Organically modified low-grade kaolin as a secondary containment material for underground storage tanks

Batch scale reactions were conducted to evaluate the efficacy of modified low-grade kaolin for the treatment of petroleum contaminants. Low-grade kaolin, which has been unvalued as material in the mining process because of its low quality for commercial products, was modified with HDTMA (hexadecyl-trimethylammonium), and its efficiency was compared with that of HDTMA-modified bentonite, which is used as a secondary containment barrier for underground storage tanks. The sorption capacity and hydraulic conductivity of both the HDTMA-modified bentonite and low-grade kaolin were investigated and showed distribution coefficients in the sorption of benzene, toluene, ethylbenzene and xylene ranging between 45.7 and 583.7 and 57.0 and 525.1, respectively. The hydraulic conductivities were 2.53 × 10⁻⁸ and 5.62 × 10⁻⁸ cm/s for the HDTMA-modified bentonite and low-grade kaolin, respectively. These results suggest that HDTMA-modified low-grade kaolin could be used as a hydraulic barrier against advection migration of petroleum contaminants. Simulation of the one-dimensional transport of benzene through a liner made of either one of the compounds was also performed. These results also showed that HDTMA-modified kaolin more effectively retards the transport of benzene.     

Rapid in situ assessment for predicting soil quality using an algae-soaked disc seeding assay

The soil quality of remediated land is altered and this land consequently exerts unexpected biological effects on terrestrial organisms. Therefore, field evaluation of such land should be conducted using biological indicators. Algae are a promising new biological indicator since they are a food source for organisms in higher soil trophic levels and easily sampled from the soil. Field evaluation of soil characteristics is preferred to be testing in laboratory conditions because many biological effects cannot be duplicated during laboratory evaluations. Herein, we describe a convenient and rapid algae-soaked disc seeding assay for assessing soil quality in the field based on soil algae. The collection of algae is easy and rapid and the method predicts the short-term quality of contaminated, remediated, and amended farm and paddy soils. The algae-soaked disc seeding assay is yet to be extensively evaluated, and the method cannot be applied to loamy sand soil in in situ evaluations. The algae-soaked disc seeding assay is recommended for prediction of soil quality in in situ evaluations because it reflects all variations in the environment. The algae-soaked disc seeding assay will help to develop management strategies for in situ evaluation.     

Indoor air quality assessment in child care and medical facilities in Korea

In order to characterize the status of indoor air pollution in some important facilities, a list of key criteria pollutants [particulate matter (PM(10)), carbon dioxide (CO(2)), carbon monoxide (CO), formaldehyde (HCHO), and bioaerosol] was measured from a total of 91 randomly selected sites in 18 different cities, Korea (February 2006 to December 2009). The target facilities include 43 child care facilities, 38 medical facilities, 6 elementary schools, and 4 postnatal care centers. The results showed that some air pollutants (e.g., CO and HCHO) did not exceed the recommended guideline [e.g., the Korean indoor air standard (KIAS) values of 10 ppm and 100 ppb, respectively]. However, concentration of PM(10), CO(2), and bioaerosol occasionally exceeded their respective guidelines (e.g., seven, three, and two cases). Discrete seasonalities were observed from indoor pollutants because of varying ventilation practice (e.g., summer time dominance of PM(10), HCHO, and bioaerosol or winter dominance of CO(2) and CO). However, as the concentrations of the indoor pollutants were scarcely above the recommended guideline level, more diversified approaches are desirable to diagnose the status of indoor pollution and to provide a realistic strategy for the improvement of IAQ.     

Recycling of tailings from Korea Molybdenum Corporation as admixture for high-fluidity concrete

The main objective of this study is to develop an eco-friendly and a large recycling technique of flotation Tailings from korea (TK) from metal mines as construction materials such as admixtures for high-fluidity concrete (HFC). TK used in this study was obtained from the Korea Molybdenum Corporation in operation. TK was used as the alternative material to adjust flowability and viscosity of HFC in the form of powder agent which enables adjustment of concrete compressive strength. In this study, we have performed concrete rheological tests and concrete flowability tests to obtain the quality characteristics of TK for using as the admixture in producing HFC. The results indicated that the adequate mix ratio of cement to TK should be 8:2 (vol%). It is more effective to use the TK as admixture to control flowability, viscosity and strength of HFC than the normal concrete. It was found that TK could be recycled construction materials in bulk such as admixture for HFC, in terms of the economic and eco-friendly aspects.     

Application of eggshell waste for the immobilization of cadmium and lead in a contaminated soil

Liming materials have been used to immobilize heavy metals in contaminated soils. However, no studies have evaluated the use of eggshell waste as a source of calcium carbonate (CaCO₃) to immobilize both cadmium (Cd) and lead (Pb) in soils. This study was conducted to evaluate the effectiveness of eggshell waste on the immobilization of Cd and Pb and to determine the metal availability following various single extraction techniques. Incubation experiments were conducted by mixing 0–5% powdered eggshell waste and curing the soil (1,246 mg Pb kg^?1 soil and 17 mg Cd kg^?1 soil) for 30 days. Five extractants, 0.01 M calcium chloride (CaCl₂), 1 M CaCl₂, 0.1 M hydrochloric acid (HCl), 0.43 M acetic acid (CH₃COOH), and 0.05 M ethylendiaminetetraacetic acid (EDTA), were used to determine the extractability of Cd and Pb following treatments with CaCO₃ and eggshell waste. Generally, the extractability of Cd and Pb in the soils decreased in response to treatments with CaCO₃ and eggshell waste, regardless of extractant. Using CaCl₂ extraction, the lowest Cd concentration was achieved upon both CaCO₃ and eggshell waste treatments, while the lowest Pb concentration was observed using HCl extraction. The highest amount of immobilized Cd and Pb was extracted by CH₃COOH or EDTA in soils treated with CaCO₃ and eggshell waste, indicating that remobilization of Cd and Pb may occur under acidic conditions. Based on the findings obtained, eggshell waste can be used as an alternative to CaCO₃ for the immobilization of heavy metals in soils.     

Transformation of recovered cobalt from lithium-ion batteries into zeolitic imidazolate framework-67

Journal of Material Cycles and Waste Management - Electrical and electronic equipment with axillaries at their end of life are considered as e-waste. Utilization/reutilization of e-waste especially...     

Warning signals confer advantage to prey in competition with predators: bumblebees steal nests from insectivorous birds

Aposematic (warning) signals of prey help predators to recognize the defended distasteful or poisonous prey that should be avoided. The evolution of aposematism in the context of predation has been in the center of modern ecology for a long time. But, the possible roles of aposematic signals in other ecological contexts have been largely ignored. Here we address the role of aposematic signals in competition between prey and predators. Bumblebees use visual and auditory aposematic signals to warn predators about their defenses. For 2 years, we observed competition for nestboxes between chemically defended insects, Bombus ardens (and possibly also Bombus ignitus), and cavity nesting birds (Parus minor and Poecile varius). Bumblebees settled in 16 and 9 % of nestboxes (in 2010 and 2011 breeding seasons, respectively) that contained bird nests at the advanced stage of nest building or at the stage of egg laying. Presence of bumblebees prevented the birds from continuing the breeding activities in the nestboxes, while insects took over the birds’ nests (a form of kleptoparasitism). Playback experiments showed that the warning buzz by bumblebees contributed to the success in ousting the birds from their nests. This demonstrates that aposematic signals may be beneficial also in the context of resource competition.     

Stabilization of lead and copper contaminated firing range soil using calcined oyster shells and fly ash

A stabilization/solidification treatment scheme was devised to stabilize Pb and Cu contaminated soil from a firing range using renewable waste resources as additives, namely waste oyster shells (WOS) and fly ash (FA). The WOS, serving as the primary stabilizing agent, was pre-treated at a high temperature to activate quicklime from calcite. Class C FA was used as a secondary additive along with the calcined oyster shells (COS). The effectiveness of the treatment was evaluated by means of the toxicity characteristic leaching procedure (TCLP) and the 0.1 M HCl extraction tests following a curing period of 28 days. The combined treatment with 10 wt% COS and 5 wt% FA cause a significant reduction in Pb (>98 %) and Cu (>96 %) leachability which was indicated by the results from both extraction tests (TCLP and 0.1 M HCl). Scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM–EDX) analyses are used to investigate the mechanism responsible for Pb and Cu stabilization. SEM–EDX results indicate that effective Pb and Cu immobilization using the combined COS–FA treatment is most probably associated with ettringite and pozzolanic reaction products. The treatment results suggest that the combined COS–FA treatment is a cost effective method for the stabilization of firing range soil.     

Comparison of metabolic nitramine degradation by denitrifying species

The biodegradation of two popular nitramine energetics were investigated. The HMX (octa‐hydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine) was mineralized by anaerobic mixed denitrifiers in digested sewage sludge culture. An initial HMX concentration of 120 mg/L decreased to a non‐detectable level (> 99% removal efficiency) in 8 days of incubation under strict anaerobic conditions. It was, however, not effectively metabolized by single denitrifying species, P. aeruginosa, B. subtilis in a nitrogen limiting condition under their optimum growth conditions. The other nitramine energetic, ADN (ammonium dinitramide), was mineralized well in the anaerobic mixed culture. The initial ADN concentration of 250 mg/L was reduced to non‐detectable levels (> 99% removal efficiency) in 5 days of incubation under anaerobic conditions. These results show that the anaerobic mixed culture, compared to the pure monoculture, is superior in the degradation of nitramine energetics.     

Assessment of soil washing for heavy metal contaminated paddy soil using FeCl3 washing solutions

Environmental Geochemistry and Health - In this study, soil washing is applied for the remediation of heavy-metal (Pb, Cu and Zn) contaminated paddy soil located near an abandoned mine area. FeCl3...