Solid Phosphorus Research Articles

Dephosphorization of unroasted oolitic ores through alkaline leaching at low temperature

Roasting followed by acid leaching has long been an established dephosphorization technique for processing the goethite iron ore in the past. However, given the high-energy requirement in the process, there still exists further room for improvement. The present study of phosphorus removal from an unroasted iron ore via alkaline leaching method examined the possibility of dephosphorization from goethite ore at low temperature. The iron ore concentrate used in this study is an oolitic type of iron ore consisting primarily of goethite, in which phosphorus does not form a discrete mineral phase, but instead is diffused throughout the entire volume of the ore. This study reveals that the reduction of particle size, the increase in both temperature and hydroxyl ion [OH¯] concentration all promote phosphorus removal. About 50% of the phosphorus can be removed in relatively low [OH¯] concentration (1.25 M), about 80% phosphorous removal was attained after further increasing the [OH¯] concentration to 15 M resulting in 0.1% phosphorus in final solids with no iron losses, which was comparable to roasting followed by acid-leaching route. The optimum conditions was identified as temperature of 85 °C, [OH¯] concentration of 15 M, 0.025–0.038 mm particle size, and 10 min of leaching time with S/L ratio of 0.25 g/ml, in which P level can be reduced from 0.73 to about 0.1 wt%P. Additionally, leaching solution was demonstrated to be readily regenerated using hydrated-lime with comparable leaching ability in terms of phosphorus removal compared to fresh solution. No significant mineralogical change observed other than the uniform removal of phosphorus during the process.

Seasonal variations of phosphorus species in the Tuohe River, China. Part I. Sediments

Sediment cores were collected at an upstream site (Jintang) and a downstream site (Neijiang) in summer and winter in the Tuohe River, which is one of the five largest tributaries of the Changjiang (Yangtze) River in China. A sequential leaching procedure was applied to determine the concentrations of the different forms of solid phosphorus, including exchangeable phosphorus (Exc-P) as well as phosphorus associated with iron oxides (Fe-P), with aluminum oxides (Al-P), with apatite (Ca-P) and with the residual fraction (Res-P), as correlated with water content and total organic carbon. The seasonal variations and the vertical distributions of phosphorus species in sediments at both sampling sites demonstrated that: 1) total phosphorus (TP) in summer and winter were ranged between 1 313–2 330, 1 491–2 228 mg/kg in Jintang and 543–2 128, 603–1 175 mg/kg in Neijiang, respectively. It can predicated the pollution of TP in Jintang is serious than that in Neijiang both in summer and winter; 2) total inorganic phosphorus (TIP) was the dominant form of TP; 3) Ca-P was the main chemical forms of TIP in the sediments. Based on the profiles in sediments and bio-available phosphorus data, it revealed that bio-available phosphorus (BAP) represented only a minor portion (0.61%–3.59%) of TP, and the vertical distribution of soluble reactive phosphorus (SRP) in corresponding porewaters was more abundant in the upper layer of the sediment, which suggests that BAP may be converted to non-bioavailable phosphorus in deeper layer of the sediment of this dynamic system.

In Situ Fabrication of Ni2P Nanoparticles Embedded in Nitrogen and Phosphorus Codoped Carbon Nanofibers as a Superior Anode for Li-Ion Batteries

A facile and cost-effective method has been developed for the fabrication of Ni2P nanoparticles encapsulated in N,P-codoped carbon nanofibers (Ni2P@NPCNFs) using the commercialized products of melamine polyphosphate (MPP) and Ni foam. During the synthetic process, MPP serves as the solid phosphorus source for the phosphidation of Ni foam, and it simultaneously performs as a carbon source for the in situ growth of functionalized carbon nanofibers, resulting in a favorable architecture of an Ni2P well-integrated carbon matrix. With this unique structure, the resultant Ni2P@NPCNFs electrode shows remarkable Li-ion storage performance, in terms of high reversible capacity and long-cyclic lifespan (850 mAh g–1 at 200 mA g–1 after 450 cycles), as well as a good rate behavior (300 mAh g–1 at 3200 mA g–1). This work not only presents a new avenue to construct advanced Ni2P-based functional nanocomposites for Li-ion batteries but also paves the way to explore unique transition-metal phosphides toward diverse appli...

The role of management instruments in the diversion of organic municipal solid waste and phosphorus recycling

Organic waste, which contains essential plant nutrients such as phosphorus, constitutes 30%–50% of municipal solid waste in developed countries. Unfortunately, much of this resource is buried in landfills or incinerated. Many jurisdictions have, therefore, adopted the diversion of organic waste and the recycling of nutrients as policy goals. We used data sets from Europe and Ontario, Canada, to explore the impact of socio-economic and management factors on the rates of organic waste diversion and examined the effect of this diversion on phosphorus recycling. Organic diversion rates were highly correlated with income in Europe and with infrastructure, such as source-separated organic waste collection, in Ontario. Significant correlations were also observed between diversion rates and the use of policy instruments such as economic incentives, legislative organic waste bans, and curbside bag limits. We estimated that 39%–63% of the phosphorus in diverted organics is returned to arable land. Ultimately, we found that although socio-economic factors influence the success of organic waste diversion, policies, accessible infrastructure, economic incentives, and legislative requirements can be leveraged to improve the recycling rate of organic waste and the nutrients they contain.

All-Solid-State Rechargeable Lithium Metal Battery with a Prussian Blue Cathode Prepared by a Nonvacuum Coating Technology.

A Prussian blue LiFeFe(CN)6 thin-film cathode is fabricated by a nonvacuum coating technology without post-annealing process. The thin film of the solid electrolyte lithium phosphorus oxynitride (LiPON) is deposited onto the cathode by using radio-frequency magnetron sputtering. Then, the lithium metal anode is deposited on the LiPON film by the thermal evaporation method to fabricate the all-solid-state LiFeFe(CN)6/LiPON/Li battery with a thickness of 16 μm and a size of ∼10 cm2. Electrochemical properties of LiFeFe(CN)6/LiPON/Li battery are first investigated at various temperatures from −30 to 80 °C. Our results demonstrated that the all-solid-state LiFeFe(CN)6/LiPON/Li battery exhibits a discharge capacity of 82.5 mA h/g for the third cycle at 60 °C and shows stable cyclic performance within 200 cycles. These results provide the feasibility to assemble an all-solid-state lithium-ion battery by combining nonvacuum and vacuum techniques through an environmentally friendly process at low temperature.

Leachate Treatment Using Up-Flow Anaerobic Sludge Blanket System

Leachate is one of the major problems to overcome in managing the landfill. Low cost treatment, less maintenance and environmental friendly are considered as the best practices to treat leachate. Without a proper treatment, leachate could give a negative effect to the environment and become a pollutant. This research focused on the effectiveness of Up-flow Anaerobic Sludge Blanket on leachate treatment using reactor tank in lab-scale. The effectiveness of this system was evaluated by comparing the percentage of nutrient removal. Moreover, leachate characteristic was conducted to determine the nutrient content. Five (5) main parameters were selected to be monitored which are Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Suspended Solid (TSS), Total Nitrogen (TN) and Total Phosphorus (TP). Experiments were run for 30 days and the readings were recorded every 3 days. Results show that the capability of UASB in the removal several parameters. This UASB had a greater ability in removal of Total Phosphorus and TSS with 89% and 81% average removal each. COD removal shows encouraging removal graph more than 70%. While BOD, 64% and Total Nitrogen as 50%. Results showed that UASB system was capable to remove major pollutants from landfill leachate.

Synthesis of a Biological‐Based Glycoluril with Phosphorous Acid Tags as a New Nanostructured Catalyst: Application for the Synthesis of Novel Natural Henna‐Based Compounds

AbstractA convenient multicomponent reaction towards the synthesis of natural henna‐based 3‐methyl‐1,4‐diphenyl‐1,4‐dihydrobenzo[6, 7]chromeno[2, 3‐c]pyrazole‐5,10‐dione derivatives by using a crabby nano glycoluril tetrakis(methylene phosphorous acid) (GTMPA), as an efficient and recyclable catalyst, under neat conditions is described. The major advantages of the synthetic methodology herein described are high yields, short reaction times, and the reusability of the catalyst, which has been fully characterized by Fourier Transform Infrared Spectroscopy (FT‐IR), Solid Phosphorus Nuclear Magnetic Resonance (31P NMR), Mass spectra (MS), X‐Ray Diffraction (XRD), High Resolution Transmission Electron Microscopy (HRTEM), Scanning Electron Microscope (SEM‐Mapp.), Energy Dispersive X‐Ray (EDX), Thermo Gravimetric Analysis (TGA), Differential Thermal Analysis (DTG), Differential Thermal Analysis (DTA) and X‐Ray Photoelectron Spectroscopy (XPS). The described biological‐based glycoluril with phosphorous acid pending may be applicable for the synthesis of gels, gelators, self‐healing and smart hydrogels.

Use of solid phosphorus fractionation data to evaluate phosphorus release from waste activated sludge

Waste activated sludge (WAS) can become an important source of phosphorus (P). P speciation was examined under anaerobic conditions, with different pH (4, 6 and 8) and temperatures (10, 20 and 35 °C). Aqueous P was measured and an extraction protocol was used to find three solid phosphorus fractions. A pH of 4 and a temperature of 35 °C gave a maximum of 51% of total P solubilized in 22 days with 50% of total P solubilized in 7 days. Batch tests indicate that little pH depression is needed to release non-apatite inorganic P (including microbial polyphosphate), while a pH of 4 rather than 6 will release more apatite inorganic P, and that organic P is relatively more difficult to release from WAS. Fractionation analysis of P in WAS can aid in design of more efficient methods for P recovery from WAS.

On the exfoliation and anisotropic thermal expansion of black phosphorus.

Black phosphorus is a bulk solid allotrope of elemental phosphorus and can be seen as an infinite stack of phosphorene sheets. It is interesting from a technological point of view as well as from an electronic structure perspective due to the importance of electron correlation effects. In a recent paper [M. Schütz, L. Maschio, A. J. Karttunen and D. Usvyat, J. Phys. Chem. Lett., 2017, 8, 1290-1294] a highly accurate exfoliation energy has been computed. Building upon these results we carefully benchmark various dispersion-corrected density functional approximations. The choice of the range-separating function that suppresses London dispersion at short interatomic distances apparently has a substantial influence on the results. Having chosen the suitable functional, we have computed the thermal expansion coefficients of black phosphorous via a quasi-harmonic approximation. The computed coefficients manifest a strong anisotropy between the two in-plane directions. Our calculations, however, do not support the existence of negative thermal expansion in black phosphorus, as reported in some theoretical studies.

Effects of rough interface on impedance of solid LiPON in MIM cells

The influences of the rough interface on the impedance of solid lithium phosphorus oxynitride (LiPON) in its metal/insulator/metal (MIM) cells over a wide frequency are studied. Using magnetron sputtering method, Al/LiPON/Al cells with different rough interfaces are fabricated. With increasing the Al films electrode roughness, the deposited LiPON films on these electrodes are correspondingly roughened, which result the interface in MIM cell roughened. Rough LiPON films make their ionic resistance decreasing and the real contact area and the bulk capacitance of MIM cells increasing. These lead to the ionic conductivity of LiPON films improved from 1.09 to 2.70 μS/cm. Meanwhile, the bulk capacitance and the electrolyte resistance in MIM cells could be separated by changing the interface roughness. Rough interfaces in MIM cells contribute to the differences in the morphology of LiPON thin films, which result in the decrease of the activation energy of ionic conductivity E g from 0.45 to 0.38 eV. Without changing LiPON components ratio and sputtering conditions for the thin films deposition, or using any heat treatment, we demonstrate an effective way to improve the ionic conductivity by increasing the roughness of the contact electrode in MIM cells, corresponding roughening the LiPON films and decreasing its ionic impedance.

Study Of Solid Planar Source For Phosphorus Diffution Process On Semiconductor Devices Fabrication

The sourcing lifetimes, microstructural staility, and diffution performance of a new solid planar phosphorus source for silicon doping were investigated in the temperature range 900-1000 0C. The source wafers were highly porous ceramic wafers containing 25 weight percentage (w/o) SiP2O7 as the “active” component in an inert refractory binder matrix. The microstructural stability and thermografimetric analysis (TGA) result indicated the structural integrity and sourcing ability of this materials at temperatures of at least 1050 0C. Theoretical lifetimesof 260 and 3400 hr at 1000 and 900 0C, respectively, have been predicted from the TGA results. Experimental data relating sheet resistance, junction depth, and diffution coefficient for silicon wafers doped using these source wafers are presented. Special material handling procedure are also described. Keywords : diffution process, solid phosphorus source, SiP2O5, semiconductor devices

Applying trait-based method to investigate the relationship between macrophyte communities and environmental conditions in a eutrophic freshwater lake, China

Trait-based community assembly analysis, which links the plant traits to the variation of community composition along environmental gradients, has potential to improve the understanding of the impacts of eutrophication on macrophytes and responding process. In this article, we pioneered the use of RLQ and Fourth-Corner methods that establish in a quantitative way the link between macrophyte traits, macrophyte community and water quality in a eutrophic shallow lake, eastern China. A total of 9 environmental variables and 11 macrophyte traits were included in the analysis. We found that total phosphorus in water (25.7%, the contribution to total inertia in RLQ analysis), suspended solids (20.7%), water transparency (17.1%) and Chlorophyll a (14.0%) were the main environmental variables that were associated the macrophyte traits matrix. Among macrophyte traits, life form (15.7%), responded to the environmental conditions the most, followed by leaf nitrogen (13.8%) and specific leaf area (13.6%). The correlation between macrophyte traits and environmental gradients showed that macrophytes with higher leaf nitrogen and higher specific leaf area grew at locations with clear water condition, better water transparency and with less total phosphorus, Chlorophyll a and suspended solids in this shallow eutrophic lake. The results suggested that the leaf nitrogen and specific leaf area of macrophytes had a trend to decrease with the increasing environmental stresses caused by eutrophication. Moreover, we highlighted that total phosphorus in water should be prior considered for the future macrophyte conservation and restoration in this lake.

Study on Ultra Shallow Junction n-MOS with 350°C Microwave Annealing for Activation of Phosphorus Dopants in Germanium

In this study, low-energy microwave annealing is used to fabricate ultra-shallow junctions for less than 20 nm IC node applications in a potential material: Germanium (Ge). Germanium is a new promising material and might replace silicon in the future. A novel microwave annealing technique with two steps for the solid phase epitaxial recrystallization (SPER) and phosphorus dopants activation was applied to Germanium. The purpose of the first step, microwave annealing of 1.2 kW for 75 s, is to re-grow the amorphous layer and repair the destroyed crystal lattices caused by ion implantation. In the second-step of annealing, low-energy microwave, 0.9 kW (≈350°C) for 300 s, is used to activate the phosphorus dopants effectively without diffusion and de-activation. The target dopant activation concentration level will achieve 10²⁰ cm^-3. The sheet resistance will decrease to 78 ohm/sq. The low resistance after activating is reflected to the performance of the n-MOS device fabricated by the Ge substrate. The S. S. factor is 900 mV/dec, and the I_on/off ratio rise to 2.6×10¹. This has demonstrated that the two-step MWA has excellent control, significantly regarding leakage current.

도시 하천 수질 관리를 위한 지속가능 초기 강우 오염 관리 시스템의 개발

강우 시 표면 유출에 의한 비점오염물질의 하천 유입은 도시 하천 관리에 부정적인 영향을 미치며 특히 강우 초기의 수질농도가 매우 높은 것으로 알려져 있다. 본 연구에서는 하천의 제외지 또는 유수지 등의 공간을 활용하여 침강 및 여과작용을 이용하여 최소한의 에너지 및 비용을 이용하여 오염물질을 정화시키면서 하천의 수질 및 수량 관리에 긍정적인 작용을 할 수 있는 장치와 시스템을 개발하고자 하였다. 빗물 자동 모니터링 시스템을 이용하여 초기 우수에 대한 유량 및 수질을 파악하였고 이를 토대로 처리 시스템의 설계 기준을 확립하고자 하였다. 초기우수 제어 장치는 침전 장치만으로도 총부유물질 (TSS) 84 - 95%, 총질소 (TN) 31 - 46%, 총인 (TP) 42 - 86%의 제거 효율이 나타났다. 또한 일기 예보를 통해 강우에 의한 유량 및 수질을 예측하고 처리장치의 상태 및 자동 모니터링시스템과 연계하여 시설을 종합적으로 관리할 수 있는 강우 유출 종합관리 시스템 ISTORMS (Integrated Stormwater Runoff Management System)를 개발하였다. 본 연구 결과는 도시 하천의 수질 및 유량 환경개선에 효율적으로 적용될 수 있을 것으로 기대된다. Non-point pollutants from surface runoff during rainfall exert adverse effects on urban river water quality management. In particular, the first flush effect during the initial phase of rainfall can deliver significant amounts of pollutant loads to surface waters with extremely high concentrations. In this study, a sustainable first flush effect management system was developed by using settling and filtration that require no additional power or chemicals. A pilot scale experiment has shown that the removal of total suspended solid (TSS), total nitrogen (TN) and total phosphorus (TP) are in ranges of 84 - 95%, 31 - 46%, and 42 - 86%, respectively. An Integrated Stormwater Runoff Management System (ISTORMS) was also developed to efficiently manage the developed system by linking weather forecast, flow rate and water quality modeling of surface runoff and automatic monitoring systems in fields and in the system. This study can provide effective solutions for the management of urban river in terms of both quantity and quality.

English

The work aimed to study the behavior of a prototype planted simultaneously three times with solid fertilizers, nitrogen, phosphorus and potassium, of variable rates and desired quantities. For the evaluation of the prototype, a test bench was built where helical doses and their respective direct current electric motors; three tanks for storage of fertilizers were used. Also used were: A source (12 V-DC), three power drivers (MOSFET), acquisition board and control software. The tests were performed with LabVIEW®8.6 to control the rotation of the axes, record data in maps of soil fertility and geographical location. The results showed that application values showed an error of 3:56% at the rate of 45 kg/ha and an error of 1.78% at the rate of 85 kg/ha. However, the slightest mistake was on rotation of 26 to 30 rpm because the ratio flow rates had error <1%. Therefore, the dosing speed became maximum of 35 rpm; making the variation of the theoretical flow rate from 2.6 to 93.7 kg/ha. But with low flow rate, the error was 8.3% to 4 rpm on products of  9.79 kg/ha.   Key words: Data acquisition board, flow rate, helical feeders, varying rates, power drivers.

Evaluation of the k-nearest neighbor method for forecasting the influent characteristics of wastewater treatment plant

The k-nearest neighbor (k-NN) method was evaluated to predict the influent flow rate and four water qualities, namely chemical oxygen demand (COD), suspended solid (SS), total nitrogen (T-N) and total phosphorus (T-P) at a wastewater treatment plant (WWTP). The search range and approach for determining the number of nearest neighbors (NNs) under dry and wet weather conditions were initially optimized based on the root mean square error (RMSE). The optimum search range for considering data size was one year. The square root-based (SR) approach was superior to the distance factor-based (DF) approach in determining the appropriate number of NNs. However, the results for both approaches varied slightly depending on the water quality and the weather conditions. The influent flow rate was accurately predicted within one standard deviation of measured values. Influent water qualities were well predicted with the mean absolute percentage error (MAPE) under both wet and dry weather conditions. For the seven-day prediction, the difference in predictive accuracy was less than 5% in dry weather conditions and slightly worse in wet weather conditions. Overall, the k-NN method was verified to be useful for predicting WWTP influent characteristics.

Codiffusion Sources and Barriers for the Assembly of Back-Contact Back-Junction Solar Cells

In this study, several diffusion sources are investigated, aiming at codiffusion for the fabrication of back-contact back-junction (BC-BJ) silicon solar cell. As a gaseous diffusion source, a POCl3-diffusion process is investigated, and for solid diffusion sources, phosphorus- and boron-doped silicate glass (PSG and BSG) deposited by the means of plasma-enhanced chemical vapor deposition are considered. The n+-doped areas diffused from a solid PSG layer allow for a precise adjustment of the sheet resistance $(R_{{\rm sh}})$ in the range of 40–400 Ω/sq, along with a dark saturation current density $(J_{o})$ of 55 fA/cm $^{2}$ . Subsequently, boron diffusion from solid BSG layer leads to p+-doped areas with high doping levels ( $R_{\rm sh}=$ 50 Ω/sq). However, gaseous POCl3 diffusion in combination with solid boron diffusion from the BSG layer can only be successfully performed if the BSG layer is protected with an SiO x layer. Furthermore, by adjusting the gas flows during POCl3 diffusion, n+-doped areas with $R_{{\rm sh}}$ in the range of 150– 300 Ω/sq are achieved. The corresponding surfaces feature $J_{o}$ values of 30 fA/cm $^{2}$ . The result of this study is a flexible codiffusion setup allowing for the efficient integration in advanced process chains of BC-BJ solar cells which results in the cell efficiencies well above above $\eta =$ 20%.

Pretreated magnesite as a source of low-cost magnesium for producing struvite from urine in Nepal

Struvite is a solid phosphorus fertilizer that can be recovered easily from source-separated urine by dosing it with a soluble form of magnesium. The process is simple and low-cost, however, previous studies have shown that the cost of magnesium in low-income countries is crucial to the viability and implementation of struvite precipitation. Literature has proposed producing inexpensive magnesium locally by making magnesium oxide from magnesite. This paper aimed to investigate whether process requirements, costs, and environmental impacts would make this process viable for magnesium production in decentralized settings. Magnesite samples were calcined at temperatures between 400°C and 800°C and for durations between 0.5h and 6h. The release of magnesium was tested by dissolution in phosphate-depleted urine. The optimal processing conditions were at 700°C for 1h: magnesite conversion was incomplete at lower temperatures, and the formation of large crystallites caused a decrease in solubility at higher temperatures. The narrow optimal range for magnesium production from magnesite requires reliable process control. Cost estimations for Nepal showed that using local magnesite would provide the cheapest source of magnesium and that CO2 emissions from transport and production would be negligible compared to Nepal's overall CO2 emissions.

A Combined Electrocoagulation-Electroperoxidation Process for the Tertiary Treatment of Domestic Wastewaters

The aim of this study is to develop a process that combines electrocoagulation and electroperoxidation (EC-EP) and to evaluate its performance in treating domestic wastewaters (DWW). Electrolysis was performed using a parallelepipedic electrolytic cell (0.5 L) containing one sacrificial anode (mild steel or aluminum) and one cathode (vitreous carbon). The effects of the treatment time, current density, and type of anode electrode on the process performance were examined. The experimental results revealed that a current density of 4.0 mA cm−2 was beneficial for DWW treatment. There was a decrease in the chemical oxygen demand (COD), suspended solid (SS), turbidity, color, and total phosphorus (Ptot) by 67 ± 9, 98 ± 2, 55 ± 10, 61 ± 9, and 97 ± 0 %, respectively, for a treatment time of 60 min in the electrolysis cell in the presence of mild steel (anode) and vitreous carbon (cathode) electrodes. The process was also determined to be effective for removing pathogens (99 ± 1 % removal), such as fecal coliform (the log-inactivation was higher than 2 units).

Removal efficiencies of vegetation-specific filter strips on nonpoint source pollutants

A field experiment was conducted to examine the removal efficiencies of different autochthonous vegetation-specific filter strips on nonpoint source pollutants (NPSPs) and to identify their major influencing factors under various conditions. Furthermore, the effects of five major influencing factors on the removal efficiencies were analyzed. We found that the removal efficiencies in total suspended solid (SS), total nitrogen (TN) and total phosphorus (TP) of the grass vegetation filter strip were significantly higher than those of the seabuckthorn bushy vegetation filter strip. The averaged SS concentration and mass removal efficiencies of the VFS were commonly above 90%, respectively. The TN concentration removal efficiency ranged from 50 to 70%, and the mean TN mass removal efficiency ranged from 70 to 90%. The mean concentration and mass removal efficiencies in particulate nitrogen (PN) were approximately 85 and 95%, respectively. However, the concentration and mass efficiencies in dissolved nitrogen (DN) were lower. The TP concentration removal efficiency averaged 86%, and the mean TP mass removal efficiency was about 94%. The mean concentration and mass removal efficiencies in particulate phosphorus (PP) were approximately 88 and 96%, respectively. Moreover, the concentration and mass efficiencies in dissolved phosphorus (DP) were not significantly high. This suggests that PN is the main loss form of N and PP is the major loss form of P. Overall, the mass removal efficiencies of various species of VFS on nonpoint source pollutants in various forms were higher than the concentration removal efficiencies. Additionally, the removal efficiencies of VFS on nonpoint source pollutants were subject to many factors such as vegetation coverage, initial soil water content, width of VFS, inflow discharge and inflow concentration. However, the most important influencing factors are vegetation coverage, width of VFS and inflow concentration. The width of VFS plays an essential role in N and P removal efficiencies, in that even though the width of VFS is longer, the removal efficiency of VFS is not really better. Additionally, the removal of SS should be firstly considered during the course of the application of VFS due to the SS correlating well linearly with TN and TP. Nevertheless, routine maintenance is also quite necessary to keep in good removal performance of VFS.