Fate of Metals Released from Wastewater Effluents

A special issue of Toxics (ISSN 2305-6304). This special issue belongs to the section "Metals and Radioactive Substances".

Deadline for manuscript submissions: closed (31 October 2022) | Viewed by 11339

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Guest Editor
St.Lawrence Center, Environment & Climate Change Canada, Montreal, QC, Canada
Interests: fate and exposure of metals in wastewaters
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Wastewaters, including municipal and mining effluents, represent large sources of metals released to the aquatic environment. Metals are significantly present in municipal effluents, and a number of relatively small industrial plants release metals directly into municipal sewer systems. Mining activities are well-recognized sources of metals to the aquatic environment when they are leached from recent and historical tailings. Acid mine drainage is an issue for the mining industry worldwide. Emerging metal uses, such as the growing production of engineered metal-based nanomaterials and technology-critical elements, may represent additional metal sources, following their transformation, to the environment where their environmental risk remains to be assessed.

Predicting the environmental impact of the metals contained in those effluent discharges requires an understanding of how their physical and chemical characteristics, and those of the effluent receiving waters, affect metal uptake by aquatic organisms and metal toxicity. As the biological availability of metals is influenced by their speciation, chemical associations of metals are key to assessing the mobility and equilibrium of metal forms. Methods to predict metal bioavailability and toxicity are either by direct measurement such as in electrochemistry and chromatography or using models such as MINEQL or WHAM. These models are based on chemical equilibrium constants to predict how water chemistry modifies forms of the metal and how its toxicity changes, and their results are often validated by controlled exposure experiments using testing animals.

Dr. Christian Gagnon
Guest Editor

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Keywords

  • wastewater
  • bioavailability
  • metals
  • sediment
  • fate
  • speciation
  • mine tailings
  • transformation

Published Papers (4 papers)

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Research

17 pages, 592 KiB  
Article
Evaluating the Potential Health Risks of Selected Heavy Metals across Four Wastewater Treatment Water Works in Durban, South Africa
by Babatunde Femi Bakare and Gbadebo Clement Adeyinka
Toxics 2022, 10(6), 340; https://doi.org/10.3390/toxics10060340 - 20 Jun 2022
Cited by 9 | Viewed by 4720
Abstract
Poor and inadequate sanitation systems have been considered not only a human health issue, but also an environmental threat that instigates climate change. Nine heavy metals—arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), and zinc [...] Read more.
Poor and inadequate sanitation systems have been considered not only a human health issue, but also an environmental threat that instigates climate change. Nine heavy metals—arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn)—were evaluated in influent and effluent water samples from four wastewater treatment plants in the Durban metropolis, KwaZulu-Natal, South Africa. The results indicate that the mean concentrations of all the heavy metals in the influent samples ranged from 0.122 to 1.808 mg/L, while the effluent samples had a concentration ranging from 0.118 to 0.854 mg/L. Iron was found to be in the highest concentration and the concentration of Co was the lowest across the wastewater treatment plants. The levels for most of the heavy metals in this study were found to be above the recommended maximum concentrations in surface and effluent waters as stipulated by the World Health Organization, United States Environmental Protection Agency, Food and Agriculture Organization, and the Department of Water Affairs and Forestry of South Africa. According to the toxicity effect due to non-carcinogenic risks, As, Pb, Cr, and Cd are considered to be of medium risk in this study, indicating that a probable adverse health risk is very likely to occur. Additionally, the cancer risk (RI) values were lower than 10−3, which shows that cancer development is very likely in individuals who are exposed. Cancer development associated with dermal absorption is quite negligible; thereby, it does not raise any concerns. Full article
(This article belongs to the Special Issue Fate of Metals Released from Wastewater Effluents)
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13 pages, 3080 KiB  
Article
Lanthanides Release and Partitioning in Municipal Wastewater Effluents
by Patrice Turcotte, Shirley Anne Smyth, François Gagné and Christian Gagnon
Toxics 2022, 10(5), 254; https://doi.org/10.3390/toxics10050254 - 17 May 2022
Cited by 4 | Viewed by 1646
Abstract
The use of lanthanides is increasing in our society, whether in communication technologies, transportation, electronics or medical imaging. Some lanthanides enter urban wastewater and flow through municipal wastewater treatment plants (WWTPs). However, little is known about the effectiveness of treatment processes to remove [...] Read more.
The use of lanthanides is increasing in our society, whether in communication technologies, transportation, electronics or medical imaging. Some lanthanides enter urban wastewater and flow through municipal wastewater treatment plants (WWTPs). However, little is known about the effectiveness of treatment processes to remove these elements and the concentrations released in effluents to receiving waters. The main objective of this study was to investigate the fate of lanthanides in various wastewater treatment processes. A secondary objective was to better understand the fate of medical gadolinium (Gd) complexes; anthropogenic inputs were differentiated from geological sources using an approach based on concentration normalization with respect to chondrite Post-Archean Australian Shale (PAAS). The hypothesis was that most lanthanides, especially of geological origin, are associated with the particulate phase and could be efficiently removed by WWTPs. To monitor these elements in different WWTPs, various urban influents and effluents from simple aerated lagoons to advanced treatments were sampled in Canada. The results showed that the rates of lanthanide removal by treatment processes decrease with their atomic number; from 95% for cerium (Ce) to 70% for lutetium (Lu), except for Gd, which was minimally removed. The normalization approach permitted the determination of the origin of Gd in these wastewaters, i.e., medical application versus the geological background. By distinguishing the geogenic Gd fraction from the anthropogenic one, the removal efficiency was evaluated according to the origin of the Gd; nearly 90% for geogenic Gd and a rate varying from 15% to 50% in the case of anthropogenic Gd. The processes using alum as the flocculating agent had the highest removal efficiency from wastewater. Full article
(This article belongs to the Special Issue Fate of Metals Released from Wastewater Effluents)
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21 pages, 4467 KiB  
Article
Leaching and Geochemical Modelling of an Electric Arc Furnace (EAF) and Ladle Slag Heap
by Mojca Loncnar, Ana Mladenovič, Vesna Zalar Serjun, Marija Zupančič and Hans A. van der Sloot
Toxics 2022, 10(1), 10; https://doi.org/10.3390/toxics10010010 - 1 Jan 2022
Cited by 7 | Viewed by 1743
Abstract
Old metallurgical dumps across Europe represent a loss of valuable land and a potential threat to the environment, especially to groundwater (GW). The Javornik electric arc furnace (EAF) and ladle slag heap, situated in Slovenia, was investigated in this study. The environmental impact [...] Read more.
Old metallurgical dumps across Europe represent a loss of valuable land and a potential threat to the environment, especially to groundwater (GW). The Javornik electric arc furnace (EAF) and ladle slag heap, situated in Slovenia, was investigated in this study. The environmental impact of the slag heap was evaluated by combining leaching characterization tests of landfill samples and geochemical modelling. It was shown that throughout the landfill the same minerals and sorptive phases control the leaching of elements of potential concern, despite variations in chemical composition. Although carbonation of the disposed steel slags occurred (molar ratio CO3/(Ca+Mg) = 0.53) relative to fresh slag, it had a limited effect on the leaching behaviour of elements of potential concern. The leaching from the slag heaps had also a limited effect on the quality of the GW. A site-specific case, however, was that leachates from the slag heap were strongly diluted, since a rapid flow of GW fed from the nearby Sava River was observed in the landfill area. The sampling and testing approach applied provides a basis for assessing the long-term impact of release and is a good starting point for evaluating future management options, including beneficial uses for this type of slag. Full article
(This article belongs to the Special Issue Fate of Metals Released from Wastewater Effluents)
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18 pages, 3847 KiB  
Article
A Multidisciplinary Approach for the Assessment of Origin, Fate and Ecotoxicity of Metal(loid)s from Legacy Coal Mine Tailings
by Honorine Gauthier-Manuel, Diane Radola, Flavien Choulet, Martine Buatier, Raphaël Vauthier, Tatiana Morvan, Walter Chavanne and Frédéric Gimbert
Toxics 2021, 9(7), 164; https://doi.org/10.3390/toxics9070164 - 10 Jul 2021
Cited by 5 | Viewed by 2022
Abstract
Over the course of history, the development of human societies implied the exploitation of mineral resources which generated huge amounts of mining wastes leading to substantial environmental contamination by various metal(loid)s. This is especially the case of coal mine tailings which, subjected to [...] Read more.
Over the course of history, the development of human societies implied the exploitation of mineral resources which generated huge amounts of mining wastes leading to substantial environmental contamination by various metal(loid)s. This is especially the case of coal mine tailings which, subjected to weathering reactions, produce acid mine drainage (AMD), a recurring ecological issue related to current and past mining activities. In this study, we aimed to determine the origin, the fate and the ecotoxicity of metal(loid)s leached from a historical coal tailing heap to the Beuveroux river (Franche-Comté, France) using a combination of mineralogical, chemical and biological approaches. In the constitutive materials of the tailings, we identified galena, tetrahedrite and bournonite as metal-rich minerals and their weathering has led to massive contamination of the water and suspended particles of the river bordering the heap. The ecotoxicity of the AMD has been assessed using Chironomus riparius larvae encaged in the field during a one-month biomonitoring campaign. The larvae showed lethal and sub-lethal (growth and emergence inhibition and delay) impairments at the AMD tributary and near downstream stations. Metal bioaccumulation and subcellular fractionation in the larvae tissues revealed a strong bioavailability of, notably, As, Pb and Tl explaining the observed biological responses. Thus, more than 70 years after the end of mining operations, the coal tailings remain a chronic source of contamination and environmental risks in AMD effluent receiving waters. Full article
(This article belongs to the Special Issue Fate of Metals Released from Wastewater Effluents)
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