1. Introduction and Overview. 2. Detecting Influential Observations and Outliers. 3. Detecting and Assessing Collinearity. 4. Applications and Remedies. 5. Research Issues and Directions for Extensions. Bibliography. Author Index. Subject Index.

Regression Diagnostics: Identifying Influential Data and Sources of Collinearity

Inhibition of anaerobic digestion process: A review

 Many atmospheric chemicals occur in the gas phase as well as in liquid cloud droplets and aerosol particles Therefore, it is necessary to understand the distribution between the phases According to Henry's law, the equilibrium ratio between the abundances in the gas phase and in the aqueous phase is constant for a dilute solution Henry's law constants of trace gases of potential importance in environmental chemistry have been collected and converted into a uniform format The compilation contains 17 350 values of Henry's law constants for 4632 species, collected from 689 references It is also available at http://wwwhenrys-laworg 

/pdf/compilation-of-henry-s-law-constants-version-4-0-for-water-58il9q0ogv.pdf

Compilation of Henry's law constants (version 4.0) for water as solvent

Optimisation of the anaerobic digestion of agricultural resources.

Intensive poultry production generates over 100,000 t of litter annually in West Virginia and 9×106 t nationwide. Current available technological alternatives based on thermophilic anaerobic digestion for residuals treatment are diverse. A modification of the typical continuous stirred tank reactor is a promising process being relatively stable and owing to its capability to manage considerable amounts of residuals at low operational cost. A 40-m3 pilot plant digester was used for performance evaluation considering energy input and methane production. Results suggest some changes to the pilot plant configuration are necessary to reduce power consumption although maximizing biodigester performance.

Macroscopic mass and energy balance of a pilot plant anaerobic bioreactor operated under thermophilic conditions.

An overview of the scientific principles and technological concepts and a description of several installations

Anaerobic biotechnology for industrial wastewater treatment.

Comparative process stability and efficiency of anaerobic digestion; mesophilic vs. thermophilic.

This research assayed the toxicity of 50 to 100 chemicals to each of 3 bacterial groups: aerobic heterotrophs, Nitrosomonas, and methanogens. All assays were carried out in sealed serum bottles under similar experimental conditions so that data could be compared among groups. Chemicals tested comprise important environmental pollutants such as chlorinated aliphatic hydrocarbons and halogenated and other substituted benzenes and phenols. Toxicity data were obtained from the literature for fathead minnows and for the Microtox? test for comparison with our bacterial data. Aerobic heterotrophs and methanogens showed similar sensitivities to toxicants, with the exception of an enhanced susceptibility of meth anogens to chlorinated aliphatic hydrocarbons and chlorinated alcohols. Nitrosomonas, Microtox?, and the fathead minnow showed similar sen sitivities as one another, which were significantly greater (one order of magnitude) than the sensitivities of the aerobic heterotrophs and meth anogens. Correlations among the toxicities to different organisms allow predic tions of a chemical's toxicity to one organism to be made based on the toxicity ofthat chemical to a different organism. Excellent correlations (r2 = 0.90 to 0.94) were found between chemical toxicities to the aerobic heterotrophs, methanogens (with chlorinated aliphatic hydrocarbons omitted), and fathead minnows. Good correlations (r2 = 0.70 to 0.82) were found between Microtox? and each of the other bacteria and the fathead minnow. The successful interspecies comparisons and correlations found in this study illustrate that toxicity testing may be streamlined by developing and using relationships between chemical toxicities to different aquatic organisms. Res. J. Water Pollut. Control Fed, 63, 198 (1991). A chemical's toxicity is a key consideration in evaluating its impact on organisms in the aquatic environment. Knowledge of a chemical's toxicity to bacteria has two uses. It can be used to assess the chemical's effect on bacteria in the environment or in biological wastewater treatment systems. A chemical's toxicity to one bacteria may also be used to estimate the toxicity to other bacteria or to higher organisms such as fish if a relationship has been established between the toxic responses of the two organ isms. Because testing higher organisms is significantly more costly and time consuming, preliminary determinations of toxicity based on bacterial testing can be advantageous. In this study, a set of chemicals (50 to 100 per species) was assayed to determine the toxicity to three groups of environ mental bacteria. Testing methods for each group were designed to be as similar as possible while taking into account the differing metabolic needs of the bacteria so that the results would be com parable. The environmental bacteria tested were aerobic hetero trophs, Nitrosomonas, and methanogens, key agents in the nat ural recycling of organic material in the environment and in wastewater treatment systems. Aerobic heterotrophs predomi nate in activated sludge systems and natural aerobic environ ments, converting organic material to carbon dioxide and water. Nitrosomonas convert ammonia nitrogen to nitrite as the first (and more sensitive) step in the biological oxidation of inorganic nitrogen. Methanogens are often considered the most sensitive actors in a consortium of bacteria that convert organic matter to carbon dioxide and methane in anaerobic environments. For comparison with our bacteria data, data were also collected or found in the literature for the Microtox? test and for the fathead minnow. Microtox? is a standardized toxicity test using instrumentation and supplies from the Microbics Corporation. It is a quick, easy test, yielding reproducible results even among different laboratories (Bulich, 1986). Thus it can be of great value if the toxicity values obtained can be related to toxicity to or ganisms of environmental concern.

A database of chemical toxicity to environmental bacteria and its use in interspecies comparisons and correlations

The purpose of this study was to evaluate the effect of pH and inorganic nutrient supplementations for anaerobic hydrolysis and addogenesis of paniculate organic materials at both mesophilic (35 °C) and thermophilic (55 °C) temperatures. Hydrolysis and addogenesis of a synthetic sludge was observed in batch operation for the evaluation of the pH effect. pH was uncontrolled in one reactor and controlled at 4.5, 5.5, and 6.5 in the other three reactors at both temperatures. The greatest degree of hydrolysis and addogenesis occurred when the pH was controlled at 6.5. The pH of the uncontrolled reactor dropped to 3.4 at both temperatures severely retarding hydrolysis and addogenesis. Concentrations of acetic and n‐butyric adds predominated with lower concentrations of propionic add at both temperatures in all reactors. Lactic add was produced as the earliest intermediate but as the reaction proceeded, short chain VF As were produced as final end products with a decrease in lactic add. The higher the ...

Hydrolysis and acidogenesis of particulate organic material in mesophilic and thermophilic anaerobic digestion

Mineral deficiency appears to pose a more critical problem in the anaerobic treatment process than in the aerobic treatment process. Furthermore, the methane fermentation step of anaerobic treatment appears to be the stage most sensitive to mineral deficiency. Commonly the mineral deficiency is a trace metal, and, since the fermentation step is the terminal stage in the treatment process, a build‐up of these reactants (mainly acetate, propionate, butyrate and hydrogen) can adversely affect the overall process. A review of the literature follows concerning the mineral requirements of methane fermentation in order to facilitate a proper understanding of the anaerobic process, especially in its application to treatment of industrial waste waters that are prone to be deficient in certain minerals. Types of limiting nutrients are considered with specific attention given to nitrogen, sulfur, phosphorus and the trace metals, and the physiological role and intracellular concentration of minerals is discussed. An ...

Richard E. Speece

Papers

Anaerobic biotechnology for industrial wastewater treatment.

Comparative process stability and efficiency of anaerobic digestion; mesophilic vs. thermophilic.

A database of chemical toxicity to environmental bacteria and its use in interspecies comparisons and correlations

Hydrolysis and acidogenesis of particulate organic material in mesophilic and thermophilic anaerobic digestion

Mineral requirements for methane fermentation