Reuse of effluent from the paint industry for the production of Anadenanthera peregrina seedlings: A silvicultural and ecotoxicological study

Increasing water scarcity and the need for sustainable waste management have necessitated the reuse of industrial effluents, particularly when aligned with the specific characteristics of each industrial sector. Forest nurseries represent a promising setting for this practice, as their automated irrigation systems prevent the risk of over-application and reduce effluent mobility in the soil through deep percolation. This study evaluated the feasibility of reusing effluent generated by a paint-manufacturing facility in the production of red angico (Anadenanthera peregrina) seedlings. Plant growth and development and the ecotoxicological response associated with effluent application were analyzed. Two effluent concentrations (E50% and E100%) were tested, with well water as the control. Plant-free substrate irrigated with undiluted effluent (E100% without plant) was monitored to investigate the influence of plant presence on substrate characteristics. After 100 days of irrigation, seedling growth, Dickson Quality Index values, physicochemical changes in the substrate, and ecotoxicity assays using Eisenia fetida earthworms were evaluated. Notably, the effluent, particularly at a concentration of 100%, restricted early seedling development, reducing biomass accumulation and quality indices relative to the control and demonstrating clear phytotoxicity to A. peregrina. Therefore, although the effluent can aid fertigation, its application in the production of A. peregrina seedlings requires dilution to mitigate its phytotoxic effects. However, substrate analyses revealed that undiluted effluent increased microbial activity, as indicated by basal substrate respiration, and exerted an attractant effect on earthworms. These findings indicate that A. peregrina may contribute to the phytoremediation of soils contaminated with paint industry effluents.