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Hazardous Waste Treatment 2.0

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Environmental Sciences".

Deadline for manuscript submissions: closed (25 August 2023) | Viewed by 3114
Related Special Issue: Hazardous Waste Treatment

Special Issue Editors


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Guest Editor
Department of Civil, Construction, and Environmental Engineering, University of Alabama at Birmingham, Birmingham, AL 35294-4440, USA
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Co-Guest Editor
College of Engineering, Howard University, Washington, DC 20059, USA
Interests: hazardous waste treatment; air and water pollution; separation processes, mechanism and kinetics in environmental systems
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Special Issue Information

Dear Colleagues,

Hazardous wastes that need treatment or disposal may be freshly generated from industrial, private, or commercial operations; they may be old stored chemicals, or they may have been sitting in a dumpsite for many years.

Hazardous waste can exist as solid, liquid, or gas. A hazardous waste characteristic is a property which, when present in a waste, indicates that the waste poses a sufficient threat to merit regulation as hazardous. The U.S. EPA established four hazardous waste characteristics: ignitability, corrosivity, reactivity, and toxicity. Some examples of hazardous waste are halogenated and non-halogenated organic solvents, PCBs, and pesticides.

Hazardous waste can be treated by chemical, thermal, biological, and physical methods. Chemical methods include chemical precipitation, ion exchange, oxidation and reduction, and neutralization. Among thermal methods is high-temperature incineration, which can not only detoxify certain organic wastes but also destroy them. The biological treatment of certain organic wastes, such as those from the petroleum industry, is also an option. One method used to treat hazardous waste biologically is called landfarming. Microbes can also be used to stabilize hazardous wastes on previously contaminated sites; in that case, the process is called bioremediation. When plants are used to decontaminate sites, phytoremediation and phytoextraction are applicable technologies. Landfilling is the other primary land disposal method for hazardous waste disposal in the United States.

Industries in the United States also dispose of their hazardous waste using a land disposal method called deep well injection. Liquid wastes are injected into wells located in impervious rock formations that keep the waste isolated from groundwater and surface water. Incineration is a controversial, but still common, method of handling hazardous wastes. Advanced oxidation techniques can also be used to destroy organic contaminants.

Chemical, thermal, and biological treatment methods change the molecular form of waste material. Physical treatment, on the other hand, concentrates, solidifies, or reduces the volume of waste. Physical processes include evaporation, sedimentation, flotation, and filtration. Another process is solidification/stabilization, which is achieved by encapsulating waste in concrete, asphalt, or plastic. Encapsulation produces a solid mass of material that is resistant to leaching. Waste can also be mixed with lime, fly ash, and water to form a solid, cement-like product.

Prof. Dr. Robert W. Peters
Prof. Dr. Ramesh C. Chawla
Guest Editors

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Keywords

  • hazardous waste
  • treatment techniques
  • chemical, thermal, biological, and physical methods
  • landfills
  • advanced oxidation processes
  • solidification
  • incineration
  • deep well injection
  • phytoremediation

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Published Papers (2 papers)

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Research

13 pages, 3579 KiB  
Article
Performance of the Dual-Chamber Fungal Fuel Cell in Treating Tannery Wastewater
by Mohamed S. Mahmoud, Jian-Hui Wang, Yu Shen, Zhi-Wei Guo, Yan Yang, Dao-Chen Zhu, Robert W. Peters, Mohamed K. Mostafa and Ahmed S. Mahmoud
Appl. Sci. 2023, 13(19), 10710; https://doi.org/10.3390/app131910710 - 26 Sep 2023
Cited by 2 | Viewed by 1081
Abstract
Fungi are typically expressed as excellent microorganisms that produce extracellular enzymes used in the bioaccumulation phenomenon. In this study, laboratory-scale dual-chamber fungal fuel cells (FFCs) were applied as an alternate approach for the available degradation of complex organic pollutants represented in chemical oxygen [...] Read more.
Fungi are typically expressed as excellent microorganisms that produce extracellular enzymes used in the bioaccumulation phenomenon. In this study, laboratory-scale dual-chamber fungal fuel cells (FFCs) were applied as an alternate approach for the available degradation of complex organic pollutants represented in chemical oxygen demand (COD) and total nitrogen (TN), as well as inorganic pollutants represented as total chromium (Cr), and the generation of bioenergy represented in output voltages (V), power density (PD) and current density (CD), as applied to tannery effluent. Aspergillus niger strain, (A. niger), which makes up 40% of the fungal population in tannery effluent was examined in a training study for efficient hexavalent chromium bioaccumulation, especially in high concentrations. The trained A. niger showed a faster growth rate than the untrained one in broth media containing different loaded chromium concentrations. For an external resistance of 1000 Ω, two FFCs were utilized, one with electrolytic matrices including phosphate buffer solution (PBS) and bicarbonate buffer solution (BBS), and the other without electrolytic matrices, where the energy generation and treatment efficacy of the two dual-chamber FFCs were evaluated for a period of 165 h. At 15 h, the electrolytic FFCs showed a high voltage output of 0.814 V, a power density of 0.097 mW·m−2, and a current density of 0.119 mAm−2 compared to the non-electrolytic FFC. At 165 h, the electrolytic FFCs showed high removal efficiency percentages for COD, TN, and total Cr of up to 77.9%, 94.2%, and 73%, respectively, compared to the non-electrolytic FFC. Full article
(This article belongs to the Special Issue Hazardous Waste Treatment 2.0)
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17 pages, 2054 KiB  
Article
Accumulation of Different Metals in Tomato (Lycopersicon esculentum L.) Fruits Irrigated with Wastewater
by Qaisra Tabassam, Muhammad Sajid Aqeel Ahmad, Ambreen Khadija Alvi, Muhammad Awais, Prashant Kaushik and Mohamed A. El-Sheikh
Appl. Sci. 2023, 13(17), 9711; https://doi.org/10.3390/app13179711 - 28 Aug 2023
Cited by 2 | Viewed by 1332 | Correction
Abstract
The present study assessed the accumulation and distribution of metals in tomato (Lycopersicon esculentum L.) fruits grown with wastewater. The concentrations of nine metals (Co, Cd, Mn, Cu, Ni, Fe, Zn, and Pb) were analyzed in wastewater collected from the study site. [...] Read more.
The present study assessed the accumulation and distribution of metals in tomato (Lycopersicon esculentum L.) fruits grown with wastewater. The concentrations of nine metals (Co, Cd, Mn, Cu, Ni, Fe, Zn, and Pb) were analyzed in wastewater collected from the study site. Four metals with substantially higher concentrations in wastewater, namely Fe, Zn, Mn, and Pb, were selected for further analysis in soil, plant organs, and parts of tomato fruits. In addition, the concentrations of essential nutrients (Na, K, Ca, P, and N) in all samples were also analyzed. Concentrations of Zn (0.77 mg L−1) and Pb (0.44 mg L−1) were found to be the maximum, and Mn concentration was the minimum (0.16 mg L−1) in wastewater samples. However, in soil samples, the concentrations of Fe (35.88 mg kg−1) and Pb (29.62 mg kg−1) were the highest, which ultimately led to their higher accumulation in plant tissues. When metal accumulation in the whole plant and tomato fruit was compared with the WHO permissible limits, the accumulated concentrations of Zn (16.35, 12.98, and 23.85 mg kg−1 d.wt. in peri-, endo-, and mesocarp, respectively), Mn (7.08, 7.75, and 4.6 mg kg−1 d.wt. in peri-, endo-, and mesocarp, respectively), and Pb (30.05, 29.42, and 34.95 mg kg−1 d.wt. in peri-, endo-, and mesocarp, respectively) exceeded the safe limits except for Fe (13.6, 32.3, and 63.43 mg kg−1 d.wt. in peri-, endo-, and mesocarp, respectively). Thus, the irrigation of tomato fruits with wastewater can cause health risks to humans under prolonged consumption, and the regular monitoring of metals is necessary to reduce the health risks from human consumption. Full article
(This article belongs to the Special Issue Hazardous Waste Treatment 2.0)
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