Submarine groundwater discharge(SGD)is being increasingly recognized as a significant source of nutrient into coastal waters,and generally comprises two components:submarine fresh groundwater discharge(SFGD)and recirc...Submarine groundwater discharge(SGD)is being increasingly recognized as a significant source of nutrient into coastal waters,and generally comprises two components:submarine fresh groundwater discharge(SFGD)and recirculated saline groundwater discharge(RSGD).The separate evaluation of SFGD and RSGD is extremely limited as compared to the conventional estimation of total SGD and associated nutrient fluxes,especially in marginal-scale regions.In this study,new high-resolution radium isotopes data in seawater and coastal groundwater enabled an estimation of SGD flux in a typical marginal sea of the Yellow Sea.By establishing 226Ra and 228Ra mass balance models,we obtained the SGD-derived radium fluxes,and then estimated the SFGD and RSGD fluxes through a two end-member model.The results showed that the total SGD flux into the Yellow Sea was equivalent to approximately 6.6 times the total freshwater discharge of surrounding rivers,and the SFGD flux accounted for only 5.2%–8.8%of the total SGD.Considering the nutrient concentrations in coastal fresh and saline groundwater,we obtained the dissolved inorganic nutrient fluxes(mmol m^(-2) yr^(-1))to be 52–353 for nitrogen(DIN),0.21–1.4 for phosphorus(DIP),34–226 for silicon(DSi)via SFGD,and 69–262 for DIN,1.0–3.9 for DIP,70–368 for DSi via RSGD,with the sum of nutrient fluxes equaling to(1.8–9.3)-fold,(1.3–5.6)-fold and(2.0–9.5)-fold of the riverine inputs.Compared to the conventional estimation of the total SGD flux,the nutrient fluxes derived from the separation of SFGD and RSGD were(1.6–2.1),(1.6–1.8)and(4.0–4.9)times lower for DIN,DIP and DSi,respectively,indicating that the estimates by separating SFGD and RSGD could be conservative and representative results of the Yellow Sea.Furthermore,we suggested that SGD played an important role in nutrient sources among all the traditional nutrient inputs sources,providing 15%–48%,33%–68%and 14%–43%of the total DIN,DIP and DSi input fluxes into the Yellow Sea,and the high nutrient stoichiometric ratios(i.e.,DIN/DIP)in SGD probably contributed to the increasing ratios in the Yellow Sea.In addition delivering large amounts of nutrient into the Yellow Sea,SGD would create primary productivity of 10–49,1.6–6.8 and 8.8–42 g C m^(-2)yr^(-1) based on N,P and Si,which were equivalent to 5.2%–27%,0.9%–3.7%and 4.7%–23%of the total primary productivity,respectively.In particular,the SFGD-derived DIN flux can be converted to primary productivity of 4.2–28 g C m^(-2)yr^(-1) thus demonstrating the disproportionately large role of SFGD in ecological environment of the Yellow Sea relative to its flux.Therefore,we conclude that SGD,particularly SFGD,plays an important role as a nutrient source for the Yellow Sea,and not only affects nutrient budgets and structures but also enhances the primary productivity.展开更多
Supercritical carbon dioxide(S-CO_(2))Brayton power cycle power generation technology,has attracted more and more scholars'attention in recent years because of its advantages of high efficiency and flexibility.Com...Supercritical carbon dioxide(S-CO_(2))Brayton power cycle power generation technology,has attracted more and more scholars'attention in recent years because of its advantages of high efficiency and flexibility.Compared with conventional steam boilers,S-CO_(2) has different heat transfer characteristics,it is easy to cause the temperature of the cooling wall of the boiler to rise,which leads to higher combustion gas temperature in the furnace,higher NOX generation concentration.The adoption of flue gas recirculation has a significance impact on the combustion process of pulverized coal in the boiler,and it is the most effective ways to reduce the emission of NOX and the combustion temperature in the boiler.This paper takes 1000MW S-CO_(2) T-type coal-fired boiler as the research target to investigate the combustion and NOX generation characteristics of S-CO_(2) coal-fired boilers under flue gas recirculation condition,the influence of recirculated flue gas distribution along the furnace height on the characteristics of NOX formation and the combustion of pulverized coal.The results show that the recirculated flue gas distribution has the great impact on the concentration of NOX at the boiler outlet.When the bottom recirculation flue gas rate is gradually increased,the average temperature of the lower boiler decreases and the average temperature of the upper boiler increases slightly;The concentration of NOx at the furnace outlet increases.展开更多
As the world shift towards sustainable energy solutions,solid oxide fuel cells(SOFCs)using non-carbon fuels like ammonia and hydrogen emerge as promising pathways to produce clean energy and enhance conversion efficie...As the world shift towards sustainable energy solutions,solid oxide fuel cells(SOFCs)using non-carbon fuels like ammonia and hydrogen emerge as promising pathways to produce clean energy and enhance conversion efficiency.However,current implementations encounter challenges such as nitriding effects from direct ammonia injection to the stack,overestimated benefits of anode off-gas(AOG)recirculation,and a sole focus on electrical efficiency that overlooks the thermal advantages of SOFCs.This study addresses these gaps through a comprehensive multi-objective optimization of SOFC systems fueled by ammonia and hydrogen,assessing their efficiency,fuel utilization,and heat exergy.The research translates material phenomena into mathematical constraints and quantifies the effects of control variables through systematic parameter variation.Results indicate that ammonia-fueled SOFC systems slightly outperform hydrogen,achieving an electrical efficiency of about 65% compared to 62% for hydrogen systems,although hydrogen demonstrates superior fuel utilization and exergy efficiency.Optimal AOG recirculation and NH3cracking fraction that do not compromise stack lifetime and stay in the safe operating zone of nitriding are identified.It also challenges the assumptions that a higher AOG recirculation can benefit performance,suggesting that more extensive AOG recirculation might not always enhance it.Soft sensors are provided to predict system’s performance and enable proactive adjustments to facilitate industrial applications where some parameters,such as high-temperature stack’s pressure drop,are costly or difficult to measure.This study significantly advances the practical deployment of SOFC technologies,enhancing their feasibility for sustainable energy development.展开更多
In view of the situation of multi-temperature,multi-medium and multi-discharge equipment on the integrated exhaust end platform of a natural gas distributed energy station,which is compact in layout,mutual influence,c...In view of the situation of multi-temperature,multi-medium and multi-discharge equipment on the integrated exhaust end platform of a natural gas distributed energy station,which is compact in layout,mutual influence,complex aerodynamic field and complex heat and mass transfer field,the temperature field and aerodynamic field of the platform were comprehensively studied through field experiments and numerical simulation.The research results show that the high temperature flue gas discharged from the chimney is hindered by the chimney cap and returns downward.The noise reduction walls around the chimney make the top of the platform pressurized under the crosswind,as a result,the inlet air temperature of each cooling equipment is generally higher than the ambient temperature,and the cooling efficiency is extremely low.According to the numerical simulation results,the effect of hot gas recirculation is intensified by the ambient crosswind.With the increase of the ambient crosswind,the flue gases coverage expands.The influence of ambient crosswind on inlet air temperature first increases and then decreases within the range of 1–8 m/s,showing a nearly normal distribution.Secondly,this study innovatively designed a new V-shaped chimney cap,compared with the A-shaped chimney cap,the new chimney cap effectively reduces its own obstruction to the smoke and changes the flow path of the smoke.After the smoke rises for a certain distance,the smoke returns downward,which effectively reduces the temperature of the smoke and thus reduces its impact on the air inlet of the cooling equipment.On-site measurement found that the cooling efficiency of various cooling equipment has increased by an average of 27.3%compared to before the renovation,and centrifuge’s refrigeration capacity increased by 0.78 GJ/h.展开更多
A pre-reduction sintering process with flue gas recirculation(PSP_(fsg)-FGR)was developed to mitigate alkalis harm to the blast furnace and reduce the flue gas emission in the whole ironmaking process.The results indi...A pre-reduction sintering process with flue gas recirculation(PSP_(fsg)-FGR)was developed to mitigate alkalis harm to the blast furnace and reduce the flue gas emission in the whole ironmaking process.The results indicated that the pre-reduction sintering process(PSP)can effectively remove 58.02%of K and 30.68%of Na from raw mixtures and improve yield and tumbler index to 74.40%and 68.69%,respectively.Moreover,PSP was conducive to reducing NO_(x) and SO_(2)emissions and simultaneously increasing CO content in flue gas.Circulating CO-containing flue gas to sintering bed effectively recycled CO and further improved K and Na removal ratio to 74.11%and 32.92%,respectively.Microstructural analysis revealed that the pre-reduced sinter mainly consisted of magnetite,wustite and a small quantity of metallic iron,and very few silicate glass phase was also formed.This process can simultaneously realize alkali metal elements removal as well as flue gas emission reduction from the integrated ironmaking process.展开更多
Extracorporeal therapies have a definite role in patients with acute liver failure,acute on-chronic liver failure,and progressive chronic liver disease.They act as a bridge-to-transplant in these patients.With the inc...Extracorporeal therapies have a definite role in patients with acute liver failure,acute on-chronic liver failure,and progressive chronic liver disease.They act as a bridge-to-transplant in these patients.With the increasing success of liver transplantation,the immediate postoperative complication spectrum continues to expand.Extracorporeal therapies can play an important role in managing these complications.However,the literature on extracorporeal therapies in the postliver transplant period is limited.This review article discussed various extracorporeal therapies that are still evolving or marred by limited evidence but can improve patient outcomes.These extracorporeal therapies can be divided into two subgroups:(1)Therapies for infective complications.Endotoxin and cytokine adsorption columns;and(2)Therapies for noninfective complications like small for size syndrome,primary allograft nonfunction,early allograft dysfunction,hyperacute rejection,hepatopulmonary syndrome,etc.(plasma exchange,double plasma molecular adsorption,molecular adsorbent recirculation system,and extracorporeal membrane oxygenation,among others).展开更多
Hydrothermal liquefaction(HTL)is a promising method for sustainable waste management and renewable energy production,converting mixed feedstocks into bio-crude,a precursor to various biofuels.A study focused on mixed ...Hydrothermal liquefaction(HTL)is a promising method for sustainable waste management and renewable energy production,converting mixed feedstocks into bio-crude,a precursor to various biofuels.A study focused on mixed residential waste(MRW)as an HTL feedstock investigated temperature ranges(280e360℃)and residence times(30e90 min),achieving a maximum bio-crude yield of 39.16%at 340℃and 75 min.Also,a thorough investigation of the synergistic relationships between all subcomponents of the MRW feedstock was conducted and concluded that the mixed waste(MW)feedstock samples containing a higher proportion of food and plastic wastes and MRW sample presented with a coliquefaction percentage(CE)of around 60%and 107%respectively for production of bio crude.Also,solvents such as ethanol,glycerol and aqueous phase(AQ)were tested for their potential as hydrothermal mediums and found that bio crude yield of 46.19%was obtained in case of AQ phase recirculation.Further,the quantitative and qualitative effect of usage of four different catalysts were tested individually and in combination with AQ phase recirculation and found that,although individually nanoporous ZnO and diatomaceous earth(DE)yielded bio crude in the range of 46.86%and 42.68%respectively,when used in combination,DE cateHTL with AQ resulted in maximum bio crude yield of 54.35%.Furthermore,qualitatively,the bio crude from DE cateHTL with AQ presented with a high carbon and energy recovery percentage of 62.20%and 72.95%respectively and a high hydrocarbon content of 58.98%.展开更多
Real-time detection of unhealthy fish remains a significant challenge in intensive recirculating aquaculture.Early recognition of unhealthy fish and the implementation of appropriate treatment measures are crucial for...Real-time detection of unhealthy fish remains a significant challenge in intensive recirculating aquaculture.Early recognition of unhealthy fish and the implementation of appropriate treatment measures are crucial for preventing the spread of diseases and minimizing economic losses.To address this issue,an improved algorithm based on the You Only Look Once v5s(YOLOv5s)lightweight model has been proposed.This enhanced model incorporates a faster lightweight structure and a new Convolutional Block Attention Module(CBAM)to achieve high recognition accuracy.Furthermore,the model introduces theα-SIoU loss function,which combines theα-Intersection over Union(α-IoU)and Shape Intersection over Union(SIoU)loss functions,thereby improving the accuracy of bounding box regression and object recognition.The average precision of the improved model reaches 94.2%for detecting unhealthy fish,representing increases of 11.3%,9.9%,9.7%,2.5%,and 2.1%compared to YOLOv3-tiny,YOLOv4,YOLOv5s,GhostNet-YOLOv5,and YOLOv7,respectively.Additionally,the improved model positively impacts hardware efficiency,reducing requirements for memory size by 59.0%,67.0%,63.0%,44.7%,and 55.6%in comparison to the five models mentioned above.The experimental results underscore the effectiveness of these approaches in addressing the challenges associated with fish health detection,and highlighting their significant practical implications and broad application prospects.展开更多
Hydrolysis at changing hydraulic retention time,recirculation,bedding straw content in the feed,bioaugmentation and the impact of those changes on gradient formation in the liquid phase in plug-flow reactors(PFRs)was ...Hydrolysis at changing hydraulic retention time,recirculation,bedding straw content in the feed,bioaugmentation and the impact of those changes on gradient formation in the liquid phase in plug-flow reactors(PFRs)was examined.The pH-value,conductivity and oxidation-reduction potential(ORP)were monitored at three spots along the PFRs to study potential correlations to process performance during a total process time of 123 weeks.The on-line monitoring showed good correlations to acidogenesis:namely,the pH and ORP to the acidification,to butyric(and lactic)acid concentration and to the acid yield.The ORP(measured at the inlet)showed the most stable correlation to acidogenesis under dynamic operation,while the conductivity(at the outlet)correlated to the acid concentration in dependence on the feedstock.Multiple measurement spots as used in this study allow to gain more information about acidogenic fermentation than a single spot,simplifying process control and automation attempts with recalcitrant feedstock.展开更多
The characteristics of swirler flow field, including cold flow field and combustion flow field, in gas tur- bine combustor with two-stage swirler are studied by using particle image velocimetry （PIV）. Velocity compo...The characteristics of swirler flow field, including cold flow field and combustion flow field, in gas tur- bine combustor with two-stage swirler are studied by using particle image velocimetry （PIV）. Velocity compo- nents, fluctuation velocity, Reynolds stress and recirculation zone length are obtained, respectively. Influences of geometric parameter of primary hole, arrangement of primary hole, inlet air temperature, first-stage swirler an- gle and fuel/air ratio on flow field are investigated, respectively. The experimental results reveal that the primary recirculation zone lengths of combustion flow field are shorter than those of cold flow field, and the primary reeir- culation zone lengths decrease with the increase of inlet air temperature and fuel/air ratio. The change of the geo- metric parameter of primary hole casts an important influence on the swirler flow field in two-stage swirler com- bustor.展开更多
The establishment of water circulation aquaculture system realized the hi- erarchical use of nitrogen, phosphorus and other eutrophic substances in aquaculture wastewater and the recirculation use of water resource. H...The establishment of water circulation aquaculture system realized the hi- erarchical use of nitrogen, phosphorus and other eutrophic substances in aquaculture wastewater and the recirculation use of water resource. However, no research has been reported on the detailed calculation of the relationship between the area of aquaculture pond and purification pond. In this study, referring to the absorption ability of aquatic plants to pollutants in aquaculture wastewater and pollutant generation and discharge coefficient in aquaculture pond, based on the general rules of water quality management in freshwater aquaculture system, a calculation mode was es- tablished to investigate the relationship between the area of aquaculture pond and purification pond in freshwater recirculation aquaculture system, which was feasible to explain related cases and would provide theoretical basis to reduce the economic costs in the construction of water circulation aquaculture system and realize the bal- ance between the ecological benefits and the economic benefits.展开更多
To investigate pharmacokinetics ofbaicalin after an oral administration of different Shuang-Huang-Lian （SHL） formulations to rats. Different SIlL formulations were orally administered to rats. The concentrations of ...To investigate pharmacokinetics ofbaicalin after an oral administration of different Shuang-Huang-Lian （SHL） formulations to rats. Different SIlL formulations were orally administered to rats. The concentrations of baicalin in rat plasma were determined by HPLC, the non-compartmental pharmacokinetic parameters and population pharmacokinetic parameters of baicalin were estimated by WinNonlin and NONMEM. The plasma concentration profiles of baicalin demonstrated double-peak phenomenon except for group microemulsion prescription 2. Population pharmacokinetic model developed includes four covariates, which were the effect of formulation （FORM） on CL/F and V/F, the effect of body weight （BW） on Ka, and the effect of gender （GEND） on V/F. Numbers 1 to 6 denote SHL formulation decoction, oral liquid, colloidal solution, microemulsion prescription 1, microemulsion prescription 2 and granule, respectively. The equations for the parameters are as following： CL/F = （0.432 ＋ 0.529）. e^ηCl L/h if formulation was 2 or 6, otherwise CL/F = 0.432. e^ηCl L/h ; V/F = （11.3- 4.03 - 3.87. GEND）. e^ηv L if formulation was 5, otherwise V/F = （11.3 - 3.87. GEND）. e^ηv L ; Ka = 0.475. [1 - 0.0223. （BW - 195.1）]. e^ηKah^-1. SHL formulations have significant effects on the nharmacokinefic narameters.展开更多
Livestock wastewater has been a major contributor to Chinese cultural eutrophication of surface waters. Constructed wetlands are under study as a best management practice to treat wastewater from dairy and swine opera...Livestock wastewater has been a major contributor to Chinese cultural eutrophication of surface waters. Constructed wetlands are under study as a best management practice to treat wastewater from dairy and swine operations, but the removal efficiency of pollutants is relatively low. Enhancing the treatment efficiency of livestock wastewater by effluent recirculation was investigated in a pilot-scale vertical-flow constructed wetland. The wetland system was composed of downflow and upflow stages, on which narrow-leaf Phragmites communis and common reed Phragraites Typhia are planted, respectively; each stage has a dimension of 4 m^2 （2 m × 2 m）. Wastewater from facultative pond was fed into the system intermittently at a flow rate of 0.4 m^3/d. Recirculation rates of 0, 25%, 50%, 100% and 150% were adopted to evaluate the effect of the recirculation rate on pollutants removal. It shows that with effluent recirculation the average removal efficiencies of NH4-N, biological oxygen demand （BOD5） and suspended solids（SS） obviously increase to 61.7%, 81.3%, and 77.1%, respectively, in comparison with the values of 35.6%, 50.2%, and 49.3% without effluent recirculation. But the improvement of TP removal is slight, only from 42.3% to 48.9%. The variations of NH4-N, dissolved oxygen（DO） and oxidation-reduction potential（ORP） of inflow and outflow reveal that the adoption of effluent recirculation is benefi- cial to the formation of oxide environment in wetland. The exponential relationships with excellent correlation coefficients （R2 〉0.93） are found between the removal rates of NH4-N and BOD5 and the recirculation rates. With recirculation the pH value of the outflow decreases as the alkalinity is consumed by gradually enhanced nitrification process. When recirculation rate is kept constant 100%, the ambient temperature appears to affect NH4-N removal, but does not have significant influence on BOD5 removal.展开更多
A three-dimensional numerical model was established to simulate the hydrodynamics within an octagonal tank of a recirculating aquaculture system. The realizable k-e turbulence model was applied to describe the flow, t...A three-dimensional numerical model was established to simulate the hydrodynamics within an octagonal tank of a recirculating aquaculture system. The realizable k-e turbulence model was applied to describe the flow, the discrete phase model （DPM） was applied to generate particle trajectories, and the governing equations are solved using the finite volume method. To validate this model, the numerical results were compared with data obtained from a full-scale physical model. The results show that： （1） the realizable k-e model applied for turbulence modeling describes well the flow pattern in octagonal tanks, giving an average relative error of velocities between simulated and measured values of 18% from contour maps of velocity magnitudes; （2） the DPM was applied to obtain particle trajectories and to simulate the rate of particle removal from the tank. The average relative error of the removal rates between simulated and measured values was 11%. The DPM can be used to assess the self-cleaning capability of an octagonal tank; （3） a comprehensive account of the hydrodynamics within an octagonal tank can be assessed from simulations. The velocity distribution was uniform with an average velocity of 15 cm/s; the velocity reached 0.8 m/s near the inlet pipe, which can result in energy losses and cause wall abrasion; the velocity in tank corners was more than 15 cm/s, which suggests good water mixing, and there was no particle sedimentation. The percentage of particle removal for octagonal tanks was 90% with the exception of a little accumulation of 〈5 mm particle in the area between the inlet pipe and the wall. This study demonstrated a consistent numerical model of the hydrodynamics within octagonal tanks that can be further used in their design and optimization as well as promote the wide use of computational fluid dynamics in aquaculture engineering.展开更多
To improve the efficiency of a CycloBio fluidized sand bed(CB FSB) in removal of dissolved wastes in recirculating aquaculture systems, the hydrodynamics of solid-liquid flow was investigated using computational fluid...To improve the efficiency of a CycloBio fluidized sand bed(CB FSB) in removal of dissolved wastes in recirculating aquaculture systems, the hydrodynamics of solid-liquid flow was investigated using computational fluid dynamics(CFD) modeling tools. The dynamic characteristics of silica sand within the CB FSB were determined using three-dimensional, unsteady-state simulations with the granular Eulerian multiphase approach and the RNG k-ε turbulence model, and the simulation results were validated using available lab-scale measurements. The bed expansion of CB FSB increased with the increase in water inflow rate in numerical simulations. Upon validation, the simulation involving 0.55 mm particles, the Gidaspow correlation for drag coefficient model and the Syamlal-O'Brien correlation for kinetic granular viscosity showed the closest match to the experimental results. The volume fraction of numerical simulations peaked as the wall was approached. The hydrodynamics of a pilot-scale CB FSB was simulated in order to predict the range of water flow to avoid the silica sand overflowing. The numerical simulations were in agreement with the experimental results qualitatively and quantitatively, and thus can be used to study the hydrodynamics of solid-liquid multiphase flow in CB FSB, which is of importance to the design, optimization, and amplification of CB FSBs.展开更多
Inlet recirculation is proved as an effective way for centrifugal compressor surge margin extension,and is successively used in some engineering applications.Unfortunately its working mechanism is still not being well...Inlet recirculation is proved as an effective way for centrifugal compressor surge margin extension,and is successively used in some engineering applications.Unfortunately its working mechanism is still not being well understood,which leads to redesigning of inlet recirculation mostly by experience.Also,most study about inlet recirculation is steady to date.It is necessary to study surge margin extension mechanism about inlet recirculation.To expose the mechanism in detail,steady and unsteady numerical simulations were performed on a centrifugal compressor with and without inlet recirculation.The results showed that,with inlet recirculation,the inlet axial velocity is augmented,relative Mach number around blade tip leading edge area is significantly reduced and so is the flow angle.As the flow angle decreased,the incidence angle reduced which greatly improves the flow field inside the impeller.Moreover,inlet recirculation changes the blade loading around blade tip and restrains the flow separation on the blade suction side at the leading edge area.The unsteady results of static pressure around blade surface,entropy at inlet crossflow section and vorticity distributions at near tip span surface indicated that,at near stall condition,strong fluctuation exists in the vicinity of tip area due to the interaction between tip leakage flow and core flow.By inlet recirculation these strong flow fluctuations are eliminated so the flow stability is greatly enhanced.All these improvements mentioned above are the reason for inlet recirculation delays compressor stall.This research reveals the surge margin extension reason of inlet recirculation from an unsteady flow viewpoint and provides important reference for inlet recirculation structure design.展开更多
The properties of circulating gas have a significant effect on sintering with flue gas recirculation,and the influence of CO in sintering process was investigated.The results show that the post-combustion of CO conduc...The properties of circulating gas have a significant effect on sintering with flue gas recirculation,and the influence of CO in sintering process was investigated.The results show that the post-combustion of CO conducts in sinter zone when flue gas passes through the sintering bed,which releases much heat and reduces the consumption of solid fuel.The ratio of coke breeze can be reduced from 5% to 4.7% with 2% CO in circulating flue gas.In addition,with the increase of CO content in circulating flue gas,the combustion efficiency of fuel is improved,and the flame front is increased slightly while still matches with the heat transfer front.These are beneficial to increasing the maximum temperature and prolonging the high temperature duration,especially in the upper layer of sintering bed.As a consequence,the productivity,vertical sintering velocity and quality of sinter are improved.展开更多
Wastewater stabilization ponds generate low cost by-products that are useful for agriculture. The utilization of these by-products for soil amendment and as a source of nutrients for plants requires a high level of sa...Wastewater stabilization ponds generate low cost by-products that are useful for agriculture. The utilization of these by-products for soil amendment and as a source of nutrients for plants requires a high level of sanitation and stabilization of the organic matter, to maintain acceptable levels of soil, water and air quality. In this study, two aquaculture wastewater treatment systems; recirculating system and a floating plant bed system were designed to improve the quality of irrigation water in local communities with low income. In both systems the grass species Lolium perenne Lam was used as a plant biofilter while vegetable specie Amaranthus viridis was used to evaluate the performance of the system and the suitability of the phyto-treated water for irrigation. It was found that the harmful material removal rate for recirculating system was 88.9% for TAN （total ammonia nitrogen）, 90% for NO2--N, 64.8% for NO3--N while for floating plant bed system 82.7% for TAN, 82% for NO2--N and 60.5% for NO3--N. Comparative analysis of the efficiency of waste element removal between the two systems revealed that both systems performed well, however, plant growth was not robust for floating plant bed system while recirculating system is energy consuming. Although both systems did not attain sufficient levels of TN （total nitrogen） and TP （total phosphorus） load reduction, the treatment with L. perenne remarkably improved the irrigation water quality. A. viridis plants irrigated with the phyto-treated discharge water had lesser concentrations of heavy metals in their tissues compared to those irrigated with untreated discharge. The control plants irrigated with untreated discharge were also found to be highly lignified with few stems and small leaves.展开更多
基金This research was supported by the National Natural Science Foundation of China(Grants Nos.41376089,41576083,41976040)the National Science and Technology Major Project of the Ministry of Science and Technology of China(2016YFC1402106)China Postdoctoral Science Foundation(2020M671048)。
文摘Submarine groundwater discharge(SGD)is being increasingly recognized as a significant source of nutrient into coastal waters,and generally comprises two components:submarine fresh groundwater discharge(SFGD)and recirculated saline groundwater discharge(RSGD).The separate evaluation of SFGD and RSGD is extremely limited as compared to the conventional estimation of total SGD and associated nutrient fluxes,especially in marginal-scale regions.In this study,new high-resolution radium isotopes data in seawater and coastal groundwater enabled an estimation of SGD flux in a typical marginal sea of the Yellow Sea.By establishing 226Ra and 228Ra mass balance models,we obtained the SGD-derived radium fluxes,and then estimated the SFGD and RSGD fluxes through a two end-member model.The results showed that the total SGD flux into the Yellow Sea was equivalent to approximately 6.6 times the total freshwater discharge of surrounding rivers,and the SFGD flux accounted for only 5.2%–8.8%of the total SGD.Considering the nutrient concentrations in coastal fresh and saline groundwater,we obtained the dissolved inorganic nutrient fluxes(mmol m^(-2) yr^(-1))to be 52–353 for nitrogen(DIN),0.21–1.4 for phosphorus(DIP),34–226 for silicon(DSi)via SFGD,and 69–262 for DIN,1.0–3.9 for DIP,70–368 for DSi via RSGD,with the sum of nutrient fluxes equaling to(1.8–9.3)-fold,(1.3–5.6)-fold and(2.0–9.5)-fold of the riverine inputs.Compared to the conventional estimation of the total SGD flux,the nutrient fluxes derived from the separation of SFGD and RSGD were(1.6–2.1),(1.6–1.8)and(4.0–4.9)times lower for DIN,DIP and DSi,respectively,indicating that the estimates by separating SFGD and RSGD could be conservative and representative results of the Yellow Sea.Furthermore,we suggested that SGD played an important role in nutrient sources among all the traditional nutrient inputs sources,providing 15%–48%,33%–68%and 14%–43%of the total DIN,DIP and DSi input fluxes into the Yellow Sea,and the high nutrient stoichiometric ratios(i.e.,DIN/DIP)in SGD probably contributed to the increasing ratios in the Yellow Sea.In addition delivering large amounts of nutrient into the Yellow Sea,SGD would create primary productivity of 10–49,1.6–6.8 and 8.8–42 g C m^(-2)yr^(-1) based on N,P and Si,which were equivalent to 5.2%–27%,0.9%–3.7%and 4.7%–23%of the total primary productivity,respectively.In particular,the SFGD-derived DIN flux can be converted to primary productivity of 4.2–28 g C m^(-2)yr^(-1) thus demonstrating the disproportionately large role of SFGD in ecological environment of the Yellow Sea relative to its flux.Therefore,we conclude that SGD,particularly SFGD,plays an important role as a nutrient source for the Yellow Sea,and not only affects nutrient budgets and structures but also enhances the primary productivity.
基金This paper is supported by the National Key R&D Program of China(2017YFB0601805).
文摘Supercritical carbon dioxide(S-CO_(2))Brayton power cycle power generation technology,has attracted more and more scholars'attention in recent years because of its advantages of high efficiency and flexibility.Compared with conventional steam boilers,S-CO_(2) has different heat transfer characteristics,it is easy to cause the temperature of the cooling wall of the boiler to rise,which leads to higher combustion gas temperature in the furnace,higher NOX generation concentration.The adoption of flue gas recirculation has a significance impact on the combustion process of pulverized coal in the boiler,and it is the most effective ways to reduce the emission of NOX and the combustion temperature in the boiler.This paper takes 1000MW S-CO_(2) T-type coal-fired boiler as the research target to investigate the combustion and NOX generation characteristics of S-CO_(2) coal-fired boilers under flue gas recirculation condition,the influence of recirculated flue gas distribution along the furnace height on the characteristics of NOX formation and the combustion of pulverized coal.The results show that the recirculated flue gas distribution has the great impact on the concentration of NOX at the boiler outlet.When the bottom recirculation flue gas rate is gradually increased,the average temperature of the lower boiler decreases and the average temperature of the upper boiler increases slightly;The concentration of NOx at the furnace outlet increases.
基金supported by National Key Research and Development Program of China(2024YFE0207200)financial support from the project AMON。
文摘As the world shift towards sustainable energy solutions,solid oxide fuel cells(SOFCs)using non-carbon fuels like ammonia and hydrogen emerge as promising pathways to produce clean energy and enhance conversion efficiency.However,current implementations encounter challenges such as nitriding effects from direct ammonia injection to the stack,overestimated benefits of anode off-gas(AOG)recirculation,and a sole focus on electrical efficiency that overlooks the thermal advantages of SOFCs.This study addresses these gaps through a comprehensive multi-objective optimization of SOFC systems fueled by ammonia and hydrogen,assessing their efficiency,fuel utilization,and heat exergy.The research translates material phenomena into mathematical constraints and quantifies the effects of control variables through systematic parameter variation.Results indicate that ammonia-fueled SOFC systems slightly outperform hydrogen,achieving an electrical efficiency of about 65% compared to 62% for hydrogen systems,although hydrogen demonstrates superior fuel utilization and exergy efficiency.Optimal AOG recirculation and NH3cracking fraction that do not compromise stack lifetime and stay in the safe operating zone of nitriding are identified.It also challenges the assumptions that a higher AOG recirculation can benefit performance,suggesting that more extensive AOG recirculation might not always enhance it.Soft sensors are provided to predict system’s performance and enable proactive adjustments to facilitate industrial applications where some parameters,such as high-temperature stack’s pressure drop,are costly or difficult to measure.This study significantly advances the practical deployment of SOFC technologies,enhancing their feasibility for sustainable energy development.
基金support from the Shandong Provincial Science and Technology SMEs Innovation Capacity Improvement Project(2023TSGC0087)the Shandong Natural Science Foundation(Grant No.ZR2022ME008)China Postdoctoral Science Foundation(2023M732102).
文摘In view of the situation of multi-temperature,multi-medium and multi-discharge equipment on the integrated exhaust end platform of a natural gas distributed energy station,which is compact in layout,mutual influence,complex aerodynamic field and complex heat and mass transfer field,the temperature field and aerodynamic field of the platform were comprehensively studied through field experiments and numerical simulation.The research results show that the high temperature flue gas discharged from the chimney is hindered by the chimney cap and returns downward.The noise reduction walls around the chimney make the top of the platform pressurized under the crosswind,as a result,the inlet air temperature of each cooling equipment is generally higher than the ambient temperature,and the cooling efficiency is extremely low.According to the numerical simulation results,the effect of hot gas recirculation is intensified by the ambient crosswind.With the increase of the ambient crosswind,the flue gases coverage expands.The influence of ambient crosswind on inlet air temperature first increases and then decreases within the range of 1–8 m/s,showing a nearly normal distribution.Secondly,this study innovatively designed a new V-shaped chimney cap,compared with the A-shaped chimney cap,the new chimney cap effectively reduces its own obstruction to the smoke and changes the flow path of the smoke.After the smoke rises for a certain distance,the smoke returns downward,which effectively reduces the temperature of the smoke and thus reduces its impact on the air inlet of the cooling equipment.On-site measurement found that the cooling efficiency of various cooling equipment has increased by an average of 27.3%compared to before the renovation,and centrifuge’s refrigeration capacity increased by 0.78 GJ/h.
基金Project(52274290)supported by the National Natural Science Foundation of ChinaProject(72088101)supported by the Basic Science Center Project for National Natural Science Foundation of China。
文摘A pre-reduction sintering process with flue gas recirculation(PSP_(fsg)-FGR)was developed to mitigate alkalis harm to the blast furnace and reduce the flue gas emission in the whole ironmaking process.The results indicated that the pre-reduction sintering process(PSP)can effectively remove 58.02%of K and 30.68%of Na from raw mixtures and improve yield and tumbler index to 74.40%and 68.69%,respectively.Moreover,PSP was conducive to reducing NO_(x) and SO_(2)emissions and simultaneously increasing CO content in flue gas.Circulating CO-containing flue gas to sintering bed effectively recycled CO and further improved K and Na removal ratio to 74.11%and 32.92%,respectively.Microstructural analysis revealed that the pre-reduced sinter mainly consisted of magnetite,wustite and a small quantity of metallic iron,and very few silicate glass phase was also formed.This process can simultaneously realize alkali metal elements removal as well as flue gas emission reduction from the integrated ironmaking process.
文摘Extracorporeal therapies have a definite role in patients with acute liver failure,acute on-chronic liver failure,and progressive chronic liver disease.They act as a bridge-to-transplant in these patients.With the increasing success of liver transplantation,the immediate postoperative complication spectrum continues to expand.Extracorporeal therapies can play an important role in managing these complications.However,the literature on extracorporeal therapies in the postliver transplant period is limited.This review article discussed various extracorporeal therapies that are still evolving or marred by limited evidence but can improve patient outcomes.These extracorporeal therapies can be divided into two subgroups:(1)Therapies for infective complications.Endotoxin and cytokine adsorption columns;and(2)Therapies for noninfective complications like small for size syndrome,primary allograft nonfunction,early allograft dysfunction,hyperacute rejection,hepatopulmonary syndrome,etc.(plasma exchange,double plasma molecular adsorption,molecular adsorbent recirculation system,and extracorporeal membrane oxygenation,among others).
文摘Hydrothermal liquefaction(HTL)is a promising method for sustainable waste management and renewable energy production,converting mixed feedstocks into bio-crude,a precursor to various biofuels.A study focused on mixed residential waste(MRW)as an HTL feedstock investigated temperature ranges(280e360℃)and residence times(30e90 min),achieving a maximum bio-crude yield of 39.16%at 340℃and 75 min.Also,a thorough investigation of the synergistic relationships between all subcomponents of the MRW feedstock was conducted and concluded that the mixed waste(MW)feedstock samples containing a higher proportion of food and plastic wastes and MRW sample presented with a coliquefaction percentage(CE)of around 60%and 107%respectively for production of bio crude.Also,solvents such as ethanol,glycerol and aqueous phase(AQ)were tested for their potential as hydrothermal mediums and found that bio crude yield of 46.19%was obtained in case of AQ phase recirculation.Further,the quantitative and qualitative effect of usage of four different catalysts were tested individually and in combination with AQ phase recirculation and found that,although individually nanoporous ZnO and diatomaceous earth(DE)yielded bio crude in the range of 46.86%and 42.68%respectively,when used in combination,DE cateHTL with AQ resulted in maximum bio crude yield of 54.35%.Furthermore,qualitatively,the bio crude from DE cateHTL with AQ presented with a high carbon and energy recovery percentage of 62.20%and 72.95%respectively and a high hydrocarbon content of 58.98%.
基金supported by The Agricultural Science and Technology Independent Innovation Fund Project of Jiangsu Province(CX(22)3111)the National Natural Science Foundation of China Project(62173162)partly by the Changzhou Science and Technology Support Project(CE20225016).
文摘Real-time detection of unhealthy fish remains a significant challenge in intensive recirculating aquaculture.Early recognition of unhealthy fish and the implementation of appropriate treatment measures are crucial for preventing the spread of diseases and minimizing economic losses.To address this issue,an improved algorithm based on the You Only Look Once v5s(YOLOv5s)lightweight model has been proposed.This enhanced model incorporates a faster lightweight structure and a new Convolutional Block Attention Module(CBAM)to achieve high recognition accuracy.Furthermore,the model introduces theα-SIoU loss function,which combines theα-Intersection over Union(α-IoU)and Shape Intersection over Union(SIoU)loss functions,thereby improving the accuracy of bounding box regression and object recognition.The average precision of the improved model reaches 94.2%for detecting unhealthy fish,representing increases of 11.3%,9.9%,9.7%,2.5%,and 2.1%compared to YOLOv3-tiny,YOLOv4,YOLOv5s,GhostNet-YOLOv5,and YOLOv7,respectively.Additionally,the improved model positively impacts hardware efficiency,reducing requirements for memory size by 59.0%,67.0%,63.0%,44.7%,and 55.6%in comparison to the five models mentioned above.The experimental results underscore the effectiveness of these approaches in addressing the challenges associated with fish health detection,and highlighting their significant practical implications and broad application prospects.
基金financially supported by the Fachagentur für Nachhaltige Rohstoffe e.V.(FNR),grant number 22039818.
文摘Hydrolysis at changing hydraulic retention time,recirculation,bedding straw content in the feed,bioaugmentation and the impact of those changes on gradient formation in the liquid phase in plug-flow reactors(PFRs)was examined.The pH-value,conductivity and oxidation-reduction potential(ORP)were monitored at three spots along the PFRs to study potential correlations to process performance during a total process time of 123 weeks.The on-line monitoring showed good correlations to acidogenesis:namely,the pH and ORP to the acidification,to butyric(and lactic)acid concentration and to the acid yield.The ORP(measured at the inlet)showed the most stable correlation to acidogenesis under dynamic operation,while the conductivity(at the outlet)correlated to the acid concentration in dependence on the feedstock.Multiple measurement spots as used in this study allow to gain more information about acidogenic fermentation than a single spot,simplifying process control and automation attempts with recalcitrant feedstock.
基金Supported by the National Natural Science Foundation of China(50906040)the Nanjing University of Aeronautics and Astronautics Research Funding(NZ2012107,NS2010052)~~
文摘The characteristics of swirler flow field, including cold flow field and combustion flow field, in gas tur- bine combustor with two-stage swirler are studied by using particle image velocimetry （PIV）. Velocity compo- nents, fluctuation velocity, Reynolds stress and recirculation zone length are obtained, respectively. Influences of geometric parameter of primary hole, arrangement of primary hole, inlet air temperature, first-stage swirler an- gle and fuel/air ratio on flow field are investigated, respectively. The experimental results reveal that the primary recirculation zone lengths of combustion flow field are shorter than those of cold flow field, and the primary reeir- culation zone lengths decrease with the increase of inlet air temperature and fuel/air ratio. The change of the geo- metric parameter of primary hole casts an important influence on the swirler flow field in two-stage swirler com- bustor.
基金Supported by Special Fund for the Construction of Modern Agricultural Industry Technology System(CARS-46)Special Fund for Basic Research and Operating Expenses of Central-level Research Institutes(2007JBFA03)~~
文摘The establishment of water circulation aquaculture system realized the hi- erarchical use of nitrogen, phosphorus and other eutrophic substances in aquaculture wastewater and the recirculation use of water resource. However, no research has been reported on the detailed calculation of the relationship between the area of aquaculture pond and purification pond. In this study, referring to the absorption ability of aquatic plants to pollutants in aquaculture wastewater and pollutant generation and discharge coefficient in aquaculture pond, based on the general rules of water quality management in freshwater aquaculture system, a calculation mode was es- tablished to investigate the relationship between the area of aquaculture pond and purification pond in freshwater recirculation aquaculture system, which was feasible to explain related cases and would provide theoretical basis to reduce the economic costs in the construction of water circulation aquaculture system and realize the bal- ance between the ecological benefits and the economic benefits.
基金National Natural Science Foundation of China (Grant No. 30472195)
文摘To investigate pharmacokinetics ofbaicalin after an oral administration of different Shuang-Huang-Lian （SHL） formulations to rats. Different SIlL formulations were orally administered to rats. The concentrations of baicalin in rat plasma were determined by HPLC, the non-compartmental pharmacokinetic parameters and population pharmacokinetic parameters of baicalin were estimated by WinNonlin and NONMEM. The plasma concentration profiles of baicalin demonstrated double-peak phenomenon except for group microemulsion prescription 2. Population pharmacokinetic model developed includes four covariates, which were the effect of formulation （FORM） on CL/F and V/F, the effect of body weight （BW） on Ka, and the effect of gender （GEND） on V/F. Numbers 1 to 6 denote SHL formulation decoction, oral liquid, colloidal solution, microemulsion prescription 1, microemulsion prescription 2 and granule, respectively. The equations for the parameters are as following： CL/F = （0.432 ＋ 0.529）. e^ηCl L/h if formulation was 2 or 6, otherwise CL/F = 0.432. e^ηCl L/h ; V/F = （11.3- 4.03 - 3.87. GEND）. e^ηv L if formulation was 5, otherwise V/F = （11.3 - 3.87. GEND）. e^ηv L ; Ka = 0.475. [1 - 0.0223. （BW - 195.1）]. e^ηKah^-1. SHL formulations have significant effects on the nharmacokinefic narameters.
文摘Livestock wastewater has been a major contributor to Chinese cultural eutrophication of surface waters. Constructed wetlands are under study as a best management practice to treat wastewater from dairy and swine operations, but the removal efficiency of pollutants is relatively low. Enhancing the treatment efficiency of livestock wastewater by effluent recirculation was investigated in a pilot-scale vertical-flow constructed wetland. The wetland system was composed of downflow and upflow stages, on which narrow-leaf Phragmites communis and common reed Phragraites Typhia are planted, respectively; each stage has a dimension of 4 m^2 （2 m × 2 m）. Wastewater from facultative pond was fed into the system intermittently at a flow rate of 0.4 m^3/d. Recirculation rates of 0, 25%, 50%, 100% and 150% were adopted to evaluate the effect of the recirculation rate on pollutants removal. It shows that with effluent recirculation the average removal efficiencies of NH4-N, biological oxygen demand （BOD5） and suspended solids（SS） obviously increase to 61.7%, 81.3%, and 77.1%, respectively, in comparison with the values of 35.6%, 50.2%, and 49.3% without effluent recirculation. But the improvement of TP removal is slight, only from 42.3% to 48.9%. The variations of NH4-N, dissolved oxygen（DO） and oxidation-reduction potential（ORP） of inflow and outflow reveal that the adoption of effluent recirculation is benefi- cial to the formation of oxide environment in wetland. The exponential relationships with excellent correlation coefficients （R2 〉0.93） are found between the removal rates of NH4-N and BOD5 and the recirculation rates. With recirculation the pH value of the outflow decreases as the alkalinity is consumed by gradually enhanced nitrification process. When recirculation rate is kept constant 100%, the ambient temperature appears to affect NH4-N removal, but does not have significant influence on BOD5 removal.
基金Supported by the Application Research Project of Post-Doctoral Researchers in Qingdao(No.ZQ51201415037)the Modern Agriculture Industry System Construction of Special Funds(No.CARS-50-G10)+1 种基金the Special Project about Independent Innovation and Achievement Transformation of Shandong Province(No.2014ZZCX07102)the Key R&D Program of Jiangsu Province(No.BE2015328)
文摘A three-dimensional numerical model was established to simulate the hydrodynamics within an octagonal tank of a recirculating aquaculture system. The realizable k-e turbulence model was applied to describe the flow, the discrete phase model （DPM） was applied to generate particle trajectories, and the governing equations are solved using the finite volume method. To validate this model, the numerical results were compared with data obtained from a full-scale physical model. The results show that： （1） the realizable k-e model applied for turbulence modeling describes well the flow pattern in octagonal tanks, giving an average relative error of velocities between simulated and measured values of 18% from contour maps of velocity magnitudes; （2） the DPM was applied to obtain particle trajectories and to simulate the rate of particle removal from the tank. The average relative error of the removal rates between simulated and measured values was 11%. The DPM can be used to assess the self-cleaning capability of an octagonal tank; （3） a comprehensive account of the hydrodynamics within an octagonal tank can be assessed from simulations. The velocity distribution was uniform with an average velocity of 15 cm/s; the velocity reached 0.8 m/s near the inlet pipe, which can result in energy losses and cause wall abrasion; the velocity in tank corners was more than 15 cm/s, which suggests good water mixing, and there was no particle sedimentation. The percentage of particle removal for octagonal tanks was 90% with the exception of a little accumulation of 〈5 mm particle in the area between the inlet pipe and the wall. This study demonstrated a consistent numerical model of the hydrodynamics within octagonal tanks that can be further used in their design and optimization as well as promote the wide use of computational fluid dynamics in aquaculture engineering.
基金supported by the 12th Five-year National Technology Support Project(2011BAD13B04)
文摘To improve the efficiency of a CycloBio fluidized sand bed(CB FSB) in removal of dissolved wastes in recirculating aquaculture systems, the hydrodynamics of solid-liquid flow was investigated using computational fluid dynamics(CFD) modeling tools. The dynamic characteristics of silica sand within the CB FSB were determined using three-dimensional, unsteady-state simulations with the granular Eulerian multiphase approach and the RNG k-ε turbulence model, and the simulation results were validated using available lab-scale measurements. The bed expansion of CB FSB increased with the increase in water inflow rate in numerical simulations. Upon validation, the simulation involving 0.55 mm particles, the Gidaspow correlation for drag coefficient model and the Syamlal-O'Brien correlation for kinetic granular viscosity showed the closest match to the experimental results. The volume fraction of numerical simulations peaked as the wall was approached. The hydrodynamics of a pilot-scale CB FSB was simulated in order to predict the range of water flow to avoid the silica sand overflowing. The numerical simulations were in agreement with the experimental results qualitatively and quantitatively, and thus can be used to study the hydrodynamics of solid-liquid multiphase flow in CB FSB, which is of importance to the design, optimization, and amplification of CB FSBs.
文摘Inlet recirculation is proved as an effective way for centrifugal compressor surge margin extension,and is successively used in some engineering applications.Unfortunately its working mechanism is still not being well understood,which leads to redesigning of inlet recirculation mostly by experience.Also,most study about inlet recirculation is steady to date.It is necessary to study surge margin extension mechanism about inlet recirculation.To expose the mechanism in detail,steady and unsteady numerical simulations were performed on a centrifugal compressor with and without inlet recirculation.The results showed that,with inlet recirculation,the inlet axial velocity is augmented,relative Mach number around blade tip leading edge area is significantly reduced and so is the flow angle.As the flow angle decreased,the incidence angle reduced which greatly improves the flow field inside the impeller.Moreover,inlet recirculation changes the blade loading around blade tip and restrains the flow separation on the blade suction side at the leading edge area.The unsteady results of static pressure around blade surface,entropy at inlet crossflow section and vorticity distributions at near tip span surface indicated that,at near stall condition,strong fluctuation exists in the vicinity of tip area due to the interaction between tip leakage flow and core flow.By inlet recirculation these strong flow fluctuations are eliminated so the flow stability is greatly enhanced.All these improvements mentioned above are the reason for inlet recirculation delays compressor stall.This research reveals the surge margin extension reason of inlet recirculation from an unsteady flow viewpoint and provides important reference for inlet recirculation structure design.
基金Projects(51174253,51304245)supported by the National Natural Science Foundation of ChinaProject(2013bjjxj015)supported by the Outstanding and Creative Doctor Scholarship of Central South University,ChinaProject supported by the Hunan Provincial Innovation Foundation for Postgraduate,China
文摘The properties of circulating gas have a significant effect on sintering with flue gas recirculation,and the influence of CO in sintering process was investigated.The results show that the post-combustion of CO conducts in sinter zone when flue gas passes through the sintering bed,which releases much heat and reduces the consumption of solid fuel.The ratio of coke breeze can be reduced from 5% to 4.7% with 2% CO in circulating flue gas.In addition,with the increase of CO content in circulating flue gas,the combustion efficiency of fuel is improved,and the flame front is increased slightly while still matches with the heat transfer front.These are beneficial to increasing the maximum temperature and prolonging the high temperature duration,especially in the upper layer of sintering bed.As a consequence,the productivity,vertical sintering velocity and quality of sinter are improved.
基金Project supported by the Technology Department Zhejiang Province of China(No. 2005C22060).
文摘Wastewater stabilization ponds generate low cost by-products that are useful for agriculture. The utilization of these by-products for soil amendment and as a source of nutrients for plants requires a high level of sanitation and stabilization of the organic matter, to maintain acceptable levels of soil, water and air quality. In this study, two aquaculture wastewater treatment systems; recirculating system and a floating plant bed system were designed to improve the quality of irrigation water in local communities with low income. In both systems the grass species Lolium perenne Lam was used as a plant biofilter while vegetable specie Amaranthus viridis was used to evaluate the performance of the system and the suitability of the phyto-treated water for irrigation. It was found that the harmful material removal rate for recirculating system was 88.9% for TAN （total ammonia nitrogen）, 90% for NO2--N, 64.8% for NO3--N while for floating plant bed system 82.7% for TAN, 82% for NO2--N and 60.5% for NO3--N. Comparative analysis of the efficiency of waste element removal between the two systems revealed that both systems performed well, however, plant growth was not robust for floating plant bed system while recirculating system is energy consuming. Although both systems did not attain sufficient levels of TN （total nitrogen） and TP （total phosphorus） load reduction, the treatment with L. perenne remarkably improved the irrigation water quality. A. viridis plants irrigated with the phyto-treated discharge water had lesser concentrations of heavy metals in their tissues compared to those irrigated with untreated discharge. The control plants irrigated with untreated discharge were also found to be highly lignified with few stems and small leaves.
