Heavy Metal Control and Dry Matter Assessment in Digested Sewage Sludge for Biogas Production

Krzysztof Michalski, Magdalena Kóska-Wolny, Krzysztof Chmielowski, Michał Gąsiorek (), Klaudiusz Grübel, Konrad Kalarus and Wiktor Halecki
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Krzysztof Michalski: AQUA S.A., ul. 1 Maja 23, 43-300 Bielsko-Biała, Poland
Magdalena Kóska-Wolny: AQUA S.A., ul. 1 Maja 23, 43-300 Bielsko-Biała, Poland
Krzysztof Chmielowski: Department of Natural Gas Engineering, Faculty of Drilling, Oil and Gas, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Kraków, Poland
Michał Gąsiorek: Department of Soil Science and Agrophysics, University of Agriculture in Krakow, Al. Mickiewicza 21, 31-120 Kraków, Poland
Klaudiusz Grübel: Department of Environmental Protection and Engineering, University of Bielsko-Biala, ul. Willowa 2, 43-309 Bielsko-Biała, Poland
Konrad Kalarus: Institute of Technology and Life Sciences, National Research Institute, Falenty, Al. Hrabska 3, 05-090 Raszyn, Poland
Wiktor Halecki: Institute of Technology and Life Sciences, National Research Institute, Falenty, Al. Hrabska 3, 05-090 Raszyn, Poland

Energies, 2025, vol. 18, issue 10, 1-20

Abstract: The expansion of sewage networks and treatment facilities results in considerable amounts of municipal sludge, which is essential for biogas production as part of energy diversification efforts. Principal Component Analysis (PCA) demonstrated a strong correlation between biogas production and its utilization in power generation units. Modernization efforts led to an increase in biogas utilization in power units but a decrease in boiler utilization, independent of the overall biogas production levels. The general linear model (GLM) further confirmed that biogas production was positively influenced by the amount of waste digested, while utilization in power units increased post modernization. A repeated measures ANOVA (Analysis of Variance) indicated significant increases in both dry matter and mineral content in digested sludge compared to raw sludge. SIMPER (Similarity Percentage) analysis revealed that the addition of glycerin water significantly reduced the nitrogen, ammonium nitrogen, and calcium content, while modernization increased these elements and slightly decreased the magnesium concentration. Multivariate dispersion analysis showed that samples treated with glycerin water exhibited less variability in metal content. Regression models explored the factors influencing mineral elements and dry mass in fermented sludge. The zinc content was positively associated with mineral content, while copper showed a negative correlation. The addition of glycerin water increased the mineral content, whereas modernization had the opposite effect. The nitrogen content was negatively correlated with dry mass. These findings provide valuable insights into optimizing sewage sludge treatment and biogas production processes by underlining the approaches for enhancing sludge properties to support efficient biogas production.

Keywords: biogas; post-fermented sewage sludge; potentially toxic elements; glycerin water (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2025
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