Journal of Hazardous, Toxic, and Radioactive Waste

From the perspective of emergency process safety, this paper studies cause factors in the emergency process of fire accidents for oil and gas storage and transportation systems. Through the statistical analysis of actual accident cases and combining expert consultation, 23 influence factors from four aspects—human, material-environment, and management—are determined, and a cause factor system of secondary accidents in the emergency process is established. The relationships between cause factors are analyzed using interpretative structural modeling (ISM), and a nine-layer hierarchical ISM model of cause factors in emergency processes is established. Based on the ISM model, the direct factors, indirect factors, and root factors leading to secondary accidents are obtained. The importance of each factor is decided by calculating the weight with the analytic hierarchy process (AHP) method, and management factors and material factors are found to be the main cause factors leading to secondary accidents. Finally, two actual accident cases are taken as examples to analyze their cause factors in the emergency process using the established ISM model. Research results provide a scientific basis for determining the mechanisms of secondary accidents in oil and gas storage and transportation systems and realizing active prevention and control in the emergency process in advance.

This study investigated the occurrence and treatment of endocrine disrupting chemicals (EDCs), i.e., nonylphenol (NP) and bisphenol-A (BPA), in Taiwanese drinking water sources. The performance of coagulation-sedimentation and rapid filtration in removing a suite of EDCs was evaluated. The rapid filtration process was more effective in removing EDCs than the coagulation and sedimentation processes. In addition, the bioassay techniques E-SCREEN and T47D-KBluc were also used to assess water quality for human health protection. The humic acid may form a gel cake on the surface of membrane and enhance the removal efficiency. Calcium ions not only increase the ionic strength of the solution but also compress the double layer between the adsorbent and the adsorbate, resulting in enhanced removal efficiency. It was thus concluded that both enhancements of ionic strength and molecular size would increase the efficiency of EDC removal. The two selected bioassays suggested that the water quality in Taiwan is satisfactory and good for human health.

Riverbank filtration (RBF) is a cost-effective method to pretreat the surface and groundwater supplies. A safe distance of the pumping well is a function of water quality, soil condition, and the rate of pumping. This article reports findings of an analytic element method (AEM) based on logistic function and hydrodynamic groundwater flow. The logistic model was used to find the safe distance of a pumping well from a polluted river with respect to specific log cycle reduction in harmful pathogen concentration, whereas the hydrodynamic equation was used to measure the travel time of a parcel of water to decide the specific location of a production well. Pathogen transport considering dispersion and decay by applying an explicit finite difference scheme was analyzed. In this article, pathogen transport in groundwater was simulated using a developed model called LIFI-PATRAM that integrated an AEM flow solution with a pathogen transport model. The variation of pathogen concentration with distance at different times was also analyzed for the specific pumping rate. To achieve the objective of limiting pumping rate, the desired reduction of pathogen concentration was evaluated. The findings revealed that the variation of logarithmic concentration of pathogen with distance became linear under hydrodynamic equilibrium condition, which helped to forecast the appropriate location of a pumping well.

In order to facilitate an affordable, sustainable, and technologically viable alternative to traditional brewery wastewater remediation technologies, vermifiltration was explored in this study. The impacts of high organic loading rates (OLRs) on removal of organics and nutrients from a vermifilter and their relationship with earthworm inoculation rates were the principal focus. The current study also investigated the role of dissolved oxygen (DO) in vermifiltration. To conduct this study, OLRs ranged $2.25–11.25\mathrm{kgCOD}/{\mathrm{m}}^3·\mathrm{d}$, while earthworm numbers varied $0–\mathrm{10,000}{\mathrm{per}\mathrm{m}}^3$. The average effluent DO was in the range $0.8–0.9\mathrm{mg}/\mathrm{L}$ from biofilters and $1.5–2.1\mathrm{mg}/\mathrm{L}$ from vermifilters. A chemical oxygen demand (COD) removal efficiency of 92%–96% and a ${\mathrm{NH}}_4^{+}\text{-}\mathrm{N}$ conversion efficiency of 81%–85% were observed when OLRs ranged $2.25–3.15\mathrm{kgCOD}/{\mathrm{m}}^3·\mathrm{d}$ and earthworm density (EWD) ranged $\mathrm{5,000}–\mathrm{10,000}·{\mathrm{NO}}_3^{-}\text{-}\mathrm{N}$ generation was also observed to be in parity with ${\mathrm{NH}}_4^{+}\text{-}\mathrm{N}$ conversion from the system. The impact of DO on COD removal, nitrification, and denitrification was found to be significant. A maximum total nitrogen (TN) removal efficiency of 24% was observed at an EWD of 10,000. Unlike nitrogen removal, phosphorous removal was mostly dependent on adsorption due to dolochar and fine soil particles produced by earthworms. Maximum removal efficiencies of 61% and 44% were observed for ${\mathrm{PO}}_4^{3-}\text{-}\mathrm{P}$ and total phosphates (TP), respectively. The results obtained indicate that DO plays a crucial role in vermifiltration and that EWD and OLR play pivotal roles in maintaining DO in the effluents obtained from vermifiltration.

Contamination in an abundance that is sufficient to threaten human health or the environment is herein termed consequential contamination. Both intuition and the precautionary principle support the need for a diligent sampling effort to ensure appropriate action is taken when consequential contamination is present. However, the most common approach to sample plan design inherently assumes the absence of discovered contamination is sufficient evidence to conclude the absence of consequential contamination. This assumption is indefensible if it can be reasoned that consequential contamination might exist between sampling locations. It is prudent that both soil characterization and rules for decision making minimally provide an acceptable chance of responding to the reasonably conceivable smallest consequential quantity of contamination. A conceptual model for a smallest consequential quantity of contamination is defined by a probability density function and an area-fraction function. Use of these functions to evaluate and prepare sample plan designs is demonstrated. The discussion presents the method’s value, concerns, and limitations.

The efficacy of chemical columns in attenuating leaching of major and trace elements from sedimented ash beds was presented. Sedimented ash beds were formed and treated with a centrally installed sodium hydroxide (NaOH) column of 18 M concentration. After specified curing periods, leachate specimens were extracted and analyzed for elements such as Na, Ca, Mg, Fe, Ni, Pb, Zn, Cu, Cr, As, and Hg. The concentration of elements was found to be a function of the pH of the pore fluid, stabilization period, and location of the specimens. At initial days of curing, the concentration of elements increased marginally; subsequently, a considerable reduction in concentration occurred. The reaction products encapsulated the elements in matrix structures, reducing their concentration. The contamination potential ratio (CPR) was found to be a function of hydraulic conductivity, microstructure, pH of the pore fluid, stabilization period, and location. A decline in CPR value with stabilization period was primarily due to the reduction in hydraulic conductivity, encapsulation of metals in the reaction matrix, and precipitation of metal hydroxides in a highly basic environment.

Mordenite, semibaked dolomite, and activated carbon were chosen as adsorbents in a column for purifying water contaminated with radioactive materials. Under the static condition, distribution coefficients of radioactive isotopes (${}^{137}\mathrm{Cs}$, ${}^{90}\mathrm{Sr}$, ${}^{106}\mathrm{Ru}$, ${}^{144}\mathrm{Ce}$, and ${}^{131}\mathrm{I}$) in water on mordenite, semibaked dolomite, and activated carbon were determined. Distribution coefficients of radioactive isotopes on columns charged with individual adsorbents (granular size = 0.2–0.315 mm) were also determined. Based on those experimental data, as radioactive contaminated water [specific radioactivity of $4–6\times {10}^3\mathrm{imp}\mathrm{u}\mathrm{l}\mathrm{s}\mathrm{e}(\mathrm{i}\mathrm{m}\mathrm{p})/(\mathrm{mL}·\min )$] traveled at a flow rate of $0.1\mathrm{mL}/\min$ through a column charged with those adsorbents together, radioactive isotopes (${}^{137}\mathrm{Cs}$, ${}^{90}\mathrm{Sr}$, ${}^{106}\mathrm{Ru}$, ${}^{144}\mathrm{Ce}$, and ${}^{131}\mathrm{I}$) were removed completely from water at volume 200 times that of the total adsorbents’ bed volume. Thus, this column may be used to purify radioactive contaminated water.