Avaliação da fitoxicidade de lodo de estação de tratamento de efluentes de indústria de pescado utilizando olerícolas como bioindicadores
Description
Dewatered sludge from fish-processing wastewater treatment contains recoverable nutrients, but evidence for direct agricultural reuse remains limited and is often weakened by pseudoreplication or unpaired chemical and biological measurements. We reanalyzed raw seed-bioassay and greenhouse data to evaluate species-specific phytotoxicity and growth responses. A 1:10 sludge-water extract was tested with lettuce (Lactuca sativa), cucumber (Cucumis sativus) and arugula (Eruca sativa) across four sampling blocks, with three control and three extract plates per block. Greenhouse responses of lettuce and arugula were evaluated under four soil treatments: lime-amended control (T1), lime plus sludge (T2), lime plus mineral NPK (T3), and sludge without lime (T4). Block-normalized germination indices averaged 344.7 ± 267.7% for lettuce, 184.3 ± 16.2% for cucumber and 164.1 ± 13.4% for arugula. The exact four-block sign-flip test was inconclusive (minimum attainable two-sided p = 0.125), highlighting limited inferential resolution despite mean indices above 100%. In the greenhouse, lettuce shoot traits did not differ among treatments; root length was lower in T4 than T1 at the nominal endpoint level, but not after across-endpoint false-discovery-rate adjustment. Arugula showed strong treatment responses: T2 produced the largest leaf number, root length, and shoot fresh and dry masses, while T4 was generally intermediate. These findings support crop-specific agronomic potential rather than a general safety claim. Field validation, matched soil/sludge chemistry, pathogen assessment and contaminant bioavailability are required before recommending agricultural application.
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Institutions
- Instituto Federal Sul-rio-grandenseRio Grande do Sul, Pelotas