Pyrolysed sewage sludge for metal(loid) removal and immobilisation in contrasting soils: Exploring variety of risk elements across contamination levels

• Published in: The Science of the total environment 2024-03, Vol.918, p.170572-170572, Article 170572
• Main Authors: Mitzia, Aikaterini, Böserle Hudcová, Barbora, Vítková, Martina, Kunteová, Barbora, Casadiego Hernandez, Daniela, Moško, Jaroslav, Pohořelý, Michael, Grasserová, Alena, Cajthaml, Tomáš, Komárek, Michael
• Format: Article
• Language: English
• Subjects: adsorption; Contaminant removal mechanisms; environment; Nutrient stabilisation; risk; sewage sludge; sewage treatment; Sludge biochar; Sludge mineralogy; soil; Soil remediation; solubilization; Waste-derived amendments
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2024.170572

Efficient treatment of sewage sludge may transform waste into stable materials with minimised hazardous properties ready for secondary use. Pyrolysed sewage sludge, sludgechar, has multiple environmental benefits including contaminant sorption capacity and nutrient recycling. The properties of five sludgechars were tested firstly for adsorption efficiency in laboratory solutions before prospective application to soils. A wide variety of metal(loid)s (As, Cd, Co, Cr, Cu, Ni, Pb, Sb, and Zn) was involved. Secondly, the sludgechars (3 % v/v) were incubated in five soils differing in (multi)-metal(loid) presence and the level of contamination. The main aim was to evaluate the metal(loid) immobilisation potential of the sludgechars for soil remediation. Moreover, nutrient supply was investigated to comprehensively assess the material's benefits for soils. All sludgechars were efficient (up to 100 %) for the removal of metal cations while their efficiency for metal(loid) anions was limited in aqueous solutions. Phosphates and sulphates were identified crucial for metal(loid) capture, based on SEM/EDS, XRD and MINTEQ findings. In soils, important fluctuations were observed for Zn, being partially immobilised by the sludgechars in high-Zntot soils, while partially solubilised in moderate to low-Zntot soils. Moreover, pH showed to be crucial for material stability, metal(loid) adsorption ability and their immobilisation in soils. Although metal(loid) retention was generally low in soils, nutrient enrichment was significant after sludgechar application. Long-term evaluation of the material sorption efficiency, nutrient supply, and ageing in soil environments will be necessary in future studies. [Display omitted] •Metal(loid) contamination calls for sustainable remediation solutions.•Use of 5 pyrolysed sludges for various soils remediation was evaluated.•Efficient metal cation sorption and no excessive contaminant leaching was observed.•Phosphate and sulphate formation affected metal(loid)s and nutrients availability.•Immobilisation tailored to soil contaminant levels and element-specific remediation.