Are the ecotoxicological tools viable to evaluate the effectiveness of wastewater treatment plant effluents?

Abstract

Ecotoxicological tools have proved to be sensitive and appropriate for the evaluation of the effectiveness of treatments used in wastewater treatment plants (WWTP). The objective of this study was to assess the applicability of bioassays and biomarkers to evaluate the efficiency of different treatments throughout WWTP samples[A—raw influent, B—preliminary effluent, C—final effluent, and D—receiving stream], seasonally over 1 year, through a multispecies approach: i) bacterial cell viability [Escherichia coli, Rhodopirellulla rubra, Arthrobacter sp., and Pseudomonas putida]; ii) microalgae Raphidocelis subcapitata and the macrophyte Lemna minor growth inhibition; and iii) microcrustacean Daphnia magna acute and feeding rate assays. Total chlorophyll, malondialdehyde, and proline levels were evaluated in L. minor, and catalase, glutathione-S-transferase activities, and thiobarbituric acid reactive substances levels were quantified in D. magna, after exposure to wastewater samples. Overall, the tested species showed different sensitivities, P. putida = Arthrobacter sp. = R. rubra < R. subcapitata < E. coli = D. magna = L. minor, to the collected samples. The results obtained in D. magna and L. minor assays demonstrated that these organisms can be used in programs for monitoring and environmental assessment of wastewater effluents. The present study demonstrates the usefulness of ecotoxicological tools, with multispecies and different endpoints, to assess the effectiveness of WWTPs. Moreover, it is important to ensure that WWTP implements a monitoring program to minimize the discharge of effluents that compromise the environment in order to guarantee the good ecological quality of the environmental ecosystems.

Antibiotic-Resistant Bacteria across a Wastewater Treatment Plant

“…Different bacteria were found across all the sampling sites, including sampling site C, which corresponded to the effluent after the MBR treatment with an ultrafiltration process. The presence of antibiotic-resistant isolates from the entrance to the exit of the WWTP was in agreement with previous reports, which indicated that the MBR treatment applied was insufficient to reduce the microbial load [18]. This reinforces the need to apply additional strategies at this WWTP to ensure the proper removal of microorganisms, which may require the development of novel technologies and procedures [34].…”

“…Wastewater samples were collected in May 2021 and in July 2021 from four different points within a wastewater treatment plant located in the northern region of Portugal (the WWTP features are detailed in reference [18]). The four sampling points represented: A-raw influent of untreated wastewater; B-preliminary effluent already treated for the removal of coarse solids, sands, oils and fats; C-final effluent after membrane bioreactor (MBR) treatment with an ultrafiltration process but before the discharge in the river; and D-the stream receiving the WWTP effluent [18]. Samples were collected in 100 mL sterile flasks and kept in cold conditions until they were processed.…”

Assessment of ecotoxicological effects of Fojo coal mine waste elutriate in aquatic species (Douro Coalfield, North Portugal)

“…Lemna minor growth inhibition assays were conducted according to standard guidelines (OECD, 2006), with microplate adaptation (Diogo et al, 2023). Four replicates per elutriate were used, and in each replicate 12.5 mL of elutriate and four fronds of L. minor were added.…”

“…Catalase (CAT) represents one of the first enzymes involved in the antioxidant defense system (responsible for the catalysis of hydrogen peroxide, a reactive oxygen species that if not eliminated or neutralized by antioxidant defenses can induce oxidative stress, in water) (Alkimin et al, 2020). On the other hand, malondialdehyde (MDA) is a final product of lipid peroxidation, that can be used as an important indicator of physiological stress (Diogo et al, 2023).…”

Comparative Phytotoxicity of Metallic Elements on Duckweed Lemna gibba L. Using Growth- and Chlorophyll Fluorescence Induction-Based Endpoints

“…The following supporting information can be downloaded at , File S1: metadata for Figures S1–S4 (main text); Figure S5: 3-parameter log-logistic concentration–response model fittings of RGR frond ; Figure S6: 3-parameter log-logistic concentration–response model fittings of F v /F o ; Figure S7: 3-parameter log-logistic concentration–response model fittings of Y(II); and Table S1: The results of the 3-parameter log-logistic model fittings with calculated EC 20 and EC 50 values for the studied endpoints. References [ 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 , 108 , 109 ,…”