Biomonitoring of water and soil quality: a case study of ecotoxicological methodology application to the assessment of reclaimed agroindustrial wastewaters used for irrigation

The aim of the work was to evaluate the ecotoxicity of reclaimed agroindustrial wastewaters used for irrigation through ecotoxicological bioassays and biomarkers. The ecotoxicological monitoring was addressed on both treated wastewaters and irrigated soils. Wastewater biomonitoring was performed by the acute test with Daphnia magna, the Microtox® test, and a new in vitro patented method. Soil quality monitoring was performed by the acute and chronic tests with the earthworm Eisenia fetida and biomarker analysis, such as lysosomal membrane stability, general stress biomarker of chemical pollution, and metallothionein, specific biomarker of exposure to heavy metals. Overall the integrated ecotoxicological analysis excluded the presence of ecotoxicity both in the reclaimed waters resulting from tertiary treatment and in the irrigated soils. In particular, the analysis of metallothionein allowed to exclude the accumulation of bioavailable heavy metals in the soil. This study suggests the suitability of ecotoxicological methods for the biomonitoring of water and soil during the reclaimed wastewaters reuse for irrigation, contributing to improving the process of agricultural re-use of wastewater in terms of assessment of the toxicological safety of the waters for the environment, for traders and consumers.