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The purpose of this study was to investigate the influence of substrates (quartz sand and coke) on the removal of pollutants (COD, NH4+-N and TP), electrochemical characteristics and microbial communities of vertical flow constructed wetlands (VFCW) under high pollutant loads. During operation, the removal rates of COD, NH4+-N and TP by VFCW-C (coke as substrate) were higher than that of VFCW-Q (quartz sand as substrate) by 9.73–19.41%, 5.03%–13.15% and 8.83%–14.58%, respectively. And the resistances of the VFCW-Q and VFCW-C were increased by 1228.9 Ω and 38.3 Ω, while their potentials were dropped from 182.4 mV to 377.9 mV–85.6 mV and 222.0 mV, respectively. The dominant bacteria at the bottoms of VFCW-Q and VFCW-C were individually aerobic denitrifying bacteria (ADNB; 14.98%)/ammonia oxidizing bacteria (AOB; 5.73%) and organics aerobic degrading bacteria (OADB; 12.48%)/ammonia oxidizing bacteria (AOB; 7.24%), while the predominant bacteria at their tops were separately ADNB (11.36%)/OADB (10.52%)/AOB (4.69%) and ADNB (15.09%)/AOB (8.86%) and OADB (3.20%) The removal of pollutants by VFCW-Q and VFCW-C may be mainly attributed to substrate adsorption and microbial degradation.

This study investigates the influence of multilayer substrate configuration in horizontal subsurface flow constructed wetlands (HSCWs) on their treatment performance, biofilm development, and solid accumulation. Three pilot-scale HSCWs were built to treat campus sewage and have been operationalfor three years. The HSCWs included mono-layer (CW1), three-layer (CW3), and six-layer (CW6) substrate configurations with hydraulic conductivity of the substrate increasing from the surface to bottom in the multilayer CWs. It was demonstrated the pollutants removal performance after 3-year operation improved in the multilayer HSCWs (49-80%) compared to the mono layer HSCW (29-41%). Simultaneously, the multilayer HSCWs exhibited significant features that prevented clogging compared to the monolayer configuration. The amount of accumulated solids was notably higher in the monolayer CW compared to multilayer CWs. Further, multilayer HSCWs could delay clogging by providing higher biofilm development for organics removal and consequently, lesser solid accumulations. Principal component analysis strongly supported the visualization of the performance patterns in the present study and showed that multilayer substrate configuration, season, and sampling locations significantly influenced biofilm growth and solid accumulation. Finally, the present study provided important information to support the improved multilayer configured HSCW implication in the future.

Horizontal subsurface flow constructed wetlands (HSCWs) are widely used for wastewater treatment. The objective of this study was to assess the effects of substrate size selection and layout optimisation on pollutant removal and microbial community distribution responses in HSCWs. Three pilot-scale constructed wetlands (CWs) were established at Guilin University of Technology, China, to treat campus sewage. The three CWs included monolayer (CW1), three-layer (CW2), and six-layer (CW3) substrate structures with the hydraulic conductivity of the substrate increasing from the surface to the bottom in the multilayer CWs. Under an aerial influent loading rate of 0.38 m per day (volumetric loading rate of 0.63 per day), CW3 exhibited the highest removal performance for chemical oxygen demand (COD), NH4+-N, and total nitrogen (TN), with mean values of 81, 81, and 74%, respectively, followed by CW2 (68, 71, and 60%, respectively) and CW1 (56, 46, and 41%, respectively). Nitrification was demonstrated to be the limiting factor of TN removal, and higher TN removal performance in the multilayer CWs was attributed to the higher proportions of nitrifiers, including ammonia-oxidising bacteria (AOB) and nitrite-oxidising bacteria (NOB). Moreover, 454-pyrosequencing showed a significantly different spatial distribution of the N-transforming microbial community in multilayer HSCWs with substrate layout optimisation.

This study aimed at optimizing horizontal subsurface flow constructed wetlands (CWs) to improve hydraulic performance and pollutant removal efficiency. A groundwater modeling package (MODFLOW) was used to optimize three design parameters (length-to-width ratio, inlet/outlet-to-length ratio, and substrate size configuration). Using the optimized parameters, three pilot-scale CWs were built to treat actual wastewater. For model validation, we used a tracer test to evaluate hydraulic performance, and investigated the pollutant spatial distributions and removal efficiencies. We conclude that MODFLOW is suitable for designing CWs, accurately predicting that increasing hydraulic conductivity from surface to bottom layers could improve performance. However, the effect of vegetation, which decreased the hydraulic conductivity of the surface layer, should be considered to improve simulation results. Multilayer substrate configuration, with increasing hydraulic conductivity from the surface to bottom layers, significantly increased pollutant removal compared with monolayer configuration. The spatial variation in pollutant transport and degradation through the filling substrate showed that the multilayer configuration was able to increase use of the available space and moderately reduced short-circuiting and dead zones. Thus, multilayer CWs had higher experimental retention times, effective volume fractions and hydraulic efficiencies, and lower short-circuiting compared with monolayer CWs operating under similar conditions.

Despite the recent advances in contemporary therapeutic, operative as well as supportive care sepsis and its associated co-morbidity/mortality are still a common occurrence in the critically ill trauma/surgical patient. Thus, it remains important to continue to expand our understanding of pathological components which drive the development of immune dysfunction contributing to subsequent multiple organ failure. Here we overview some of the immuno-pathological processes, cells and mediators which may play a role in the development of this immune dysfunctional condition.

Nano-polyc rystalline silver (Ag) particles with the diameter of 60 nm were synthesized by the reducing agent sodium citrate. An amorphous zinc oxide (ZnO) shell layer was then coated on the surface of silver particles using wet chemical method. The Ag/ZnO core–shell structure was characterized by scanning electron microscope, transmission electron microscopy, ultraviolet–visible spectroscopy and fluorescence (FL) measurement. The results showed that nano-Ag/ZnO core–shell particles with an average diameter of ~100 nm were prepared successfully, and the FL intensity of Rhodamine 6G (R6G) mixed with Ag/ZnO nanoparticle was 53 % greater than that of the same amount of R6G without any nanoparticles, which may be related to the effect of surface plasmon resonance.