Grantee Research Project Results

The Use of Microfiltration and Ultrafiltration Membranes for the Separation, Recovery, and Reuse of Surfactant/Contaminant Solutions

EPA Grant Number: R825540C003
Subproject: this is subproject number 003 , established and managed by the Center Director under grant R825540
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: Duke University Center for Environmental Implications of NanoTechnology
Center Director: Wiesner, Mark R.
Title: The Use of Microfiltration and Ultrafiltration Membranes for the Separation, Recovery, and Reuse of Surfactant/Contaminant Solutions
Investigators: Jones, Kimberly L.
Institution: Howard University
Current Institution: Howard University
EPA Project Officer: Hahn, Intaek
Project Period:    
RFA: Hazardous Substance Research Centers - HSRC (1989) RFA Text |  Recipients Lists
Research Category: Hazardous Substance Research Centers , Land and Waste Management

Objective:

The overall goal of this research is to develop a method to separate VOCs from surfactant-VOC solutions in order to reuse the surfactant in surfactant enhanced aquifer remediation (SEAR) applications. In the proposed system, a pervaporation (PV) process will be used to separate VOCs from a surfactant-VOC stream, and an ultrafiltration membrane will be used to concentrate the recovered surfactant (Figure 1). Individual objectives of this research are to: 1) evaluate the capacity of the pervaporation membrane for separating VOCs from a surfactant solution under conditions relevant to TRAC II SEAR efforts, 2) develop a suitable model to determine the optimal mass transport conditions of the system, and 3) test the pervaporation/microfiltration system under field conditions using the Bachman site. The research will be expanded to include application-specific information, such as cost and flux/selectivity models for different system designs.

 

 

Approach:

Mass transfer through a pervaporation membrane can be expressed by the resistance-in-series model, which relates the permeate flux to the concentration difference between the bulk permeate and feed phase by an overall mass transfer coefficient:

 

      ( 1

where J_voc = flux of solute from bulk solution to permeate (mol/cm²*s), K_ov = overall mass transfer coefficient (cm/s), c = concentration (mol/cm³), and the subscripts "b" and "p" represent bulk and permeate concentrations, respectively. The overall mass transfer coefficient consists of the following four individual mass transfer coefficients: k_s (surfactant), k_l (liquid boundary layer), k_m (membrane) and k_g (vacuum boundary layer):

     ( 2

There are three phase interfaces involved in the separation - micelle/bulk liquid , bulk liquid/membrane and membrane/vacuum boundary layer. Three partition coefficients can be defined for each of the three phase interfaces:

 

where c_s' = concentration of VOC in the liquid feed phase at the micelle/bulk interface (mol/cm³), K_a = micelle/aqueous phase partition coefficient (-), c_b' = concentration in the membrane at liquid/membrane interface, K_m = distribution coefficient of VOC between the liquid and membrane, c_m = concentration in the membrane at the membrane/liquid interface, c_v'= concentration at the of VOC in the membrane at the membrane/vacuum interface, K_v is the distribution coefficient between the membrane and the vacuum side and c_mv is the concentration of VOC in the membrane at the membrane/vacuum interface.

The individual mass transfer rates can be expressed as follows:

Micelle/bulk liquid interface:           (6

Liquid/Membrane interface:          (7

Membrane surface:                        (8

Membrane/vacuum interface:         (9

At steady state, the fluxes are all equal to the overall flux in equation 1, and the resistance of the vacuum side boundary layer is negligible compared to the other resistances (Das et al., 1998). The mass transfer resistance of the mono-molecular surfactant layer will be calculated and compared to the other mass transfer coefficients to determine the effect of surfactant on the overall transport process.

Supplemental Keywords:

RFA, Scientific Discipline, TREATMENT/CONTROL, INTERNATIONAL COOPERATION, Waste, Water, Hazardous, Chemical Engineering, Environmental Chemistry, Contaminated Sediments, Hazardous Waste, Treatment Technologies, Bioremediation, Ecology and Ecosystems, Environmental Engineering, alternative endpoints, bioavailability, hazardous organic compounds, contaminant transport, bioremediation of soils, kinetic studies, contaminated sediment, microfiltration, ultrafiltration, in-situ bioremediation, fate and transport , contaminated groundwater, groundwater remediation, contaminated soil, bioaccumulation, environmentally acceptable endpoints, groundwater, biodegradation, in situ remediation, bioacummulation, membrane processes, contaminants in soil, contaminated soils

Progress and Final Reports:

2000 Progress Report

Final

Main Center Abstract and Reports:

R825540    Duke University Center for Environmental Implications of NanoTechnology

Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R825540C001 Development and Verification of A Molecular Modeling Approach for Predicting the Sequestration and Bioavailability/Biotoxicity Reduction of Organic Contaminants by Soils and Sediments
R825540C002 Molecular Modeling of Hydrophobic Organic Contaminants Uptake and Sequestration by Soil Organic Matter
R825540C003 The Use of Microfiltration and Ultrafiltration Membranes for the Separation, Recovery, and Reuse of Surfactant/Contaminant Solutions
R825540C004 A Contained Simulation of Field Application of Genetically Engineered Microorganisms (Gems) for the Bioremediation of PCB Contaminated Soils