Mow S. Lin

Biochemical processing of heavy oils and residuum

During the past several decades, the petroleum industry has adjusted gradually to accommodate the changes in market product demands, government regulations, and the quality and cost of feedstock crude oils. For example, the trends show that the demand for distillate fuels, such as diesel, as compared to gasoline are increasing. Air-quality standards have put additional demand on the processing of heavier and higher sulfur feed stocks. Thus, the 1990 Clean Air Act amendments require the industry to produce greater quantities of oxygenated gasoline, and lower sulfur diesel and reformulated gasoline. Biochemical technology may play an important role in responding to these demands on the petroleum industry. Since oil is of biological origin, some biochemical reactions started at the beginning of its formation are still continuing in reservoirs on a geological time scale. Although these rates are very slow, many reactions can proceed readily under optimal conditions. This article will address some of the reactions that may be useful for processing heavy oils and refinery residuum. 6 refs., 2 figs., 3 tabs.

Geothermal waste treatment biotechnology

Studies at the Brookhaven National Laboratory (BNL) have led to the development of a technically and economically feasible, as well as environmentally acceptable, biochemical process for detoxification of geothermal residues. For this process, selected microorganisms that live in extreme environments have served as models for the new biotechnology. Assuming a 2,500-kg / h sludge production rate, the new technology is capable of a better than 80% removal rate of toxic metals, usually in less than a 25-hour period. The process itself depends on a number of flexible parameters, allowing this technology to be tailored to specific needs of different geothermal producing regimes, such as those found in the Salton Sea and the Geysers area of California. Thus geothermal residual sludges and brines can be processed to remove only a few metals, such as arsenic and mercury, or many metals, ranging from valuable metals such as chromium, gold, and silver to radionuclides, such as radium. In some cases, combined metal removal and metal recovery processes may be cost efficient and therefore advantageous. The emerging biotechnology for the treatment of geothermal energy production wastes is versatile and offers a number of application options, which are discussed in the paper.

The significance of chemical markers in the bioprocessing of fossil fuels

Abstract Biochemical conversion of crude oils is a multi-step process proceeding through a series of biochemical reactions. These reactions can be characterized by a set of chemical markers which are associated with the chemical composition of crude oils. Reactions with heavy crude oils indicate that there is an overall decrease in the concentration and chemical speciation of organic sulfur compounds, and a redistribution of hydrocarbons and organometallic species. The contents of trace metals in the crude oils, such as nickel and vanadium, also decrease. Further, heavy ends of crudes, containing the asphaltenes and the polar nitrogen, sulfur, and oxygen containing fractions, as well as the organometallic compounds and complexes, are biochemically converted to lower molecular weight chemical species. In the studies reported in this paper, microorganisms used to mediate such reactions were thermophilic (> 60°C) and pressure tolerant (up to 2500 psi). These organisms are also capable of biochemical conversion of bituminous and lignite coals in an analogous manner to their action on crude oils and follow similar trends characterized by chemical markers. For example, X-ray absorption near-edge structural (XANES) analyses of biotreated crude oils and low grade coals show that biochemical reactions lead to decreases in organic sulfides and thiophenes with a concurrent increase in sulfoxide contents. Chemically related constituents present in heavy crude oil fractions and low grade coals are the asphaltenes. Asphaltenes are complex structures containing heteroatoms and metals involved in inter- and intra-molecular bridges and stereochemical configurations. The chemical markers associated with the biochemical conversion of oils and coals indicate multiple biochemical processes involving chemical reactions at sites containing heteroatoms and metals leading to a breakdown of the structure(s) to smaller molecular weight units. Thus, using chemical markers as diagnostic tools, the extent and the efficiency of fossil fuel bioconversion may be predicted and monitored, allowing for better cost-efficient field trials. Recent results in this area will be presented and discussed in this paper.

Biodegradation of coals

Abstract Selected strains of bacteria [from the Brookhaven National Laboratory (BNL) collection], capable of degrading heavy crude oils, were used to treat bituminous and lignite coals. Products resulting from biochemical reactions among several microorganisms and different coals were examined by pyrolysis gas chromatography-mass spectrometry (Py. g.c.-m.s.), and X-ray absorption near edge structure (XANES) spectroscopy. The results indicated considerable variations in the organic sulfur as well as modifications in coal structure. Furthermore, biochemical reactions involved in the microbial interactions with coals appeared to be microbial species dependent.

The use of chemical markers in the evaluation of crude oil bioconversion products, technology, and economic analysis

Abstract Experimental data gathered over the past several years show that the interactions of microorganisms with crude oils are variable and depend on the microbial species and the chemical composition of crude oils. Systematic studies of chemical mechanisms by which selected microorganisms react with crude oils have led to the identification of biochemical markers characteristic of the interactions of microbes with oils. These biomarkers belong to several groups of natural products ranging from saturate and polyaromatic hydrocarbons containing heterocyclics to organometallic compounds. Chemical marker analyses indicate that the interaction of microbes with crude oils involves multiple chemical reactions resulting from the biochemical interactions between microbes and oils. Different interactions may influence the efficiency of processes in which single or mixed microbial species are used for the oil treatment and may also suggest possible combinations of biological and chemical technologies. Further, the biochemical conversions of oils can be monitored by these chemical markers, which is particularly useful in the optimization of biochemical processing, cost efficiency, and engineering studies. Recent results from these studies will be discussed.

Interaction between thermophilic microorganisms and crude oils: recent developments

Abstract A considerable research effort in the area of microbially enhanced oil recovery (MEOR) has shown that it is promising and that a recovery biotechnology may be developed. Successful biochemical processes would have to be cost effective and have certain attributes, such as being able to produce emulsifying agents and acidify the media. Further, the microbes producing these conditions should be tolerant to high salt concentrations and be capable of metabolizing high molecular weight compounds. Since oil reservoirs are also subject to temperature and pressure variations, successful microbial strains should be able to adapt to such environments. Thermophilic microorganisms, which usually live in harsh environments, appear to be good candidates for MEOR. Continuing work in Brookhaven National Laboratory dealing with the chemistry and biochemistry of microorganisms living under extreme conditions has been expanded to a systematic study of the interaction of thermophilic microorganisms with crude oils and oil derivatives. Some recent results of these studies are presented.

Developments in geothermal waste treatment biotechnology

Abstract Disposal of toxic solid waste in an environmentally and economically acceptable way may be in some cases a major impediment to large geothermal development. The major thrust of the R &D effort in this laboratory is to develop low-cost processes for the concentration and removal of toxic materials and metals from geothermal residues. In order to accomplish this, biochemical processes elaborated by certain microorganisms which live in extreme environments have served as models for a biotechnology. It has been shown that 80% or better removal of toxic metals can be achieved at fast rates (e.g., 25 hours or less) at acidic pH and temperatures of about 60°C. There are several process variables which have to be taken into consideration in the development of such biotechnology. These include reactor size and type, strain of microorganisms, biomass growth, temperature, loading concentrations of residual geothermal sludge, and chemical nature of metal salts present. Recent data generated by the research and development effort associated with the emerging biotechnology will be presented and discussed.

Applications of Bacteriorhodopsin in Membrane Mimetic Chemistry

The chemistry of the photoreceptors of higher animals is a topic that reaches back more than forty years. By 1970, the photoreceptors of more than four hundred species of animals had been studied. All these species have in their visual pigments a common chromophore, retinal, connected to the protein opsins through a Schiff base bond. This protein complex, called rhodopsin, with its associated lipids makes up the photosensitive membrane in photoreceptor cells.1,2