Journal of Hazardous, Toxic, and Radioactive Waste

Earthquake-induced liquefaction causes soil to exhibit fluidlike behavior due to a sudden increase in pore water pressure and a concurrent decrease in effective stress. The liquefaction can destroy or damage existing substructures and superstructures that results in considerable economic and human losses. Hence, there is a need for ground improvement in liquefiable soils for liquefaction hazard mitigation. Various conventional methods, such as soil replacement, densification, and grouting have been used for liquefaction mitigation historically. However, these methods are carbon-intensive, uneconomic, and environmentally unfriendly. Recently, some researchers have demonstrated new techniques that can significantly mitigate liquefaction and achieve cost-effectiveness, are ecologically friendly, and have less associated disturbances. The objective of this review is to provide an overview and the associated challenges of emerging techniques that increase the liquefaction resistance of sandy soils. Initially, the advantages and disadvantages of conventional methods are discussed to justify the requirement for advanced methods. The rapid evolution of novel materials and techniques, as well as multidisciplinary collaborations, has led to new and innovative advanced methods for effective mitigation of liquefaction. Among these methods, the biogeotechnological methods that have received great attention recently are discussed in detail. Many studies have reported the effects of biotreatment on soil properties and liquefaction resistance, factors affecting the biocementation process, and various challenges associated with the biocementation methods. Finally, additional research directions needed for biogeotechnical methods to be effective, sustainable, and resilient for liquefaction mitigation in actual field applications are presented.

A study was conducted to evaluate the treatment efficiency and applicability of a novel two-stage anaerobic onsite sanitation system to improve primary treatment of black water generated at a residential school. The system was designed to accommodate two bioreactors. The first reactor was a modified septic reactor and the second one was an upflow anaerobic reactor. Both reactors were contained in a compact single unit. The system began functioning with no inoculum. It was able to deliver considerably high removal efficiency of 72.6%, 81.4%, and 83.2% for chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total suspended solids (TSS), respectively. The fecal coliform removal in the system was observed to be 2.84 log. The analysis of accumulated sludge within the system was categorized as high-strength fecal sludge. This system has a simple design and requires less maintenance. Moreover, it involves low cost and requires no electricity. Thus, the system promises to be a better replacement for the conventional septic tank for a better primary treatment of black water in unsewered areas of developing countries such as India.

This paper presents an approach to retrofit an existing municipal solid waste (MSW) dumpsite by enhancing the bioremediation process. The current practice of containing the waste in dumpsites/landfills is considered unsustainable due to their negative impact on the environment, society, and economy. Remediation of the existing open dumpsite helps in recovering the valuable land area at a faster rate due to the reduction in the time required for the waste stabilization process. The problem of leachate treatment can also be addressed adequately during the remediation process. Therefore, remediating an existing dumpsite can be classified as a step toward achieving sustainability in landfilling practice. In this study, an approach for remediating an existing municipal solid waste (MSW) dumpsite in Bangalore city is presented by addressing the three major aspects, viz., landfill gas (LFG), leachate, and the recovery of air space. In order to accelerate the biodegradation of MSW and avoid the possible groundwater contamination, a leachate recirculation system is designed. Modeling tools are used to estimate the LFG emission and to design the leachate collection and recirculation system. The methane oxidation potential of the digested mechanically and biologically treated (MBT) waste as a biotic system media is evaluated using column experiments. Biowindrows are then designed to mitigate the LFG emissions from the dumpsite.

Sewage sludge resulting from wastewater treatment process by infiltration/percolation using a matrix of adsorbent (coal ash waste/sand) was found to contain harmful elements. As an alternative approach for a sustainable valorization of this sludge, the present study intends to study the possibility of partially substituting clay in fired clay brick for sludge. Different bricks were manufactured incorporating a varied rate of sludge (5%, 10%, 15%, 20%, and 25%, by dry weight), as well as a reference brick that includes only the conventionnel raw materials. To evaluate their suitability as engineering building materials, the bricks specimens have been submitted to a set of trial experiments; linear drying shrinkage; absorption by capillarity, bulk density, mechanical resistance strength; and radiological proprieties. Bulk density and compressive strength were found to be inversely proportional to the amount of sewage sludge, and the results are respectively ranged from 1,882.81 to 1,921.87 kg/m³, and from 5.78 to 16.1 MPa. Specimens meet the Moroccan norm that requires a minimum of 5 MPa in compressive strength resistance for brick type class RC 50. Sludge/clay bricks favor the reduction of linear shrinkage, and specimens including up to 25% of waste sludge are improved on an order of 38.04% compared to the reference. The radiological assessment of sludge bricks ensures their safety since they are far below the required limits (less than 10 mSv · y⁻¹). According to results, incorporating up to 25% of sludge in bricks is suitable for building purposes.

Most matured landfill leachate contains organic recalcitrant molecules that cannot be easily separated by biological processes alone. Integrating an advanced oxidation process (AOP) and a biological process would be a better option for treating matured landfill leachate. Among the different AOPs, the Electro-Fenton (EF) process is the most promising technology as it is economical, effective, and environmentally friendly in processing organic waste material. Better effluent quality and a lower footprint are the significant merits of membrane bioreactor (MBR) technology, making it an attractive choice for wastewater treatment. In this study, the EF process is integrated with a MBR for treating matured landfill leachate. In EF treatment, the effect of independent variables such as pH, current density, H₂O₂ dosage, and reaction time on the biodegradability index [biological oxygen demand (BOD)/chemical oxygen demand (COD)] was determined using response surface methodology (RSM). Under optimum conditions (pH 2.85, current density 129.5 A/m², H₂O₂ dosage 55.75%, reaction time 40 min), the biodegradability index of the matured landfill leachate increased from 0.21 to 0.45. The EF-MBR integrated system gave a total reduction in total suspended solids, BOD, COD, ammonia nitrogen, phosphate, sulfate, sulfide, and chloride of 94.2%, 90.62%, 94.55%, 84.66%, 100%, 83.19%, 85.07%, and 83.37% respectively. The economic analysis revealed that the total cost of an EF-MBR integrated treatment is $0.488/kg of COD digested and $10.68/m³ of matured landfill leachate treated. The study reveals the possibility of enhancing BOD/COD by EF and reducing the amount of pollutants considerably through an EF-MBR integrated process to guarantee environmental protection.

The long-term safety of radioactive waste disposal facilities is ensured by developing performance assessment models. The general requirement of these models is to assess the risk caused by failure of disposal systems that leads to radionuclide release into the geosphere and their migration toward the near-field biosphere. The radiation dose and risk due to disposal practice are the endpoints of assessment of the model. A two-dimensional radionuclide transport model with a decaying source is modeled numerically to compute the radiological impact caused by radionuclide, iodine-129 (I-129) in the biosphere. The intrinsic part of the performance assessment model requires consideration of uncertainties and variabilities in the system that are indicated by the inherent variability (heterogeneity in the geological medium), measurement, and modeling uncertainties (the geohydrological, geochemical properties of the radionuclides being released and transported). In this study, the spatial variability in the geological medium is addressed by treating the hydraulic conductivity of the medium as a random field. The probability of the radiation dose exceeding the design threshold (i.e., the probability of failure) is computed using subset simulation method. The influence of autocorrelation length and coefficient of variation of hydraulic conductivity on the probability of failure and the transport behavior of radionuclide are also studied. Thus, the results showed that a probabilistic framework that accounts for spatial variability in the geological medium is necessary for performance assessment of radioactive waste disposal facilities.

In the past few decades, waste generation has increased significantly in India, as well as across the globe. Therefore, to avoid the acquisition of new landfill sites, vertical expansion of existing municipal solid waste (MSW) landfills is a requirement of the present scenario. Owing to the heterogeneous nature of waste and varying degrees of decomposition in MSW, the conventional practices to calculate safety margins may not be suitable to handle the variability of the design parameters. Therefore, a system reliability framework is proposed for the optimum design of mechanically stabilized earth (MSE) retaining walls against external failure modes. The properties associated with MSW landfills, their foundation soil, and MSE walls are considered as random variables. The overturning, sliding, and bearing capacity failure modes are considered using a three-part wedge mechanism. The design charts are provided to obtain the adequate length of the reinforcement and the dimensions of the MSE wall. For satisfactory performance of the MSE wall, the minimum ratio of the length of the reinforcement to the height of the MSE wall should be 0.55 to 0.6 when an additional waste mass is placed on the existing height of the landfill.

This study aims to understand the influence of compaction state, and the drying–wetting cycles on cracks propagation in biochar-amended soils (BAS). The objective of the study is to carry out multiple regression analysis (MRA) and develop a multiple regression model (MRM) for estimating the crack intensity in BAS based on basic soil and biochar properties. MRA can help to understand the impact of each parameter, such as compaction, plastic limit, liquid limit, biochar content (%), and the specific gravity of soil on the crack intensity. To obtain the objective, the soil and various biochar were mixed and compacted at 65% and 80% of maximum dry density (MDD). Observations were made that wood biochar (WB) had a higher resistance to crack propagation as compared with pig manure biochar (PMB). MRA shows that there is a reduction in crack intensity with an increase in the biochar content. It was also observed that as specific gravity and plastic limit (PL) increase, the crack intensity of samples also increases. The effect of PL is more pronounced in WB as compared with PMB. The proposed MRM provides a preliminary qualitative information of cracks intensity in samples when basic soil properties are known.

Microbial electrosynthesis (MES) uses microbes and electricity to convert CO₂ to high-grade chemicals alleviating greenhouse gas (GHG) emissions. Little is known on the environmental loads associated with the scale-up of the technology. Initially, the MES environmental impacts of synthesizing acetic, formic, or propionic acids, methanol, or ethanol were assessed using GaBi LCA software, and electricity produced 60% from fossil fuels. The results show that formic acid production had the lowest environmental impact in all eco-indicators due to the comparatively low energy requirements of its reactor and rectification unit. Second, three different formic acid production methods were compared with MES. Hydrolysis of methyl formate, the main conventional method was shown to be less environmentally harmful than the other three CO₂ utilizing technologies analyzed when the electricity used was generated from fossil fuels except for the impact on climate change. Producing electricity from renewable sources (hydro, biogas, wind, and photovoltaic) made MES able to mitigate climate change with the lowest negative impact on the environment compared with others. Synthesis of products through MES using wind generated electricity could provide considerable benefits and should be considered when MES is industrially applied.

Fifteen soil–cement mix designs, cured for up to 270 days, were tested on sand and peaty sands from a Waterfront Toronto Brownfields site having a total petroleum hydrocarbon (TPHC) concentration of approximately 20,000 mg/kg. The peaty sand was created using fibrous peat and sands from the site blended at a 25:75 v/v ratio to reflect the lithology targeted for stabilization/solidification (S/S). Portland slag–cement blends (6–14 wt%) added to wet soil with 0.5 wt% bentonite applied to the sandy soil provided 28-day unconfined compressive strengths (UCSs) of the order of 400–2,500 kPa, which increased to approximately 700–4,300 kPa by 56 days. The performance of the peaty sands was lower: 8–25 wt% cement blends with 0.5 wt% bentonite had UCSs of approximately 140–1,725 kPa at 28 days and 175–3,400 kPa by 56 days. Brazilian tensile strengths of the S/S-treated soils were 10%–16% of UCSs. The minimum cement doses to pass the freeze/thaw test (12 cycles; ASTM D560) after 28 days were 10 and 25 wt% for the sandy and peaty sand soils, respectively. For similar reagent doses, the sandy soil mixes were typically 3–130 times less permeable than the peaty sand mixes after 28 days curing, with all mix designs except one having a hydraulic conductivity less than 10⁻⁶ cm/s. Total (n) and effective (n_eff) porosity testing conducted at 210 days showed that the sandy soil mixes had values of n and n_eff that were, respectively, 20% and 85%–90% less than the peaty sand mixes. The maximum values of n_eff of the S/S-treated sands and peaty sands were 9% and 14%, respectively. Computed tomography (CT) of the S/S-treated soils at 210 days confirmed the porosity trends and provided insight into the freeze/thaw failures of the peaty sands. TPHC leaching of the untreated soils and select 28-day cured mix designs as a function of the liquid/solid (L/S) ratio were similar, consistent with other studies where particle crushing of the S/S-treated materials occurred.

This study aims to investigate the radiological impact of phosphogypsum (PG) discharge on the marine environment along the coast of the province of El Jadida (Morocco). The specific activity of the main radionuclides present in the raw phosphates, PG, and coastal sands will be measured using gamma spectrometry. The volume activities of radon in samples of sand, seawater, and mussel type Mytilus galloprovincialis will be evaluated using passive alpha dosimetry based on the use of LR115 detectors. The analysis shows that the radioactivity of the raw phosphates was mainly attributed to the radionuclides of the uranium (²³⁸U) family that has a specific activity of approximately 1,264 Bq/kg. The results revealed that the production of phosphoric acid (H₃PO₄)using the wet process has caused a dramatic radioactive imbalance in the ²³⁸U family presented in the formed PG. This disequilibrium was due to a reduction in the amount of ²³⁸U radionuclides by 84% with a quantitative release of radium (²²⁶Ra) radionuclides (845 Bq/kg). Therefore, the discharge of PG into the high seas has caused the contamination of natural beach sand by ²²⁶Ra and ²³⁸U radionuclides. The specific activity of ²²⁶Ra in beach sand increased from 16 to 217 Bq/kg when approaching the industrial discharge point of the phosphates. A large variation was noticed in the volume activities of radon measured in different samples of sand, seawater, and mussel, from 174 to 7,287 Bq/m³, 11 to 354 Bq/m³, and 18 to 497 Bq/m³, respectively. This marine radioactive contamination is spreading over a large area around the PG discharge points, which has a diameter of 10 km. This radioactive pollution could damage marine and coastal ecosystems and harm the livelihood of entire communities.

Evaluating kinetic and probabilistic approaches for describing pathogen variation in riverbank filtration (RBF) was conducted at a site at Muzaffarpur, Bihar, India. The total coliform (TC) was observed in the range of 1,600–110 counts per 100 mL of water sample in the Burhi Gandak River, and from four to two counts per 100 mL of water sample from a pumping well for longer than one year during 2010–11. As the polluted river water moves from river to the production well, the water quality is improved because of RBF. It was observed that the river water quality did not meet WHO and Bureau of Indian Standards of drinking water quality, especially in case of TC. Considering this, simplified models, such as deterministic and probabilistic approaches, have been applied and their utilities were tested at the Muzaffarpur RBF site. Using the resultant water quality from the river and the water quality from RBF, kinetic models as well as a semi-empirical probabilistic model were used to investigate the variation in the bacteriological quality of the river water. The kinetic coefficient and probability of clogging both varied with the natural logarithm of concentrations of TC in the river water. It was observed that the kinetic approach and the probabilistic approach both had potential for simulating the variation of pathogen in source water and riverbank filtrate at the RBF Muzaffarpur site.

Ruthenium (Ru) was impregnated with bismuth (Bi) to reduce the spectrum demand for the excitation of Ru to employ it as photocathode catalyst (Bi-Ru) in a microbial fuel cell (MFC) to ameliorate its power output in the presence of visible spectrum. The coulombic efficiency (CE) and power density of an MFC with Bi–Ru (MFC–BiRu) were 26.7 ± 0.8% and 10.0 ± 0.5 W/m³, respectively, which were two and six times higher than the control MFC that was operated without any cathode catalyst. Moreover, the CE and power density of the MFC–BiRu was 12.5% and 22% higher than the MFC that was operated with platinum (MFC–Pt) as the cathode catalyst (24.0 ± 0.7% and 8.2 ± 0.4 W/m³, respectively). Furthermore, the chemical oxygen demand (COD) removal efficiency and net energy recovery (NER) of MFC–BiRu were 91.8 ± 1.5% and 722 W-h/m³, which was almost 10% and 1.8 times higher than the MFC–Pt, respectively. Therefore, the results illustrated that Bi–Ru could be a plausible alternative to replace Pt as a cathode catalyst; therefore, rendering the field-scale application of MFC.

This research focuses on the viability of removing basic dye methylene blue (MB) from water solutions by the application of sugarcane bagasse (SCB), an economic natural biosorbent. Batch experiments were conducted based on solution pH, contact period, initial adsorbate dye concentration, biosorbent amount, and temperature as independent variables by employing a central composite design approach of response surface methodology (RSM). With the use of RSM, the optimization of the MB biosorption process was carried out for maximum MB removal. The biosorption equilibrium of the dye solution was achieved after a contact time of 90 min and explained by the Langmuir and Freundlich isotherms. The biosorption data is employed for the kinetic modeling, from pseudo-first- and pseudo-second-order kinetic equation. Thermodynamic parameters (Enthalpy change ΔH, entropy change ΔS, and Gibbs free energy ΔG) were studied, which showed that biosorption is natural and endothermic in nature by reducing color randomness at the liquid and solid interface. Biosorbent characterization explained in this analysis is performed through Fourier-transform infrared spectroscopy before and after MB biosorption. Characteristic tests and separation factor proved that SCB was able to be used as an option to commercial biosorbents for the aqueous solution and removal of MB from wastewater.

The application of industrial waste in construction reduces the dependency on natural resources. The materials, including red mud (RM) and fly ash (FA), proved to be favorable materials. However, the materials potential together as a geopolymer composite for road applications has rarely been explored. This study will examine the possibility of the replacement of natural materials in subgrade applications. To achieve this, the geopolymer compositions will be prepared by replacing RM with FA at replacement rates of 10%, 20%, and 30% by dry weight basis. The alkaline activator solution of 8 M will be prepared using sodium hydroxide (NaOH) and sodium silicate to develop geopolymer composites. The strength properties will be studied using the California Bearing Ratio (CBR) and unconfined compression strength (UCS) and validated with microstructural analysis using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). The results reveal that geopolymer composites could achieve a maximum CBR value of 12% and UCS of 2,700 kPa. The microstructural analysis revealed that the formation of dense calcium aluminate hydrate (C-A-H) and calcium silicate hydrate (C-S-H) are the reason for strength improvement. The leaching studies show that the toxic elements were within the permissible limits. Overall, the test results confirmed that the geopolymer composites meet the required strength and could be used as a subgrade material in road construction.

Persistent organic pollutants, such as polychlorinated biphenyls (PCBs), pose a serious risk for human health and the environment. In this study, PCBs contamination and sources of ambient air, road dust, and sediments in the most polluted city in India, Raipur, has been measured over the period 2008–2015. The seasonal variations of particulate matter (PM), elemental carbon (EC), organic carbon (OC), and carbonate carbon (CC) were studied, and maximum concentrations were detected in the December–January period each year. Total PCBs concentrations in the ambient air (associated with PM), road dust, and sediments samples during 2008 were in the 186–645 pg m⁻³, 102–537, and 241–538 ng g⁻¹ range, respectively. 2-chlorobiphenyl (PCB-1) and 4-chlorobiphenyl (PCB-3) were the dominant chemical compounds identified. A substantial vertical migration of the PCBs in the sediments was observed. Concentration variations (spatial and temporal), correlations, and sources of PCB are discussed. In particular, an average increment rate of 6.2%, 4.9%, and 5.4% of PCBs concentration in the particulate matter (PM₁₀), road dust, and sediments, respectively, was observed over the 2008–2015 period. The reported data points to India's low degree of accomplishment of the Stockholm Convention's requirement to phase out the use of PCBs in equipment by 2025 and ensure elimination of PCBs by 2028.

Ecofriendly dye decolorization is a prerequisite for textile industries to tackle hazardous textile effluents. In the present study, we have reported a laccase producing (19.12 ± 3.45 U/mL) fungal endophyte, namely, Penicillium megasporum Orpurt et Fennell NFCCI 3977. The endophytic laccase was evaluated for synthetic textile dyes (congo red, orange G, and rhodamine B) decolorization by considering the carbon, nitrogen, and pH effects. The endophytic-based laccase decolorization showed promising results with the decolorization of congo red (89.4 ± 3.2%), orange G (76.2 ± 2.5%), and rhodamine B (54 ± 2.8%) using glucose and beef extract as carbon and nitrogen sources at pH 6.0. Thus, the present study demonstrated the efficiency of new endophytic fungi for decolorization ability of synthetic textile dyes in an ecofriendly manner. The research findings showcase the handling of the proper disposal of hazardous synthetic textile dyes into the environment through the biological approach by replacing the existing toxic chemical-based disposal approaches.

Several areas in Hawaii have background concentrations of unexploded ordnance (UXO) as a consequence of past and current military training. The presence of UXO and the release of their chemical compounds can be of environmental concern. The complete and incomplete detonation of explosives can ignite vegetation fires that cause organics in the topsoil to burn, and therefore, impact the environmental fate of these compounds. The sorption and transport of two UXOs, HMX and RDX, were investigated in a surface soil that was previously exposed to a fire event. In addition, a control soil that had not been exposed to a fire event was used. The use of burned and unburned soil to simulate soil that has been directly impacted by the explosion of UXOs combined with the uniqueness of the soil properties in Hawaii represents the novelty of this study. The surface soil that had been previously exposed to a fire event showed greater adsorption than the control, which was possibly due to a reduction of macropores in the burned soil and the presence of fine charcoal particles. Regardless of the presence or absence of a fire event, HMX showed a greater sorption affinity than RDX.