Ash transformation during single-pellet gasification of sewage sludge and mixtures with agricultural residues with a focus on phosphorus

Hannl, Thomas Karl; Häggström, Gustav; Hedayati, Ali; Skoglund, Nils; Kuba, Matthias; Öhman, Marcus

doi:10.1016/j.fuproc.2021.107102

Cited by 19 publications

(28 citation statements)

References 67 publications

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“…The P phase formation depends on the chemical elements present in the biomass before thermal processing as previously reported by Hannl et al. (2022) in sewage sludge-based ashes.…”

Section: Resultssupporting

confidence: 57%

“…TABLE 2 Pearson's correlation between sequentially extracted P with distilled deionized water (P H2O ), 1 M NH 4 Cl at pH 7 (P NH4Cl ), 0.1 M NaOH (P NaOH ), and 0.5 M HCl (P HCl ) from gB, gBM, cBM and cBS ashes with total mass fractions of potassium (K), sodium (Na), calcium (Ca), magnesium (Mg), iron (Fe) and aluminum (Al) in the ashes (A), and with phosphorus (P) uptake from the ashes (B). The P phase formation depends on the chemical elements present in the biomass before thermal processing as previously reported by Hannl et al (2022) in sewage sludge-based ashes. In the cBS ash, high mass fractions of Fe and Al from sewage sludge (Supplementary Material S1) facilitated the formation of AlPO 4 , which was soluble in 0.1 M NaOH and 0.5 M HCl.…”

Section: Crystalline P Phases In Bagasse-based Ashessupporting

confidence: 57%

“…All bagasse-based ashes from small-scale processing contained CaK 2 P 2 O 7 and whitlockite (Ca 9 M(PO4) 7 ), which most commonly contain Ca, K, Fe, and/or Mg at the placeholder "M"; (Herzel et al, 2020). In an earlier study, Hannl et al (2022) detected K-whitlockite in alkali-rich ash and (Mg, Fe)-whitlockite and AlPO 4 in Fe-and Al-rich ash. In cB ash, amorphous phases masked potential P phases (Supplementary Material S7).…”

Section: Crystalline P Phases In Bagasse-based Ashesmentioning

confidence: 96%

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Sugarcane bagasse ash as fertilizer for soybeans: Effects of added residues on ash composition, mineralogy, phosphorus extractability and plant availability

et al. 2022

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Sugarcane bagasse is commonly combusted to generate energy. Unfortunately, recycling strategies rarely consider the resulting ash as a potential fertilizer. To evaluate this recycling strategy for a sustainable circular economy, we characterized bagasse ash as a fertilizer and measured the effects of co-gasification and co-combustion of bagasse with either chicken manure or sewage sludge: on the phosphorus (P) mass fraction, P-extractability, and mineral P phases. Furthermore, we investigated the ashes as fertilizer for soybeans under greenhouse conditions. All methods in combination are reliable indicators helping to assess and predict P availability from ashes to soybeans. The fertilizer efficiency of pure bagasse ash increased with the ash amount supplied to the substrate. Nevertheless, it was not as effective as fertilization with triple-superphosphate and K2SO4, which we attributed to lower P availability. Co-gasification and co-combustion increased the P mass fraction in all bagasse-based ashes, but its extractability and availability to soybeans increased only when co-processed with chicken manure, because it enabled the formation of readily available Ca-alkali phosphates. Therefore, we recommend co-combusting biomass with alkali-rich residues to increase the availability of P from the ash to plants.

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“…The P phase formation depends on the chemical elements present in the biomass before thermal processing as previously reported by Hannl et al. (2022) in sewage sludge-based ashes.…”

Section: Resultssupporting

confidence: 57%

Section: Crystalline P Phases In Bagasse-based Ashessupporting

confidence: 57%

Section: Crystalline P Phases In Bagasse-based Ashesmentioning

confidence: 96%

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Sugarcane bagasse ash as fertilizer for soybeans: Effects of added residues on ash composition, mineralogy, phosphorus extractability and plant availability

et al. 2022

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“…However, the high concentrations of these ash-forming elements also present several opportunities since ashes obtained from these biomasses could be a great source of nutrients and valuable elements. The recovery of these elements has recently received more attention. − Therefore, detailed knowledge about ash transformation reactions during the combustion of agricultural biomasses plays an important role in mitigating ash-related problems as well as in recovering valuable nutrient elements such as K and P from ash.…”

Section: Introductionmentioning

confidence: 99%

Ash Transformation during Fixed-Bed Combustion of Agricultural Biomass with a Focus on Potassium and Phosphorus

et al. 2022

Self Cite

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In this study, ash transformation during fixed-bed combustion of different agricultural opportunity fuels was investigated with a special focus on potassium (K) and phosphorus (P). The fuel pellets were combusted in an underfed fixed-bed pellet burner. Residual ashes (bottom ash and slag) and particulate matter were collected and characterized by scanning electron microscopy–energy-dispersive X-ray spectroscopy, X-ray diffraction, inductively coupled plasma, and ion chromatography. The interpretation of the results was supported by thermodynamic equilibrium calculations. For all fuels, almost all P (>97%) was found in residual-/coarse ash fractions, while K showed different degrees of volatilization, depending on fuel composition. During combustion of poplar, which represents Ca–K-rich fuels, a carbonate melt rich in K and Ca decomposed into CaO, CO2, and gaseous K species at sufficiently high temperatures. Ca5(PO4)3OH was the main P-containing crystalline phase in the bottom ash. For wheat straw and grass, representing Si–K-rich fuels, a lower degree of K volatilization was observed than for poplar. P was found here in amorphous phosphosilicates and CaKPO4. For wheat grain residues, representing P–K-rich fuels, a high degree of both K and P retention was observed due to the interaction of K and P with the fuel-bed constituents, i.e., char, ash, and slag. The residual ash was almost completely melted and rich in P, K, and Mg. P was found in amorphous phosphates and different crystalline phases such as KMgPO4, K2CaP2O7, K2MgP2O7, and K4Mg4(P2O7)3. In general, the results therefore imply that an interaction between ash-forming elements in a single burning fuel particle and the surrounding bed ash or slag is important for the overall retention of P and K during fuel conversion in fixed-bed combustion of agricultural biomass fuels.

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“…However, since not all phosphates are more stable than silicates, phosphates compete with silicates for alkali and alkaline metals. Generally, instead of being released to the atmosphere, most of P is likely to be retained in the ash with K. 138 Hedayati et al 139 found that for the single-pellet combustion of several agricultural residues, low fractions of P (≤20%) can be released at temperatures of 600, 800, and 950 °C mainly during the devolatilization stage. The formed K phosphates tend to incorporate Ca or Mg. 140 The distribution of alkali metals also differs significantly for the combustion of P-rich and P-lean biomass.…”

Section: Effect Of P On Agglomerationmentioning

confidence: 99%

Review of Biomass Agglomeration for Fluidized-Bed Gasification or Combustion Processes with a Focus on the Effect of Alkali Salts

Cao

Zhao

2022

Energy Fuels

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Agglomeration inhibits the smooth operation of fluidized-bed reactors by forming relatively large agglomerates to interrupt fluidization during gasification or combustion processes. Generally, biomass tends to induce agglomeration because inorganic elements from biomass together with or without inorganic elements from bed materials can generate molten compounds to adhere bed materials together to form agglomerates. Alkali metals, which mainly are present in biomass as different types of alkali salts (carbonates, sulfates, phosphates, or chlorides), are generally responsible for biomass agglomeration. Although there are several reviews about biomass agglomeration for fluidized-bed reactors, how different types of alkali salts influence biomass agglomeration has seldom been summarized. In addition, the interaction between alkali salts with organic compounds in biomass can influence biomass agglomeration by altering the occurrence mode of alkali salts. Therefore, this review highlights the interaction between different types of alkali salts in biomass with either the bed material or the organic compound in biomass, the contribution of gas−solid interactions between alkali salts with bed materials to bed agglomeration, and how reaction atmosphere affects the behavior of alkali salts for bed agglomeration. In addition, the role of calcium (Ca) and phosphorus (P) and their interactions play in biomass agglomeration, which is seldom overviewed in other reviews, are also explored. The investigation of these aspects can provide a deep and systematic understanding of biomass agglomeration. To give a background knowledge of biomass agglomeration, several well-established agglomeration mechanisms, including the "coating-induced" and "melting-induced" mechanisms, the "burning char" mechanism, and other mechanisms are presented. The process of the time-dependent coating layer formation for silica sand is provided and compared with other bed materials. This review contributes to the utilization of different types of biomass species in fluidized-bed gasification or combustion processes.

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Ash transformation during single-pellet gasification of sewage sludge and mixtures with agricultural residues with a focus on phosphorus

Cited by 19 publications

References 67 publications

Sugarcane bagasse ash as fertilizer for soybeans: Effects of added residues on ash composition, mineralogy, phosphorus extractability and plant availability

Sugarcane bagasse ash as fertilizer for soybeans: Effects of added residues on ash composition, mineralogy, phosphorus extractability and plant availability

Ash Transformation during Fixed-Bed Combustion of Agricultural Biomass with a Focus on Potassium and Phosphorus

Review of Biomass Agglomeration for Fluidized-Bed Gasification or Combustion Processes with a Focus on the Effect of Alkali Salts

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