Advances in Application of Non-aqueous Phase Enzymatic Catalysis in Food Additive Production

Non-aqueous phase enzymatic catalysis technology has been widely ap- plied in the area of food additives production. This paper reviewed the types of re- action medium of non-aqueous phase enzymatic catalysis reaction, introduced the application of non-aqueous phase enzymatic catalysis technology in catalysis of L-ascorbic （isoascorbic） acid esters, short-chain acid esters, sugar esters, vitamin A esters, vi- tamin E esters, and other food additives, and finally predicted the prospects of non- aqueous phase enzymatic catalysis technology.

Modeling Non-aqueous Phase Liquid Displacement Process

A pore-network model physically based on pore level multiphase flow was used to study the water-non-aqueous phase liquid （NAPL） displacement process, especially the effects of wettability, water-NAPL interracial tension, the fraction of NAPL-wet pores, and initial water saturation on the displacement. The computed data show that with the wettability of the mineral surfaces changing from strongly water-wet to NAPL-wet, capillary pressure and the NAPL relative permeability gradually decrease, while water-NAPL interfacial tension has little effect on water relative permeability, but initial water saturation has a strong effect on water and NAPL relative permeabilities. The analytical results may help to understand the micro-structure displacement process of non-aqueous phase liquid and to provide the theoretical basis for controlling NAPL migration.

Kinetic Mass Transfer Between Non-aqueous Phase Liquid and Gas During Soil Vapor Extraction

The mass transfer between non-aqueous phase liquid(NAPL) phase and soil gas phase in soil vapor extraction(SVE) process has been investigated by one-dimensional venting experiments. During quasi-steady volatilization of three single-component NAPLs in a sandy soil, constant initial lumped mass transfer coefficient (λgN,0) canbe obtained if the relative saturation (ξ) between NAPL phase and gas phase is higher than a critical value (ξc), andthe lumped mass transfer coefficient decreases with ξ when ξ＜ξc. It is also shown that the lumped mass transfercoefficient can be increased by blending porous micro-particles into the sandy soil because of the increasing of theinterfacial area.

NON-AQUEOUS REVERSED PHASE HPLC WITH LOW-WAVELENGTH UV DETECTION FOR TRIGLYCERIDE ANALYSIS

Glycerides are first separated to classes of triglycerides(TGs), diglycerides(DGs) and monoglycerides(MGs) by normal phase HPLC on silica gel column. Individual triglyceride separation is then achieved by non-aqueous reversed phase(NARP) HPLC on C_(18) column with UV detection at 215nm.

Testing of NAPL simulator to predict migration of a light nonaqueous phase liquid(LNAPL) under water table fluctuation in a sandy medium

Nanoqueous phase liquid(NAPL) simulator is a powerful and popular mathematical model for modeling the flow and transport of non-aqueous phase liquids in subsurface,but the testing of its feasibility under water table fluctuation has received insufficient attention.The feature in a column test was tested through two cycles of water table fluctuation.The sandy medium in the column was initially saturated,and each cycle of water table fluctuation consisted of one water table falling and one rising,resulting in a drainage and an imbibition of the medium,respectively.It was found that the difference between the simulated and measured results in the first drainage of the column test was minor.However,with the propagation of the water table fluctuations,the simulation errors increased,and the simulation accuracy was not acceptable except for the first drainage in the two fluctuation cycles.The main reason was proved to be the estimation method of residual saturation used in this simulator.Also,based on the column tests,it was assumed that the resulting residual saturation from an incomplete imbibition process was a constant,with a value equal to that of the residual value resulting from the main imbibition process.The results obtained after modifying NAPL simulator with this assumption were found to be more accurate in the first cycle of water table fluctuation,but this accuracy decreased rapidly in the second one.It is concluded that NAPL simulator is not adequate in the case of LNAPL migration under water table fluctuation in sandy medium,unless a feasible assumption to estimate residual saturation is put forward.

NUMERICAL STUDY OF NON-AQUEOUS PHASE LIQUID TRANSPORT IN A SINGLE FILLED FRACTURE BY LATTICE BOLTZMANN METHOD

In this article,the Non-Aqueous Phase Liquid（NAPL）transport in the single filled fracture was studied with the Shan-Chen multi-component multiphase Lattice Boltzmann Method（LBM）with special consideration of wettability effects.With the help of the model,the contact angle of the non-wetting phase and wetting phase interface at a solid wall could be adjusted.By considering a set of appropriate boundary conditions,the fractured conductivity was investigated in condition that the NAPL blocks the channels in the single filled fracture.In order to study the wettability effects on the NAPL transport,a constant driving force was introduced in the Shan-Chen multi-component multiphase LBM.Flow regimes with different wettabilities were discussed.Simulated results show that the LBM is a very instrumental method for simulating and studying the immiscible multiphase flow problems in single filled fracture.

两相分配生物反应器治理有机废气研究进展

通过研究国内外关于两相分配生物反应器治理有机废气进展,介绍了搅拌釜生物反应器、生物滴滤塔等多种两相分配生物反应器的结构及其工作原理;分析了硅油、十六烷等不同非水相对于不同目标污染物的去除效果;研究了两相分配生物反应器对有机废气的处理性能;最后指出如何消除液态非水相的泡沫化和反应器的堵塞问题是今后研究的关键。

Flow, Transport and Biodegradation of Toluene During Bioventing

Bioventing is conducted on one-dimensional soil columns. A numerical model is developed for simulating the mass exchange, advective and dispersive transport and biodegradation of toluene. The model parameters are estimated independently through laboratory batch experiments, or from literature. Simulations are found to provide reasonable agreement with experimental data. Experimental results show that toluene removal due to biodegradation is more important at the later stage. The total cleanup time when NAPL (non-aqueous phase liquid) phase exists was twice more than that without NAPL. Sensitivity analysis of parameters suggests that model predictions are mainly dependent on mass transfer coefficient and microbial parameters, such as the half-saturation coefficient and maximum specific substrate utilization rate.

Remediation of BTEX-Contaminated Groundwater by Air Sparging:A Simulation Study

BTEX contaminants in groundwater seriously impact the ecological environment and human health that has become one of the urgent problems needed to be solved.Due to its low density,low solubility and strong volatility,BTEX in groundwater usually form non-aqueous phase liquid(NAPL) contaminants and exist in three phases:gas,aqueous and oil phase.Air sparging(AS) is an in situ treatment technology

Environmental Fate of Petroleum Hydrocarbons in Soil:Review of Multiphase Transport,Mass Transfer,and Natural Attenuation Processes

The increasing use of petroleum-derived fuels over the last few decades has subsequently augmented the risk of spills in the environment. Soil pollution with petroleum hydrocarbons(principally caused by leaks in pipelines and underground storage tanks) is one of the major sources of soil degradation. Once in soil, fuel hydrocarbons suffer from a wide variety of multiphase processes including transport(advection, diffusion, and dispersion) among and within phases(aqueous and non-aqueous liquid, gas, and soil solids), mass transfer among phases(volatilization, sorption, and solution), and other natural attenuation processes, such as biodegradation and plant uptake and metabolism. This review identifies and describes the major processes occurring in soil that have a significant influence on the environmental fate of petroleum hydrocarbons. The definition of the processes involved in pollutant migration and distribution in soil and the formulation of adequate equations using accurate parameters(e.g., diffusion coefficients, velocity of advective flows, and mass transfer coefficients) will allow prediction of the final fate of soil pollutants. In addition to transport and mass transfer processes,which are more widely studied, the incorporation of attenuation mechanisms driven by microorganisms and plants is essential to predict the final concentration of the pollutants in the whole multiphase scenario. This work underlines the importance of the determination of accurate parameters through the performance of laboratory and/or field-scale experiments to develop precise pollutant migration models.