The marine bacterium Pseudoalteromonas tunicata produces target-specific inhibitory compounds against bacteria, algae, fungi and invertebrate larvae and is frequently found in association with living surfaces in the marine environment. This study examined the ability of P. tunicata to form biofilms under continuous culture conditions within the laboratory. P. tunicata biofilms exhibited a characteristic architecture consisting of differentiated microcolonies surrounded by water-channels. Interestingly, a repeatable pattern of cell death in the centre of microcolonies was observed. The antibacterial and autolytic protein, AlpP, produced by P. tunicata was found to be involved in this biofilm killing and a

Thesis (M. Phil.)--University of Hong Kong, 1979.

Sweden’s energy consumption is divided into three major sectors. One of them is the industry sector. One third of Sweden’s energy consumption is converted in the industries. The chemical industry is one of those industries with great energy needs. This thesis looks into energy efficiency in industry, in particular the plastics manufacturing industry. Efficiency concerning heat exchangers, their fouling resistance and also pumps. This thesis also relates to the industry in the big picture as heat exchangers and pumps are widely used and these has a great energy and environmental efficiency. This thesis presents an algorithm especially developed for this issue. The thesis has been written by dividing the work into measurements and data, implementation and analysis. The result of this thesis is an Excel-sheet that may be used to calculate the fouling resistance in a plate heat exchanger. / Sveriges energianvändning är uppdelad i tre stora sektorer. Ett av dem är industrin. En tredjedel av Sveriges energiförbrukning omvandlas inom industrierna. Kemiindustrin är av dem industrier som har stort energibehov. Detta examensarbete tar upp effektivisering inom industrin, närmre sett plasttillverkningsindustrin. Effektiviseringen berör värmeväxlare och dess foulingresistans och även pumpar. Examensarbetet kan spegla industrin i den stora bilden då värmeväxlare och pumpar finns väldigt utspritt och effektiviseras dessa har en stor energi och miljöeffektivisering gjorts. För att energieffektivisera inom detta examensarbete har en beräkningsalgoritm tagits fram. Arbetet har delats upp i mätvärden, beräkningar genomförande och analys. Resultatet blev en Excel-ark som kan användas för att beräkna foulingresistansen i en plattvärmeväxlare.

The objective of this study was to identify and characterize naturally-occurring communities of Bacteria and Fungi fouling the surfaces of concrete structures in Georgia, USA, through the use of culture-independent and culture-dependent approaches. Genomic DNA was extracted and ribosomal RNA genes were PCR amplified from 4 biofouled sites located in or around the cities of Atlanta, Gainesville, LaGrange, and Savannah. Bacterial and fungal community composition was determined by phylogenetic analysis. Molecular analysis revealed five bacterial phyla, and representatives of the phylum Cyanobacteria and the classes Betaproteobacteria and Gammaproteobacteria dominated the bacterial clone libraries. Fungal clone libraries showed the dominant phylotypes to be most closely related to Alternaria, Cladosporium, Epicoccum and Udeniomyces. Phylogenetically distinct microbial populations were present at each of the biofouled sites. In addition, cultured isolates were obtained from sites and tested for their ability to foul concrete of varied compositions under laboratory-controlled conditions. Biofouling tests revealed that fungal isolates obtained from the field were able to colonize concrete surfaces when supplied with moisture (95-100% relative humidity) and a nutrient source, and that fouling was affected by concrete water/cement ratio, surface roughness, and the presence of photocatalytically-activated cement added to inhibit microbial growth.

No description available.

Central Arizona Project (CAP) water was treated using the process of slowsand filtration, chemical pretreatment and RO membrane. Both bench scale plate and frame reactor and pilot scale tests suggested RO membrane fouling by clay and organic matter with minor scaling by CaCO3 and BaSO4. Several strategies were studied to reduce RO membrane fouling and scaling. The first is choosing optimized operation conditions through bench scale tests. The second is to modify the traditional concentration polarization model for a better fouling/scaling prediction. This modified model was also used to optimize concentrate spacer design, which leads to reduced concentration polarization index. The third is to develop a method for anti-scalant test and comparison, which can be used for anti-scalant selection and dose optimization.Additional to these strategies, pre-oxidation pretreatment for RO membrane in water reuse application was investigated at bench and pilot scale. In the MBR-Ozone-RO train study, ozone showed certain impact on RO membrane fouling, but no significant difference was made on membrane cleaning frequency. UV and UV/AOP impacts on RO membrane fouling tests were done on plate and frame reactor. UV did not show any competency to reduce membrane fouling, while UV/AOP tests showed promising results by reducing RO membrane fouling rate by 50%.

No description available.

No description available.

Thesis (M.S.)--University of Akron, 2004. / Title from Web page (viewed on Dec. 17, 2007). "August, 2004." Includes bibliographical references (p. 121-127).

This thesis investigates the fouling of a microfiltration membrane by biological solutions. Membrane fouling is recognized as a major drawback for the application of microfiltration in the purification of biotechnology products. Membrane fouling was analyzed and compared for filtrations performed with a hollow fiber microfiltration module operated at constant permeate flux using bovine serum albumin (BSA) solutions or Chinese hamster ovary (CHO) cell culture broths as feed solutions. A mechanistic model was developed to represent the fouling of a cross-flow microfiltration membrane operated at constant permeate flux. Fouling was observed as an increase in the transmembrane pressure (TMP) and assumed to occur first by pore blockage followed by cake formation over the blocked pores. The effect of the cross-flow action was described by the removal of deposits from the membrane surface thereby reducing the pore blockage and the mass of the cake. The model was fitted to the TMP profiles obtained during the filtration of BSA solutions and Chinese hamster ovary (CHO) cell culture broths with a 0.45 µm polysulfone hollow fiber membrane. According to the fitted model, pores blocked faster and more cake was formed with increasing BSA concentration. In the case of CHO cell culture broth, increasing the wall shear rate (proportional to cross-flow velocity) seemed to lead to the formation of a less pronounced cake but more pore blockage. The cross-flow mechanistic model was applied to the microfiltration of CHO cell culture supernatants harvested at different days of the fermentation process. The filtrations were performed at two different shear rates and with two different membrane pore sizes. The cell culture supernatant caused membrane fouling observed as an increase in both the TMP and the membrane hydraulic resistance estimated from water flux measurements at the end of the filtrations. The highest TMP increase was observed for the filtrations with the smaller membrane pore size (0.2 µm) and the higher shear rate (8000 s-1). The hydraulic resistance estimates of the fouled membrane also revealed a higher irreversible fouling for the smaller (0.2 µm) membrane pore size while the model analysis indicates that more fouling occurred at the entrance of the membrane pores. The shear rate was found to strongly influence the contribution of the reversible fouling to the total hydraulic resistance of the membrane. The cross-flow mechanistic model indicates a higher pore blockage for the most severe membrane fouling observed experimentally for the smaller membrane pore size and the higher shear rate. At the same time, a smaller cake deposit was predicted for the higher shear rate. The different cell culture harvest time investigated in this study did not reveal any differences in membrane fouling. BSA solutions were used to evaluate the contribution of BSA aggregates, fresh cell culture medium and the non-ionic surfactant Pluronic F-68 to membrane fouling. A simple empirical model was developed to represent the TMP increase and to derive the initial fouling rate. The initial fouling rate, the normalized TMP and the irreversible membrane resistance at the end of the filtration were analyzed to determine the effect of BSA solution characteristics on membrane fouling. The initial fouling rate increased with increasing BSA aggregate content consistent with a two-step fouling mechanism that was proposed for membrane fouling by BSA. Increased BSA concentration and the use of fresh cell culture medium compared to potassium phosphate buffer resulted in an increase in initial fouling rate, TMP and irreversible membrane fouling. The addition of the non-ionic surfactant Pluronic-F68 to the BSA solutions decreased the long-term fouling and the irreversible fouling but did not affect the initial fouling rate.