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Evaluation of fly ash in terms of its suitability for fertilizer purposes by type of combustion and feedstock - literature review Cover

Evaluation of fly ash in terms of its suitability for fertilizer purposes by type of combustion and feedstock - literature review

Open Access
|Dec 2025

Figures & Tables

Leachability of selected compounds and elements from fly ash from co-firing and biomass combustion of different types of fluidized-bed boilers from aqueous solution, according to PN-G-11011 standard (mg/l)

Type of pollutantCo-firing of hard coal with biomass in a pulverized coal boilerBiomass combustion in a fluidized-bed boilerBiomass combustion in a fluidized-bed boiler with natural circulationBiomass combustion in a fluidized-bed boiler with a bubbling bed
Chlorides150.30445.601449.00658.30
Sulphates790.501436.905745.804779.70
K223.00604.009446.003161.00
Na26.0025.0083.0067.00
As0.01·< 0.01·
Cd< 0.01< 0.01< 0.01< 0.01
Cu0.040.450.160.20
Cr< 0.01< 0.01< 0.01< 0.01
Hg< 0.01< 0.01< 0.01< 0.01
Pb< 0.01< 0.01< 0.010.34
pH11.9612.2512.7912.46

Elemental composition of ashes from coal and lignite combustion (% by weight)

Elemental compositionSilica ash: Power plants in Kozienice and Dolna OdraLime ash: Power plant in BelchatowLimestone ash: Power Plant in Pątnów
Na0.590.29–0.310.51
Mg0.941.11–1.131.95
Al15.5211.30–12.808.72
Si25.6821.10–22.7024.73
P0.26<0.010.03
S0.100.42–0.460.56
K3.290.21–0.241.65
Ca0.1818.70–23.8020.16
Ti1.211.00–1.100.80
Fe3.593.56–3.592.13

Concentration of microelements (including heavy metals) in ashes after coal and lignite combustion (mg/kg)

ElementsSilica ash from hard coal – conventional boilerFluidized bed coal ash – fluidized bed boilerBelchatow Power plant – lime ashAshes –biomass 100 % fluidized bed boilersAshes – co-firing 70% biomass + 30% hard coalAshes – co-firing 10% biomass + 90% hard coal
Cd2.20< 0.503.80–4.6010.70–19.104.91.30
Cr42< 2130–15744.30–88.3031.9083.60
Pb762024–32262.2–23435.10156
Zn2653211–105470–868418249
Hg···0.10–2.040.100.60
Co41< 0.5011–12···
Ni56136–4632.70–60.8018.40117
Cu86534–5589.50–34265.2083.80
As···7.2–16.202.7031.50
Mn74542····
V2402····
Sr11040····
Ba41036349–754···
Na84115–87···
Be20< 2····
B9601····

Content of selected elements in fly ash from combustion of municipal waste in fluidized-bed boilers

ParameterContent (mg/kg)
Ca8.60–170
K0.66–16
Mg0.24–26
Mn> 3.20
Na2.2–42
P0.44–10.50
As0.12–19.00
Ba69–57.00
Cd3–70
Cu232–250.00
Cr20–34000
Mo2.50–28.00
Ni7–43.00
Pb74–1.56
Se0.05–10
Sn2–47.00
Ti< 0.01–0.23
V16–12.00
Zn10–20.00
Hg< 0.01–0.12

Natural radioactivity coefficients for coal-combustion fly ash

ElementBelchatow power plant – lignite coalŻerań power plant – hard coalSiekierki CHP plant – hard coalDolna Odra power plant – hard coal
(Bq/kg)
40K···787–1045
226Ra···102–149
228Ra···104
224Ra···104
228Th···60–112
F2**69.60–136101.03162.35102–149
(-)
F1**0.43–0.850.891.090.82–1.11

Contents of selected compounds and elements in waste from waste gas treatment, fly ash and boiler dust removal ash from municipal waste incineration process

ParameterWaste from waste gas cleaning 19 01 07*Fly ash 19 01 13*Dust from boiler dust removal 19 01 15*
CaSO4 [% d.m.]6.16–14.139.82–23.8210.11–28.54
CaCO3 [% d.m.]3.89–10.964.07–8.772.05–5.10
CaCl2 [% d.m.]11.31–14.87··
CaO [% d.m.]16.70–36.7013.80–20.8011.90–16.10
NaCl [% d.m.]4.73–12.150.74–4.581.99–3.51
KCl [% d.m.]4.46–6.521.60–4.862.52–3.95
SiO2 [% d.m.]2.97–9.2520.60–49.3028.20–44.90
HCl (undissolved) [% d.m.]0.63–3.475.34–10.574.41–5.98
Sb [mg/kg d.m.]226–386125–294250–279
As [mg/kg d.m.]6.80–16.405.74–8.718.57–11.80
Pb [mg/kg d.m.]993–2250121–571408–637
Cd [mg/kg, d.m.]85–22313.00–34.6035.30–48.50
Co [mg/kg d.m.]4.27–9.6625.80–49.7022.50–29.70
Cu [mg/kg d.m.]293–523301–425271–533
Ni [mg/kg d.m.]12.80–28.6053–24445.40–67.50
Hg [mg/kg d.m.]6–24··
Zn [mg/kg d.m.]4.60–11.603.58–6.364.58–7.72
pH (eluate)12.20–12.3012.30–12.5012.00–12.60

Contents of natural radioactive isotopes in ashes from municipal sewage sludge incineration

Type of ashIsotopes40K226Ra228Th (228Ra)F1F2Specific activity 226Ra + 228Ra
Sample No.[Bq/kg][Bq/kg][Bq/kg][-][Bq/kg][Bq/kg]
Fly ash1388 ± 2052 ± 326 ± 20.43 ± 0.0252 ± 378 ± 4
2512 ± 2776 ± 432 ± 30.58 ± 0.0276 ± 4108 ± 5
3410 ± 2594 ± 634 ± 20.62 ± 0.0294 ± 6190 ± 8
Waste from flue gas cleaning4175 ± 1126 ± 212 ± 20.21 ± 0.0126 ± 238 ± 3
5152 ± 1142 ± 313 ± 20.26 ± 0.0142 ± 383 ± 4

Content of selected components of fly ash by type of fuel used and type of combustion

Fly ashBottom ash
Fuel and type of combustionHard coalLigniteCo-firing of hard coal with biomass (10%–40%)100% biomass (Wood and forest biomass)100% biomass (80% forest biomass + 20% agricultural biomass)Ash after flue gas desulphurization – Rybnik Power Plant and Ciech Thermal Power PlantCombustion of municipal wasteCo-firing of coal and biomassCombustion of municipal waste
ElementSourceBoilerFluidized bed boilerDust boilerConventional boilerFluidized bed boilerDust boilerDust boilerFluidized bed boilerFluidized bed boiler·Fluidized bed boilerFluidized bed boilerFluidized bed boiler
S0.14–0.310.30–3.340.250.36–1.761.52–0.320.15–3.300.16–0.871.08–2.332.84–4.001.67–8.641.12–5.560.12–4.500.04–1.96
P0.12–0.23·0.13–0.180.000.030.010–0.013≥ 0.0130.00–0.430.140.22–0.460.24–0.96
K0.49–1.800.66–0.860.26–2.350.4–1.180.26–0.580.05–0.290.7–1.871.54–10.15.69–7.511.070.81–1.600.52–0.640.42–1.25
Ca1.44–3.793.03–14.100.46–5.151.98–21.7811.39–14.280.22–22.261.56–5.241.5–22.6315.09–16.4610.25–26.1810.14–25.280.72–13.148.57–16.50
Mg0.43–1.201.19–1.890.86–1.010.44–1.450.94–1.080.12–1.220.81–1.721.08–3.353.40–4.111.180.98–1.870.66–1.401.21–2.59
Na0.19–0.470.27–0.590.13–0.520.07–0.860.39–0.610.06–0.940.38–0.470.14–0.360.12–0.220.22·0.18–0.29·
Cl0.0020.120.160.008–0.010.025–0.03> 0.010.0031.06–1.19··0.93–8.1·0.1–5.9
Ti0.68–0.880.45–0.550.47–2.050.981.02–2.300.12–0.480.750.18·0.490.65–1.34·0.54–1.4
Ba0.05–0.12··0.03·····0.130.09–0.20··
Sr0.08–0.12··0.07···0.03·0.050.04–0.06··
Cr0.01–0.013············
Source[Różycka et al. 2008], [Borowski 2010], [Ostrowski 2011], [Kosiar-Kazberuk et al. 2011], [Jóźwiak-Niedźwiecka et al. 2012], [Uliasz-Bocheńczyk et al. 2015], [Czarna-Juszkiewicz et al. 2018], [Cader et al. 2018][Różycka et al. 2008], [Łaskawiec et al. 2010], [Borowski et al. 2010], [Gawlicki 2014], [Uliasz-Bocheńczyk et al. 2015]Haustein et al. 2012], [Kasprzyk et al. 2017], [Tkaczewska et al. 2019][Dąbrowska et al. 2014], [Cader et al. 2018][Sybilski et al. 2004], [Ostrowski 2011], [Jóźwiak-Niedźwiecka 2012], [Kledyński et al. 2016][Ostrowski 2011], [Garbacik et al. 2013], [Kasprzyk et al. 2017], [Hycnar et al. 2017][Kosior-Kazberuk 2011], [Giergiczny et al. 2012], [Haustein et al. 2012], [Poluszyńska et al. 2015], [Uliasz-Bocheńczyk et al. 2016][Rajczyk et al. 2013], [Poluszyńska 2013], [Uliasz-Bocheńczyk et al. 2015], [Poluszyńska et al. 2015], [Dróżdż et al. 2023][Uliasz-Bocheńczyk et al. 2016][Sybilski et al. 2004], [Plaskacz-Dziuba et al. 2014][Nakano et al. 2007], [Czop 2020][Kasprzyk et al. 2017][Nakano et al. 2007]

Leachability of elements from bottom sludge from co-firing of biomass and hard coal (%)

Leachability from aqueous extract (%)
SbBaBeCrZnCdCoMnCuMoNiPbSrTIVHgCr+6
-1.50.90.20.10.5-0.00.269.00.10.616.4-1.7--

Contents of heavy metals in ashes from sewage sludge combustion depending on temperature and combustion time

No. of repetitionCr [mg/kg d.m.]Zn [mg/kg d.m.]Cu [mg/kg d.m.]Cd [mg/kg d.m.]Ni [mg/kg d.m.]Pb [mg/kg d.m.]Combustion temp. (°C)Burning time (min.)
S1174.802755.23553.511.0953.76170.2860011
S270.481430.76351.790.8138.400.3298011
S3105.332479.30383.800.9042.22108.82655.604.60
S4103.242730.79433.90-52.4793.8379020
S5166.923091.66462.880.7057.27156.01655.6017.40
S696.001620.01314.940.0646.590.25924.4017.40
S797.972542.87388.930.1847.8887.3779011
S7-bis106.322616.96387.360.1651.6897.6579011
S884.242844.42401.13-54.2275.557902
S953.661398.53326.37-40.25-924.404.60

Trace elements in fly ash from the combustion of selected hard and brown coals (mg/kg d_m_)

ElementBurning hard coal without flue gas desulphurizationCoal combustion with flue gas desulphurizationCoal combustion lignite without flue gas desulphurization
Be7–215–16< 2–4
Sc18.30–18.3119.90–26.1016–19.10
V129–459183–270130–194
Cr87–230131–170130–157
Co21–7428–6711–12
Ni45–27369–20236–46
Cu70–16782–21334–55
Zn16–507190–752105–111
Na2–12015–9516–85
Se< 3–43< 3–78–21
Br7–219–285.1–7
Rb120–17671–139< 15– < 20
Sr543–1214438–1183662–728
Y46–8435–7744–76
Zr162–196108–147191
Mo< 5–20< 5–94–13
Ag< 0.40–1.70< 0.40–1.700.50–1
Cd< 0.50–2.701.20–3.703.80–4.60
Sb4.20–145.40–221.10–1.70
Cs13–27.3015.90–20.703.30–4.00
Ba927–1600879–1600349–754
La51.1–7042.7–6163–95.80
Ce110–14190–118120–172
Nd40–5439–54120–172
Sm9.10–12.107.50–10.4010–15
Eu2–2.701.60–2.202.20–2.70
Tb1.40–1.801.10–1.50< 0.50–2.20
Yb4.20–6.103.30–4.904.90–5.50
Lu0.60–0.800.30–0.700.70–0.80
Hf4.50–63.40–85–5.30
Ta< 0.50–2< 1–6< 0.50– < 1
W< 3–9< 1–7< 3
Hg< 1< 1< 1
Pb43–50736–10834–322
Bi< 5–8< 5–6< 5
Th20–25.1015–2217.20–26
U7.60–13.705.70–10.908.40–13.80
Ir (ppb)< 5< 5< 5
Au (ppb)< 5–284–105–10
DOI: https://doi.org/10.2478/oszn-2025-0012 | Journal eISSN: 2353-8589 | Journal ISSN: 1230-7831
Language: English
Page range: 18 - 30
Published on: Dec 26, 2025
In partnership with: Paradigm Publishing Services
Publication frequency: 4 issues per year
Related subjects:

© 2025 Adriana Solecka, Barbara Gworek, Marta Gabryszewska, published by National Research Institute, Institute of Environmental Protection
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.