Journal of Hazardous, Toxic, and Radioactive Waste

The performance of near-surface disposal facilities (NSDFs) for low-level radioactive waste depends on the type of materials used in the construction of barrier system, the properties of geological formations around the facility, and the type of waste containment system. By taking into account the effect of the factors mentioned here, a mathematical model can be developed to evaluate the migration of contaminants and radionuclides (via the contaminant transport model) from NSDFs to the nearest geosphere and biosphere, and assess the performance of the whole system. The model for migration of contaminants in a multibarrier system is considered in this paper for the safety assessment of NSDFs. The model considers scenarios during dumping period, after the dumping period, and after the closure of the NSDF. The annual radiation dose due to a radionuclide through drinking water pathway (for the single dump mode and multiple dump mode) is evaluated with the model. In the present work, a comprehensive analysis is carried out to estimate the radiation dose of seven radionuclides (${}^3\mathrm{H}$, ${}^{14}\mathrm{C}$, ${}^{59}\mathrm{Ni}$, ${}^{99}\mathrm{Tc}$, ${}^{129}\mathrm{I}$, ${}^{237}\mathrm{Np}$, and ${}^{239}\mathrm{Pu}$) for different modes of disposal. Among these radionuclides, radioactive carbon (${}^{14}\mathrm{C}$) delivered the maximum concentration in groundwater. To consider variability in the model parameters and quantify the uncertainties due to inherent variability, the presence of a heterogeneous medium, and variability associated with the long time scales of interest, a probabilistic method called the collocation-based stochastic response surface method (CSRSM) is used. In this method, a complex analytical equation is approximated by a higher-order polynomial [using polynomial chaos expansion (PCE)]. Radioactive carbon (${}^{14}\mathrm{C}$) is used for probabilistic analysis, considering groundwater velocity, thickness of unsaturated zone, dispersivity, and distribution coefficient as random variables. In all the scenarios, a third-order polynomial gave the best fit for the model and coefficient of determination ($R^2$) of 0.99 was obtained for a third-order polynomial. Reliability analysis was carried out, and the probability of failure of an annual radiation dose of ${}^{14}\mathrm{C}$ exceeding the permissible limits was estimated for different scenarios. The results show that the probability of failure of system in all the scenarios is very low, confirming the adequacy of the system.

Nature’s ability of programming the synthesis of different metallic nanoparticles has paved way to a new green era in an unforeseen fashion. However, there is a timely need to delve into the practical implications and challenges of this green science. The working principles of green synthesis need a critical analysis for the factual evaluation of different green domains endorsed in it. The inclusion of nongreen elements, such as heat energy and organic solvents, seems to alter the original scope of green synthesis. Moreover, green chemistry principles, green nanotechnology, and green synthesis should be reconsidered within the zone of their interception for conclusive evidence. A new concept, “all green,” is foreseen in this article for a greener nanoscience and analyzed for its practical feasibility.

An investigation was conducted on different agro-industrial byproducts to evaluate their potentiality for simultaneous removal of ${\mathrm{Pb}}^{2+}$, ${\mathrm{Zn}}^{2+}$, ${\mathrm{Cu}}^{2+}$, ${\mathrm{Ni}}^{2+}$, ${\mathrm{Cd}}^{2+}$, ${\mathrm{Cr}}^{3+}$, ${\mathrm{UO}}_2^{2+}$, and ${\mathrm{Th}}^{4+}$ from aqueous solutions. All experiments were performed in batch mode at ambient temperature. According to the results obtained from pH, rice bran was selected as the most effective biosorbent. In a single step, more than 91% of studied cations (except ${\mathrm{Ni}}^{2+}$ and ${\mathrm{Cr}}^{3+}$) were simultaneously removed by rice bran from aqueous solution with RSD less than 2.19%. Also, the sorption process was very quick, and sorption equilibrium was achieved in about 10 min for all studied cations. The obtained results from all experiments showed that sorption behavior of ${\mathrm{Th}}^{4+}$ onto rice bran was different from other heavy metals, so that its sorption efficiency ($>95\%$) did not have considerable change with varying pH from 3 to $-0.6$. The electrostatic complexation mechanism was recognized between hard-functional groups of rice bran biomass and ${\mathrm{Th}}^{4+}$. Furthermore, attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopic analysis clearly revealed that C=O, O-H, and N-H functional groups on the biomass surface were linked with ${\mathrm{Th}}^{4+}$ ions. Matrix effect was not observed in most real samples in sorption of cations. The selected biosorbent has the potential to be applied on the industrial scale because of economic and operational benefits.

The increase of pollution loads and of the diversity of pollutants threatening water resources calls for sophisticated management of water resources. This paper shows that the thermal stratification of water in reservoirs and the variation of its density with reservoir depth make it possible to manage sudden water-pollution events by controlling water release as a function of lake depth to minimize effects associated with the release of polluted water from reservoirs. The best outlet level of a reservoir to release polluted water is selected in this paper using the technique for order performance by similarity of ideal solution (TOPSIS). The latter is a multicriteria decision-making (MCDM) tool for managing water quality in reservoirs. The application of MCDM is illustrated with the management of reservoir releases to cope with the sudden spill of $30{\mathrm{m}}^3$ of methyl tertiary butyl ether (MTBE) into the Amirkabir reservoir (Iran). The CE-QUAL-W2 calibrated model is used to simulate the spreading of MTBE in the reservoir. Pollutant spreading is predicted under four seasonal pollution scenarios and one scenario considering all seasons simultaneously. This allows for the consideration of the effects of climatic and water demand conditions on reservoir water quality. This paper’s results show that the water should be released from the low-elevation gate in spring and winter and from the high-elevation gate in summer and autumn to optimally manage the sudden release of MTBE spills in the Amirkabir reservoir.

This paper is the first in a series on the Tyco Fire Products LP Sediment Removal Project (Marinette, Wisconsin) describing the dredging, stabilization and solidification (S/S) treatment, and nonhazardous disposal of arsenic-impacted sediments. Arsenic (As) impacts were associated primarily with the release of monomethyl arsonic acid (MMA) [${\mathrm{CH}}_3\mathrm{AsO}{(\mathrm{OH})}_2$] and dimethyl arsinic acid (DMA) [${({\mathrm{CH}}_3)}_2\mathrm{AsO}(\mathrm{OH})$] derived from historic herbicide manufacturing and storage activities. Two main sediment horizons were affected: an upper soft sediment [soft dredged material (DM)] and an underlying semiconsolidated material (SCM) layer. One soft DM surrogate had a total As content of $\mathrm{6,295}\mathrm{mg}/\mathrm{kg}$; toxicity characteristic leaching procedure (TCLP) As of $34.6\mathrm{mg}/\mathrm{L}$, moisture contents (MCs) between 169 and 200%; and a loss on ignition of 15.4. Two types of SCMs were evaluated. One was a very sandy nonplastic sediment with a total As content of $\mathrm{1,066}\mathrm{mg}/\mathrm{kg}$ and TCLP As of $32\mathrm{mg}/\mathrm{L}$. The other was TCLP As compliant but was more water sensitive, with a total As content of $884\mathrm{mg}/\mathrm{kg}$ and MC of 81%. A treatability study was conducted to determine the S/S treatments, using no more than two reagents simultaneously, that would yield a product meeting all disposal criteria (TCLP As $<5\mathrm{mg}/\mathrm{L}$, pass paint filter test, and maintain a pH between 2 and 12) within 3 days, and be moreover workable. More than 200 mix designs were performed. The conventional approach to immobilizing inorganic arsenic with traditional pozzolans (lime, cement, cement kiln dust, lime kiln dust) led to a doubling of the TCLP As values into the $70\mathrm{mg}/\mathrm{L}$ range. The inclusion of ferric iron was decisive, and combinations of ferric sulfate (wet and dry for As immobilization) with limited quantities of portland cement sufficient to achieve solidification were found to perform the best.

This paper is the second in a series on the Tyco Fire Products LP Sediment Removal Project, Marinette, Wisconsin, describing the dredging, stabilization and solidification (S/S) treatment, and nonhazardous disposal of arsenic (As)–impacted sediments. The high spatial variability of the As effects drove the need to develop a screening program to assess the environmental quality of sediments in scows within their 6-h decanting period before off-loading for purposes of reagent dose optimization, versus a default dose of 25% by weight ferric sulfate (60% aqueous) plus 10% by weight portland cement ($\$78.82/\mathrm{t}$). Portable X-ray fluorescence (XRF) and 3-h mini–toxicity characteristic leaching procedure (TCLP) techniques calibrated to wet sediments (plus moisture content) were shown to be a quick, reliable means of assessing sediment quality (10 samples per scow) to enable reagent dose optimization on a scow-by-scow basis. The maximum measured XRF As and TCLP As values were $\mathrm{76,981}\mathrm{mg}/\mathrm{kg}$ and $195\mathrm{mg}/\mathrm{L}$, respectively, well above the sediment surrogates tested in the S/S treatability study. For 330 dredged scows (198 S/S-treatment bins) during the 2013 season (May 5 to November 23) processed at a typical daily rate of $\mathrm{1,600}–\mathrm{3,000}\mathrm{t}/\mathrm{day}$, only four bins required retreatment, for an overall 2% failure rate on bins processed. In total, 348,000 t of S/S-treated sediments were transported to nonhazardous landfill.

Bottom ash is a by-product produced from burning of pulverized coal in thermal power plants. The increasing production of bottom ash and its disposal in an eco-friendly manner is a matter of concern. This paper concisely describes the suitability of bottom ash to be used in civil engineering applications as a way to minimize the amount of its disposal in the environment and in the direction of sustainable development. The proposed geomaterial was prepared by blending bottom ash with expanded polystyrene (EPS) beads and a binder such as cement. The experiments were conducted by adding EPS beads with different mix proportions. The mix ratio percentages 0.3, 0.6, 0.9, 1.2, and 1.5 were used in the study. The cement to bottom ash (C/BA) ratios of 10 and 20% were used in the study. All the ratios used in the study are with respect to weight of bottom ash. The compressive strength of geomaterial was evaluated for curing periods of 7, 14, and 28 days. The effects of various mix ratios, cement content, and curing periods on the density, compressive strength, and initial tangent modulus was studied and the results were incorporated. Test result indicated that the density of geomaterial reduced from 650 to $360\mathrm{kg}/{\mathrm{m}}^3$ with addition of EPS beads from 0.3 to 1.5%. For a particular curing period, compressive strength reduced marginally following the inclusion of EPS beads in geomaterial. For each mix ratio, compressive strength increased with increasing curing periods. The initial tangent modulus of the geomaterial decreased with increasing mix ratio values. The prepared geomaterial was light in weight comparitively and it can be used as a substitute to conventional fill materials.

Aquifers are one of the main water supply resources for drinking, agricultural, and industrial purposes. Therefore, it is crucial to study and evaluate different remediation methodologies that can be used to enhance the quality of groundwater. In situ bioremediation is one of the most efficient and cost-effective cleanup methodologies to treat groundwater pollution. This methodology relies on the microorganisms of a contaminated aquifer to treat polluted groundwater. This paper presents a multiobjective simulation-optimization (S-O) model to achieve the best in situ bioremediation system design for a groundwater with contaminated dissolved hydrocarbons. Minimizing the design and operational costs along with the sum of squared cleanup standard violations (SCSV) are the two main objectives of this study. The results of optimization are presented in the form of Pareto possibility frontiers. A model from the literature and a nondominated sorting genetic algorithm are used for groundwater simulation and optimization, respectively, in this work. Single-objective and multiobjective cleanup optimized designs were obtained. The results of the single-objective design confirmed the capability and accuracy of the developed S–O model. The multiobjective optimization results yielded a Pareto frontier that can be used by regulators to select the best design tradeoff between the cleanup standard requirements and the financial resources. For example, an optimal option that reduces total cost about 51.3% increases the SCSV about 1.9%. Moreover, the option that increases the SCSV by about 12.6% decreases the total cost equal to 76.2%. A sensitivity analysis was performed for some of the bioremediation parameters such as hydraulic conductivity, initial oxygen concentration, injected oxygen concentration, remediation time, and the ratio of oxygen to hydrocarbon consumed. The results show that the hydraulic conductivity and remediation time had the most impact on the effectiveness of the bioremediation operation.

In this study, mixed wastes composed of high levels of phenol, formalin, and ethanol emanating from biotechnology and health science laboratories on the Florida Gulf Coast University (FGCU) campus were degraded under anaerobic conditions in a hybrid suspended-attached growth system. Batch experiments were conducted using 80% removal of initial phenol concentrations as an end point. Formalin concentration was used to set the initial feeding constraints. After a stable, low level of phenol and chemical oxygen demand (COD) removal were established, three experimental periods demonstrated the simultaneous removal of 80% of influent COD, 97% removal of formalin, and at least 85% removal of phenol (concentrations of 1,000, 110, and $170\mathrm{mg}·{\mathrm{L}}^{-1}$, respectively). A biogas was produced continuously, but was not quantified nor identified because of constraints. Further research is needed to determine mineralization and possible intermediate formation and to prove such a system is a viable option for the on-site treatment of university or small-scale research-generated hazardous mixed wastes.

The use of Triton X-100 (Triton) significantly improves enzyme economy for the removal of phenol from wastewater with crude soybean peroxidase (SBP, Enzyme Commission Number 1.11.1.7), a polymerization process that forms (poly) phenolic precipitates. The observation of SBP elution from phenolic precipitates in the presence of Triton was considered a competitive adsorption displacement phenomenon in order to explain the protection mechanism (Triton effect). Both SBP and Triton adsorption on the precipitates were characterized by Langmuir adsorption isotherms as single-adsorbate systems. As a binary-adsorbate system, the adsorption of Triton gradually reversed the adsorbed SBP back into the aqueous phase. The sigmoid elution curve was consistent with an orogenic displacement mechanism. A quantitative relationship between SBP elution as a function of Triton and precipitates concentrations was established by adapting the curves to a logistic function. The concept of using phenolic precipitates as an affinity matrix for concentrating SBP from dilute solution was proven and the feasibility of developing a related process was validated in both single-batch and consecutive cycles of operation. The process has the potential for producing low-cost enzyme concentrate, thereby enabling its application for industrial wastewater treatment.