| 51. |
- Amofah, Lea Rastas, et al.
(author)
-
Nutrient recovery in a smallscale wastewater treatment plant in cold climate
- 2006
-
In: Vatten. - 0042-2886. ; 62:4, s. 355-368
-
Journal article (other academic/artistic)abstract
- An onsite wastewater treatment plant at Brändön, north of Luleå, receiving primarily treated wastewater from a village, was operated and investigated during one year. The wastewater flow was 0.5 m3/d. The main treatment steps were a prefilter, mainly to distribute the flow, a vegetation filter consisting of two different clones of Salix and two phosphorus filters with Filtralite-P and blast furnace slag (BF slag) operated in parallel. The willow bed reduction of BOD7 was in average about 80% and of phosphorus (P) and nitrogen (N) 20-30%. The main mechanism was believed to be filtration in the bed. The reduction through plant uptake was minor. The Filtralite-P filter reduced BOD7, P and N with 67%, 72% and 20%, respectively. The BF slag filter reduced P and N with 53% and 3%, respectively. The release of sulphuric compounds from the BF slag filter increased the BOD7 content in the effluent. The Filtralite-P system achieved the requirements of the normal protection level given by the Swedish Environmental Protection Agency but not all of the requirements of the high protection level. The BF slag system did not fullfil the requirements of the two protection levels.
|
|
| 52. |
|
|
| 53. |
- Andersen, Anders J., et al.
(author)
-
Characterization of salmon calcitonin in spray-dried powder for inhalation : effect of formulation and process variables
- 2006
-
In: 2006 AAPS Annual Meeting and Exposition. - : American Association of Pharmaceutical Scientists.
-
Conference paper (peer-reviewed)abstract
- To characterize physicochemical properties of salmon calcitonin in spray-dried powder for inhalation and understand the interplay between stability, formulation and process parametersSalmon calcitonin (sCT) was spray-dried together with mannitol and chitosan that acts as stabiliser and absorption enhancer, respectively. Two process variables, i.e. inlet temperature and atomizing air volumetric flow rate, were investigated. Solid state properties of the spray-dried powders were characterized using SEM, TGA, XRPD and DSC. The physicochemical stability of salmon calcitonin in the dry powder was investigated by FTIR, HPLC and LC-MS techniques.A high yield of up to 80 % spray-dried powder was obtained with an improved cyclone assembled with B-290 Mini Spray Drier. Nevertheless, the yield was markedly reduced when addition of chitosan exceeded a certain proportion in spray drying formulation. XRPD and DSC results indicated that crystallinity of mannitol was inhibited with an increase of chitosan in the formulation. Residual moisture levels in the spray dried powders were 1-2%. As indicated by FTIR analysis, sCT retained its structural integrity under the spray drying conditions studied, i.e. 100-180 ºC inlet temperature and 357-742 L/h atomizing air volumetric flow rate. Addition of mannitol and chitosan in the spray drying formulation did not improve stabilization of sCT, in which around 7 % degraded impurities were found at a condition of 180 ºC inlet temperature. Yet no obvious degraded impurities were found in plain sCT spray-dried powder under the conditions studied. The LC-MS analysis showed that oxidation was the main degradation pathway at high inlet temperature. Other minor impurities originated from deamidation of Asn26, N-O acyl migration on Ser29 and dimerization by cross-linkage of the disulfide bonds. Two fragments, i.e. H-(Cys1-Gly28)-OH and H-(Ser29-Pro32)-NH2, could also be found when the degraded ester bond between Gly28 and Ser29 was further hydrolysed in phosphate buffer.Salmon calcitonin can be spray-dried into dry powders with good physical integrity under certain conditions. Chemical stability of sCT in spray-dried powder could be improved by the optimization of formulation and process variables.
|
|
| 54. |
- Andersons, J., et al.
(author)
-
Stiffness and strength of flax fiber/polymer matrix composites
- 2006
-
In: Polymer Composites. - : Wiley. - 0272-8397 .- 1548-0569. ; 27:2, s. 221-229
-
Journal article (peer-reviewed)abstract
- Flax fiber composites with thermoset and thermoplastic polymer matrices have been manufactured and tested for stiffness and strength under uniaxial tension. Flax/polypropylene and flax/maleic anhydride grafted polypropylene composites are produced from compound obtained by coextrusion of granulated polypropylene and flax fibers, while flax fiber mat/vinylester and modified acrylic resin composites are manufactured by resin transfer molding. The applicability of rule-of-mixtures and orientational averaging based models, developed for short fiber composites, to flax reinforced polymers is considered.
|
|
| 55. |
|
|
| 56. |
- Andersson-Chan, Anneli
(author)
-
Attempted biofiltration of reduced sulphur compounds from a pulp and paper mill in Northern Sweden
- 2006
-
In: Environmental progress. - : Wiley. - 0278-4491 .- 1547-5921. ; 25:2, s. 152-160
-
Journal article (peer-reviewed)abstract
- The objective of this study was to identify the reduced sulphur compounds (RSCs) present in waste gas from a specific deaerator at a pulp and paper mill in northern Sweden, and to investigate the feasibility of a multi-stage biofilter to treat these compounds in an industrial setting. Two filter media, rockwool mats and an organic peat and compost mixture, were used as biofilter media. A mixed population of heterotrophs and a strain of Hypomicrobium were examined for DMS and DMDS degradation. Two experimental periods were performed for 45 days each, in the fall and winter in cold climate. Process parameters as well as the number of viable cells of the filter were monitored during operation. Results were inconsistent due to the fluctuations of the system, and a number of operational problems were identified, differing from those developed under controlled, laboratory set-ups. Process conditions varied greatly, that is, fluctuating temperatures, pollutant concentrations, and airflows that led to insufficient residence times. Both biological and mass transfer limitations are possible explanations for the poor treatment results. This study can contribute to assessing the feasibility of biofilters in the pulp and paper industry, and help reduce the knowledge gap between laboratory studies and field conditions.
|
|
| 57. |
- Andersson-Chan, Anneli
(author)
-
Biofiltration of odorous gas emissions
- 2006
-
Doctoral thesis (other academic/artistic)abstract
- Biofiltration has shown its potential as an interesting treatment alternative for contaminated gas streams. Unlike conventional technologies, such as adsorption, scrubbers, and incineration, biofiltration offers effective pollution control at relatively low capital and operating costs, and without the generation of secondary pollution that may require subsequent treatment. The disadvantages of biofiltration have been the large space requirements and frequent media replacements as a result of deterioration or ageing. Extensive biofilter research and development have taken place over the past 20 years internationally, in particular laboratory experiments that address the removal of single pollutants at fairly high concentrations under constant operating conditions. In field applications, such conditions are highly unusual and the feasibility of treating complex mixtures at very low concentrations relevant to many odorous gas emissions has not received much attention. The overall objective of this thesis was to reduce the knowledge gap between laboratory studies and field conditions on the topic of biofiltration for odorous gas emissions. Various operational and process related problems, such as fluctuating flows, temperatures, and pollutant concentrations, that affected the biofilter performance by creating suboptimal living conditions for the microbes were identified. A newly designed compact pilot-scale biofilter was used in three different applications with odour problems, namely restaurant, pulp mill and wastewater pumping station. The gas streams were complex mixtures with chemically diverse contaminants whose concentrations varied significantly with time. Aldehydes were the dominant compounds in restaurant emissions, while reduced sulphur compounds, primarily dimethyl sulphide, dominated the pulp mill and wastewater emissions. Overall, very low concentrations of individual compounds were found (ppb-level), and very low or no removal of the targeted compounds was achieved in the biofilter. Limitations of the biomass density in the filter media is a plausible explanation since pollutant concentrations at the ppb-level may have been too low to build up and support the bacteria. Due to the low solubility of many identified compounds, a mass transfer limitation may also have occurred due to the prevailing short residence times. Drying of the filter medium was partly a problem, pointing to the need for an improved humidification system or using a trickling filter design. In a case study at a wastewater treatment plant, a method to evaluate odour problems was developed involving local observers in an odour panel together with operational data and weather observations. Working with an odour panel proved useful in several ways; they took an active interest in and increased their knowledge of the complexity of odour problems. However, relating the panel reports to specific events at the treatment plant proved difficult, and the reports were not always consistent with current wind directions.
|
|
| 58. |
- Andersson-Chan, Anneli
(author)
-
Evaluation of a Rockwool biofilter media for odorous waste gas treatment
- 2006
-
In: 2006 Conference of the Water Environment Federation and the Air and Waste Management Association on Odors and Air Emissions, Connecticut Convention Center, Hartford, Connecticut (USA), 9-12 Apr 2006. - : WEF.
-
Conference paper (other academic/artistic)
|
|
| 59. |
- Andersson-Chan, Anneli, et al.
(author)
-
Kompetens för driftspersonal vid VA-verk : Bakgrund och utveckling
- 2006
-
Reports (other academic/artistic)abstract
- The competence of operators at Swedish water and wastewater treatmentplants is analysed and sorted into four groups. A basis for future educationand continued education is discussed in relation to selected factors ofdevelopment for the surrounding world.
|
|
| 60. |
- Andersson-Chan, Anneli, et al.
(author)
-
Odorous wastewater emissions
- 2006
-
In: Vatten. - 0042-2886. ; 62:3, s. 227-236
-
Journal article (peer-reviewed)abstract
- The objective of this article is to review odour problems of wastewater treatment facilities and air emission treatment methods. The malodorous wastewater emissions consist of a complex mixture of substances with different properties. A screening of volatile organic and reduced sulphur compounds revealed very low concentrations of individual compounds (< 50 ppb), and only dimethyl sulphide, hydrogen sulphide and methyl mercaptan were found at concentrations above threshold values. Indicating one single compound responsible for the foul odours was not possible. Two case studies are presented and discussed. In the first, a compact biofilter was evaluated for the treatment of gas streams from a sewage pumping station. A rockwool filter media was inoculated with a mixed bacterial wastewater culture that established successfully. However, evaluating the biofilter's performance proved analytically difficult and expensive due to the low concentrations of incoming gases. In the second case study the odour nuisance situation around a wastewater treatment plant was evaluated and a holistic approach to manage the odour problems was developed. An odour panel of local observers worked well, since they got involved in the process. However, using the panel's reports on odour episodes to find the source of the odour was difficult.
|
|
