Journal of Hazardous, Toxic, and Radioactive Waste

The world is being burdened with excessive usage and indiscriminate dumping of plastic waste. The world presently produces nearly 400 million tons of plastic every year: less than 10% is recycled, 8% is incinerated, and the rest is dumped in landfills. The reduction of plastic has become a significant challenge due to the lower degradation rate. A substantial amount of this waste turns out to be litter in the oceans or landfills due to limited recycling or reuse in an environmentally friendly way. Compared with incineration and landfilling processes, recycling plastic waste is more productive. Hence, the utilization of plastic waste in civil engineering applications is found to have the maximum potential for consumption in bulk quantities, which can also help in minimizing disposal issues. This article reviews the characteristic properties of waste plastic and its utilization in civil engineering applications, specifically in bricks, blocks, road embankment, pavement layers, plastic aggregates, and voided slabs, which are systematically comprehended with various international standards. The use of waste plastic either retained or slightly improved the properties of the materials to which it is added. The paper also discusses the leaching properties of different kinds of plastic waste; their limitations along with probable opportunities associated with plastic waste utilization.

Solid waste management (SWM) is a global problem that is closely related to everyone in the world. Rapid urban and population growth, and improved living standards have resulted in high rates of municipal solid waste (MSW) generation in urban areas. In India, approximately 70%–90% of allocated budgets are spent on waste collection and transportation and a minuscule budget is available for treatment and disposal. The selection of an appropriate combination of solid waste treatment facilities for cost-effective and efficient waste management is a complex problem. In this study, six cases will be made based on individual or combinations of available treatment and disposal facilities, and five scenarios will be made based on the characterization of MSW, which vary from 0% to 100% in the treatment of MSW for a life cycle cost assessment (LCCA) for an available option. The results reveal that the total cost of the waste treatment option in Scenario 1 has a maximum cost of treatment (INR 1,197/t) when all collected wastes were disposed of in facilities without segregation. Similarly, Case V (Sanitary landfill_Composting_Refuse derived fuel) (SLF_COM_RDF) in Scenario 5 has a minimum cost of treatment (INR 389/t), which is 7.2 times higher than the cost of open dumping (OD). This study will show that the COM treatment facility is an important and cost-effective treatment facility for compressive SWM. The results demonstrate that the life cycle costing (LCC) technique is suitable for the long-term planning of cost-effective MSW management for urban cities.

This work was focussed on synthesizing a polyvinylidene fluoride (PVDF)–polytetrafluoroethylene (PTFE) hybrid flat sheet membrane using a nonhazardous solvent dimethyl sulfoxide (DMSO) for ethanol–water separation via vacuum membrane distillation (VMD). The base polymer (PVDF) concentrations were varied from 12 wt% to 16 wt% and the copolymer (PTFE) loading were ranged from 1 wt% to 2 wt% (e.g., 1.0 wt%, 1.5 wt%, and 2.0 wt%). The morphological characteristics, porosity, and contact angle (CA) were examined for the synthesized membranes. An increased CA was observed when PTFE loading was increased in the dope solution. The addition of PTFE to the dope solution efficiently diminished the formation of micro voids and increased the hydrophobicity of the membrane with improved characteristics. Membrane pore size, porosity, and thickness increased significantly from 0.17 µm to 0.21 µm, 48.37% to 67.79%, and 79.31 µm to 107.62 µm, respectively, within the studied range. A pure PVDF membrane CA of 88° was increased to 117.3° for 2 wt% loaded PTFE in PVDF. The synthesis of PVDF–PTFE hybrid membranes that used DMSO as a solvent and distilled water as a nonsolvent in a coagulation bath appears to be viable for membrane preparation via phase inversion to provide a reliable and sustainable separation process with a safer environment. The performance of the synthesized membrane was studied for flux and the separation factor. The maximum ethanol flux and separation factor obtained were 11 kg/m²/h and 7.0, respectively. This work suggests that the PVDF–PTFE hybrid flat sheet membranes could be used for ethanol separation in VMD.

Numerous studies have been conducted to remove lead (Pb) from the soil. This study proposed a novel approach that used carbon dioxide (CO₂) as a cleaning reagent for the remediation and immobilization of Pb contamination in sandy soil. First, contaminated soil with 5,000 ppm lead nitrate (Pb(NO₃)₂) was prepared in a setup box. Then, sodium hydroxide solution (NaOH) (2 M) was injected into the soil to react and create sodium tetrahydroxyplumbate (II) [Na₂[Pb(OH)₄]]. The CO₂ gas was then introduced into the contaminated soil to react, which resulted in the formation of lead carbonate (PbCO₃) minerals. The soil samples were collected from across the setup box at different distances and depths from the injection tube after various times. PbCO₃ crystals were identified as cerussite by scanning electron microscope (SEM) and X-ray diffraction (XRD) investigations. Cerussite had poorer solubility under acidic conditions (e.g., 0.5% at pH 7 and 6.25% at pH 5), according to the results of mineral durability. PbCO₃ precipitated more near the injection tube during mineral sequestration and CO₂ carbonation. The highest precipitation was 0.12% with an inlet CO₂ rate of 0.7 L/min. In conclusion, Pb was removed from the soil at a rate of 99%. The permeability of the contaminated soil was reduced (from 4.6 × 10⁻³ to 3.7 × 10⁻⁴ cm/s) as PbCO₃ deposition increased between soil particles, although this did not affect the soil hydraulic conductivity. The results demonstrated the efficacy of CO₂ use as a unique technique to remove Pb from the soil.

Pharmaceutical industries are known for their batch operations using wide varieties of solvents, reactants, and catalysts. To study the efficiency of production process within a pharmaceutical industry, synthesis of an active pharmaceutical ingredient (API) namely, aliskiren hemifumarate (AH) was analyzed, which is a blood-pressure-lowering medicine. The process mass index, a metric to assess the efficiency of AH production, was calculated. It was found that the process mass index for the AH synthesis was 109 kg raw materials/kg of product, which showed the amount of waste generated during its synthesis. In addition, a life cycle assessment (LCA) study was performed on AH synthesis to understand the overall impacts throughout the life cycle of the product. The results of the LCA revealed that among the various raw materials required, the metal catalyst palladium and solvent dichloromethane were found to have the highest impact on the environment as well as on human health. Both the metal catalyst and solvent play important roles in improving the sustainability of the production. Therefore, the study was extended by comparing the base case with two scenarios of process modification, replacing the toxic palladium with other catalysts and replacing dichloromethane with ethanol, acetone, and benzene. The results of the modified case showed a reduction in the impacts on human health by 97.7%, on the ecosystem by 98.3%, and on resources by 74.1%, thus enhancing the sustainability of the overall process.

This research investigates the use of avocado (Persea americana) seed coat as a potential adsorptive material for removal of Ni(II) and Cr(VI) from aqueous solutions using a batch experimental technique of adsorption. Fourier transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive x-ray spectroscopy techniques were used to characterize the biosorbent. Biosorbent dose, pH, contact time, and concentrations of metal ions were varied to probe the adsorption efficiency of the avocado seed coat biosorbent. The effects of competing ions on the biosorption of nickel and chromium from aqueous solutions were also explored. Adsorption characteristics were well explained by the Elovich and Langmuir models with maximum monolayer coverages of 10.38 mg · g^–1 (Ni²⁺) and 12.25 mg · g^–1 (Cr⁶⁺). Removal of the metal ions was slightly inhibited by the presence of interference ions. The biosorption process was nonspontaneous and exothermic. Recovery of Ni(II) was more promising using ethylenediaminetetraacetic and hydrochloric acid than was the recovery of Cr(VI). Overall, avocado pear seed-coat powder is a good adsorbing material for removal of Ni(II) and Cr(VI) from water.

Thermal power plants in India produce a large quantity of fly ash, which is harmful to the environment. Underutilization of fly ash and the scarcity of natural minerals have created the need for an unusual construction strategy to prevent huge waste dumps on valuable land and to preserve fast-depleting resources. A study was conducted to determine the efficacy of lime-stabilized fly ash blended with quarry fines as flexible pavement subbase materials. The laboratory investigations were conducted to determine compaction characteristics, unconfined compressive strength, California bearing ratio (CBR), and durability to obtain the optimal quarry fines, fly ash, and lime (QFL) mix. The durability of QFL mixes was studied using 12 wetting–drying cycles. Using the strength and durability criteria specified by the Indian Road Congress, the optimum mix proportion of 40Q:60F+3L was determined. Pavement analyses were performed using the IITPAVE program. The QFL mix was observed to be superior to conventional granular subbase (GSB) layer material in terms of service life and cost-effectiveness. A field investigation was carried out on trial test sections constructed using the optimum QFL mix and GSB in the subbase layer of pavement. Field dry density and dynamic cone penetrometer (DCP) tests were performed on the compacted subgrade and subbase layers to assess the desired quality assurance in the construction of test sections. The early structural performance assessment of pavement sections using a falling weight deflectometer (FWD) test indicated that QFL could effectively replace conventional GSB.

The most widely used pesticides for residential areas and agriculture purposes, which belong to the organophosphates and synthetic pyrethroids, were evaluated in this study for their LC₀ toxicity. In an aquatic environment, these pesticides are highly toxic to nontargeted organisms. Oreochromis niloticus (Nile tilapia) was selected for the bioassay tests due to its presence in the trophic levels and high bioaccumulation of the toxicants. This study evaluated the impact of pesticides on the activity of alkaline phosphatase (ALP) enzymes in the brain, gills, and muscles of O. niloticus. The fish were exposed to the LC₀ concentrations of malathion (1.425 ppm), chlorpyrifos (0.125 ppm), and λ-cyhalothrin (0.0039 ppm) for 24 and 48 h. For biochemical assays, malathion, chlorpyrifos, and λ-cyhalothrin measurements were carried out using spectrophotometry. ALP activity in the brain and gills was elevated and showed significant inhibition (p < 0.05) at 24- and 48-h exposure, respectively. For the muscle tissues, a statistically important (p < 0.05) inhibition was recorded for the activity of ALP after 24- and 48-h treatments. The highest (+138%) and the lowest (+28%) enhancement in ALP activity were reported in the gills and brain tissues, which were treated with chlorpyrifos and malathion, respectively. The minimum and maximum reduction in ALP levels were noted in the 48- and 24-h malathion-treated muscle tissues, respectively. The data for the muscle tissue sample showed good consistency, because inhibition in ALP activity was noted. Therefore, the assessment of ALP activity in different organs and tissues in fish for the detection of chemical hazards in the environment is recommended. These findings confirmed that pesticides should be consistently monitored in the environment, to lower the pollutant stress on nontargeted organisms, especially fish, because the pesticides have a toxic effect on the health of aquatic organisms.

In this study, the ecotoxicological effects posed by bulk of the material obtained from landfill mining, that is, fine fraction (<10 mm), were assessed by performing bioassays tests with the aim of using the data in geoenvironmental applications, such as landfill biocover to control residual methane emissions from old landfills. Attention is mainly focused on the possible interaction of fine fractions with the test organism. The tested eluates of fine fraction exhibited low acute toxicity toward the bacteria Allivibrio fischeri and Escherichia coli, the marine rotifer Brachionus plicatilis, and brine shrimp Artemia salina. The eluates showed slight inhibitory effects on the germination of seeds of lettuce Lactuca sativa L. and timothy Phleum pratense L., and no inhibitory effects on germination of seeds of perennial ryegrass Lolium perenne L. The fine fraction studied in the present study can be characterized as acutely nontoxic or slightly acutely toxic. Correlation analysis revealed moderate positive correlation between lethality of rotifers and soluble content of organic compounds in the fine fraction eluates. In conclusion, the conducted experiments demonstrated that the usage of fine fraction for onsite applications such as landfill biocover may pose minimal environmental consequences, based on the ecotoxicity assessment.

Biokinetic parameters have been extensively used to decide on the treatment methodology of a waste. Although literature reports studies on biokinetic parameters in wastewater treatments, their significance in the anaerobic treatment of municipal solid waste is not well explored. Furthermore, to the best of authors’ knowledge, the applicability of biokinetic parameters in estimating the gas emission characteristics of a waste have not been reported anywhere. TOUGH2 Landfill Bioreactor Model (T2LBM), a module for the TOUGH2 simulator that provides simulation capabilities for the process of biodegradation of waste governed by a modified form of Monod’s growth model, is used to investigate the same. As an initial step, numerical modeling with T2LBM is carried out to validate the gas emission characteristics of an anaerobic bioreactor that degrades a mechanically and biologically treated (MBT) waste. A good match for the gas yield and waste settlement proves the model’s capability to simulate the process of biodegradation. A parametric study of the biokinetic parameters (namely the yield coefficient, saturation constant, growth rate, and death rate of microbes) helped establish the relation of these parameters with the methane emission characteristics through Monod’s kinetics. The relation of these parameters with the methane yield is also substantiated using time-dependent variation of substrate utilization. The values of the biokinetic parameters of the MBT waste indicate the suitability of anaerobic digestion to degrade MBT waste.

The creation of electronic waste (e-waste) has increased as a result of advances in recent tools and digital technologies. Consequently, there is a need to forecast the amount of e-waste generated over a specific period of time in order for society to be able handle this e-waste environmentally safely. This study focused on forecasting the generation of e-waste by a specific number of students in a university in Bangladesh––Shahjalal University of Science and Technology (SUST), Sylhet––in order to achieve this goal. The students were chosen from several departments. Estimates of the e-waste generated by the students from electronic items, such as mobile phones, laptops, desktops, pen drives, headphones, and computer components such as keyboards, motherboards, and mouses are described in this paper. The volume of the e-waste was estimated using consumption-and-use and waste-stream approaches. The total amount of electronic waste generated at SUST in 2016 was 2,494.38 kg, estimated using the linear-trend forecasting approach. Our forecasting also revealed that the e-waste generated will gradually increase, reaching 4,070.62 kg in 2024, more than double the amount generated in 2016. The basic ideas behind, and terminology of, e-waste management, as they relate to environmental sustainability, are also discussed.

Most of the solid waste from Ulaanbaatar city during the cold season is ash from the partial combustion of coal. Burial of the ashes with other solid wastes has affected radioactive isotope levels in the soil. We investigated levels of radionuclides ²²⁶Ra, ²³²Th, ⁴⁰K, and ¹³⁷Cs in soil samples collected from the Naran Enger landfill using a gamma-ray spectrometer. The radioactivity of naturally occurring radionuclides in the soil samples was highest underneath the buried waste zone, and lowest around the ger areas and at the initial reference location. In the buried zone, activity of ⁴⁰K isotope was two times higher than the world average. The results showed that radium equivalent activity (Ra_eq) ranged between 69 and 183 Bq · kg⁻¹, and the Ra_eq of ash was 338.3 Bq · kg⁻¹. The external and internal hazard indexes were 0.2 and 0.5, respectively. From the Ra_eq, H_in, H_ex, D_out, and D_in values, we calculated lifetime cancer risk and found the risk to be (0.8−1.58) × 10⁻³. Current values of Ra_eq and hazard indices were found to be within the recommended limits.

Lead in drinking water is a metabolic poison that causes mental retardation, temporary cerebral damage, and reproductive problems. Chemical precipitation, membrane technology, and ion exchange are some of the expensive and extravagant techniques used to eradicate lead from water. The process of accumulating heavy metals from wastewater using biological materials is referred to as biosorption. In this study, biosorption is examined using three biomasses obtained from Foeniculum vulgare (fennel), that is, its seeds, leaves, and stem, to treat lead-contaminated water. Physicochemical parameters, such as initial concentration of lead (II), contact time, biomass quantity, and pH of the solution are assessed. The optimum contact time to achieve equilibrium is found to be 45 min. The optimum biosorbent dosage, pH, and initial metal concentration are found to be 3.34 g/L, 6.4, and 1 mg/L, respectively. Langmuir, Freundlich, and Temkin models are used for modeling adsorption equilibrium isotherms. The Freundlich model provides the best fit for the biosorption process, with a correlation coefficient R² greater than 0.999 for all three biosorbents. Adsorption kinetics can be described using pseudo first- and second-order kinetic models. The experimental data fit better with the pseudo second-order kinetic model, as the deviations in the experimental and calculated values of biosorption capacities at the time of equilibrium are 5.02%, 4.15%, and 4.66%, respectively, for Foeniculum vulgare seeds, leaves, and stem as biomasses. The process is found to be exothermic and spontaneous, as indicated with a negative change of Gibbs energy value of −1.958, −3.224, and −2.608 KJ mol⁻¹, respectively, for fennel seeds, leaves, and stem. The study shows that the powdered form of Foeniculum vulgare seeds, leaves, and stem is a moderately effective, feasible, and economical adsorbent for the removal of lead from water.