Foam separation has been successfully developed on a 4-1 laboratory column, an 80-1 field column installation and a 6000 gal pilot plant trough type system as a novel process for detoxifying bleached kraft mill effluents. Toxic surface active materials such as resin and unsaturated fatty acids collect at the gas-liquid interface of rising air bubbles and concentrate in the foam. The highly toxic collapsed foam represents 1-2% by volume of the influent and is subsequently detoxified by biological treatment. Process parameters controlling detoxification efficiency are pH, gas-liquid interfacial area, initial toxicity level and mode of operation. The gas-liquid interfacial area and pH are of utmost importance. For a typical effluent with MST of 3-4 hr, approximately 20-2 30 m²/l of interfacial area given to an effluent at pH > 7.0 are required for detoxification. Foam separation is universally applicable and reliable for detoxifying kraft whole mill effluent. Over 80% of 205 samples from 10 Canadian mills were detoxified. A 1 gal/min, one and two stage continuous flow systems detoxified over 90% of samples at pH 8 and 1-2 hr retention time over 80 days of operation period. Study of detoxification mechanism indicated that foam fractionation accounts for 77.5% of detoxification, volatization for 5.4% and unidentified mechanisms for 17.1%. Depending on the mode of operation, up to 5% of effluent volume was discharged as foam. The foam volume could be reduced to < 2% by increasing foam retention time and enhancing internal reflux. Collapsed foam was readily detoxified by a biodisc or aerated lagoon process. In addition to detoxification, foam separation removed 20-60% of suspended solids, 66% resin acids, 12% B0D5 (10% TOC), 8% color and 80% foaming tendency. Suspended solids removal could be increased to 88% if an expensive dissolved air system were used for bubble generation. Commercially available equipment for foam generation and foam breaking was reviewed. Jet aerators and turbine systems were assessed as most suitable for commercial application. Pilot plant evaluation of this equipment indicated that reliable and consistent operation could be obtained. The results were used to establish empirical formulae for use in process scale up. During a 4 month continuous flow study, approximately 5-7 m²/l of gas-liquid interfacial area was provided to detoxify 80-100 gal/min of mill A effluent with MST of 6-10 hr. The detoxification success rate of a large number of samples increased from 50 to 86 and to 100% as the operation changed from 1 to 2 to 3 stages. The foam produced by the pilot plant was collapsed by a 12" diameter turbine at 100% efficiency all the time. Costs of foam separation were examined for a projected 3 stage foam separation process, treating 25 M gal/day of bleached kraft whole mill effluent. Capital costs for pH control, foam generation, foam breaking and foam treatment were estimated at $2.26 M. Operating costs were estimated at $2.35/ton of pulp. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

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Thesis (M.S.)--University of Wisconsin--Madison, 1980. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 121-126).

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Graduation date: 1996

This project explored the feasibility of using fungi in a constructed wetland for the treatment of pulp mill effluent. The effluent is high in dissolved lignins (some of which are chlorinated), which have proven very difficult to degrade biologically. Mindful of work done with the (terrestrial) white rot fungi, especially Phanerochaete chtysosporium, the question is asked, Is there a fungus which can tolerate submerged conditions while degrading a significant amount of dissolved lignins? Two fungal species with lignin-degrading capability were isolated from submerged films in a log pond. These fungi have been evaluated for decolorization potential under different environmental conditions. Results of laboratory experiments show that one of these fungi, identified as Acremonium sp., was capable of 44% decolorization of pulp mill effluent under sterile, submerged, room temperature conditions. The fungal decolorization was evaluated both in floating cultures and as a film inoculated on wood chips. In addition, bench-scale examination of the potential of this fungus to decolorize pulp mill effluent in non-sterile conditions was completed. / Graduation date: 1994

Graduation date: 1994

Mediated microbial sensors utilizing two different yeast isolates (SPT1 and SPT2) were developed for the estimation of biochemical oxygen demand (BOD). Measurements of glucose/glutamic acid (GGA) standard solution with potassium ferricyanide mediation resulted in linear ranges extending from the detection limits (i.e. 2 and 5 ppm BOD) to 100 and 200 ppm BOD for the SPT1- and SPT2-based sensors, respectively. The standard error of the mean (SEW for 10 ppm. BOD measurements was 10.1% (SPT1) and 3.9% (SPT2). Response reproducibility had 10.6% error between three identically prepared SPT1 sensors. Response times for concentrations of 20 ppm BOD were within 10 minutes. For pulp mill effluent, the detection limits were 2 (SPT1) and 1 (SPT2) ppm BOD, with SEMs of 3.6% and 14.3% for the SPT1 and SPT2 sensors, respectively. Based on the results obtained in this study, it is concluded that SPT2 is the more suitable biocatalyst for pulp mill wastewater analysis. / While 18S rRNA gene sequence analyses, including BLAST homology searches, have suggested that isolate SPT1 is a close relative of Candida sojae (99.8% homology), no close matches have been found for isolate SPT2. The closest match for SPT2 was to Candida krusei (76.0% homology). Evidence from biochemical tests, fatty acid analysis, and 18S rRNA gene sequence analyses, indicates that isolate SPT2 is a novel yeast species.

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