NH_3-N Degradation Dynamics and Calculating Model of Filtration Bed Height in Constructed Soil Rapid Infiltration

The research on Constructed Soil Rapid Infiltration(CSRI) system is in its infancy at home and abroad.There are several details about the mechanism and application of CSRI system needed to be further studied.A major limitation in the current research is the absence of degradation dynamics of pollutants,and the height of filtration bed in CSRI system currently determined by empirical judgment lacks accuracy and logicality.To solve these two prob-lems,the soil column of CSRI system was utilized to treat domestic wastewater,meanwhile,the NH3-N degradation dynamics were studied according to the Monod equation,the research of Mann A T and the NH3-N degradation law.Then the mathematical model of filtration bed height was built based on NH3-N degradation dynamics equation in the soil column.It has been proven that within a limited range this model can calculate the appropriate height of filtration bed accurately in order to optimize technological parameters of hydraulic load and the concentration of influent NH3-N,improving the effluent quality of CSRI system.

Filtration performance and modeling of granular bed for dust removal from coal pyrolytic vapors

Dust removal from pyrolytic vapors at high temperatures is an obstacle to the industrialization of the coal pyrolysis process.In this work,a granular bed with expanded perlites as filtration media was designed and integrated into a 10 t·d^(–1)coal pyrolysis facility.The testing results showed that around 97.56%dust collection efficiency was achieved.As a result,dust content in tar was significantly lowered.The pressure drop of the granular bed maintained in the range of 356 Pa to 489 Pa.The dust size in the effluent after filtration exhibited a bimodal distribution,which was attributed to the heterogeneity of the dust components.The effects of filtration bed on pyrolytic product yields were also discussed.A modified filtration model based on the macroscopic phenomenological theory was proposed to describe the performance of the granular bed.The computation results were well agreed with the experimental data.

Deep bed filtration model for cake filtration and erosion

Many phenomena in nature and technology are associated with the filtration of suspensions and colloids in porous media. Two main types of particle deposition,namely, cake filtration at the inlet and deep bed filtration throughout the entire porous medium, are studied by different models. A unified approach for the transport and deposition of particles based on the deep bed filtration model is proposed. A variable suspension flow rate, proportional to the number of free pores at the inlet of the porous medium, is considered. To model cake filtration, this flow rate is introduced into the mass balance equation of deep bed filtration. For the cake filtration without deposit erosion,the suspension flow rate decreases to zero, and the suspension does not penetrate deep into the porous medium. In the case of the cake filtration with erosion, the suspension flow rate is nonzero, and the deposit is distributed throughout the entire porous medium. An exact solution is obtained for a constant filtration function. The method of characteristics is used to construct the asymptotics of the concentration front of suspended and retained particles for a filtration function in a general form. Explicit formulae are obtained for a linear filtration function. The properties of these solutions are studied in detail.

Asymptotics for filtration of polydisperse suspension with small impurities

A model for deep bed filtration of a polydisperse suspension with small impurities in a porous medium is considered.Different suspended particles move with the same velocity as the carrier water and get blocked in the pore throats due to the size-exclusion mechanism of particle retention.A solution of the model in the form of a traveling wave is obtained.The global exact solution for a multiparticle filtration with one high concentration and several low concentrations of suspended particles is obtained in an explicit form.The analytic solutions for a bidisperse suspension with large and small particles are constructed.The profiles of the retained small particles change monotony with time.The global asymptotics for the filtration of a polydisperse suspension with small kinetic rates is constructed in the whole filtration zone.

Experimental and Numerical Analysis of Particle Migration and Patterning Behavior in a Gravel Pack

Due to its long lifespan and high sand-removal efficiency,gravel packing is one of the most applied sand control methods during the recovery of reservoirs with sanding problems.The blockage and retention of injected sand in a gravel pack is a complex process affected by multiple mechanisms.The majority of existing studies based on the phenomenological deep bed filtration(DBF)theory focused on the gravel pack’s overall permeability damage and failed to obtain the inner-pore particle distribution pattern.In this work,experiments and simulations were carried out to reveal the particle distribution in a gravel pack during flooding.In particular,through real-time monitoring of particle migration,the penetration depth and distribution pattern of invaded particles with different gravel-sand particle ratios,fluid viscosities and injection rates could be determined.By simplifying each unit bed element(UBE)into a pore-throat structure with four tunnels(two horizontals for discharge and two verticals for sedimentation),a new network simulation method,which combines deep bed filtration with a particle trajectory model,was implemented.Cross comparison of experimental and numerical results demonstrates the validity and accuracy of the model.

Lead removal from water using organic acrylic amine fiber(AAF)and inorganic-organic P-AAF,fixed bed filtration and surface-induced precipitation

Granular porous sorbents were normally used for heavy metals removal from water.To search for the new commercial sorbent and treatment strategy,an organic acrylic amine fiber(AAF)and phosphorus loading inorganic-organic AAF(P-AAF)were prepared and used for lead(Pb)removal from water.A new strategy of inorganic-organic coupling technology was proposed for Pb removal,based on the hypothesis of surface-induced precipitation mechanism.The AAF showed a Pb adsorption capacity of 417 mg/g from the Langmuir fitting,while the column filtration technology was further applied to measure the adsorption edge and applications.Effects of different initial Pb concentrations,hydraulic retention time,and co-existing P were considered in the filtration experiments.The presence of 0.8 mg/L P in water significantly improved the Pb breakthrough point from 15,000 to 41,000 bed volumes of water spiked with 85μg/L Pb,while the P-AAF fixed bed showed better removal of Pb than AAF SEM/EDX and XRD spectra were employed for determining the surface functional groups and the formation of surface-induced precipitation of pyromorphite(Pb_5(PO_4)_3 OH)on AAF.This study verified the application of AAF sorbent for Pb removal and the enhanced effect of coating P on AAF,thus improved our fundamental understanding and application of the surface chemistry process of Pb with P.

Wetting and its influence on the filtration ability of ceramic foam filters

Deep bed filtration in aqueous media is a well-known process for solid-liquid separation. However, the use of deep bed filtration for the purification of metal melts is a relatively new field of application, In particular, the separation mechanism of metal melts filtration is a new area for investigation. The current paper aims at examining the influence of wetting on the filtration efficiency of ceramic foam filters that is an important feature of the metal melts filtration process. A model system was designed using water and alumina particles （〈200μm）. The particles and filter medium were coated to model poor wetting. Thus, examination of the influence of wetting on the adhesion energy and filtration performance was possible. Furthermore, the effect of fluid velocity was studied. To this end, the experiments were carried out under atmospheric conditions and at 20℃. The findings showed that poor wetting between the fluid and solid phase significantly increased the filtration efficiency.