of a particular surfactant in the mixture to the reduction of water surface tension. The changes of the aqueous solution ternary surfactants mixture surface tension at the constant concentration of TX100 and CTAB mixture at which the water surface tension was reduced to 60 and 50 mN/m as a function of fluorocarbon surfactant concentration, were considered with regard to the composition of the mixed monolayer at the water-air interface. Next, this composition was applied for the calculation of the concentration of the particular surfactants in the monolayer using the Frumkin equation. On the other hand, the Gibbs surface excess concentration was determined only for the fluorocarbon surfactants. The tendency of the particular surfactants to adsorb at the water-air interface was discussed, based on the Gibbs standard free energy of adsorption which was determined using different methods. This energy was also deduced, based on the surfactant tail surface tension and tail-water interface tension.


Author(s):  
Mohsen Nasrabadi ◽  
Yaser Mehri ◽  
Amin Ghassemi ◽  
Mohammad Hossein Omid

Abstract Hydraulic jump typically occurs downstream of hydraulic structures by converting the supercritical to subcritical flow regimes. If the tail-water depth is greater than the secondary depth of the hydraulic jump, the jump will be submerged (SHJ). In these conditions, the momentum equations will not have an analytical solution and a new solution is required. In this study, after dimensional analysis, an experimental study was conducted in a rectangular flume with a length of 9 m, a width of 0.5 m and a depth of 0.45 m in a wide range of Froude numbers (Fr = 3.5 to 11.5) and submergence ratios (Sr = 0.1 to 4). The data were then normalized and divided into two parts of training and testing. A new technique, DGMDH, was used to predict the submerged hydraulic jump characteristics. The results were then compared with the GMDH model. The results showed that DGMDH model estimated the relative submergence depth, jump length, and relative energy loss with accuracy of R2 = 0.9944 and MAPE = 0.038, R2 = 0.9779 and MAPE = 0.0387, and R2 = 0.9932 and MAPE = 0.0192, respectively. While the accuracy of GMDH model for relative submergence depth, jump length, and relative energy loss was respectively R2 = 0.9923 and MAPE = 0.043, R2 = 0.9671 and MAPE = 0.0527, and R2 = 0.9932 and MAPE = 0.0192. Due to superiority of the DGMDH model over the GMDH model, it is recommended to use this model to estimate the submerged hydraulic jump characteristics. Highlight The results showed that DGMDH model have more accurate results than the GMDH model in predicting the relative submergence depth, jump length, and relative energy loss.


2021 ◽  
pp. 014459872110204
Author(s):  
Yan Wang ◽  
Yanguang Liu ◽  
Kai Bian ◽  
Hong Zhang ◽  
Xiaojun Wang ◽  
...  

Seepage and heat transfer in the carbonate reservoir under low-temperature tail water reinjection is a complex coupling process, which is an important basis for scientific and reasonable evaluation of geothermal resource sustainability. This study based on the tracer test of double-well reinjection for carbonate heat reservoir, a coupling model of seepage field and temperature field of fracture network is established by using the finite element software COMSOL. The uncertainty analysis is carried out to study the fluid-thermal coupling process of carbonate fracture under the condition of low-temperature tail water reinjection.The variation law of seepage field and temperature field of thermal reservoir under low-temperature geothermal tail water reinjection is revealed, The variation of measured temperature of thermal reservoir pumping side under different reinjection conditions is predicted. The results show that the dominant fracture channels between wells of the fractured heat reservoir in Xian county geothermal field play an important role in controlling the seepage heat transfer. Under the coupling action of the seepage field, pressure field and the temperature field of the heat reservoir, the low-temperature tail water reinjection forms a preferential flow along the dominant channels, which is one of the important factors to consider in the prediction of thermal breakthrough. Reinjection pressure, temperature and well spacing are the main factors for artificial control of geothermal production and reinjection system. In the pumping and reinjection system of Xian county geothermal field, under the conditions of 0.5 MPa reinjection pressure, 30 °C reinjection tail water temperature and 270 m spacing between pumping and reinjection wells, the heat reservoir temperature at the pumping side decreased by 1.5 °C in 100 years.


2021 ◽  
Vol 768 (1) ◽  
pp. 012003
Author(s):  
Li Gaohui ◽  
Zhang Mengjie ◽  
Chen Xiangrong ◽  
Zheng Quanchun ◽  
Cui Weijie ◽  
...  

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