CONICET | Buscador de Institutos y Recursos Humanos

Introduction: Poultry slaughterhouse industry is becoming more common in the Pampa region (Argentina) producing an increasing impact in the aquatic ecosystems. The wastewaters are characterized by a high BOD and COD, large amounts of nutrients and trace chemicals which may have toxic and genotoxic potential. Floating and submerged aquatic macrophytes have been used for wastewater treatment and resource recovery due to their high capacity to improve water quality by removing nutrients and heavy metals. The objectives of this study was to assess the genotoxicity of wastewater from a poultry slaughterhouse located in Buenos Aires (Argentina), to evaluate the phytoremediation alternative using aquatic macrophytes commonly reported in this region, Hydrocotile ranunculoides and Lemna gibba, and to evaluate the effectiveness of this treatment using the Allium cepa genotoxicity test. Materials and Methods: One hundred liters of wastewater were taken 1000 meters downstream the discharge of a poultry slaughterhouse. Three continuous flow reactors were performed by triplicate with 9 L of wastewater and aquatic macrophytes: a) L. gibba (T1), b) H. ranunculoides (T2) and c) L. gibba and H. ranunculoides (T3). After 6 days, the plants were removed. To evaluate nutrients removal, N-NH4+, SRP, TP and TOC, were measured both at the beginning and end of the assay. To evaluate the genotoxic potential, the A. cepa assay was carried out. One hundred onion seeds (Valcatorce variety) were germinated on petri dishes with paper filter and 5 ml of wastewater and treated waters. Distilled water was used as negative control and methylmethansufonate (MMS) (2 x 10-4 M) as positive control. After germination (4 days), the roots were fixed in alcohol-acetic acid (3:1) for 24 h. A total of 5000 meristematic root cells were counted. The frequencies of chromosome aberrations (CA) and micronucleus (MN) were obtained by counting 200 anaphases-telophases and 2000 interphases, respectively. Statistical analysis was carried out using the non-parametric Kruskal-Wallis test. Results and discussion: Higher removal percentages (%R) for all nutrients were obtained, being significantly larger in T1 and T3, with maximum removals of 77.9 ± 5.3 % for N-NH4+; 47.6 ± 8.3 % for SRP and 60.6 ± 6.1 % for TP in T3 and 77.6 ± 0.6 % for TOC in T1. The CA obtained in the negative control, MMS and wastewater sample were 0.01 ± 0.03, 0.81 ± 0.30 and 0.17 ± 0.43. The MN in the negative control, MMS and wastewater sample were 0.07 ± 0.09, 5.89 ± 1.76 and 1.22 ± 0.61. At the end, CA in T1, T2 and T3 were 0.35 ± 0.45, 0.19 ± 0.26 and 0.00 ± 0.00, respectively. MN in T1, T2 and T3 were 1.00 ± 1.18, 0.38 ± 0.26 and 0.00 ± 0.00, respectively. No significant differences were obtained among the wastewater sample, negative control and the three treatments in CA frequencies. However, MN was significantly different between the sample and the negative control, indicating mutagenicity. Significant differences were obtained between the control and the treatments T1 and T2 in MN, indicating the presence of mutagenic compounds after those two treatments. However, no significant differences were observed between T3 and the control. These results showed the reduction of mutagenicity of the sample, being T3 more effective than the other two treatments. Significant differences were obtained between T3 and T1, and T3 and T2. Conclusion: The wastewater sample from the poultry slaughterhouse was potentially genotoxic. The phytoremediation treatment using L. gibba and H. ranunculoides simultaneously was more effective to reduce genotoxicity than using the two plants separately. The two species were also effective in removal nutrients.