| 11. |
- Andersson Chan, Anneli, 1971-, et al.
(author)
-
Increased nitrogen removal in existing volumes at Sundet wastewater treatment plant, Växjö
- 2014
-
In: Water practice and technology. - : IWA Publishing. - 1751-231X. ; 9:2, s. 215-224
-
Journal article (peer-reviewed)abstract
- Many wastewater treatment plants need to improve their nitrogen removal due to stricter requirements and increasing loads. This often means larger bioreactor volumes, which can be very expensive and is sometimes impossible if space is limited. Therefore, there is a need for compact hybrid solutions that can increase capacity within existing volumes. Two full-scale demonstration projects using moving bed biofilm reactor (MBBR) technology has proven to be an efficient way to treat nitrogen in existing volumes at Sundet wastewater treatment plant in Växjö. Increased nitrification and denitrification capacity in parts of the main stream were demonstrated through the Hybas™ process, a combination of MBBR and activated sludge using the integrated fixed-film activated sludge technology. The ANITA™ Mox process, using autotrophic N-removal through anaerobic ammonium oxidation (anammox), provided high nitrogen removal for the sludge liquor. Data collected on-site for over a year are analyzed and compared with the performance of conventional treatment systems. These two full-scale demonstration projects have been a successful learning experience in identifying and correcting both process and operational issues, which may not have arisen at pilot scale. The set objectives in terms of nitrogen removal were met for both processes and design modifications have been identified that will improve future operation at Sundet WWTP.
|
|
| 12. |
|
|
| 13. |
- Bengtsson, Simon, et al.
(author)
-
Production of polyhydroxyalkanoates by activated sludge treating a paper mill wastewater
- 2008
-
In: Bioresource Technology. - : Elsevier BV. - 1873-2976 .- 0960-8524. ; 99:3, s. 509-516
-
Journal article (peer-reviewed)abstract
- Production of polyhydroxyalkanoates (PHAs) in activated sludge treating wastewater represents an economical and environmental promising alternative to pure culture fermentations. A process for production of PHA from a paper mill wastewater was examined at laboratory scale. The three stage process examined consisted of acidogenic fermentation to convert wastewater organic matter to volatile fatty acids (VFAs), an activated sludge system operating under feast/famine conditions to enrich for PHA producing organisms and accumulation of PHA in batch experiments. After fermentation of the wastewater, 74% of the soluble COD was present as VFA (acetate, propionate, butyrate and valerate) and the resulting PHA after batch accumulation consisted of 31-47 mol% hydroxybutyrate and 5369 mol% hydroxyvalerate. The maximum PHA content achieved was 48% of the sludge dry weight and the three stage process exhibited a potential to produce 0.11 kg of PHA per kg of influent COD treated. (c) 2007 Elsevier Ltd. All rights reserved.
|
|
| 14. |
- Bråred Christensson, Johanna, 1965, et al.
(author)
-
Air-oxidized linalool: a frequent cause of fragrance contact allergy.
- 2012
-
In: Contact Dermatitis. - : Wiley. - 0105-1873 .- 1600-0536. ; 67:5, s. 247-259
-
Journal article (peer-reviewed)abstract
- Background. Linalool is a common fragrance terpene that, in pure form, is not allergenic or is a very weak allergen. However, linalool autoxidizes on air exposure, and the oxidation products can cause contact allergy. In a Swedish study, oxidized linalool 6.0% in petrolatum (pet.) gave 5% positive patch test reactions in 2500 dermatitis patients. Objectives. To investigate whether oxidized linalool 6%, with a stable concentration of the main haptens, the linalool hydroperoxides (Lin-OOHs) in pet., could be a useful tool for the detection of contact allergy in an international setting. Methods. Oxidized linalool 6.0% (Lin-OOHs 1%) pet. was tested in 2900 consecutive dermatitis patients in Denmark, the United Kingdom, Singapore, Spain, Sweden, and Australia. Results. Overall, 6.9% (range 3–13%) of the patients showed positive patch test reactions to oxidized linalool. Doubtful reactions were found in 9.2% of the patients (range 0–36%). Few irritant reactions were seen. Conclusions. In an international setting, oxidized linalool has been shown to be a common allergen. Oxidized linalool 6.0% (Lin-OOHs 1%) pet. is a useful, standardized and stable tool for the detection of contact allergy in dermatitis patients. Many patients showing positive patch test reactions to oxidized linalool would not have been informed of their fragrance allergy if this specific test had not been performed
|
|
| 15. |
- Bråred Christensson, Johanna, 1965, et al.
(author)
-
An international multicentre study on the allergenic activity of air-oxidized R-limonene
- 2013
-
In: Contact Dermatitis. - : Wiley. - 0105-1873. ; 68:4, s. 214-223
-
Journal article (peer-reviewed)abstract
- Background. Limonene is a common fragrance terpene that, in its pure form, is not allergenic or is a very weak allergen. However, limonene autoxidizes on air exposure, and the oxidation products can cause contact allergy. Oxidized R-limonene has previously been patch tested in multicentre studies, giving 2–3% positive patch test reactions in consecutive patients. Objectives. To investigate whether oxidized R-limonene 3.0% in petrolatum, with a stable concentration of the main haptens, limonene hydroperoxides (Lim-OOHs), could be a useful tool for the detection of contact allergy in an international setting. Methods. Oxidized R-limonene 3.0% (Lim-OOHs 0.33%) pet. was tested in 2900 consecutive dermatitis patients in Denmark, the United Kingdom, Singapore, Spain, Sweden, and Australia. Results. Overall, 5.2% (range 2.3–12.1%) of the patients showed a positive patch test reaction to oxidized R-limonene. Doubtful reactions were found in 7.0% of the patients (range 0–24%). Few irritant reactions were seen. Conclusions. Oxidized R-limonene at 3.0% pet. with a specified content of Lim-OOHs 0.33% is a standardized and useful tool for the detection of contact allergy in dermatitis patients. Many patients showing positive patch test reactions to oxidized R-limonene would not be informed of their fragrance allergy if this specific test had not been performed.
|
|
| 16. |
- Bråred Christensson, Johanna, 1965, et al.
(author)
-
Linalool - a significant contact sensitizer after air exposure
- 2010
-
In: Contact Dermatitis. - : Wiley. - 0105-1873 .- 1600-0536. ; 62:1, s. 32-41
-
Journal article (peer-reviewed)abstract
- Background: Linalool is a widely used fragrance terpene. Pure linalool is not allergenic or a very weak allergen, but autoxidizes on air exposure and the oxidation products can cause contact allergy. Oxidized (ox.) linalool has previously been patch tested at a concentration of 2.0% in petrolatum (pet.) in 1511 patients, and 1.3% positive patch test reactions were observed. Objective: To investigate the optimal patch test concentration for detection of contact allergy to ox. linalool. Methods: Four concentrations of ox. linalool (2.0%, 4.0%, 6.0%, 11.0% pet.) were tested in 3418 consecutive dermatitis patients. Results: Ox. linalool 2.0%, 4.0%, 6.0%, and 11.0% pet. detected positive patch test reactions in 0.83%, 3.2%, 5.3%, and 7.2% of the tested patients, respectively. The doubtful reactions increased with rising concentrations but relatively less, giving 5.1%, 6.4%, and 7.3% doubtful reactions, respectively, for ox. linalool 4.0%, 6.0%, and 11.0% pet. Few irritative reactions were seen. Conclusions: Raising the patch test concentration for ox. linalool gave a better detection of contact allergy, as many as 5-7% positive patch test reactions were detected. We suggest a patch test concentration of ox. linalool 6.0% pet. for future patch testing, giving a dose per unit area of 2.4 mg/cm(2) when 20 mg test substance is tested in small Finn Chambers (R).
|
|
| 17. |
|
|
| 18. |
- Bråred Christensson, Johanna, 1965, et al.
(author)
-
Positive patch test reactions to oxidized limonene: exposure and relevance
- 2014
-
In: Contact Dermatitis. - : Wiley. - 0105-1873 .- 1600-0536. ; 71:5, s. 264-272
-
Journal article (peer-reviewed)abstract
- Background. R-Limonene is a common fragrance terpene found in domestic and industrial products. R-Limonene autoxidizes on air exposure, and the oxidation products can cause contact allergy. In a recent multicentre study, 5.2% (range 2.3-12.1%) of 2900 patients showed a positive patch test reaction to oxidized R-limonene. Objective. To study the exposure to limonene among consecutive dermatitis patients reacting to oxidized R-limonene in an international setting, and to assess the relevance of the exposure for the patients' dermatitis. Methods. Oxidized R-limonene 3.0% (containing limonene hydroperoxides at 0.33%) in petrolatum was tested in 2900 consecutive dermatitis patients in Australia, Denmark, the United Kingdom, Singapore, Spain, and Sweden. A questionnaire assessing exposure to limonene-containing products was completed. Results. Overall, exposure to products containing limonene was found and assessed as being probably relevant for the patients' dermatitis in 36% of the limonene-allergic patients. In Barcelona and Copenhagen, >70% of the patients were judged to have had an exposure to limonene assessed as relevant. Conclusions. Oxidized R-limonene is a common fragrance allergen, and limonene was frequently found in the labelling on the patients' products, and assessed as relevant for the patients' dermatitis. A large number of domestic and occupational sources for contact with R-limonene were identified.
|
|
| 19. |
- Christensson, Albin, et al.
(author)
-
Similar migration for medial congruent and cruciate-retaining tibial components in an anatomic TKA system : a randomized controlled trial of 60 patients followed with RSA for 2 years
- 2022
-
In: Acta Orthopaedica. - : Medical Journals Sweden AB. - 1745-3674 .- 1745-3682. ; 93, s. 68-74
-
Journal article (peer-reviewed)abstract
- Background and purpose — There is an ongoing debate regarding the appropriate level of constraint in primary TKA. To provide increased stability and better kinematics, more resembling a natural knee, a medial congruent (MC) tibial insert has been introduced. To investigate potential impact on implant migration, we evaluated the cemented Persona TKA, randomizing between MC and cruciate-retaining (CR) tibial designs. Patients and methods — 60 patients with primary osteoarthritis were randomized to either the CR or MC tibial component. Radiostereometric analysis (RSA) examinations, evaluating translational and rotational migration as well as maximal total point motion (MTPM), were performed on the first postoperative day, at 3 months, and 1 and 2 years after surgery. Preoperative, and 1- and 2-year patient-reported outcome measures (PROMs) data (KOOS and FJS) were collected. Results — The mean tibial MTPM at 3 months were 0.48 mm (95% CI 0.37–0.58) and 0.56 mm (0.45–0.67) for the CR and MC respectively. 2 years postoperatively the respective values were 0.62 mm (0.50–0.73) and 0.73 mm (0.49–0.96). There was no statistically significant difference in migration between groups, for either the femoral or the tibial component, regarding x-, y-, and z-translations or rotations. Both CR and MC groups improved as expected in PROM scores pre- to postoperatively, but without a statistically significant difference between groups. There were no revisions or other serious adverse events related to surgery. Interpretation — The results are promising, indicating good fixation for both designs, and this is in line with other well-performing TKAs on the market. The increased medial congruity of the MC inlay does not seem to affect the migration or the PROMs up to 2 years.
|
|
| 20. |
- Christensson, Magnus
(author)
-
Enhanced Biological Phosphorus Removal - Carbon Sources, Nitrate as Electron Acceptor, and Characterisation of the Sludge Community
- 1997
-
Doctoral thesis (other academic/artistic)abstract
- Enhanced biological phosphorus removal (EBPR) was studied in laboratory scale experiments as well as in a full scale EBPR process. The studies were focused on carbon source transformations, the use of nitrate as an electron acceptor and characterisation of the microflora. A continuous anaerobic/aerobic laboratory system was operated on synthetic wastewater with acetate as sole carbon source. An efficient EBPR was obtained and mass balances over the anaerobic reactor showed a production of 1.45 g poly-b-hydroxyalcanoic acids (PHA), measured as chemical oxygen demand (COD), per g of acetic acid (as COD) taken up. Furthermore, phosphate was released in the anaerobic reactor in a ratio of 0.33 g phosphorus (P) per g PHA (COD) formed and 0.64 g of glycogen (COD) was consumed per g of acetic acid (COD) taken up. Microscopic investigations revealed a high amount of polyphosphate accumulating organisms (PAO) in the sludge. Isolation and characterisation of bacteria indicated Acinetobacter spp. to be abundant in the sludge, while sequencing of clones obtained in a 16S rDNA clone library showed a large part of the bacteria to be related to the high mole % G+C Gram-positive bacteria and only a minor fraction to be related to the gamma-subclass of proteobacteria to which Acinetobacter belongs. Operation of a similar anaerobic/aerobic laboratory system with ethanol as sole carbon source showed that a high EBPR can be achieved with this compound as carbon source. However, a prolonged detention time in the anaerobic reactor was required. PHA were produced in the anaerobic reactor in an amount of 1.24 g COD per g of soluble COD taken up, phosphate was released in an amount of 0.4-0.6 g P per g PHA (COD) produced and 0.46 g glycogen (COD) was consumed per g of soluble COD taken up. Studies of the EBPR in the UCT process at the sewage treatment plant in Helsingborg, Sweden, showed the amount of volatile fatty acids (VFA) available to the PAO in the anaerobic stage to be limiting phosphorous removal. Operating the primary clarifier to obtain an enhanced hydrolysis and fermentation of primary sludge was shown to generate extra VFA and improve EBPR. VFA were shown to be transformed to PHA in the anaerobic stage of the plant, giving a PHA production of 1.5 g COD per g VFA (COD). Phosphate-P was released in an amount of 0.31 g per g PHA (COD) produced. Nitrate was used as an electron acceptor for oxidation of stored PHA in the anoxic stage of the plant during simultaneous P-uptake. Approximately 30% of the P-uptake could be accounted for by this reaction.
|
|
