Direct freezing has been extensively and successfully used for the desalination of saline waters, and for the concentration and recovery of by-products from industrial wastes. In this investigation the direct slurry freeze conditioning of waste-activated sludge was studied, and it was shown that it produces a considerable improvement in dewatering. Dewatering characteristics were adequately defined by the specific resistance and coefficient of compressibility values, by settling, and by filter cake quality when vacuum filtration and gravity drainage on sand beds were utilized. The sludge samples for the principal part of the investigation were obtained from three different sources: two extended aeration plants treating domestic sewage and a conventional activated sludge plant treating combined industrial domestic wastes. During the latter part of the research, waste activated sludge samples from a plant treating pulp and paper waste and from aerobic digesters were also conditioned by the process. Gravity settled sludge concentrations after freezing and thawing ranged from 10 to 14 percent. Filter cake moisture contents after vacuum filtration of the conditioned sludge ranged from 40 to 80 percent while cake moisture after gravity drainage on sand beds followed by seven days of air drying ranged from 30 to 90 percent. Very little change in supernatant quality occurred during direct slurry freeze conditioning. Direct microscopic and wet sieve analysis indicated that the principal mechanism of conditioning was the promotion of flocculation. It was found that the degree of conditioning is a function of the "butane contact" or freezing time with better conditioning occurring with longer detention times. Variables affecting conditioning such as the feed solids A concentration and the butane flow rate were evaluated as were various factors that affect the dewatering of the conditioned sludge. An economic evaluation indicated that the direct slurry freezing process has an economic advantage when compared to other sludge conditioning processes such as indirect freezing and heat treatment. A cost estimate of $6 to $20 per ton of dry solids processed was projected. / Ph. D.

One autotrophic and two heterotrophic chemostats were operated during the study period. The autotrophic unit was operated using an inorganic synthetic ammonium medium to provide a culture of nitrifying organism and to study cell yield. The two heterotrophic units were operated with a feed containing 50 and 100 mg/l COD respectively along with the inorganic ammonium medium to determine the effects of heterotrophic activity on the nitrification process. The parameters monitored included mixed liquor suspended solids, suspended solids concentration in the effluent and influent; effluent ammonia and nitrate nitrogen concentration. The culture from the autotrophic unit was used as inoculum of nitrifying organisms for the other phases of the study. These phases of the study included determination of the effect of ammonium concentration, temperature and pH on nitrification. Temperature was found to be the main controlling factor for nitrification. An equation for the sludge age required at operating temperature was developed and a graph was prepared to determine the MLSS required, for a given influent BOD and the determined sludge age, that will assure nitrification on yearly basis. Changes in the pH within the range of 7 to 9 were found to have no significant influence on the nitrification rate. The nitrification rate decreased at pH outside this range. It was found that the presence of heterotrophic activity had no effect on the nitrification. In fact the presence of heterotrophic biomass was found desirable because of the improvement in the effluent quality. / Master of Science

A flotation column has been developed Incorporating the use of fine air bubbles (less than 100 microns) to remove ash-forming minerals from micronized coal. The microbubble generator used In this work has been characterized and found to yield a very narrow size distribution. Microbubble column flotation tests have been conducted to study a series of operating variables such as time, bubble size, feed rate, feed point, feed percent solids, column height, bubble number concentration, make-up water addition and countercurrent wash water addition. The results show that i) fine air bubbles are Inherently better suited for floating small particles; ii) both ash and recovery rates Increase with Increasing feed rate, distance of the feed point from the tailings port, feed percent solids and bubble number concentration; iii) taller columns result In Improved recovery and ash rejection; and iv) the countercurrent wash water addition minimizes the entrainment of mineral matter to the froth product. Proper control of these parameters makes It possible to produce super clean coal (< 2% ash). / M.S.

Ubiquitinierung ist eine essentielle posttranslationale Proteinmodifikation (PTM), die vielfältige Prozesse in eukaryotischen Zellen steuert. Ubiquitin wird zu unterschiedlichen polymeren Ketten zusammengesetzt, wobei E2-Ubiquitin-konjugierende Enzyme häufig eine entscheidende Rolle spielen. Im Rahmen meiner Promotion habe ich die molekularen Grundlagen der Ub Kettensynthese durch die E2-Enzyme Ubc1 und Ubc7 untersucht. Dies geschah mithilfe von in vitro Ubiquitinierungs-Reaktionen, biochemischen und strukturellen Untersuchungen sowie zellbiologischen Experimenten. Ich konnte zeigen, dass zugehörige Ubiquitin-Binde-Domänen (UBDs) die Funktion der E2-Enzyme maßgeblich regulieren. Als einziges unter elf E2-Enzymen in S. cerevisiae enthält Ubc1 eine Ub-bindende UBA Domäne, deren Funktion bisher unklar blieb. Ubc1 modifiziert ausschließlich Lysin 48 (K48) in Ub und wurde mit Proteinqualitätskontrolle sowie der Regulation des Zellzyklus in Verbindung gebracht. Meine Ergebnisse zeigen, dass Ubc1 mithilfe seiner UBA-Domäne vorzugsweise mit K63-verknüpftem Polyubiquitin interagiert, wodurch K48/K63 verzweigte Ub-Ketten entstehen. Basierend auf vorhandenen Strukturinformationen und meinen eigenen röntgenkristallographischen Untersuchungen zeige ich eine Modellstruktur für die Reaktion auf. Meine Ergebnisse stellen eine wesentliche Untersuchungsgrundlage für verzweigten Ub-Ketten dar, über deren Vorkommen und Funktion bisher wenig bekannt ist. Ubc7 assembliert mithilfe seines Kofaktors Cue1 K48-verknüpfte Ub-Ketten im Rahmen des Endoplasmatisches-Retikulum-assoziierten Proteinabbaus (ERAD). In einem kollaborativen Projekt haben wir die Ub-bindende CUE-Domäne in Cue1, die hierfür eine Schlüsselrolle spielt, untersucht. Sie ermöglicht die Ausrichtung des E2-Enzyms an der distalen Spitze der Ub-Kette für eine schnelle Kettenverlängerung, besitzt einzigartige auf den Prozess angepasste Bindungseigenschaften und ihre Beeinträchtigung stört den Abbau des ERAD-Substrates Ubc6. / Ubiquitination is an essential posttranslational protein modification (PTM) that regulates widespread intracellular processes in eukaryotic cells. Ubiquitin (Ub) can be assembled into polymeric chains through its seven internal lysine residues and the N-terminus enabling the formation of a complex "Ubiquitin Code". Factors that guide the molecular machinery which produces this code remain poorly understood. In this study, I demonstrate that ubiquitin binding domains (UBDs) associated with the E2 enzymes Ubc1 and Ubc7 substantially contribute to the assembly of particular Ub chains. Uniquely among the eleven E2 enzymes of S. cerevisiae Ubc1 contains a ubiquitin binding UBA domain. Ubc1 exclusively modifies lysine 48 (K48) in Ub and has been implicated in protein quality control and cell cycle progression. However, the function of its UBA domain remained elusive. I identified Ubc1 to preferentially target specific Ub molecules in K63-linked polyubiquitin via its UBA domain. This activity results in the assembly of K48/K63 branched Ub chains. Based on existing structural information and my own X-ray crystallographic experiments, I propose a structure for the transition state of branched chain assembly by Ubc1. My findings provide a basis for the study of this unusual Ub chain type. Ubc7 has previously been shown to be activated by its co-factor Cue1 to assemble Ub chains linked through lysine 48 (K48) in the context of endoplasmic reticulum associated protein degradation (ERAD). In collaboration with Dr. Maximilian von Delbrück and Dr. Andreas Kniss, we identified the ubiquitin binding CUE domain in Cue1 to play a key role in aligning Ubc7 with the distal tip of a K48-linked Ub chain for rapid chain elongation. Furthermore, we showed how binding of Ub by the CUE domain is well adapted towards the chain elongation process and how its disruption impairs degradation of the ERAD substrate Ubc6.

No description available.