Günther Laufenberg

Organophilic pervaporation: prospects and performance

Among the different membrane processes, organophilic pervaporation is one of the most promising technologies for environmental applications. The aim of this paper is to give a thorough introduction to organophilic pervaporation in the context of wastewater treatment. The emerging process of organophilic pervaporation is introduced together with other membrane processes relevant for environmental applications. With regard to the performance of pervaporation, an engineering model is presented which will enable ready assessment of process and module design. Sorption and coupled diffusion are covered in the model. Selection criteria for membranes and transport resistances for the mass transport as key process engineering parameters are included. The influences of permeate pressure and temperature upon performance are discussed and a description of commercial pervaporation modules given. Following a brief description of the hierarchy of waste management practice, guidelines for applying and integrating pervaporation into a process are proposed. The importance of considering hybrid processes is highlighted. A case study for phenol recovery with water treatment to 5 ppm is considered. Finally, present restrictions on the use of pervaporation in wastewater treatment such as (a) the unavailability of appropriate membranes and (b) fouling of the membrane are discussed and approaches to overcome the restrictions are presented.

Fish oil stabilisation by microencapsulation with modified cellulose

Fish oil is the richest dietary source of long-chain omega-3 polyunsaturated fatty acids (PUFA). Stabilisation of omega-3 PUFA against oxidation is an important task in food processing. The ability of modified celluloses to act as microencapsulating agents for fish oil was investigated. Fish oil microcapsules were produced by spray-drying of homogenised emulsions containing modified celluloses and maltodextrin as coating materials. The quality of microcapsules was evaluated by scanning electron microscopy, determination of encapsulation efficiency, peroxide value during storage and solubility in water. Methylocellulose (MC) and hydroxypropyl methylocellulose (HPMC) showed good emulsifying properties. Homogenisation of emulsions resulted in creation of high amount of stable foam. More damage occurred in the powders coated with HPMC. The oil retention level was very high, 98.5% (i.e. up to 400.0 g/kg ready powder). Samples with fish oil content of approximately 500.0 g/kg exhibited more structural damage impairing the stabilisation effect. This study indicates that the use of modified cellulose, especially MC, as a coating material for the preparation of spray-dried fish oil microcapsules improves the stability and the concentration of fish oil in the powder.

Use of Pervaporation‐Bioreactor Hybrid Processes in Biotechnology

Pervaporation is a membrane separation process with considerable innovative possibilities in the area of biotechnology. Above all, the combination of bioreactor and pervaporation has potential in the longer term as an alternative to conventional batch processes. This article considers the state of the art pervaporation-bioreactor hybrid processes. The possible applications of such hybrid processes are discussed and compared with conventional processes. It becomes apparent that the use of pervaporation-bioreactor hybrid processes can avoid product inhibition and greatly enhance the productivity of biotechnological processes.

Rejection of acetic acid and its improvement by combination with organic acids in dilute solutions using reverse osmosis

Detailed knowledge of the reciprocal interactions of different solute components in RO, their permeation capacity and their influence on the level of rejection is scarce. In order to examine whether and to what extent the rejection of a target substance is influenced by the addition of other substances during RO, the alteration of permeability of acetic acid through a polyamide membrane was investigated. Therefore, acetic acid was combined with 26 further acids.

The influence of intermolecular interactions on the selectivity of several organic acids in aqueous multicomponent systems during reverse osmosis

Abstract This work investigates the extent to which the rejection of a target substance is influenced by the addition of other substances. The alteration effects on the permeation of acetic acid through a aromatic polyamide membrane when combined with one of 27 further organic acids was studied. The operating conditions were kept constant during all investigations. It was found that the retention of a target substance was dependant on the other compounds in particular aromatics and short-chained monocarboxylic and dicarboxylic acids. Acids which significant influenced acetic acid retention were additionally combined with other target substances, formic and propionic acid. The results showed that, in general, it is only possible to increase the direction of the target substances rejection, a higher rejection can only be increased, a lower rejection can only be decreased. These results were used to create and investigate quaternary solutions which showed that, in principle, it is possible to intensify the increasing effect of retention. Using the experiment data it should be possible to determine the separation capacity by concentration complex mixtures through reverse osmosis (RO).

Separation of aqueous organic multi-component solutions by reverse osmosis : development of a mass transfer model

In this paper the separation of aqueous organic multi-component solutions through a polyamide reverse osmosis membrane was systematically investigated. To analyze coupling effects and competing reactions between substances at or inside the membrane and to determine the influence of the solution components on the separation behaviour, experiments with model solutions were carried out. For the model solutions one of 34 different organic substances was added to an aqueous 1-propanol solution. The substances were chosen due to their environmental relevance and regarding their physico-chemical properties. The observed changes in separation and mass transfer of 1-propanol were used to develop a general mass transport model for reverse osmosis. This model was based on the Kimura-Sourirajan Analysis (KSA) developed by Sourirajan in 1963. It was modified to include the interactions among different substances in multi-component solutions by means of their physico-chemical properties. The model describes the mass transport through a reverse osmosis membrane and enables the prediction of the retention behaviour of organic multi-component solutions.

Possibilities of Calcium Fortification of Spreadable Fat

The aim of the study was to evaluate selected quality attributes of low-fat spread fortified with calcium complex isolated form cow milk. Calcium preparations added into foods may influence texture properties of product. In the study texture parameters of milk derived calcium complex enriched spreadable fat were measured using instrumental and sensory methods. Additionally overall sensory quality and chemical indicators i.e. peroxide value and acid value were estimated. All measurements were carried out during 3 months of storage. There was not significant influence of fortification on samples quality. Results of peroxide value measurements may suggest protective influence of added milk calcium complex against oxidation. The average daily portion of enriched spread (30 g) might provide at least 160 mg of best available calcium of milk origin, i.e. 15% of its recommended daily intake, which can significantly improve dietary calcium level.