Biologischer Abbau chlorierter Kohlenwasserstoffe

Biological Degradation of Chlorinated Hydrocarbons . Chlorinated hydrocarbons (CHC) have been produced on an industrial scale since the 1920's and 1930's and are frequently used as solvents, extractants, and disinfectants. Because their low biodegradability they are often enriched in the food chains of animals, resulting in high mortality. It is therefore necessary to prevent the discharge of CHC's into water, air, and soil. They are often not biodegraded in municipal or industrial activated sludge plants or in trickling filters. Until harmless substitutes become widely available, CHC's will continue to pose a threat and must be eliminated from all effluents before entering wastewater treatment plants. Information about specific conditions for anaerobic and aerobic biodegradation of selected CHC's is given below. Two topics will be discussed in greater detail: the kinetics of dechlorination and mineralization and some examples of the reaction engineering process in lab and pilot scale.     

Einsatz und Verfahrenstechnik der anaeroben Abwasserreinigung

Application and engineering of anaerobic waste water treatment. Anaerobic processes are suitable for waste water from various sources with a high organic burden. New scientific insights suggest that the application of energysaving anaerobic plant will increase because the drop in fermentation time reduces the volume requirements and hence also the necessary investment. Apart from energy savings for introduction of oxygen, anaerobic processes also afford high-energy biogas having many potential uses. The chemical engineering, dimensions, and optimum loading will continue to make considerable demands on research into metabolic performance under the operating conditions of sewage treatment plant.     

Versuche zum biochemischen Abbau von Fettsäuren bei der Abwasserreinigung

Experiments for Biochemical Degradation of Fatty Acids during Waste Water Purification Investigations of anaerobic fat degradation (soya oil) in the one step laboratory fermenter are reported. The velocity was limited by souring. The CSB load was not permitted to exceed 5 kg CSB/m³ · d. Investigations of anaerobic treatment of wool washing water were carried out in semi-technical scale. They showed that a biological degradation of wool fats and waxes takes place in a very slow and incomplete way. A flotative separation of these substances after a “biological destruction” of the emulsion is effective.     

Kinetik der aeroben Abwasserreinigung durch Abbau von organischen Verbindungen und durch Nitrifikation

Kinetics of aerobic waste water treatment by degrading organic compounds and by nitrification . Both aerobic degradation of organic substances and nitrification can be described by the double substrate kinetics of Monod; dissolved organic material and ammonium or nitrite are the first substrate and oxygen the second one. The determination of the different kinetic coefficients by evaluation of measurements on a laboratory scale is explained first, and known results are then presented and discussed. Finally, it is demonstrated by two examples, viz. the simultaneous oxidation of carbon and nitrogen compounds and oxygen-limited substrate removal, how reaction kinetic models can be used to obtain important information about the characteristics of the bioreactions.     

Einsatz von mathematischer Simulation und Miniplant-Technik in der Verfahrensentwicklung

Use of mathematical simulation and miniplant techniques in process development . An integrated study of synthesis and workup or of entire processes is often required in the development of chemical processes. This leads to a large number of possible solutions, of which the most economic one must be selected. This variety can only be mastered at reasonable expense with the aid of present-day techniques. Examples are presented to show how just a few economic possibilities can be selected and optimized from the plethora of alternatives in simulation calculations based on just a few properties of the materials involved. Economics is the basis of all evaluation. Use of miniplants is considered in the second part of the article, and costs and time-expenditure are compared with those for industrial pilot plants. Planning and evaluation of experiments raise the effectiveness of this empirical work. Problems of scale-up are considered, and the advantages of physico-chemically sound scale-up models are demonstrated.     

Untersuchungen zum Abbau von PVC-Folien durch Wärme und Licht

The degradation of films of copolymers of vinyl chloride and carbon monoxide or oxygen by heat and light was investigated. With increasing carbonyl content the instability increases. The thermal degradation is accelerated by oxygen, the photodegradation is retarded. Due to the influence of light polyene sequences are formed on the surface layers of the polymer film. Therefore the lower layers are not damaged.     

Kinetik und Reaktionstechnik der anaeroben Abwasserreinigung

Kinetics and reaction engineering of anaerobic sewage treatment. In numerous papers the reaction rate of acetic acid metabolism by methanogenic bacteria, which is frequently suspected as the slowest step in anaerobic digestion, is described by Monod kinetics using total acetic acid concentration as the substrate for catabolism. However, in some papers the authors try to include the influence of pH by using only the un-ionized acetic acid as the substrate in a Haldane-kinetic term taking substrate inhibition into account. From this viewpoint, some conclusions regarding reaction engineering aspects of anaerobic waste water treatment are drawn and simple models for the conventional and for the contact process are discussed. The advantage of using support materials for anaerobic bacteria is shown. The space loading can be increased in a two step cascade of fixed bed reactors with external loops for water recycling, with the system being filled with synthetic foam particles as support.     

Untersuchungen zum Abbau von Nickelseifen während der Hydrierung von Rapssamenöl

Investigations of Degradation of Nickel Soaps During Hydrogenation of Rape Seed Oil The presence of free fatty acids in oils that are to be hardened leads generally to Ni-soap formation and has effects on the activity of the Ni-catalyst. In the submitted work first the solubility of the Ni-steatate in vegetable oil was investigated, which increases in a temperature range of 80–200° C of 0.01 to 0.38 mg Ni/g oil. In presence of a Ni-catalyst in the hydrogen reduction milieu Ni-soap is degradated in the first stage to about 80 % on an average. The reaction is reversible and for a Ni-soap content during the limits of solubility the state of equilibrium is adjusted to the average value of 70 %. The hydrogenation is advanced by a small amount of Ni-soap. The dependence of the rate constant on Ni-soap concentration was established.     

Einsatz von Beutelfiltern in der Speiseöl- und Margarineproduktion

Use of Filter Sacks in Edible Oil and Margarine Production Filter sacks, made out of felt, are used in various steps of production of margarine and edible oil, such as clarification of miscella, post deodorization (before or after the cooler), and polishing filtration before blending and packaging. This filter sack system offers excellent economy and simple operation. The rapid change of filter sacks, compact size of the pressure filter, and high flow rates at long periods of use are illustrated with practical examples of application.     

Untersuchungen zum Einsatz oxidierter Futterfette in der Schweinemast

Investigations about die Use of Oxidized Feed Fats in the Mast for Swine The influence of oxidized feed fats in case of sufficient supply with vitamin E and linoleic acid was investigated by a trial of mast for swine with 32 pigs of the German country race with a weight of 23 to 100 kg. The effect on fattening perfomance, butcher's meat quality, composition of fatty acids of the neck fat and the α-tocopherol content of liver, muscle and neck fat tissue was investigated. Besides the tissue was investigated for residues of butylhydroxytoluene (BHT).