| 1. |
- Awasthi, S. K., et al.
(författare)
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Can biochar regulate the fate of heavy metals (Cu and Zn) resistant bacteria community during the poultry manure composting?
- 2021
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Ingår i: Journal of Hazardous Materials. - : Elsevier. - 0304-3894 .- 1873-3336. ; 406
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the influence of coconut shell biochar addition (CSB) on heavy metals (Cu and Zn) resistance bacterial fate and there correlation with physicochemical parameters were evaluated during poultry manure composting. High-throughput sequencing was carried out on five treatments, namely T1−T5, where T2 to T5 were supplemented with 2.5%, 5%, 7.5% and 10% CSB, while T1 was used as control for the comparison. The results of HMRB indicated that the relative abundance of major potential bacterial host altered were Firmicutes (52.88–14.32%), Actinobacteria (35.20–4.99%), Bacteroidetes (0.05–15.07%) and Proteobacteria (0.01–20.28%) with elevated biochar concentration (0%−10%). Beta and alpha diversity as well as network analysis illustrated composting micro-environmental ecology with exogenous additive biochar to remarkably affect the dominant resistant bacterial community distribution by adjusting the interacting between driving environmental parameters with potential host bacterial in composting. Ultimately, the amendment of 7.5% CSB into poultry manure composting was able to significantly reduce the HMRB abundance, improve the composting efficiency and end product quality.
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| 2. |
- Pettersson, Anita, 1965
(författare)
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Characterisation of Fuels and Fly Ashes from Co-Combustion of Biofuels and Waste Fuels in a Fluidised Bed Boiler. A Phosphorus and Alkali Perspective
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the efforts to create sustainable production of heat and power and to reduce the net CO2 emissions to the atmosphere, alternative fuels are today being utilised. These fuels are, for example, biofuels and waste derived fuels such as different residues from the agricultural sector and the pulp and paper industry, municipal sewage sludge and municipal sorted solid waste. These fuels put new demands on the combustion facilities due to their chemical composition and this in turn calls for methods of prediction for the evaluation of their combustion behaviour. Most significant for the majority of these fuels are the high alkali and chlorine concentrations which cause bed agglomeration, deposit formation and corrosion on heat transfer surfaces. These problems can be solved if sufficient knowledge is obtained of the specific fuel or fuel mix. In this work, chemical fractionation, a step by step leaching method, was used on fuels, fuel mixes and fly ashes from co-combustion in a fluidised bed combustor. In addition, XRD and SEM-EDX were used for the fuel and fly ash characterisation. Different alkali chloride reducing additives i.e. kaolin, zeolites and sulphur were investigated as was the influence of various bed materials: silica sand, olivine sand and blast furnace slag (BFS).Some of the new, alternative fuels, such as municipal sewage sludge and meat and bone meal (MBM) contain high concentrations of phosphorus which is a very important nutrient essential in many biological processes. Phosphorus rock used as raw material in the phosphate industry is a depleting natural resource estimated to last for only 30-200 years according to different sources. The combustion of municipal sewage sludge enriches the phosphorus in the ashes while hazardous components such as pathogens and organic pollutants are rendered harmless after combustion. However, toxic heavy metals are also enriched in the ashes. One aim of the work was to find a sufficiently effective and low cost method for phosphorus extraction from fly ashes derived from municipal sewage sludge combustion. Two types of municipal sewage sludges were investigated using different chemicals for the phosphorus cleaning step in the waste water treatment plants. The first sewage sludge derived from a plant using iron sulphate as flocculant to precipitate phosphorus as iron phosphate. The second sludge meanwhile came from a plant using aluminium sulphate as flocculant to precipitate phosphorus as aluminium phosphate. Both sewage sludges were dewatered prior to combustion and co-combusted with wood pellets. At pH 1 nearly all the phosphorus was released from the fly ash derived from the sewage sludge where aluminium sulphate was used as a phosphorus precipitation agent. Iron sulphate as precipitant inhibited the phosphorus extraction from the ashes, resulting in only 50-80% of the phosphorus being released. Furthermore, the mobility of heavy metals to the leachates was investigated to establish whether the leachates were suitable as fertilisers. Only minor fractions of Pd, Hg, Cr, Cu, Mn, Co, Ni, As, Sb, V and Zn were found in the leachates, all well within the legislated limitations for fertilisers. However, one exception was Cd that was nearly totally dissolved in the leachate. Thus a decadmiation of the leachate is necessary prior to any utilisation of the ashes and reuse of phosphorus as fertiliser.
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| 3. |
- Li, W., et al.
(författare)
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Interrelationships between tetracyclines and nitrogen cycling processes mediated by microorganisms : A review
- 2021
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Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 319
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Forskningsöversikt (refereegranskat)abstract
- Due to their broad-spectrum antibacterial activity and low cost, tetracyclines (TCs) are a class of antibiotics widely used for human and veterinary medical purposes and as a growth-promoting agent for aquaculture. Interrelationships between TCs and nitrogen cycling have attracted scientific attention due to the complicated processes mediated by microorganisms. TCs negatively impact the nitrogen cycling; however, simultaneous degradation of TCs during nitrogen cycling mediated by microorganisms can be achieved. This review encapsulates the background and distribution of TCs in the environment. Additionally, the main nitrogen cycling process mediated by microorganisms were retrospectively examined. Furthermore, effects of TCs on the nitrogen cycling processes, namely nitrification, denitrification, and anammox, have been summarized. Finally, the pathway and microbial mechanism of degradation of TCs accompanied by nitrogen cycling processes were reviewed, along with the scope for prospective studies. © 2020
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| 4. |
- Pettersson, Anita, et al.
(författare)
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Application of chemical fractionation methods for characterisation of biofuels, waste derived fuels and CFB co-combustion fly ashes
- 2008
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Ingår i: Fuel. - : Elsevier Ltd. - 0016-2361 .- 1873-7153. ; 87:15-16, s. 3183-3193
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Tidskriftsartikel (refereegranskat)abstract
- In the important efforts to decrease the net CO2 emissions to the atmosphere, new, alternative fuels are being included in the fuel mixes used in utility boilers. However, these fuels have ash properties that are different from those of the traditionally used fuels and in some cases technical problems, such as ash fouling and corrosion occur due to this. Therefore, diagnostic and predictive methods are developed and used to avoid such problems. Determination of the chemical association forms of important elements, such as potassium and sodium, in the fuel by chemical fractionation is a method well defined for coal and biofuels, such as wood pellets, bark and forest residues. Chemical fractionation is a step by step leaching method extracting water soluble salts in the first step, ion exchangeable elements, such as organically associated sodium, calcium and magnesium in the second step and acid soluble compounds such as carbonates and sulfates in the third step. The solid residue fraction consists of silicates, oxides, sulfides and other minerals. The compound extracted in the two first steps is considered reactive in the combustion with a few exceptions. In this work, it has been applied to some waste fuels, i.e. sewage sludge, straw and refuse derived fuel (RDF), as well as to coal and wood. The present work also includes results from combustion tests in a fluidised bed boiler where three blends of the investigated fuels were used. The fractionation results for the fuel blends are weighted results of the fractionations of the pure fuels discussed above which are compared with fractionations of their corresponding fly ashes. The co-combustion strategy gave very good results in reducing ash problems. Possible chemical mechanisms involved are discussed in the article.
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| 5. |
- Ramamoorthy, Sunil Kumar, et al.
(författare)
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Reusing Textile Waste As Reinforcements In Composites
- 2014
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Ingår i: Journal of Applied Polymer Science. - : Wiley. - 0021-8995 .- 1097-4628. ; 131:17, s. 1-16
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Tidskriftsartikel (refereegranskat)abstract
- Polyester (PET) has wide applications in textile industries as textile fiber and its share continues to grow. Substantial quantities of cotton/polyester blend fabrics are disposed every year due to technical challenges, which pose a big environmental and waste-dumping problem. The aim of this study is to evaluate the potential of discarded cotton/PET fabrics as raw materials for composites. If their inherent reinforcement properties can be used in composites, an ecological footprint issue can be solved. In this study, we investigate three concepts for reuse of cotton/PET fabrics for composites: compression molding above the Tm of PETs, use of a matrix derived from renewable soybean oil, use of thermoplastic copolyester/polyester bi-component fibers as matrix. All three concepts have been explored to make them available for wider applications. The effects of processing parameters such as compression temperature, time and pressure are considered in all three cases. The third concept gives the most appealing properties, which combine good tensile properties with toughness; more than four times better tensile strength than the first concept; and 2.2 times better than the second concept.
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