Impact of solid waste on the growth of helianthus: potential for soil restoration and decontamination

Abstract The phytoremediation potential of Helianthus annuus and Helianthus giant was assessed in soils contaminated with solid wastes, including fireplace ash, oil burner dust, forge dust, land of Milos (pozzolan), and land of Milos mixed with olive core. A total of 25 experimental treatments were applied, with waste concentrations ranging from 0.0 to 17.8 kg m⁻ 3 . Plant growth was monitored from germination to the completion of biological cycles over a period of 90 days. Experimental treatments involved varying concentrations of these wastes, with plant growth monitored from germination to the completion of biological cycles. Both sunflower species completed their cycles in most treatments, except at high concentrations of fireplace ash and oil burner dust. Helianthus annuus exhibited higher resistance and growth rates, with effective phytoremediation thresholds established for fireplace ash (≤ 4.4 kg m⁻ 3 ), oil burner dust (≤ 2.2 kg m⁻ 3 ), forge dust (≤ 1.1 kg m⁻ 3 ), and land of Milos mixed with olive core (≤ 2.2 kg m⁻ 3 each). Helianthus giant was effective at lower waste concentrations but unsuitable for oil burner dust remediation. Risk mitigation is essential to prevent bioaccumulated contaminants from entering the food chain through sunflower tissues or products. These findings highlight the influence of substrate composition and waste concentration on phytoremediation efficiency and emphasize the potential of sunflowers for soil restoration, biomass production, and agricultural applications under controlled conditions. Graphical abstract