| 1. |
- Bauer, Torben, et al.
(författare)
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Co-digestion of sewage sludge and wood fly ash
- 2022
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Ingår i: Environmental technology. - : Taylor & Francis. - 0959-3330 .- 1479-487X. ; 43:12, s. 1853-1859
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Tidskriftsartikel (refereegranskat)abstract
- This study uses a new approach for the recycling of plant nutrients by co-digesting sewage sludgewith fly ash from a wood combustion. Sewage sludge and fly ash both are enriched with nutrientsof the wastewater resp. wood, which makes these products an enhanced source for recycledfertilizers. The effects of the ash addition to the anaerobic digestion are studied in several labscale experiments including effects on the gas production and microbial activity. Following that,the fertilizing qualities of the digestate are evaluated by plant growth experiments. The resultsshow that the fertilizing qualities of the digested sludge were improved by the ash addition.Next to this, gas production results show that the methane production was not affected by theash addition, while the total gas release was reduced. The sulphur addition by the ashstimulated sulphate reducing bacteria. The sulphate reducing bacteria did not markedly inhibitthe methanogens.
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| 2. |
- Chernyaeva, Larisa, et al.
(författare)
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Reduced binding of apoE4 to complement factor H promotes amyloid-β oligomerization and neuroinflammation
- 2023
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Ingår i: EMBO Reports. - 1469-221X. ; 24:7
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Tidskriftsartikel (refereegranskat)abstract
- The APOE4 variant of apolipoprotein E (apoE) is the most prevalent genetic risk allele associated with late-onset Alzheimer's disease (AD). ApoE interacts with complement regulator factor H (FH), but the role of this interaction in AD pathogenesis is unknown. Here we elucidate the mechanism by which isoform-specific binding of apoE to FH alters Aβ1-42-mediated neurotoxicity and clearance. Flow cytometry and transcriptomic analysis reveal that apoE and FH reduce binding of Aβ1-42 to complement receptor 3 (CR3) and subsequent phagocytosis by microglia which alters expression of genes involved in AD. Moreover, FH forms complement-resistant oligomers with apoE/Aβ1-42 complexes and the formation of these complexes is isoform specific with apoE2 and apoE3 showing higher affinity to FH than apoE4. These FH/apoE complexes reduce Aβ1-42 oligomerization and toxicity, and colocalize with complement activator C1q deposited on Aβ plaques in the brain. These findings provide an important mechanistic insight into AD pathogenesis and explain how the strongest genetic risk factor for AD predisposes for neuroinflammation in the early stages of the disease pathology.
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| 3. |
- Hakkola, Jukka, et al.
(författare)
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Expression of CYP1B1 in human adult and fetal tissues and differential inducibility of CYP1B1 and CYP1A1 by Ah-receptor ligands in human placenta and cultured cells
- 1997
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Ingår i: Carcinogenesis. - 0143-3334 .- 1460-2180. ; 18:2, s. 391-7
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Tidskriftsartikel (refereegranskat)abstract
- Expression of the Ah receptor-regulated cytochrome P4501B1 (CYP1B1) gene was studied in human adult and fetal tissues and cells in culture by reverse transcriptase-coupled polymerase chain reaction (RT-PCR). In adults, CYP1B1 mRNA was detected in liver, lymphocytes, cells of bronchoalveolar lavage samples and uterine endometrium, but not in lung. The level of expression was very low in adult liver and only three out of six fetal livers expressed CYP1B1. Extrahepatic fetal tissues, especially brains and kidneys, expressed high levels of CYP1B1. CYP1B1 mRNA was constitutively detected at a low level in first trimester and full-term placental samples. A competitive RT-PCR assay was developed to assess the regulation of CYP1B1. CYP1B1 mRNA was not induced in placenta by maternal cigarette smoking. Inducibility of CYP1B1 in cells in culture by the Ah receptor ligand 2,3,7,8-tetrachlorodibenzo-p-dioxin was studied in primary fibroblasts and chorion carcinoma cell line JEG-3 having different CYP1A1 induction properties. Inducibility of CYP1B1 was found to be regulated independently from CYP1A1. In JEG-3 cells CYP1A1 mRNA was induced up to 9000-fold, while the expression of CYP1B1 was not affected. Expression of Ah receptor and Ah receptor nuclear translocator (regulators of the CYP1 family) was determined in human placenta and in the JEG-3 cell line. Expression of these transcription factors was found neither to be co-regulated nor affected by Ah receptor ligands. This study provides evidence that in addition to the Ah receptor complex, other cell-specific factors modulate the response of CYP1B1 and CYP1A1 to Ah receptor ligands.
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| 4. |
- Lagerkvist, Anders, et al.
(författare)
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Quick-start of full-scale anaerobic digestion (AD) using aeration
- 2015
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Ingår i: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 38, s. 102-104
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Tidskriftsartikel (refereegranskat)abstract
- A conventional 1300 m3 continuously stirred anaerobic tank reactor at the city of Boden, north Sweden, which was receiving a feed of both sewage sludge and food waste, was put out of operation due to the build-up of a float phase. The reactor was emptied and cleaned. At start-up there was no methanogenic sludge available, so an unconventional start-up procedure was applied: The reactor was rapidly (8 days with 1200 kg of total solids (TS) added daily) filled with thickened, and slightly acidic sewage sludge, showing only slight methane generation, which was subsequently heated to 55 °C. Then compressed air was blown into the digester and within a month a fully functional methanogenic culture was established. The transfer from acidogenic to methanogenic conditions happened in about one week. As a start-up technique this is fast and cost efficient, it only requires the access of a compressor, electricity and a source of air. In total, about 16 tonnes of oxygen were used. It is proposed that this method may also be used as an operational amendment technique, should a reactor tend to acidify.
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| 5. |
- Pelkonen, Markku, et al.
(författare)
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Biological nitrogen removal from landfill leachate : A pilot-scale study
- 1999
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Ingår i: Waste Management & Research. - : Wiley. - 0734-242X .- 1096-3669 .- 1399-3070. ; 17:6, s. 493-497
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Tidskriftsartikel (refereegranskat)abstract
- A pilot-scale two-stage process including an anaerobic pretreatment (up-flow anaerobic sludge blanket, UASB) unit and a pre-denitrification activated sludge process was studied for treating leachates from a municipal landfill (waste aged 4 to 5 years, area 2.5 ha) and from a windrow composting area (1 ha). A single-stage pilot process was used for nitrification studies. The leachate characteristics were as follows: COD 740 to 2400 mg l-1 (chemical oxygen demand), BOD7 (biochemical oxygen demand) approximately 1000 mg l-1, N(tot) 40 to 120 mg l-1 and the temperature was between 2 and 21°C. The results show that 45 to 50 COD removal could be achieved in the UASB reactor even at temperatures below 10°C. The activated sludge process was operated with a 1.1 to 2.2 d hydraulic retention time and at between 8 and 21°C. The removal efficiencies were 80 to 90 for COD, over 98 for BOD7, over 90 for NH4-N and over 70 for N(tot). The dependence of denitrification efficiency on leachate biodegradable COD fraction and COD to N ratio was evaluated. Overall treatment efficiencies were good and applicable for design purposes. The total costs were estimated for a full scale pre-denitrification process at FIM 10 to 20 m-3 and FIM 50 to 90 (kg N removed)-1 (3.5 to 7 DM m-3 and 17 to 30 DM [kg N removed]-1) for a landfill representing circumstances in Southern Finland with an annual average flow of 50 m3 d-1.
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| 6. |
- Pelkonen, Markku, et al.
(författare)
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Leachate direct-discharge limits and incentives related to landfill aftercare costs
- 2017
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Ingår i: Journal of Material Cycles and Waste Management. - : Springer. - 1438-4957 .- 1611-8227. ; 19:1, s. 413-422
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Tidskriftsartikel (refereegranskat)abstract
- Society needs sustainable methods for landfilling from an environmental perspective, but they have to be cost effective and affordable. Aftercare represents considerable costs within waste management system and costs can be expected to accrue over a long period of time showing the need to compare different management options. Direct-discharge limits for leachate COD and nitrogen are different in various (European) countries. When leachate COD or nitrogen has decreased at the latter part of the aftercare period, effluent limits 50 or 200 mg/l for COD and 10 or 70 mg/l for nitrogen have a considerable impact on period length. The objective of this paper is to discuss the effects of leachate discharge limits on landfill aftercare and leachate management costs in various conditions. Landfill simulator results and modelling are used to estimate leachate concentrations in three different scenarios. It is suggested that stricter discharge limits (shown before) impact on the costs of activated carbon filtration (1.4-fold) and biological treatment (1.1–1.24-fold). Stricter limits also extend the aftercare period length considerably, but with substantial water circulation the differences are clearly smaller. These results support the recent suggestion of aftercare incentives, and some details of applying these incentives in different conditions are discussed.
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| 7. |
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| 8. |
- Pelkonen, Markku, et al.
(författare)
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New control parameters and measurement techniques for the activated sludge process
- 1993
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Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 27:5-6, s. 287-295
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Tidskriftsartikel (refereegranskat)abstract
- An on-line oxygen uptake and CO2-production rate measurement system was used to analyse the biomass activity. CO2-production rate corresponded well with oxygen uptake rate in the carbon oxidation process. In the nitrification process the ratio CO2-prod./O2-consumed (r(q)) had a larger variation, but CO2-production had a good correlation with utilized COD; variation of the r(q)-value indicate differences in the auto-/heterotrophic oxidation balance. From this basis the oxygen uptake rate for carbon oxidation and nitrification can be separated. The comparison with two biomass determination methods based on ATP-analysis shows that for heterotrophic biomass the methods indicate clearly different changes of ATP, for nitrification process the results were more compatible. By combining the biomass and on-line measurements with biomass growth model based on IAWPRC-model equations reasonably good estimates were obtained. Best fit of model was in the nitrification process; by using VSS as the measure of biomass the fit was poor. The differences in the ATP-measurement results affect also the model coefficients.An on-line oxygen uptake and CO2-production rate measurement system was used to analyze the biomass activity. CO2-production rate corresponded well with oxygen uptake rate in the carbon oxidation process. In the nitrification process the ratio CO2-prod./O2-consumed (rg) had a larger variation, but CO2-production had a good correlation with utilized COD; variation of rg-value indicate differences in auto-heterotrophic oxidation and nitrification can be separated. The comparison with two biomass determination methods based on ATP-analysis shows that for heterophil biomass the methods indicate clearly different changes of ATP, for nitrification process the results were more compatible. By combining the biomass and on-line measurements with biomass growth model based on IAWPRC-model equations reasonably good estimated were obtained. Best fit of model was in the nitrification process; by using VSS as the measure of biomass the fit was poor. The differences in the ATP-measurement results affect also the model coefficients
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| 9. |
- Pelkonen, Markku
(författare)
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Upgrading oxygen transfer in the activated sludge process
- 1990
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Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 22:7-8, s. 253-260
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Tidskriftsartikel (refereegranskat)abstract
- The objectives were to get some information on the variation of the alpha factor and to study factors affecting oxygen transfer efficiency in fine-bubble aeration. Results from a 5 week continuous operation of a batch aeration column process show that the variation of the alpha factor was considerable in the aeration basin, especially at the inlet end. The variation follows a diurnal rhythm and the weekly variation is much smaller. The off-gas method was used to examine factors affecting oxygen transfer in process conditions. Regression models were constructed to describe the transfer process both on a semitechnical scale and on a full scale. The most important factors are the specific air flow rate, the respiration rate and the DO concentration. The enhancement in OTE through the respiration rate and the DO concentration is due to a biological mechanism. To optimize the transfer process it is necessary to maintain a high respiration rate and a sufficiently high DO concentration.The objectives were to get some information on the variation of the alpha factor and to study factors affecting oxygen transfer efficiency in finebubble aeration. Results from a 5 week continuous operation of a batch aeration column process show that the variation of the alpha factor was considerable in the aeration basin, especially at the inlet end. The variation follows a diurnal rhythm and the weekly variation is much smaller. The off-gas method was used to examine factors affecting oxygen transfer in process conditions. Regression models were constructed to describe the transfer process both on a semitechnical scale and on a full scale. The most important factors are the specific air flow rate, the respiration rate and the DO concentration. The enhancement in OTE through the respiration rate and the DO concentration is due to a biological mechanism. To optimize the transfer process it is necessary to maintain a high respiration rate and a sufficiently high DO concentration.--------------------------------------------------------------------------------
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| 10. |
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