Journal of Hazardous, Toxic, and Radioactive Waste

This work assessed ball-milling treatment for remediation of cesium (Cs)-contaminated soil. The immobilization efficiency increases from 56.4% in the absence of treatment to 89.9, 91.5, 97.7, and 96.4% when the soil is ball milled for 30, 60, and 120 min, respectively. However, the addition of nanometallic $\mathrm{Ca}/\mathrm{CaO}$ and ${\mathrm{NaH}}_2{\mathrm{PO}}_4$ increased the immobilization efficiency to approximately 96.4% compared with ball milling alone, even when the milling time was decreased to 60 min. Actually, with the addition of $\mathrm{Ca}/\mathrm{CaO}$ and ${\mathrm{NaH}}_2{\mathrm{PO}}_4$, the leachable fraction of Cs was reduced in the soil after a short milling time. These promising results suggest that ball milling can be regarded as applicable for the remediation of cesium-contaminated soil in dry and water-free conditions. This treatment method requires no expensive reagent and does not generate exhaust gases. It requires only electricity with cheap and commercially available reagents. This treatment process is an environmentally friendly depollution technique.

Bench-scale treatability of an ensemble of gasoline compounds was investigated using unactivated and activated persulfate. The activation strategies explored were chelated-iron, peroxide, alkaline conditions, and the presence of aquifer solids. Batch reactor trials were designed with an initial total petroleum hydrocarbon (TPH) concentration of $\sim 25\mathrm{mg}/\mathrm{L}$, and nine organic compounds were monitored over a 28-day reaction period. First-order oxidation rate coefficients ($k_{\mathrm{obs}}$) were estimated for all experimental trials. Unactivated persulfate at a concentration of $20\mathrm{g}/\mathrm{L}$ resulted in almost complete oxidation of benzene, toluene, ethylbenzene, and xylenes (BTEX) ($>99\%$), trimethylbenzenes ($>95\%$), and significant oxidation of naphthalene ($\sim 70\%$). Oxidation rate coefficients were enhanced by 2–15 times using the peroxide or chelated-iron activation strategy. Alkaline activation at pH 11 or 13 yielded $k_{\mathrm{obs}}$ that were $\sim 2$ times higher than the unactivated case, except for the $k_{\mathrm{obs}}$ for benzene, toluene, and ethylbenzene, which were reduced by 50% at pH 13. Natural activation by two aquifer materials resulted in $k_{\mathrm{obs}}$ similar to the unactivated case. Significant oxidant strength (60–85%) was observed in all $20\mathrm{g}/\mathrm{L}$ persulfate reactors, implying significant persulfate persistence under gasoline-contaminated conditions. The overall bulk gasoline stoichiometry for these experimental trials varied from 120 to 340 g-persulfate/g-TPH.

The storage and management of road salt piles can cause contamination of drinking water aquifers owing to precipitation runoff that ultimately contaminates the groundwater. Such sites can be remediated using direct current (DC) electric fields in conjunction with relatively inexpensive direct-push wells. When soil and groundwater are subjected to DC electric fields, the pore water moves toward the cathode via electroosmosis while cations also migrate to the cathode and anions migrate toward the anode by electromigration. A series of anode and cathode wells placed in the soil can be used to separate and remove chloride ($\mathrm{Cl}-$) and sodium ($\mathrm{Na}+$), respectively. To accommodate the use of well-based electrodes on a large scale basis, a two-dimensional model, approximating a cylinder, was developed to simulate the electromigration and electroosmosis aspects of sodium and chloride transport in soil with a center cathode surrounded by anodes. To validate the model, a small pilot-sized experiment was conducted, and sodium was used as the primary monitored ion owing to its conservativeness and stability at the cathode. The model predicted a sodium transport time of 4 days for sodium ions to travel the 20.3 cm (8-in.) distance and reach the cathode. The actual sodium flow into the cathodes was elevated and steady for about 5 days followed by the steady drop-off out to day 14 as expected. On the basis of whole hexagon and background soil samples, 80% of the sodium was removed. Sodium removal was significant owing to the removal at the cathode wells while chloride accumulated at the anode where some was oxidized. On the basis of this model, cost for a full scale implementation can be estimated.

Stakeholder decision making is needed for implementing policies that affect both initial purchase decisions of electronic gadgets and ultimate decisions about land disposal/recycling or storage of electronic waste. In consumer electronics, a long-term relationship between manufacturer and consumer might lead to contracts that create incentives for consumers to return used electronic gadgets. The result could be more effective economically and environmentally for involved stakeholders like manufacturers, consumers, and society as a whole. If a stakeholder can further obtain more profit through collaborating with others in some coalition, it will be preferred to collaborate rather than participating individually. This paper discusses the noncooperation as well as cooperation of stakeholders and gives a formulation for the calculation of their profits. After that, based on game theory, a scheme to decide which strategy is better suited, gaining the maximum profit, to a stakeholder and also the profit allocation of each stakeholder in the coalitions rationally and impartially is proposed. Results for stakeholders verified the principle that cooperation is better than competition.

The purpose of remediation projects is to protect human health and the environment by removing harmful substances from the environment. The carbon footprint of an environmental remediation site can be reduced by powering the project with green or sustainable energy. This paper describes a sustainable remediation project that involves the use of a single-axis passive tracking photovoltaic array to power a pump-and-treat system at a Missouri Drycleaning Environmental Response Trust Fund site. The tetrachloroethene-contaminated groundwater is pumped by way of a positive displacement piston pump and treated using granular activated carbon. Previous works studying the performance of solar-powered pumping systems were performed using known or constant water heads that are typically unknown at active remediation sites. A stochastic analysis was performed using the two inherently random variables solar radiation and pumping flow rates. Two models were developed for the estimation of the amount of water that would be pumped from a solar-powered system given (1) the amount of solar radiation observed at the site, or (2) the amount of energy consumed by the pump, both of which can be determined by using data from the free online resource PVWatts. The results showed that even given substantial effects from bioremediation activities, a long-form model was able to accurately predict data within the central range of probabilities for five of the seven months studied.

Heavy metal contamination in rural soils severely threatens the food chain, and consequently, human health. The addition of organic amendments to contaminated soils is considered an effective method to immobilize heavy metals. However, the sequential decomposition of soil organic matter still poses a risk, the rerelease of heavy metals, to animals and plants. This study aims to determine the amount of Cd and Pb in different organic fractions including dissolved organic matter, humic acid (HA), fulvic acid (FA), and residual fraction after the addition of a pine bark compost to tropical acidic soils. Four controlled samples, contaminated to 20, 40, 60, and $80\mathrm{mg}/\mathrm{kg}$ for Cd, and 200, 400, 600, and $800\mathrm{mg}/\mathrm{kg}$ for Pb, were used in this study. The soil samples, both with and without the pine bark compost, were incubated for 120 days for further analysis. The results of the sequential extraction of organic matter indicated that the proportions of Cd and Pb were transferred from the residual fraction into the soluble HA and FA fractions after the compost was mixed into the soil. Additionally, the proportion of Cd in the soluble fraction and Pb in the HA and FA fractions elevated as incubation time increased, indicating the gradual decomposition of residual fractions and more available Cd and Pb in the soil. The diethylene triamine pentaacetic acid extraction result revealed an increased bioavailability of Cd and Pb after the addition of the compost that gradually increased as the organic matter in the amended soils decomposed further. The results demonstrated that the application of pine bark compost to the soil increased the proportions of Cd in soluble fractions and Pb in humic fractions. Furthermore, the results confirmed the potential risk of bioavailable Cd and Pb rereleasing into the amended soil over time.

The performance of a novel natural agent, bamboo juice, in enhancing the desorption of heavy metals (Cd, Cu, and Pb) from contaminated soil was investigated in the present study. The bamboo juice was obtained from bamboo at elevated temperatures. The bamboo juice greatly enhanced the desorption of Cd and Cu and slightly enhanced the desorption of Pb from the soil. The maximum desorption efficiencies of Cd, Cu, and Pb reached 15.2, 25.7, and 5.9%, respectively, with the addition of 10.45% bamboo juice. The soil slurry pH dropped from 6.0 to 3.0 with the increase in bamboo juice concentration from 0 to 10.45%. The mechanism for the enhanced desorption was explained as the combined effect of pH drop and complexation. The desorbed fractions of Cd, Cu, and Pb with the addition of bamboo juice were exchangeable, followed by those bound to organic matters and Fe-Mn oxides. Although the performance of desorption enhancement by the addition of bamboo juice was lower than that of the addition of ethylenediamine tetraacetic disodium acid salt (EDTA), bamboo juice could be promising in enhancing the desorption of heavy metals from contaminated soils because of its low cost and environmental friendliness.

The Hazaribagh tannery area of Bangladesh is considered an extremely polluted site owing to the disposal of untreated Cr-enriched tannery effluent. This study was undertaken from 2006–2008 to characterize the nature and extent of pollution in the area, the associated health risks, and to assess the feasibility and effectiveness of the selected cleanup strategies. A comprehensive soil, wastewater, and groundwater sampling and detailed laboratory analysis were done. The results of the study indicated that the site is extremely polluted by Cr (up to $37,000\mathrm{mg}/\mathrm{kg}\mathrm{dm}$), mineral oils, and extractable organohalogenic compounds (EOX), and the most severe soil pollution was confined up to a depth of 10–20 ft (3.048–6.096 m). The phenol index and chromium level in the tannery effluent were very high, and most of this Cr was found to adsorb onto suspended solids in the wastewater. Analysis of groundwater samples from tubewells in the Hazaribagh area indicated that groundwater is not contaminated by Cr or any other heavy metals. Soil leaching tests indicated a very low Cr mobility and thus a low risk of spreading with infiltrating rainwater. Most of the Cr in the subsoil exists as Cr(III) and was found to be very stable. The scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis of the Cr-containing soil structures showed that the Cr is predominantly present in association with clay mineral structures.

Uncontrolled municipal solid waste landfills potentially release harmful substances to the subsurface in the form of leachate, thus posing a significant hazard of groundwater contamination. The evaluation of groundwater contamination hazard posed by landfills is important for prioritizing them to undertake necessary pollution control and remedial measures in a phased manner. In this paper, a new groundwater contamination hazard rating system (HARAS), which has been presented in detail elsewhere, is applied to 11 municipal solid waste landfills—eight Indian and three European. The study shows that among the landfills studied, the Ghazipur, Okhla, and Bhalswa landfills in Delhi, the Kodungaiyur dumping ground in Chennai, the Pirana landfill in Ahmedabad, and the Dhapa landfill in Kolkata are categorized as “very high” hazard landfills, thereby indicating that these landfills are in urgent need of control and remedial measures. The study also shows that the Indian landfills pose a much greater hazard than the European landfills. This is primarily because the Indian landfills are uncontrolled, they are larger in size, and the groundwater underlying them is used for more varied purposes, including human consumption. A comparison of HARAS with existing hazard rating systems shows that the former is more sensitive to varied site conditions and makes a better tool for site ranking for adopting remedial measures.

A simulated high-strength [chemical oxygen demand (COD) $\sim 85,000\mathrm{mg}/\mathrm{L}$] wastewater containing primarily acrylic acid, acetic acid, and formaldehyde was treated in an anaerobic membrane bioreactor. The reactor consisted of a 25 L complete-mix tank fitted with three Kubota flat-panel membrane cartridges. The reactor was operated at an organic loading rate of $3.4\mathrm{kg}\mathrm{COD}/{\mathrm{m}}^3\text{-}\mathrm{day}$. More than 99% removal of COD and formaldehyde was achieved. Acrylic acid concentration in the effluent stream was below the detection limit. This preliminary study, which lasted for 45 days, showed the potential of application of anaerobic membrane bioreactors in treatment of high-strength wastewaters containing toxic substances like acrylic acid and formaldehyde.