Ultra-high molecular weight polyhydroxyalkanoates (PHAs) with low polydispersity index (PDI = 1.3) were produced in a novel, pilot scale application of mixed cultures of nitrogen-fixing bacteria. The number average molecular weight (M (n)) of the poly(3-hydroxybutyrate) (P(3HB)) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(3HB-co-3HV)) was determined to be 2.4 x 10(6) and 2.5 x 10(6) g mol(-1), respectively. Using two types of carbon sources, biomass contents of the P(3HB) and P(3HB-co-3HV) were 18% and 30% (PHA in dry biomass), respectively. The extracted polymers were analysed for their physical properties using analytical techniques such as nuclear magnetic resonance (NMR) spectroscopy, differential scanning calorimetry (DSC) and gel permeation chromatography (GPC). NMR confirmed the formation of homopolymer and copolymer. DSC showed a single melting endotherm peak for both polymers, with enthalpies that indicated crystallinity indices of 44% and 37% for P(3HB) and P(3HB-co-3HV), respectively. GPC showed a sharp unimodal trace for both polymers, reflecting the homogeneity of the polymer chains. The work described here emphasises the potential of mixed colony nitrogen-fixing bacteria cultures for producing biodegradable polymers which have properties that are very similar to those from their pure-culture counterparts and therefore making a more economically viable route for obtaining biopolyesters.

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Pulp and paper mill wastewaters normally contain very low concentrations of nitrogen, but many pulp mill aerated stabilization basin (ASB) treatment systems are operated with no supplemental nitrogen, while achieving high biochemical oxygen demand (BOD5) removal. A nutrient mass‐balance study, undertaken across one of the aerated lagoons in such an ASB system, found that a substantial input of nitrogen was occurring within this pond, amounting to approximately 600 kg nitrogen per day. Direct measurement of acetylene reduction (nitrogen fixation), both in the pond and in a laboratory simulation, showed that bacterial nitrogen fixation was responsible for the input of nitrogen. Most of the nitrogen for bacterial growth within the lagoon was supplied by atmospheric nitrogen fixation, and, consequently, nitrogen fixation was critical to overall system effectiveness. It appears that elevated dissolved oxygen concentrations may inhibit fixation. This may be an important constraint on the operation of such ASB systems, especially for the first lagoon, and represents a potential change to current thinking. The implications of bacterial nitrogen fixation, with respect to the effective operation and control of kraft mill ASB systems, are discussed.

The nature and mass flows of atmospheric emissions from an industrial kiln, drying radiata pine (Pinus radiata D. Don) at 100°C dry bulb and 70°C wet bulb, were assessed by measuring the concentration of chemical components in the kiln atmosphere at regular time intervals and determining air-flows and temperature differentials across the stack. The volatile organic compounds (VOC) were trapped on activated carbon and analyzed by GC-MS. The aldehydes were trapped in 2,4-dinitrophenol-hydrazine solution and the aldehyde derivatives analysed by HPLC. Polar compounds were trapped in water and then alcohols were analysed by GC and organic acids by ion exchange chromatography. The two major VOC found were a-pinene and b-pinene, which made up 90% of the total discharge (405 g/m 3 wood). Most of the VOC fraction was released during the early stages of drying. The release of potentially hazardous components (formaldehyde, acetaldehyde, furfural) was found to be relatively low (1.1, 8.7, and 0.1 g/m 3 wood, respectively) provided the kiln emissions are well dispersed, these levels of release are unlikely to cause adverse environmental effects. Abschätzen der Luftemissionen beim industriellen Trocknen von KiefernholzArt und Menge der gasförmigen Emissionen während des industriellen Trocknens von Kiefernholz (P. radiata D. Don) wurden abgeschätzt. Die Trockentemperatur betrug 100°C, die Feuchttemperatur 70°C. Chemische Komponenten in der Ofenluft wurden in regelmäßigen Zeitintervallen gemessen sowie die Luftbewegungen und Temperaturdifferenzen innerhalb des Holzstapels bestimmt. Die flüchtigen organischen Bestandteile (VOC) wurden an Aktivkohle adsorbiert und mittels GC-MS analysiert. Aldehyde wurden in Lösungen von 2,4-Dinitrohydrazin aufgefangen und die entsprechenden Aldehydderivate mittels HPLC analysiert. Polare Komponenten wurden in Wasser absorbiert, wonach die Alkohole mittels GC und die organischen Säuren mit Ionenaustauschern aufgetrennt wurden. Die Hauptkomponenten der VOC waren Alpha-und Beta-Pinen, die zusammen 90% des Massenverlustes (405 g/m 3 Holz) ausmachten. Die Hauptmenge wurde im frühen Trockungsstadium freigesetzt. Die Freisetzung von eventuell schädlichen Komponenten war relativ gering (Formaldehyd 1,1 g/m 3 , Acetaldehyd 8,7 g/m 3 und Furfural 0,1 g/m 3 ). Wenn die Ofenabluft gut verdünnt ist, sollten diese Mengen kaum Umweltschäden verursachen.

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