Sequential application of activated sludge and phytoremediation with aquatic macrophytes on tannery effluents: in search of a complete treatment

FERNÁNDEZ, M.;; GÓMEZ R.; P.S. GONZÁLEZ.; BARROSO CN,; PAISIO, C.E.;

Environmental Science and Pollution Research

Springer Science and Business Media Deutschland GmbH

Año: 2023 vol. 30 p. 74196 - 74206

Tannery effluents with a high organic matter load (indicated by their COD level) have to be treated before they are discharged,so as to minimize their negative impact on the environment. Using field mesocosm systems, this study evaluated the feasibilityof treating such effluents through bioaugmentation with activated sludge, followed by phytoremediation with aquaticmacrophytes (Lemnoideae subfamily). Regardless of its quality, the activated sludge was able to remove approximately 77%of the COD from effluents with a low initial organic load (up to 1500 mg/L). The macrophytes then enhanced removal (up to86%), so the final COD values were permissible under the current legislation for effluent discharge. When the initial organicload in the undiluted effluents was higher (around 3000 mg/L), the COD values obtained after consecutive bioaugmentationand phytoremediation were close to the legally allowed limits (583 mg/L), which highlights the potential of phytoremediationas a tertiary treatment. This treatment also brought total coliform counts down to legally acceptable values, without plantbiomass decreasing over time. Moreover, the plant biomass remained viable and capable of high COD removal efficiency(around 75%) throughout two additional reuse cycles. These findings indicate that the efficiency of the biological treatmentsassayed here depends largely on the initial organic load in the tannery effluents. In any case, the sequential application ofactivated sludge and aquatic macrophytes proved to be a successful alternative for remediation.