The study assesses the contamination, classification and phytotoxicity of foundry waste. The presented results are a part of the research on the agrotechnical use of foundry waste. Landfilled foundry waste (LFW) and dust samples were taken from one of the Polish foundries. An analysis of the waste and its leachate composition was conducted. Phytotoxicity tests were carried out using Lepidium sativum. The aim of the phytotoxicity study was to evaluate germination and root growth after 72 h and the accumulation of heavy metals after 7 days. LFW was least contaminated with heavy metals and metalloids compared to dust. The composition of the foundry dusts depended on the unit of the foundry, from which it was collected. It was found that electric arc furnace dust (EAFD) was the most polluted by heavy metals among the dust samples. According to the requirements of Polish regulations most of tested waste were classified as non–hazardous, and EAFD as hazardous waste due to high Pb concentration in leachate. Phytotoxicity tests have shown a low phytotoxicity of the leachate from most of the tested waste. The results of the accumulation test showed that an excess of metal and metalloids in leachate was not directly related to its accumulation in plants. A negative correlation between EC, Cu, Co, Fe, Pb, Cr, K, Na, sulfate, fluoride, ammonia, phenol and formaldehyde concentration in leachate and GI was found. It was stated that the Fe, Mn, As and Se in plants was significantly correlated with concentrations in leachate.
In contrast to chlorides and sulfates, fluorides are toxic to biota even at low concentrations (Stevens et al. 2000; Palmieri et al. 2014). Fluoride concentration was analyzed in the leachate, as it may be present in foundry waste. Organic binders are the main source of fluorides in foundry waste leachate (http://life-foundrysand.com). The fluoride concentration was low in all tested leachate. Plant resistance to fluoride depends on the plant species. Stevens et al. (1998) report the toxic for plants is fluoride concentration at 50–260 µM (1–5 mg/L) for tomatoes to 2532–13157 µM (50–250 mg/L) for cabbage. Gupta et al. (2009) found a negative effect of aqueous fluoride extracts on rice seeds on germination >20 mg/L and root elongation >30 mg/L, respectively.
References used in Excerpt:
Gupta S, Banerjee S, Mondal S (2009) Phytotoxicity of fluoride in the germination of paddy (Oryza sativa) and its effect on the physiology and biochemistry of germinated seedlings. Fluoride 42(2):142–146. http://fluoridealert.org/wp-content/uploads/gupta-2009.pdf
Palmieri MJ, Luber J, Andrade–Vieira LF, Davide LC (2014) Cytotoxic and phytotoxic effects of the main chemical components of spent pot–liner: a comparative approach. Mutat Res Genet Toxicol Environ Mutagen 763:30–35. https://doi.org/10.1016/jmrgentox201312008
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