A bacteria injection scheme for in situ bioaugmentation.

This article presents an innovative design for inoculating the desired organisms to stratified geological layers at desired rates during in-situ bioaugmentation. The new delivery system consists of intermittent porous tubes connected in series with impermeable polyethylene tubes that run horizontally in each stratified layer of a contaminated aquifer. A bioaugmentation test using the new delivery system was conducted to inject an enriched culture of Escherichia coli (E. coli). Results of the test indicated that the distribution of E. coli through each porous tube was fairly uniform. A mathematical model previously developed to calculate the distribution of water flow through each porous tube was modified to calculate the distribution of E. coli. Geological layers often have different hydraulic conductivities. By controlling the permeability and the length of porous tubes placed in stratified layers, the new design provides a means to selectively deliver aqueous bacteria to various layers at desired rates according to aquifer heterogeneity.

A nutrient injection scheme for in situ bio-remediation.

Geological layers often have different hydraulic conductivities. This paper presents an innovative design for delivering aqueous substrates and nutrients to various stratified layers at desired rates during in-situ bio-stimulation. The new delivery system consists of intermittent porous tubes connected in series with impermeable polyethylene tubes that run horizontally in each stratified layer of a contaminated aquifer. Results of the tracer test indicated that the distribution of tritium through each porous tube was fairly uniform. A mathematical model was also developed to calculate the distribution of water flow through each porous tube. By controlling the permeability and the length of porous tubes placed in stratified layers, the new design provides a means to selectively deliver nutrients to various layers at desired rates according to aquifer heterogeneity.

Pilot studies for in-situ aerobic cometabolism of trichloroethylene using toluene-vapor as the primary substrate.

In-situ pilot studies of aerobic cometabolism were conducted to evaluate the injection of toluene-vapor and air into TCE-contaminated aquifer. Delivery of primary substrate (toluene) in a vapor state with air enhanced the growth of indigenous toluene-utilizing bacteria that would degrade TCE by aerobic cometabolism. Meanwhile, delivering toluene in a vapor state effectively reduced potential clogging near the injection points due to excessive microbial growth, which was observed in the field when the injection of neat toluene was employed. Over 90% removal of TCE was achieved with primary substrate (toluene) degraded to a concentration below 10 microg/L.

A model and experimental study for dissolution efficiency of gaseous substrates through in situ sparging.

Delivering electron acceptors, electron donors, and nutrients in gas state has been practiced for in situ bioremediation. A mathematical model based on air-channel concept was developed in this paper to assess the dissolution transient behavior of gaseous substrates for an in situ sparging process using their chemical and physical properties, aquifer-media characteristics, and field operating conditions. Using toluene as an example, the model was verified with experimental data obtained at field sparging rates ranging from 40 to 80Lair/min. The verified model is a useful means of predicting the dissolution behavior of gaseous substrates during sparging in an unconfined aquifer.

Biochemical analysis and electron microscopy of human mitral valve collagen in patients with various etiologies of mitral valve diseases.

Biochemical analyses and electron microscopy of mitral valve collagen were carried out in 29 patients with various mitral valve diseases. They were divided into 3 groups: (1) rheumatic heart disease (15 patients), (2) isolated rupture of chordae tendineae (8 patients), and (3) floppy mitral valve (6 patients). Normal mitral valves obtained at necropsy from 6 patients who died from extracardiac causes were used for control observations. Results of the electrophoretic analysis of the collagen of normal and diseased valves showed that all valves contained collagen types I, III, and AB collagen with similar electrophoretic patterns. Electron microscopic observations and comparisons of the segment-long-spacing crystallites of each type of collagen revealed similar band patterns, irrespective of the normal or diseased valves sources. It is concluded that the composition and primary molecular structure of mitral valve collagen are usually not altered in a wide variety of disease processes affecting the mitral valve.