Hazardous Waste Treatment

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

Deadline for manuscript submissions: closed (30 August 2020) | Viewed by 42560
Related Special Issue Open for Submissions: Hazardous Waste Treatment 2.0

Special Issue Editors

Department of Civil, Construction, and Environmental Engineering, University of Alabama at Birmingham, Birmingham, AL 35294-4440, USA
Interests: environmental sustainability; energy conservation in building infrastructure; condensate recovery in air handling units; vertical garden systems; vegetative roofs; stormwater management
Special Issues, Collections and Topics in MDPI journals
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

Special Issue Information

Dear Colleagues,

Hazardous wastes that need treatment or disposal may be freshly generated from an industrial, private, or commercial operation; 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 enough 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 not only can detoxify certain organic wastes but also can destroy them. 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

Published Papers (8 papers)

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Research

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13 pages, 5354 KiB  
Article
Ultrasonic Regeneration Studies on Activated Carbon Loaded with Isopropyl Alcohol
by Hsuan-Yi Hong, Niels Michiel Moed, Young Ku and Hao-Yeh Lee
Appl. Sci. 2020, 10(21), 7596; https://doi.org/10.3390/app10217596 - 28 Oct 2020
Cited by 7 | Viewed by 2282
Abstract
Ultrasonic regeneration of activated carbon loaded with isopropyl alcohol (IPA) was studied. IPA adsorption was performed batchwise at varying solution pH. Adsorption was optimal at solution pH 7, which was closest to the point of zero charge of the activated carbon (6.7). Ultrasonic [...] Read more.
Ultrasonic regeneration of activated carbon loaded with isopropyl alcohol (IPA) was studied. IPA adsorption was performed batchwise at varying solution pH. Adsorption was optimal at solution pH 7, which was closest to the point of zero charge of the activated carbon (6.7). Ultrasonic regeneration was performed on IPA-loaded activated carbon with three factors being tested: ultrasonic intensity, solution temperature and ethanol addition. Regeneration efficiency increased with ultrasonic intensity up to 32.4 W/cm2. A higher intensity led to a higher desorption but damaged the activated carbon, shown by a decrease in the particle size of activated carbon. The regeneration efficiency increased with solution temperature primarily because desorption is endothermic and because the surface tension and viscosity of a solution are reduced with increasing temperature, promoting cavitation bubble production. Ethanol addition increased regeneration efficiency up to 10%, as ethanol reduces tensile stress, facilitating cavitation bubble generation. At 15% and above, regeneration decreases, possibly due to coalescence of bubbles into larger, more stable bubbles. Under optimal parameters, the regeneration efficiency was 83%, which dropped to 64% after four regeneration cycles. Full article
(This article belongs to the Special Issue Hazardous Waste Treatment)
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20 pages, 7701 KiB  
Article
Application of Satellite Remote Sensing in Monitoring Elevated Internal Temperatures of Landfills
by Rouzbeh Nazari, Husam Alfergani, Francis Haas, Maryam E. Karimi, Md Golam Rabbani Fahad, Samain Sabrin, Jess Everett, Nidhal Bouaynaya and Robert W. Peters
Appl. Sci. 2020, 10(19), 6801; https://doi.org/10.3390/app10196801 - 28 Sep 2020
Cited by 13 | Viewed by 3038
Abstract
Subsurface fires and smoldering events at landfills can present serious health hazards and threats to the environment. These fires are much more costly and difficult to extinguish than open fires at the landfill surface. The initiation of a subsurface fire may go unnoticed [...] Read more.
Subsurface fires and smoldering events at landfills can present serious health hazards and threats to the environment. These fires are much more costly and difficult to extinguish than open fires at the landfill surface. The initiation of a subsurface fire may go unnoticed for a long period of time and undetected fires may spread over a large area. Unfortunately, not all landfill operators keep or publish heat elevation data and many landfills are not equipped with a landfill gas extraction system to control subsurface temperatures generated from the chemical reactions within. The timely and cost-effective identification of subsurface fires is an important and pressing issue. In this work, we describe a method for using satellite thermal infrared imagery at a moderate spatial resolution to identify the locations of subsurface fires and monitor their migration within landfills. The focus of this study was the Bridgeton Sanitary Landfill in Bridgeton, MO, USA where a subsurface fire was first identified in 2010 and continues to burn today. Observations from Landsat satellites over the last seventeen years were examined for surface temperature anomalies (or hot spots) that may be associated with subsurface fires. The results showed that the locations of hot spots identified in satellite imagery match the known locations of the subsurface fires. Changes in the hot-spot locations with time, as determined by in situ measurements, correspond to the spreading routes of the subsurface fires. These results indicate that the proposed approach based on satellite observations can be used as a tool for the identification of landfill subsurface fires by landfill owners/operators to monitor landfills and minimize the expenses associated with extinguishing landfill fires. Full article
(This article belongs to the Special Issue Hazardous Waste Treatment)
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19 pages, 3157 KiB  
Article
Investigating Effects of Landfill Soil Gases on Landfill Elevated Subsurface Temperature
by Samain Sabrin, Rouzbeh Nazari, Md Golam Rabbani Fahad, Maryam Karimi, Jess W. Everett and Robert W. Peters
Appl. Sci. 2020, 10(18), 6401; https://doi.org/10.3390/app10186401 - 14 Sep 2020
Cited by 4 | Viewed by 3238
Abstract
Subsurface temperature is a critical indicator for the identification of the risk associated with subsurface fire hazards in landfills. Most operational landfills in the United States (US) have experienced exothermic reactions in their subsurface. The subsurface landfill area is composed of various gases [...] Read more.
Subsurface temperature is a critical indicator for the identification of the risk associated with subsurface fire hazards in landfills. Most operational landfills in the United States (US) have experienced exothermic reactions in their subsurface. The subsurface landfill area is composed of various gases generated from chemical reactions inside the landfills. Federal laws in the US mandate the monitoring of gases in landfills to prevent hazardous events such as landfill fire breakouts. There are insufficient investigations conducted to identify the causes of landfill fire hazards. The objective of this research is to develop a methodological approach to this issue. In this study, the relationship was investigated between the subsurface elevated temperature (SET) and soil gases (i.e., methane, carbon dioxide, carbon monoxide, nitrogen, and oxygen) with the greatest influence in landfills. The significance level of the effect of soil gases on the SET was assessed using a decision tree approach. A naïve Bayes technique for conditional probability was implemented to investigate how different gas combinations can affect different temperature ranges with respect to the safe and unsafe states of these gases. The results indicate that methane and carbon dioxide gases are strongly associated with SETs. Among sixteen possible gas combinations, three were identified as the most probable predictors of SETs. A three-step risk assessment framework is proposed to identify the risk of landfill fire incidents. The key findings of this research could be beneficial to landfill authorities and better ensure the safety of the community health and environment. Full article
(This article belongs to the Special Issue Hazardous Waste Treatment)
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17 pages, 2535 KiB  
Article
Ignition of Deposited Wood Dust Layer by Selected Sources
by Ivana Tureková and Iveta Marková
Appl. Sci. 2020, 10(17), 5779; https://doi.org/10.3390/app10175779 - 20 Aug 2020
Cited by 15 | Viewed by 3937
Abstract
The main waste of wood sanding technology is wood dust. The formation of wood dust affects its behaviour. Wood dust can be in a turbulent form and behaves explosively or in a settled form where it becomes flammable. Dust particles are barely detectable [...] Read more.
The main waste of wood sanding technology is wood dust. The formation of wood dust affects its behaviour. Wood dust can be in a turbulent form and behaves explosively or in a settled form where it becomes flammable. Dust particles are barely detectable by the naked eye, wood dust still presents substantial health, safety, fire and explosion risks to employees. This article deals with the evaluation of ignition temperature and surface temperature of deposited wood dust samples by selected ignition sources. The influence of selected physical properties of wood dust, the size of the contact area between the ignition source and the combustible material, the spatial arrangement during the ignition and the application time of the ignition source are analysed. The paper describes the behaviour of a 15 mm deposited layer of wood dust of spruce (Picea abies L.), beech (Fagus silvatica L.). oak (Quercus petraea Liebl.) caused by three potential ignition sources—a hot surface, an electric coil and a smouldering cigarette. Prior to the experimental determination of the ignition temperature, dust moisture content which did not significantly affect the ignition phase of the samples, as well as sieve analysis of tested samples were determined. The lowest minimum ignition temperature on the hot plate, as an important property of any fuel, because the combustion reaction of the fuel becomes self-sustaining only above this temperature, was reached by the oak dust sample (280 °C), the highest by the spruce dust sample (300 °C). The ignition process of wood dust was comparable in all samples, differing in the ignition time and the area of the thermally degraded layer. The least effective ignition source was a smouldering cigarette. Full article
(This article belongs to the Special Issue Hazardous Waste Treatment)
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18 pages, 6420 KiB  
Article
Experiments and Modeling for Investigation of Oily Sludge Biodegradation in a Wastewater Pond Environment
by Matthew Alexander, Najem Alarwan, Maheswari Chandrasekaran, Aishwarya Sundaram, Tonje Milde and Saad Rasool
Appl. Sci. 2020, 10(5), 1659; https://doi.org/10.3390/app10051659 - 01 Mar 2020
Cited by 4 | Viewed by 2328
Abstract
Historic operating and abandoned refineries frequently contain ponds or lagoons that contain oily sludge from historic wastewater treatment processes and separator sludge disposal activities that occurred prior to the implementation of regulations forbidding such disposal. These oily sludge-containing wastewater ponds represent a long-term [...] Read more.
Historic operating and abandoned refineries frequently contain ponds or lagoons that contain oily sludge from historic wastewater treatment processes and separator sludge disposal activities that occurred prior to the implementation of regulations forbidding such disposal. These oily sludge-containing wastewater ponds represent a long-term liability at older operating refineries or abandoned refinery sites. Dewatering and solidification/stabilization are the most common technologies used to treat these sludges; however, these approaches are labor, equipment, and material-intensive. For sites where the time required to complete treatment is not a high priority, biodegradation treatment may be effective for final site remedy. The objective of this study was to investigate potential improvements in oily material biodegradation using dispersants and petroleum-degrading microbial consortia, along with the modeling of this system. The oil dispersed with mixing or remaining in the bulk aqueous phase with biodegradation was measured using methods from a dispersant effectiveness test. The experimental results indicated that mixing at levels of 200 rpm or higher resulted in positive effects on both the extent of hydrocarbon dispersion (80 to 90% of oil dispersed) and the biodegradation of the oil phase (50 to nearly 100% degraded), while the modeling results, taken along with the experimental results, indicated smaller dispersed phase droplet sizes and promoted more efficient biodegradation. Full article
(This article belongs to the Special Issue Hazardous Waste Treatment)
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16 pages, 4469 KiB  
Article
Valorization of Waste Glycerol to Dihydroxyacetone with Biocatalysts Obtained from Gluconobacter oxydans
by Lidia Stasiak-Różańska, Anna Berthold-Pluta and Pritam Kumar Dikshit
Appl. Sci. 2018, 8(12), 2517; https://doi.org/10.3390/app8122517 - 06 Dec 2018
Cited by 14 | Viewed by 6083
Abstract
Waste glycerol is the main by-product generated during biodiesel production, in an amount reaching up to 10% of the produced biofuel. Is there any method which allows changing this waste into industrial valuable compounds? This manuscript describes a method for valorization of crude [...] Read more.
Waste glycerol is the main by-product generated during biodiesel production, in an amount reaching up to 10% of the produced biofuel. Is there any method which allows changing this waste into industrial valuable compounds? This manuscript describes a method for valorization of crude glycerol via microbial bioconversion. It has been shown that the use of free and immobilized biocatalysts obtained from Gluconobacter oxydans can enable beneficial valorization of crude glycerol to industrially valuable dihydroxyacetone. The highest concentration of this compound, reaching over 20 g·L−1, was obtained after 72 h of biotransformation with free G. oxydans cells, in a medium containing 30 or 50 g·L−1 of waste glycerol. Using a free cell extract resulted in higher concentrations of dihydroxyacetone and a higher valorization efficiency (up to 98%) compared to the reaction with an immobilized cell extract. Increasing waste glycerol concentration to 50 g·L−1 causes neither a faster nor higher increase in product yield and reaction efficiency compared to its initial concentration of 30 g·L−1. The proposed method could be an alternative for utilization of a petrochemical waste into industry applicated chemicals. Full article
(This article belongs to the Special Issue Hazardous Waste Treatment)
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Review

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26 pages, 3882 KiB  
Review
Research and Regulatory Advancements on Remediation and Degradation of Fluorinated Polymer Compounds
by Nathaniel J. Olsavsky, Victoria M. Kearns, Connor P. Beckman, Pamela L. Sheehan, F. John Burpo, H. Daniel Bahaghighat and Enoch A. Nagelli
Appl. Sci. 2020, 10(19), 6921; https://doi.org/10.3390/app10196921 - 02 Oct 2020
Cited by 12 | Viewed by 9709
Abstract
Per- and polyfluoroalkyl substances (PFAS) are a class of chemicals used in various commercial industries to include food packaging, non-stick repellent, and waterproof products. International environmental protection agencies are currently looking for ways to detect and safely remediate both solid and aqueous PFAS [...] Read more.
Per- and polyfluoroalkyl substances (PFAS) are a class of chemicals used in various commercial industries to include food packaging, non-stick repellent, and waterproof products. International environmental protection agencies are currently looking for ways to detect and safely remediate both solid and aqueous PFAS waste due to their harmful effects. Incineration is a technique that disposes of chemicals by breaking down the chemicals at high temperatures, upwards of 1400 °C. Incineration has been used on other related compounds, but PFAS presents a challenge during thermal degradation due to the molecular stability and reactivity of fluorine. Research on the efficacy of this method is currently limited, as the degradation byproducts of PFAS are not fully characterized. Current research is mostly focused on the development of benchtop methods for the safe remediation of solid PFAS waste. Aqueous fire fighting foams (AFFFs) have garnered significant attention due to extensive use since development in the 1960s. Numerous communities that are closely located near airports have been shown to have higher than average PFAS contamination from the repeated use. Detection and remediation of surface, subsurface, and wastewater have become a primary concern for environmental agencies. Use of electrochemical techniques to remove the PFAS contaminants has shown recent promise to help address this issue. Critical to the remediation efforts is development of standardized detection techniques and the implementation of local and international regulations to control the production and use of fluorinated products. No single solution has yet been developed, but much progress has been made in recent years in governmental regulation, detection, and remediation techniques. Full article
(This article belongs to the Special Issue Hazardous Waste Treatment)
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25 pages, 485 KiB  
Review
Phytoremediation and Bioremediation of Pesticide-Contaminated Soil
by Divine N. Tarla, Larry E. Erickson, Ganga M. Hettiarachchi, Sixtus I. Amadi, Madhubhashini Galkaduwa, Lawrence C. Davis, Asil Nurzhanova and Valentina Pidlisnyuk
Appl. Sci. 2020, 10(4), 1217; https://doi.org/10.3390/app10041217 - 11 Feb 2020
Cited by 48 | Viewed by 10909
Abstract
Management and destruction of obsolete pesticides and the remediation of pesticide-contaminated soil are significant global issues with importance in agriculture, environmental health and quality of life. Pesticide use and management have a history of problems because of insufficient knowledge of proper planning, storage, [...] Read more.
Management and destruction of obsolete pesticides and the remediation of pesticide-contaminated soil are significant global issues with importance in agriculture, environmental health and quality of life. Pesticide use and management have a history of problems because of insufficient knowledge of proper planning, storage, and use. This manuscript reviews recent literature with an emphasis on the management of obsolete pesticides and remediation of pesticide-contaminated soil. The rhizosphere of plants is a zone of active remediation. Plants also take up contaminated water and remove pesticides from soil. The beneficial effects of growing plants in pesticide-contaminated soil include pesticide transformation by both plant and microbial enzymes. This review addresses recent advances in the remediation of pesticide-contaminated soil with an emphasis on processes that are simple and can be applied widely in any country. Full article
(This article belongs to the Special Issue Hazardous Waste Treatment)
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