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Removal of toxic heavy metal ions from industrial effluent by meuf and membrane bioreactors
ABSTRACTS
REMOVAL IONS FROM
515
OF TOXIC
HEAVY
INDUSTRIAL
METAL
EFFLUENT
BY MEUF AND MEMBRANE BIOREACTORS S. S. Koseoglu and B. Batchelor Texas Engineering Experiment Station, Texas A & M University College Station, TX 7784
Industrial wastewaters from synfuels production, metal plating, petroleum refining, chemicals and food processing plants vary in composition and may contain toxic substances like heavy metal cations and chemical compounds in their aqueous phase and oily fractions. Regulations typically require on-site treatment to reduce biological and chemical oxidative demands and to remove toxic substances before releasing processing and surface run-off waters to municipal treatment plants or directly into rivers. Traditional methods of separating soluble compounds from a wastestream often involve a phase change, as in distillation, or extraction followed by distillation. These procedures are energy intensive; therefore, alternative low-energy separation processes are desirable. The proposed research will develop a process to completely remove the heavy metal ions from metal finishing industry's effluents. The principle of the proposed research is to combine Micellar Enhanced Ultrafiltration (MEUF) and algae containing Membrane Bioreactors (MB). MEUF, with lecithin as a surfactant, has already been shown to remove heavy metals from aqueous (50 to 90%) and non-aqueous wastes (90 to 97%). The efficiency of removal of trace levels of heavy metals will be increased by the continuous binding and separation of the ions through membrane bioreactors that are 20 to 50 times more efficient than conventional bioreactors. To develop this two-stage system, the binding of phospholipids responsible for micelle formation, two chelating agents, and that of three types of algae will be investigated. These studies will utilize the diafiltration apparatus used in the previous year's work. Further, the operating parameters of the two processes, individually and in combination, will be optimized.
remediation process in hazardous waste management. Recently the process has been applied to hazardous organic wastes with mixed results. These results have prompted further studies to examine the effectiveness of this process in containing organic contaminants. The primary goal of S/S is to contain the contaminants in a solidified form, removing them from the environment. This is accomplished by decreasing the contaminant surface area and chemically converting the waste by reducing the contaminant solubility. The most common S/S processes utilize the chemical reactions achieved in cement-based and pozzolanic mixes. The effectiveness of this process is determined by the degree to which contaminants will leach from the waste end-product. Leach models, therefore, are an effective way to predict the leaching of contaminants and to describe the immobilization and binding mechanisms that take place. The multi-component nature of oily wastes requires that a multi-component approach be taken to describe the partitioning between the aqueous and non-aqueous phases. The heterogeneous nature of these wastes precludes analysis of partitioning of all chemical species. A pseudo-component model has been developed that describes the partitioning of TOC as caused by the partitioning of a small number of pseudo-components. A pseudo-component is used to represent a group of chemical species that has similar tendencies to partition between the aqueous and non-aqueous phases. A linear partitioning relationship is used to develop the partitioning model, with the values of the partitioning coefficients chosen to represent strongly sorbed, moderately sorbed, and weakly sorbed components. The partitioning characteristics of the waste were determined in a series of sequential extractions in which different amounts of water were added. After each addition, the system was allowed to equilibrate, the added water was removed by centrifugation, and its TOC was measured. The model predicts that the measured concentrations of TOC are due to the sum of all pseudo-components in the aqueous or mobile phase.
LEACHING OF HEAVY SOLIDIFIED WASTES
METALS
FROM
A MULTI-COMPONENT PARTITIONING LEACHING WASTES
MODEL
FROM
TO PREDICT
SOLIDIFIED
OILY
Declan 0 'Cleirigh and Bill Batchelor Texas Engineering Experiment Station, Texas A&M University, College Station, TX 77843
Solidification/Stabilization
(S/S)
is
an
established
Susan Trussell and Bill Batchelor Civil Engineering Department, Texas A&M University College Station, Texas 77843-3136
The goal of solidification/stabilization is to limit the ability of disposed hazardous wastes to migrate in the environment via leaching mechanisms. The pore water components of the solidified wastes constitute the leachable fraction of the wasteform. Previous
REMOVAL IONS FROM
515
OF TOXIC
HEAVY
INDUSTRIAL
METAL
EFFLUENT
BY MEUF AND MEMBRANE BIOREACTORS S. S. Koseoglu and B. Batchelor Texas Engineering Experiment Station, Texas A & M University College Station, TX 7784
Industrial wastewaters from synfuels production, metal plating, petroleum refining, chemicals and food processing plants vary in composition and may contain toxic substances like heavy metal cations and chemical compounds in their aqueous phase and oily fractions. Regulations typically require on-site treatment to reduce biological and chemical oxidative demands and to remove toxic substances before releasing processing and surface run-off waters to municipal treatment plants or directly into rivers. Traditional methods of separating soluble compounds from a wastestream often involve a phase change, as in distillation, or extraction followed by distillation. These procedures are energy intensive; therefore, alternative low-energy separation processes are desirable. The proposed research will develop a process to completely remove the heavy metal ions from metal finishing industry's effluents. The principle of the proposed research is to combine Micellar Enhanced Ultrafiltration (MEUF) and algae containing Membrane Bioreactors (MB). MEUF, with lecithin as a surfactant, has already been shown to remove heavy metals from aqueous (50 to 90%) and non-aqueous wastes (90 to 97%). The efficiency of removal of trace levels of heavy metals will be increased by the continuous binding and separation of the ions through membrane bioreactors that are 20 to 50 times more efficient than conventional bioreactors. To develop this two-stage system, the binding of phospholipids responsible for micelle formation, two chelating agents, and that of three types of algae will be investigated. These studies will utilize the diafiltration apparatus used in the previous year's work. Further, the operating parameters of the two processes, individually and in combination, will be optimized.
remediation process in hazardous waste management. Recently the process has been applied to hazardous organic wastes with mixed results. These results have prompted further studies to examine the effectiveness of this process in containing organic contaminants. The primary goal of S/S is to contain the contaminants in a solidified form, removing them from the environment. This is accomplished by decreasing the contaminant surface area and chemically converting the waste by reducing the contaminant solubility. The most common S/S processes utilize the chemical reactions achieved in cement-based and pozzolanic mixes. The effectiveness of this process is determined by the degree to which contaminants will leach from the waste end-product. Leach models, therefore, are an effective way to predict the leaching of contaminants and to describe the immobilization and binding mechanisms that take place. The multi-component nature of oily wastes requires that a multi-component approach be taken to describe the partitioning between the aqueous and non-aqueous phases. The heterogeneous nature of these wastes precludes analysis of partitioning of all chemical species. A pseudo-component model has been developed that describes the partitioning of TOC as caused by the partitioning of a small number of pseudo-components. A pseudo-component is used to represent a group of chemical species that has similar tendencies to partition between the aqueous and non-aqueous phases. A linear partitioning relationship is used to develop the partitioning model, with the values of the partitioning coefficients chosen to represent strongly sorbed, moderately sorbed, and weakly sorbed components. The partitioning characteristics of the waste were determined in a series of sequential extractions in which different amounts of water were added. After each addition, the system was allowed to equilibrate, the added water was removed by centrifugation, and its TOC was measured. The model predicts that the measured concentrations of TOC are due to the sum of all pseudo-components in the aqueous or mobile phase.
LEACHING OF HEAVY SOLIDIFIED WASTES
METALS
FROM
A MULTI-COMPONENT PARTITIONING LEACHING WASTES
MODEL
FROM
TO PREDICT
SOLIDIFIED
OILY
Declan 0 'Cleirigh and Bill Batchelor Texas Engineering Experiment Station, Texas A&M University, College Station, TX 77843
Solidification/Stabilization
(S/S)
is
an
established
Susan Trussell and Bill Batchelor Civil Engineering Department, Texas A&M University College Station, Texas 77843-3136
The goal of solidification/stabilization is to limit the ability of disposed hazardous wastes to migrate in the environment via leaching mechanisms. The pore water components of the solidified wastes constitute the leachable fraction of the wasteform. Previous