Journal of Hazardous, Toxic, and Radioactive Waste

Recently, numerous studies have been carried out on the architecture of energy-efficient and environmentally friendly construction materials. In this study, there was studied the content of the strontium aluminate europium and dysprosium doping (SAEDD) on the properties of cement mortar. Portland cement was tested with 10%, 20%, and 30% SAEDD. The mortar cube specimens were then reacted with 5% hydrochloric (HCl) and nitric acid (HNO₃) and with 5% of sodium sulfate (Na₂SO₄) to test the material's strength and chemical stability. The mortar samples that were supplemented with 20% of SAEDD gave the best luminescence that lasted ≤10 h. The compressive strength of the mortar cubes was improved by replacing cement with 20% of the SAEDD. In addition, X-ray diffraction (XRD), Fourier-transform infrared (FTIR) and energy dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM) were used to study the performance of the SAEDD. From the results, the use of strontium aluminate (SrAlO₄)-doped phosphors in dark mortar gave luminescence ≤10 h. This work could open a novel gateway in chemistry and novel aspects of chemical engineering, possibly helping to sustain green environments.

Global demand for power generation has had an immense impact on thermal power plants that has caused a problem with fly ash disposal. Unless utilized suitably, fly ash deposits turn valuable land into dumping grounds that pose a risk to the environment and human health. In this study, the effectiveness of Class C fly ash (CFA) incorporated in a flexible pavement was investigated, which was based on laboratory and field investigations along with an environmental impact assessment. The laboratory experimentation included durability and repeated load triaxial (RLT) tests and in the field, falling weight deflectometer (FWD) tests were conducted. The test sections with a fly ash layer and a control section were constructed in the field to assess the viability of construction and service life. For the fly ash layer, the back-calculated modulus values were 4.3 and 6.5 times greater than the base and subbase of the control section, respectively. The fly ash section exhibited a service life ratio (SLR) of 1.72 compared with the control section under standard loading conditions. The energy consumed, greenhouse gas (GHG) emissions produced, and capital cost incurred in the construction of the fly ash section were reduced by 67%, 59%, and 25.7%, respectively, compared with the control section. The bulk application of fly ash was advantageous and sustainable due to better structural performance and a significantly reduced environmental impact compared with conventional base and subbase layers.

Printed circuit board (PCB) fiber in concrete is a novel and radical concept in durable concrete because it helps to reduce environmental pollution and resolve waste management issues. Concrete made from e-waste fiber is a substitute for conventional concrete because it improves the properties of traditional concrete and decreases the quantity of electronic waste dumped into nature. This paper investigates the effect of using a PCB after extracting nonmetallic parts. The remaining parts were made into fiber and added to the concrete at 1%, 2%, and 3% of the cement’s weight. The e-waste PCB fiber of aspect ratios 10 and 20 was added to M40-grade concrete with a w/c ratio of 0.45. The fresh and hardened properties of the PCB fiber concrete were investigated and compared with those of conventional concrete after 7, 14, and 28 days of curing. The experimental results revealed that electronic waste fiber concrete showed increased strength compared with control concrete. Ultrasonic pulse velocity and rebound hammer tests were also performed to evaluate the quality of e-waste PCB fiber concrete. The rebound hammer test results were compared with those of the compressive strength of e-waste fiber concrete, and both results were found to be in close agreement. This study also found that recycling hazardous electronic waste generated in the construction industry would help manage waste better and prevent environmental problems caused by electronic waste.

In this study, the aim has been to investigate the efficacy of Indian marble dust–bentonite (MD–B) subjected to electrolyte concentrations (NaCl, NaOH, and HCl) to be used as an alternative to sand–bentonite (S–B) mixes in landfill liner. The major concern of the engineered landfill liner design is to retard the migration of hazardous leachate solutions into the groundwater. Geotechnical properties, such as plasticity index, compaction characteristics, permeability, and swelling percentage, are the most important criteria to be examined for any landfill liner materials permeated with electrolyte concentrations. Hence, this study evaluates the behavior of both MD–B and S–B mixes subjected to varying concentrations of salt (i.e., NaCl of 0.1, 0.5, and 1 N), alkaline (i.e., NaOH of 1, 1.5, and 2 N), and acidic (i.e., HCl of 1, 1.5, and 2 N) solutions. The results reveal that the behaviors of MD–B and S–B mixes are similar, subjected to various concentrations of NaCl, NaOH, and HCl solutions. It has been confirmed that MD–B is a suitable alternative to S–B mixes even under different physicochemical conditions. However, marble dust and sand need to be incorporated with at least 40% and 60% bentonite to encounter the desired effect of electrolyte concentration for maintaining the coefficient of permeability (<10⁻⁷ cm/s) and other parameters, such as plasticity and swelling characteristics, when used as a landfill liner material. Physicochemical analyses [pH and electrical conductivity (EC)] and microanalyses [X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDAX)] were also performed. The cost effectiveness of marble dust for large-scale utilization is also discussed.

Abstract

Water systems contain fine sediment as a natural phenomenon. The main cause of ecological deterioration is undesirable fine sediment. Fine sediment comprises inorganic particles of sand, silt, and clay that are less than 2 mm in diameter. Fine sediment is considered to be pollutant in water bodies (rivers, streams, lakes, and reservoirs). Sediment has various channel and nonchannel sources. Fine sediment can alter the hydraulics of rivers and their morphology. It has detrimental effects on reservoir storage and function, can degrade the food chain, and affects the reproduction of aquatic animals, which ultimately affects river ecosystems. The deposition of fine sediment renders waterways difficult to navigate and hinders recreational uses. It degrades the water quality for drinking purposes, wildlife, and affects the land surrounding the bodies of water. The intrusion of fine sediment is a global problem, and with time, researchers will understand the effects on biological and physical processes. Comprehension may help scientists minimize the effects of fine sediment on river ecosystems by considering various disciplines such as ecology, hydraulics, fluvial geomorphology, and hydrochemistry. Many researchers have investigated fine sediment in rivers. This paper reviews the literature, focusing on the consequences of intrusion on the river ecosystem, river health, and associated hydraulic parameters.

Practical Application

The study of FSI is a major application in applied environmental science. It is applied to gain as complete an understanding of the physical and biological processes as possible. It has been applied to estimate the trap efficiency and to determine the live storage capacity of reservoirs. Excess fine sediment is a primary reason for the failure of water bodies, so it is important to control it and maintain necessary fluid properties such as viscosity, specific weight, and the optical properties of water. Proper control of fine sediment in bodies of water maintains both the survival and growth of plants, and the food chain of aquatic animals. It is important to control excess fine sediment to avoid turbidity in water. In brief, the topic has applications in various fields such as evaluating river health, live reservoir capacity, growth of flora and fauna, and water quality standards.

Although biosorption is an effective technique for removing potentially toxic elements (PTEs) from wastewater, it causes secondary pollution in the form of used adsorbents ending up in landfills, leading to PTE leaching into groundwater. This study used two kinds of adsorption process waste ash - adsorbed paper ash (APA) and adsorbed mulch ash (AMA)- as an additive to mortar, which added an environmental and economic value through energy recovery during the ashing process following the ideas of the waste to energy and circular economy, in addition to immobilizing the PTEs into a cement matrix aiming to close the loop of pollution. This study focused on investigating the leaching of PTEs (Cd, Zn, Cu, and Pb) at five different artificial adsorption initial concentrations (0.5, 1, 5, 10, and 50) mg/L and three different mixing weight proportions of ash with cement, as well as their pH-dependent behavior, to ensure environmental safety. To detect the release of PTEs from the mortar ash mixes, the ICP-OES technique was used. The study concluded that the used adsorbent ashes potentially could be environmentally acceptable as an additive for mortar because their ability to stabilize PTEs based on leaching values of (Pb, Zn, and Cu) was below the permissible limit under the nonhazardous waste category. Only Cd leached higher than the regulatory limit in the case of very low acidity when pH was lower than 0.

This study investigated the removal of hexavalent chromium [Cr(VI)] from a simulated industrial effluent that used electrocoagulation (EC) technology. Experimental runs were conducted in a laboratory-scale batch EC cell with vertically rotating cylindrical aluminum (Al) electrodes, which imparted the required velocity to avoid a concentration gradient within the treatment unit. The independent variables, current, influent pH, rotational speed (rpm), and initial Cr(VI) concentration [Cr(VI)_i], that affected Cr removal efficiency were optimized through a central composite design (CCD) that was initiated by the response surface methodology (RSM). The ANOVA factor of the CCD indicated that the investigated independent variables had a significant impact on the responses, such as Cr(VI) removal and specific electrical energy consumption (SEEC). Four factors, which each had three levels were considered: (1) Cr(VI)_i (15–35 mg/L); (2) applied current (1–3 A); (3) initial pH (4–6); and (4) rotational speed of the electrode (40–100 rpm). High R² values were observed for Cr(VI) (98.12%) and SEEC (98.09%), which validated the regression equations that were generated in this study. Optimizing the performance factors for the treatment process was targeted to achieve maximum Cr(VI) removal and minimum SEEC. Under the optimum condition, the Cr(VI) removal efficiency, SEEC, and operating cost were 89.808%, 0.14 kW · h/g Cr(VI) removed, and USD 0.728/m³, respectively. The optimum values that were obtained for the selected input variables were Cr(VI)_i of 4.99 mg/L, current of 2.189 A, initial pH 4.5, and a rotational speed of 72.46 rpm.

Phytoremediation is considered an effective and economical method for metal recovery along with removing toxic chemicals from contaminated soil. The studies done so far concentrate on the factors responsible for uptake of a single heavy metal from the soil. However, in nature, pollutants are generally found as a mixture of various heavy metals. Furthermore, research related to phytoremediation of mixed contaminant sites such as landfills are focused on the selection of plants rather than heavy metal uptake pattern. Thus, it becomes important to understand how phytoremediation processes change in remediating a mixed pollutant with respect to removing single metal contamination. In the present study, the phytoremediation potential of Indian marigold is compared when the soil–metal concentration is individually spiked with Cd, Pb, Ni, and Cr salt solution against the remediation potential of marigold when the soil–metal concentration is spiked by landfill leachate (mixture of heavy metal) collected from the Gazipur landfill site, New Delhi, India. The result shows that the rate of metal accumulation is highly sensitive to metal concentration and metal interactions. When the soil–metal concentration is spiked with metal salts, their respective total uptake by marigold follows the order Cd > Pb > Cr > Ni with BCF > 1, TF > 2, and EC_f > 1 for Cd and Cr making marigold a hyperaccumulator and with BCF < 1, TF > 2, and EC_f < 1 showing an avoidance toward uptake of Pb and Ni. When the heavy metal accumulation pattern is studied for soil–metal concentration spiked by landfill leachate, the order of accumulation follows Cd > Cr > Pb > Ni with BCF > 1, TF > 2, and EC_f > 1, and marigold is an accumulator for Cr. BCF > 1, TF < 2, and EC_f < 1 stabilizes Cd and Pb add by leachate and there is no uptake of Ni after reaching a tolerance level of 555 µg/kg. The study is useful for understanding change in heavy metals uptake from heterogeneous sites for better landfill management.

Dye pollutants in surface water can inflict serious damages for aquatic life and human health. In the present research, the efficacy of banana peel as biowaste adsorbent for the removal of cationic methyl green dye (MGD) and basic blue 41 dye (BB 41) from synthetic wastewater has been investigated. The banana peel adsorbent (BPA) was synthesized and characterized before and after the adsorption process by scanning electron microscope (SEM), and infrared spectroscopy (FTIR). According to SEM analysis images, the surface structure of BPA is of microrough texture and heterogeneous nature. The spectrum of FTIR analysis referred to the existence of different peaks belonging to various functional groups, such as hydroxyl, carboxylic, and amines. Adsorption experiments were conducted to investigate the effects of various parameters [i.e., contact time, pH, adsorbent (BPA) dose, and the initial concentration of dye] on the removal rate of each dye, and to obtain the optimum operating conditions. The maximum removal efficiency of MGD and BB 41 at optimal operating conditions, when adsorbed onto BPA, were found to be more than 99%. Three isotherm models (Langmuir, Freundlich, and Temkin) were utilized to exhibit the adsorption process. For both dyes, the Langmuir model was found to have greater suitability with adsorption experiment data. The kinetics of the MGD and BB 41 adsorption onto BPA were examined by utilizing pseudo-first-order, pseudo-second-order, and intraparticle diffusion kinetics models. Kinetic calculations revealed that the adsorption of MGD and BB 41 on BPA follow the pseudo-second-order kinetic. The thermodynamic parameters (free energy, enthalpy, and entropy) were determined. The regeneration and reusability study of BPA was carried out and revealed that it can be efficiently reused until the fifth cycle. The simplest method was used for the synthesis of an efficient adsorbent (BPA). For the first time, BPA proved to be an excellent bioadsorbent for the removal of aqueous MGB and BB 41 dyes, as it achieved nearly complete removal.

The monitoring of radiation levels in human-inhabited environments is imperative to avoid public exposure. The activity concentration of primordial radionuclides at Ojota Chemical Market was measured to determine the in situ activity of ²³⁸U, ²³²Th, and ⁴⁰K in ambient air using an RS-125 Super SPEC gamma spectrometry with global positioning system. The measured absorbed dose rates ranged from 28.35 to 106.55 nGy/h, giving an average value of 70.46 nGy/h. The estimated absorbed dose rate spanned from 22.25 to 101.03 nGy/h with a mean value of 65.50 nGy/h. The average concentrations of ⁴⁰K, ²³⁸U, and ²³²Th were 458.55, 30.26, and 54.77 Bq/kg respectively. The outdoor and indoor absorbed doses averaged 80.39 and 132.55 µSv/y, respectively, and the mean value of excess lifetime cancer risk was 0.26 × 10⁻⁶ µSv/y. The external and internal hazard index averaged 0.39 and 0.47, respectively, and the mean annual gonadal dose equivalent was 465.14 µSv/y. The radium equivalent dose averaged 143.45 Bq/kg while the gamma representative index averaged 1.05. The absorbed dose rate, mean concentration of ⁴⁰K and ²³²Th, the average values of excess lifetime cancer risk, the annual gonadal dose equivalent, and the gamma representative index were above the permissible limit as set by the radiation regulatory agencies. The study concluded that the human activities in Ojota Chemical Market might have increased the radiation burden of the community.

The synergistic and antagonistic effects that are involved in the adsorption of metronidazole (MNZ) and ciprofloxacin (CIP) as single and binary mixtures were investigated. First, a chitosan-modified graphene oxide (CS–GO) adsorbent was synthesized (as beads) and characterized using Fourier-transform infrared spectroscopy (FTIR), Bruaneur–Emmett–Teller (BET), X-ray diffraction (XRD), and scanning electron microscopy (SEM) analysis. The FTIR graph showed amino bond formation between a carbonyl with an amino (NH₂) group and intermolecular hydrogen (H) bond between the hydroxyl (OH) and carboxyl (COOH) with the NH₂ group of GO and CS, respectively. In addition, the SEM and XRD diagrams revealed a good attachment between CS and GO. The kinetic sorption experiments revealed that adsorption followed pseudo second-order with a higher rate constant for CIP than MNZ. In a single solute system, adsorption followed the multilayer Langmuir isotherm with maximum adsorption capacities of 29.76 and 102 mg/g for MNZ and CIP, respectively. In the binary mixture, MNZ and CIP showed antagonistic effects with a respective decrease in adsorption capacities to 13.15 and 4.3 mg/g, respectively. The major interactions inferred were π–π electron donor–acceptor (EDA), H bond, and hydrophobic interactions for both antibiotics along with electrostatic and cation–π interactions for CIP. In addition, the adsorbent showed good disinfection capability for secondary treated effluents, and the disinfection potential was further increased by the addition of a small amount of silver (Ag). The CS–GO showed good performance and stability in the removal of CIP and MNZ in single and binary mixture experiments. However, the repeated use of the adsorbent showed a decrease in the removal of CIP and MNZ, which requires further investigation.

Flooding of contaminated sites can displace and disperse hazardous materials, and the threat from flooding at several sites is growing. To address this, we present and apply a novel risk-informed framework for identifying and assessing the contaminated sites in the contiguous US that are potentially exposed to inundation in the short term due to coastal and inland flooding, and in the long term due to sea-level rise. We propose an approach to develop insights regarding the contaminated site locations that uses inundation likelihood, Social Vulnerability Index (SVI), and population in the vicinity of each contaminated site. This approach assigns an Insight Score (I-Score) that amalgamates these three factors. Our study results show that a considerable number of contaminated sites with relatively high likelihoods of inundation are located in areas with a high SVI and high population. We present a density-based representation of the I-Score for identifying potential hotspots. The efficient and practical framework proposed in this study could support policymakers in prioritizing the contaminated sites for further assessment and action.

Given the annual generation of huge quantities of mercury waste worldwide, mercury exposure is a universal issue. Mercury waste from the oil and gas industry should be of concern, owing to the presence of mercury during the whole oil and gas life cycle, as well as the industry’s importance and magnitude. Particular attention should be given to mercury waste from the Association of Southeast Asian Nations (ASEAN) oil and gas industry because of the high mercury concentrations in the regional petroleum deposits and the upcoming growth of the upstream and downstream subsectors. Therefore, this study aims to explore: (1) how mercury waste from the ASEAN oil and gas industry is managed and (2) the extent to which waste management facilities in the ASEAN can handle such waste. The paper starts with a description of some mercury forms occurring in oil and gas operations and the current situation of the ASEAN oil and gas sector. It then presents the legal frameworks and facilities for mercury waste management in the region and ends with a case study analysis of Best Mercury Technology (BMT) Thailand—a mercury waste management facility. The findings show that most countries lack specific laws on mercury waste management, while some have not legally identified mercury waste from the oil and gas industry and set thresholds for determining mercury waste as well as specific mercury emission standards for oil and gas activities. Other challenges include the lack of proper mercury waste management facilities or facilities that cannot recover mercury from the waste in some nations, including those having a strong oil and gas industry. The case study analysis demonstrates that BMT Thailand’s operations adhere to the national legal requirements as well as many international standards and conventions, indicating the availability of a world-class facility in the ASEAN to cater for the regional demand.

Uncontrolled municipal solid waste, construction waste, and sediments from streams release fine sediments into sewer and urban drainage systems. Sediment transportation and deposition in sewers and urban drainage channels are major issues faced by nations across the globe. Earlier investigations on the invert trap mainly focused on varying the flow depth, particle size, and slot opening. There are limited studies available on different invert trap geometries, which play an important role in sediment trapping. The present study focuses on invert traps with varying the geometry setup with a base geometry (top width as 32 cm, depth as 28 cm) of a rectangular chamber with a trapezoidal base (BG). The changes considered include an arc passing through three points (G1), an isosceles triangle (G2), and a right triangle (G3) for different slot openings (9 and 15 cm) and flow depths (2, 3, 4, and 5 cm) for natural sewer solids (NSS1). In the current study, two-dimensional (2D) computational fluid dynamics (CFD) modeling was performed using volume of fluid (VOF) and discrete phase model (DPM) along with a realizable k−ɛ turbulence model in fluent software for flow field simulation and retention efficiency in the considered geometries. Flow depth, slot opening, and the geometry of the invert trap are parameters that affect trap efficiency. The investigation shows that the 2D CFD VOF–DPM model predicts better trap efficiency for NSS1 with particle size (diameter ranges 0.15–0.30 mm) when compared with Mohsin and Kaushal’s experimental data. In all the considered geometries, the right triangle (G3) was observed to have the maximum trap efficiency for both the slot openings and any given flow depth.

Abstract

This research presents a numerical investigation that employs a continuous adsorptive barrier (CAB) near heavily contaminated groundwater. The source is classified as a heavy metal finite point source that is found in landfills. A decision maker could benefit from the CAB design charts that are produced in this research in table and chart forms. Based on the results, the cost of the barrier installation (C_CAB) and the estimated dimensions could be determined by a decision maker for a known finite source concentration at the site. To accomplish this, the problem is simplified and discretized using the finite-difference technique to solve a two-dimensional (2D) transport model, and the model’s accuracy is then tested against a variety of real-world scenarios. The established model (PRBFD) was used to simulate heavy metal pollution that used adsorption as the natural attenuation. Later, the required aquifer length and width for a 4-year simulation were plotted. Then, it was discovered that natural remediation took longer to reach the remediation goal, and therefore, to meet the requirements, a reactive barrier was considered. Zero-valent iron (ZVI), which is a reactive material, is introduced next to the contaminant to absorb heavy metals in a CAB. Subsequently, a plot of the maximum relative concentrations in the longitudinal and transverse directions is generated from the data for peak concentrations that are obtained at various time (t) intervals, and the requisite CAB dimensions [e.g., length (L_B) and width (W_B)] are computed where the cost incurred in the system is calculated. Finally, a sensitivity analysis is performed to determine the impact of sensitive hydraulic parameters on the barrier dimensions and its design cost, and various design charts are generated for the most probable cases, which could allow a decision maker to identify the barrier dimensions for any known source concentration value.

Practical Applications

A number of heavy metals, such as arsenic (As), lead (Pb), zinc (Zn), copper (Cu), and cadmium (Cd) adversely affect human health. Toxic metals could easily be transmitted to the human body by food or water, because heavy metals naturally transfer from the soil to crops and then into groundwater. This research was designed so that a decision maker could determine the size of the reactive barrier, along with the design cost, against known maximum concentrations of hazardous metals at the source; and permissible concentrations of the same metal contaminant at the barrier exit face without the use of mathematical modeling.