| 1. |
- Davidsson, Åsa, et al.
(författare)
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Effect of anaerobic digestion at 35, 55 and 60 °C on pharmaceuticals and organic contaminants
- 2014
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Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 69:6, s. 1282-1288
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Tidskriftsartikel (refereegranskat)abstract
- The application of treated sewage sludge on farmland is a suggested method for recycling nutrients and reducing demand for commercial fertilizer. However, sludge needs to be safe from possible contaminants which can cause acute and long-term health and environmental problems. Residual pharmaceuticals and organic contaminants are mentioned as emerging threats since wastewater treatment plants are not designed to degrade these substances. The aim of this study was to screen and evaluate the presence, and reduction, of pharmaceuticals and polycyclic aromatic hydrocarbons (PAHs) during anaerobic digestion of mixed primary and waste-activated sludge at 35, 55 and 60°C and during pasteurization at 70°C. The study showed the difficulty of analysing pharmaceutical compounds in low concentrations in the sludge matrix. No general reduction of these compounds was seen during treatment, but for individual substances some reduction occured. The PAHs were generally not reduced during digestion or pasteurization, but for three substances (indeno[1,2,3-cd]pyrene and dibenzo[a,h]anthracene (analysed together) and benzo[g,h,i]perylene) reduction (up to 60%) during digestion was seen. Digestion at 35 and 55°C resulted in about the same order of reduction of the three individual PAHs, which was higher than for digestion at 60°C.
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| 2. |
- Davidsson, Åsa, et al.
(författare)
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Effect of anaerobic digestion at 35, 55 and 60 °C ON pharmaceuticals and organic pollutants
- 2013
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Ingår i: Presented at the 1st International IWA Conference on Holistic Sludge Management, Västerås, Sweden, May 6-8, 2013. ; , s. 1-8
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Konferensbidrag (refereegranskat)abstract
- The application of treated sewage sludge on farmland is a suggested method for recycling nutrients and reducing demand for commercial fertilizer. However sludge needs to be rendered safe from possible contaminants which can cause acute and long-term health and environmental problems. Residual pharmaceuticals and organic contaminants in sludge are mentioned as emerging threats since wastewater treatment plants are not designed to degrade these substances thus yielding an accumulation in sludge. The aim of this study was to evaluate the presence, and reduction, of pharmaceuticals and polycyclic aromatic hydrocarbons (PAHs) during anaerobic digestion at 35, 55 and 60ºC and during pasteurization at 70°C. The substrate used was mixed primary and secondary sludge from a 300 000 person-equivalents municipal wastewater treatment plant in southern Sweden. In general no reduction of pharmaceuticals could be observed at any temperature or minimum exposure time, except for the beta-blocker Irbesartan and the antibiotic Trimethoprim. The results from pharmaceuticals in mesophilic sludge agreed with results in recent Swedish studies. Also, no reduction of PAHs during digestion or pasteurization (70°C – 1 hour) was seen, but for single PAHs digestion could lead to reduction.
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| 3. |
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| 4. |
- Haghighatafshar, Salar, et al.
(författare)
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Management of hydrogen sulfide in anaerobic digestion of enzyme pretreated marine macro-algae
- 2012
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Ingår i: Vatten: tidskrift för vattenvård /Journal of Water Management and research. - 0042-2886. ; 68:4, s. 265-273
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Tidskriftsartikel (refereegranskat)abstract
- Enzymatic pretreatment of algae by means of cellulose degrading enzyme was evaluated through lab-scale and pilot-scale experiments. The degradation efficiency of the enzyme depended on the initial physical quality of the algae. Lab-scale batch anaerobic digestion experiments showed comparatively low methane potential for the pretreated algae at both mesophilic and thermophilic temperatures. However, the raw algae (cut into small pieces) were found to be hardly hydrolysable. The methane potential of raw algae in thermophilic and mesophilic digestion was about 17 NmL/g VS and –36 NmL/g VS respectively. Presence of inhibitory agent(s) was obvious at both temperatures. Very fast growth of sulfate-reducing bacteria was noticed in the continuous digestion, so that in less than 20 days, hydrogen sulfide concentrations over 10000 ppm were observed in both meso- and thermophilic reactors. Inhibition of methanogenesis in the thermophilic reactor occurred at unionized dissolved sulfide concentration of about 22 mg/L (10000 ppm in the biogas) while it was mainly non-SRB acetogens that were inhibited in the mesophilic reactor at unionized sulfide concentrations as high as 50 mg/L (17000 ppm in the biogas). This shows that probably thermophilic digestion is more prone to be inhibited at high sulfide concentrations. Micro-aeration was found to be more efficient in the thermophilic reactor while its effect on the mesophilic process was negligible.
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| 5. |
- Haghighatafshar, Salar, et al.
(författare)
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Storm-water management in Malmö and Copenhagen with regard to climate change scenarios
- 2014
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Ingår i: Vatten: tidskrift för vattenvård /Journal of Water Management and research. - 0042-2886. ; 70:3, s. 159-168
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Tidskriftsartikel (refereegranskat)abstract
- The current status of storm-water management in the neighbor cities of Copenhagen and Malmö was studied with respect to present measures and the implemented systems in both cities. Application of blue-green solutions in the outer parts of Malmö started in the 1990s; hence collaboration between different departments in the municipality is more structured in the city of Malmö while in Copenhagen the process is still based on traditional pipe systems and CSO management with the exception of Ørestad. However, more blue-green solutions are to be applied in Copenhagen in the coming years. Concerning the climate adaptation plans in regard to the Three Points Approach (3PA), Copenhagen has determined the required framework for adaptation of the inner parts of the city with regard to extreme rainfalls (Cloudburst Management Plan in Copenhagen) while Malmö has focused on implementation of open systems in the suburbs taking design rain criteria into account.
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| 6. |
- Kjerstadius, Hamse, et al.
(författare)
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Hygienization of sludge through anaerobic digestion at 35, 55 and 60 ºC
- 2013
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Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 68:10, s. 2234-2239
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Tidskriftsartikel (refereegranskat)abstract
- Legislation in Sweden and the European Union concerning the use of sewage sludge in agriculture is under revision and future concentration limits for pathogens in treated sludge are likely to be expected. The aim of this study was to evaluate the hygienization of Salmonella, Escherichia coli, Enterococcus and Clostridium perfringens through continuous anaerobic digestion at 35, 55 or 60 ºC as well as to investigate process stability and methane production at 60 ºC. The results indicated that digestion at 55 or 60 ºC with a minimum exposure time of 2 h resulted in good reduction of Salmonella, E. coli and Enterococcus and that anaerobic digestion thus could be used to reach the concentration limits suggested for the EU, as well as in Sweden. Furthermore, stable continuous anaerobic digestion of sludge was achieved at 60 ºC, however with 10% less methane production compared to digestion at 35 and 55 ºC.
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