Michael Semmens

University of Minnesota, Department of Civil, Environmental, and Geo-Engineering, Emeritus

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Papers

Condensation studies in gas permeable membranes

Journal of Membrane Science, 2004

Membrane gas transfer can be compromised by water condensation during operation. Experiments repo... more Membrane gas transfer can be compromised by water condensation during operation. Experiments reported here show that the feed gas is rapidly saturated with water, whose transport is controlled by resistances in the membrane and the gas phase. This gas then becomes supersaturated because of gas dissolution, which is controlled by transport in the liquid phase. The water in the supersaturated

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Chapter 10 Membrane contactors

by Edward Cussler and Michael Semmens

Membrane Science and Technology, 1995

Laboratory study of heavy metal phytoremediation by three wetland macrophytes

International journal of phytoremediation, 2006

Detention ponds and constructed wetlands have proven to be effective in reducing peak stormwater ... more Detention ponds and constructed wetlands have proven to be effective in reducing peak stormwater runoff volume and flow, and recent interest has extended to utilizing them to improve stormwater runoff quality. A review of stormwater runoff studies indicated that lead, zinc, copper, cadmium, phosphorus, and chloride are contaminants of primary concern. In laboratory settings, the uptake of contaminants by three wetland plant species, Glyceria grandis, Scirpus validus, and Spartina pectinata, was examined and removal rates from nutrient solutions inflow and nonflow reactors were measured. The removal rates varied by plant species and target contaminant, and no one species was the best accumulator of all six contaminants. Belowground tissues of all three species accumulated higher concentrations of the four heavy metals and aboveground tissues accumulated higher concentrations of phosphorus and chloride. Plants grown in flow reactors showed significantly higher accumulation rates than ...

Treatment of Plating Wastewaters Containing Metal Cyanide Complexes by a Gas Membrane-Ion Exchange Process

by Edward Cussler and Michael Semmens

Research on the cutting edge-Biostability and microbiological quality in a chloraminated distribution system-Utility managers can use this information to better understand the factors controlling

Bench-scale and pilot-scale experiments to investigate geosmin removal options

Development of an On-Line Alkalinity Sensor Cluster for Water Treatment

Magnetically responsive membranes

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AFM-based tribology as a probe of biofilm cohesion

Designing Better Hollow Fibre Contactors

by Edward Cussler and Michael Semmens

GM-IX Process: A Novel Metal Cyanide Treatment and Recovery Technique

by Edward Cussler and Michael Semmens

Dechlorination of PCE by mixed methanogenic cultures using hollow-fiber membranes

The study investigated the use of hollow-fiber membranes for hydrogen (H2) delivery to support th... more The study investigated the use of hollow-fiber membranes for hydrogen (H2) delivery to support the biological reductive dechlorination of tetrachloroethene (PCE) Two experiments were performed in which H2 was supplied through membranes placed in stirred batch reactors containing a mixed methanogenic/dechlorinating culture and PCE (≤10 µM. Reductive dechlorination of PCE to cis-dichloroethene was sustained in the reactors receiving H2 (1% H2 and 50% H2), while negligible dechlorination was observed in control reactors (100% N2). The 1%-H2-fed reactor outperformed the 50%-H2-fed reactor in the first experiment. However, the dechlorinating performance in the two reactors was similar in the second experiment. Despite relatively high H2 concentrations (4.6 to 178 µM) that led to H2 consumption (and CH4 production) by methanogens, dechlorination was effectively maintained for the duration of the experiments (35 to 62 days). The results of this study are significant in that dechlorination was sustained in a minimal medium by membrane-delivered H2. Dechlorination was also maintained at aqueous H2 concentrations that exceeded the thermodynamic thresholds for not only dechlorination (<0.1 to 2 nM, but also methanogenesis (∼10 nM) and homoacetogenesis (94 to 400 nM. The results of these experiments suggest that membranes are a promising H2 delivery technology for stimulating the bioremediation of chlorinated ethene-contaminated aquifers.

Treatment of an RDX-TNT waste from a munitions factory

Membrane gas transfer under conditions of creeping flow: modeling gas composition effects

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Comparative economic analysis of full scale MABR configurations

Method for metal and cyanide recovery from plating baths and rinse waters

Stimulation of dechlorination by membrane-delivered hydrogen: small field demonstration

ABSTRACT Biological reductive dechlorination can be used to remediate aquifers contaminated with ... more ABSTRACT Biological reductive dechlorination can be used to remediate aquifers contaminated with chlorinated solvents. This process can be stimulated with the addition of hydrogen as an electron donor. A small field study was conducted in a trichloroethene (TCE)-contaminated aquifer at the Twin Cities Army Ammunition Plant site in Arden Hills, MN, to determine whether hollow-fiber membranes could be used to deliver hydrogen to the contaminated groundwater to stimulate bloremediation in situ. Nonporous silicone-coated membranes were placed in Geoprobe wells, where they were able to sustain hydrogen delivery over 20 months without a decline in gas transfer performance. High concentrations of hydrogen (168 +/- 13 mu M) were observed in the wells containing membrane modules. These concentrations were similar to that predicted using a clean water gas transfer gas correlation (255 mu M). High acetate concentrations (662 +/- 172 mu M) were also observed in the wells containing membrane modules during hydrogen addition. The addition of hydrogen via the hollow-fiber membranes stimulated vinyl chloride and ethene formation, likely as a result of the activity of acetotrophic dechlorinators.

High efficiency microbubble aeration

Membrane filtration for preferential removal ofemulsified oil from water

The feasibility of using selective oil filtration (SOF) with microporous hollow fiber membranes f... more The feasibility of using selective oil filtration (SOF) with microporous hollow fiber membranes for the separation and recovery of oil from spent cutting fluids was investigated. Two samples of water-based soluble cutting fluids made from petroleum products were tested. Characterization of the fluids was complicated due to proprietary information on the product and different use patterns. In general the fluids