Ecotoxicological Evaluation of Waste from the Mining and Power-Generating Industries, Including the Phytotoxkit—An Alternative Approach to Sustainable Waste Management

Environmental risk assessment of landfill solid waste should include higher plants as indicators of toxicity to support sustainable waste management. This study evaluated solid waste from mining and power-generating industries using SANS 10234, a multidisciplinary approach that combined physicochemical analysis of waste samples and the Phytotoxkit bioassay to assess plant-based toxicity. Leachate extractions from samples identified as wastes of concern were evaluated using standard toxicity tests. Based on the Phytotoxkit results, Coal solid waste A, Clinker ash, and Chrome solid waste were identified as wastes of concern, whilst the whole effluent toxicity test results of the leachate indicated that these three samples pose a low risk to aquatic ecosystems. The phytotoxicity was attributed to the waste’s physicochemical parameters. Coal solid waste A expressed a low pH of 2.60 and a high electrical conductivity of 14,557 µS/cm, while Clinker ash presented a pH of 6.72 and an electrical conductivity value of 3685 µS/cm. These values were outside the optimal range for many plants to thrive. The presence of toxic elements in some samples may have contributed to the observed phytotoxicity. These results highlight that solid waste can present varying risks to both terrestrial and aquatic systems, reinforcing the importance of including higher plants in landfill risk assessments for sustainable waste management.