Assessing the Fate of Dissolved Organic Compounds in Landfill Leachate and Wastewater Treatment Systems.

Landfill leachate and municipal wastewater are major sources of chemical pollutants that contaminate our drinking water sources. Evaluating the dissolved organic chemical composition in wastewater treatment plants is therefore essential to understand how the discharge impacts the environment, wildlife, and human health. In this study, we utilized a nontargeted analysis method coupling liquid chromatography and tandem mass spectrometry (LC-MS/MS) to analyze chemical features at different points along two landfill leachate treatment plants (LLTPs) and two municipal wastewater treatment plants (WWTPs) in the Southeastern United States.

Structural Insights into Self-Assembled Aerosol-OT Aggregates in Aqueous Media Using Atomistic Molecular Dynamics.

In water, the surfactant dioctyl sulfosuccinate (Aerosol-OT or AOT) exhibits diverse aggregate structures, ranging from micelles to lamella. An atomic-level understanding, however, of the formation and structure of these aggregates is lacking. Herein, using atomistic molecular dynamics (MD) with microsecond-long simulations, self-assembly of AOT in water is studied for concentrations of 1, 7.

Xanthobacter-dominated biofilm as a novel source for high-value rhamnose.

Rhamnose is a high-value carbohydrate used in flavorings, aromatics, and pharmaceuticals. Current demand for rhamnose is filled through plant-based sources; however, microbially originated rhamnolipids have been proposed as an alternative source. A mixed microbial biofilm, cultured from a wastewater sludge, was found to comprise > 8 dry weight% rhamnose when provided volatile fatty acids as carbon source, and 24 dry weight% when given glucose.

Life Cycle Assessment of Neodymium-Iron-Boron Magnet-to-Magnet Recycling for Electric Vehicle Motors.

Neodymium-iron-boron (NdFeB) magnets offer the strongest magnetic field per unit volume, and thus, are widely used in clean energy applications such as electric vehicle motors. However, rare earth elements (REEs), which are the key materials for creating NdFeB magnets, have been subject to significant supply uncertainty in the past decade. NdFeB magnet-to-magnet recycling has recently emerged as a promising strategy to mitigate this supply risk.

Crude oil contamination of plastic and copper drinking water pipes.

This study was conducted to determine the susceptibility of plastic (i.e., PEX, HDPE and CPVC) and copper pipes to short-term contamination by crude oil.

Tissue-specific biomass recalcitrance in corn stover pretreated with liquid hot-water: SEM imaging (part 2).

In the first part of our work, we combined compositional analysis, pretreatment and enzyme hydrolysis for fractionated pith, rind, and leaf tissues from a hybrid stay-green corn, in order to identify the role of structural characteristics on enzyme hydrolysis of cell walls. Hydrolysis experiments coupled with chemical analysis of the different fractions of corn stover showed significant differences in cell wall structure before and after liquid hot water pretreatment. The extent of enzyme hydrolysis followed the sequence rind < leaves < pith with 90% conversion of cellulose to glucose in 24 h in the best cases.

Tissue-specific biomass recalcitrance in corn stover pretreated with liquid hot-water: enzymatic hydrolysis (part 1).

Lignin content, composition, distribution as well as cell wall thickness, structures, and type of tissue have a measurable effect on enzymatic hydrolysis of cellulose in lignocellulosic feedstocks. The first part of our work combined compositional analysis, pretreatment and enzyme hydrolysis for fractionated pith, rind, and leaf tissues from a hybrid stay-green corn, in order to identify the role of structural characteristics on enzyme hydrolysis of cell walls. The extent of enzyme hydrolysis follows the sequence rind < leaves < pith with 90% conversion of cellulose to glucose in 24 h in the best cases.

Comparative study on enzymatic digestibility of switchgrass varieties and harvests processed by leading pretreatment technologies.

Feedstock quality of switchgrass for biofuel production depends on many factors such as morphological types, geographic origins, maturity, environmental and cultivation parameters, and storage. We report variability in compositions and enzymatic digestion efficiencies for three cultivars of switchgrass (Alamo, Dacotah and Shawnee), grown and harvested at different locations and seasons. Saccharification yields of switchgrass processed by different pretreatment technologies (AFEX, dilute sulfuric acid, liquid hot water, lime, and soaking in aqueous ammonia) are compared in regards to switchgrass genotypes and harvest seasons.

Effect of compositional variability of distillers' grains on cellulosic ethanol production.

In a dry grind ethanol plant, approximately 0.84kg of dried distillers' grains with solubles (DDGS) is produced per liter of ethanol. The distillers' grains contain the unhydrolyzed and unprocessed cellulosic fraction of corn kernels, which could be further converted to ethanol or other valuable bioproducts by applying cellulose conversion technology.

Enzymatic digestion of liquid hot water pretreated hybrid poplar.

Liquid hot (LHW) water pretreatment (LHW) of lignocellulosic material enhances enzymatic conversion of cellulose to glucose by solubilizing hemicellulose fraction of the biomass, while leaving the cellulose more reactive and accessible to cellulase enzymes. Within the range of pretreatment conditions tested in this study, the optimized LHW pretreatment conditions for a 15% (wt/vol) slurry of hybrid poplar were found to be 200(o)C, 10 min, which resulted in the highest fermentable sugar yield with minimal formation of sugar decomposition products during the pretreatment. The LHW pretreatment solubilized 62% of hemicellulose as soluble oligomers.

Enzyme hydrolysis and ethanol fermentation of liquid hot water and AFEX pretreated distillers' grains at high-solids loadings.

The dry milling ethanol industry produces distiller's grains as major co-products, which are composed of unhydrolyzed and unfermented polymeric sugars. Utilization of the distiller's grains as an additional source of fermentable sugars has the potential to increase overall ethanol yields in current dry grind processes. In this study, controlled pH liquid hot water pretreatment (LHW) and ammonia fiber expansion (AFEX) treatment have been applied to enhance enzymatic digestibility of the distiller's grains.

Composition of corn dry-grind ethanol by-products: DDGS, wet cake, and thin stillage.

DDGS and wet distillers' grains are the major co-products of the dry grind ethanol facilities. As they are mainly used as animal feed, a typical compositional analysis of the DDGS and wet distillers' grains mainly focuses on defining the feedstock's nutritional characteristics. With an increasing demand for fuel ethanol, the DDGS and wet distillers' grains are viewed as a potential bridge feedstock for ethanol production from other cellulosic biomass.

Process simulation of modified dry grind ethanol plant with recycle of pretreated and enzymatically hydrolyzed distillers' grains.

Distillers' grains (DG), a co-product of a dry grind ethanol process, is an excellent source of supplemental proteins in livestock feed. Studies have shown that, due to its high polymeric sugar contents and ease of hydrolysis, the distillers' grains have potential as an additional source of fermentable sugars for ethanol fermentation. The benefit of processing the distillers' grains to extract fermentable sugars lies in an increased ethanol yield without significant modification in the current dry grind technology.

Microscopic examination of changes of plant cell structure in corn stover due to hot water pretreatment and enzymatic hydrolysis.

Particle size associated with accessible surface area has a significant impact on the saccharification of plant cell walls by cellulolytic enzymes. Small particle sizes of untreated cellulosic substrate are more readily hydrolyzed than large ones because of higher specific surface area. Pretreatment enlarges accessible and susceptible surface area leading to enhanced cellulose hydrolysis.

Features of promising technologies for pretreatment of lignocellulosic biomass.

Cellulosic plant material represents an as-of-yet untapped source of fermentable sugars for significant industrial use. Many physio-chemical structural and compositional factors hinder the enzymatic digestibility of cellulose present in lignocellulosic biomass. The goal of any pretreatment technology is to alter or remove structural and compositional impediments to hydrolysis in order to improve the rate of enzyme hydrolysis and increase yields of fermentable sugars from cellulose or hemicellulose.

Pretreatment for cellulose hydrolysis by carbon dioxide explosion.

Cellulosic materials were treated with supercritical carbon dioxide to increase the reactivity of cellulose, thereby to enhance the rate and the extent of cellulose hydrolysis. In this pretreatment process, the cellulosic materials such as Avicel, recycled paper mix, sugarcane bagasse and the repulping waste of recycled paper are placed in a reactor under pressurized carbon dioxide at 35 degreesC for a controlled time period. Upon an explosive release of the carbon dioxide pressure, the disruption of the cellulosic structure increases the accessible surface area of the cellulosic substrate to enzymatic hydrolysis.

Production of L-malic acid via biocatalysis employing wild-type and respiratory-deficient yeasts.

The yeast Saccharomyces cerevisiae has been used to efficiently produce L-malic acid from fumaric acid. Fumarase is responsible for the reversible conversion of fumaric and L-malic acids in the TCA cycle. To investigate the function of mitochondrial and cytoplasmic fumarase isoenzymes in L-malic acid bioconversion, a wild-type strain and a cytoplasmic respiratory-deficient mutant devoid of functional mitochondria were employed.

Recombinant human insulin.

Insulin is a well-characterized peptide that can be produced by recombinant DNA technology for human therapeutic use. A brief overview of insulin production from both traditional mammalian pancreatic extraction and recombinant bacterial and yeast systems is presented, and detection techniques, including electrophoresis, are reviewed. Analytical systems for insulin separation are principally based on reversed-phase chromatography, which resolves the deamidation product(s) (desamido insulin) of insulin, proinsulin, and insulin.

Some considerations for optimization of desorption chromatography.

The effect of isotherm parameters of a displacer on the efficiency of desorption Chromatography has been investigated numerically. A general nonlinear multicomponent rate equation model with Langmuir isotherm was used in this study. It was found that the best displacer in this kind of operation is usually not the one that is more strongly adsorbed than the adsorbates when the operation is to displace and concentrate the adsorbates from a saturated or partially saturated column and to minimize the amount of displacer used.

Xylulokinase activity in various yeasts including Saccharomyces cerevisiae containing the cloned xylulokinase gene. Scientific note.

D-Xylose is a major constituent of hemicellulose, which makes up 20-30% of renewable biomass in nature. D-Xylose can be fermented by most yeasts, including Saccharomyces cerevisiae, by a two-stage process. In this process, xylose is first converted to xylulose in vitro by the enzyme xylose (glucose) isomerase, and the latter sugar is then fermented by yeast to ethanol.

Penalizing recidivist drunk drivers in Indiana: impediments to implementation.

In 1983, Indiana enacted a law mandating that anyone convicted a second or subsequent time of Operating While Intoxicated (OWI) receive a minimum of 48 consecutive hours in jail or 10 days of community service. A representative random sample of Indiana counties was used to determine the extent of implementation of this law by the courts in 1984 and 1985. Analysis of the 1984 data concluded that nearly 70% of the cases did comply with the law in its first year of implementation.

Application of bioenergetics to modelling the microbial conversion of D-xylose to 2,3-butanediol.

During the oxygen limiting growth of Klebsiella oxytoca, the xylose metabolism may be considered as consisting of three components: conversion to 2,3-butanediol by "fermentation," oxidation to carbon dioxide by respiration, and assimilation to cell mass. The amount of energy required for the assimilation of cell mass is assumed to determine the extent to which the two energy producing reactions occur. The activity of each energy producing pathway is also determined by the availability of oxygen and by the energy yield of each pathway.

Kinetics of immobilized sucrose phosphorylase.

Sucrose phosphorylase was immobilized on porous ceramic beads with 3-aminopropyltriethoxysilane and glutaraldehyde. It was determined experimentally that under laboratory conditions there was no diffusional resistance to the enzyme-catalyzed reaction. The half-life of the immobilized enzyme varied from about 35 days at 30 degrees C to about 5 days at 40 degrees C.

d-Xylulose Fermentation to Ethanol by Saccharomyces cerevisiae.

We used commercial bakers' yeast (Saccharomyces cerevisiae) to study the conversion of d-xylulose to ethanol in the presence of d-xylose. The rate of ethanol production increased with an increase in yeast cell density. The optimal temperature for d-xylulose fermentation was 35 degrees C, and the optimal pH range was 4 to 6.