The use of ultrasound-assisted anaerobic compost tea washing to remove poly-chlorinated dibenzo-p-dioxins (PCDDs), dibenzo-furans (PCDFs) from highly contaminated field soils

Abstract

The remediation of dioxin-contaminated soil of a specific coastal area previously employed for the manufacture of pentachlorophenol (PCP) in southern Taiwan's Tainan City has attracted much attention of researchers there. This work addresses the possibility of providing an effective and environmentally friendly option for removing PCDD/Fs from soil in that field. Soil screening/sieving was first conducted to assess particle distribution. Fine sand was observed to be the major component of the soil, accounting for more than 60% of the total mass. A combination of ultrasonification and mechanical double-blade agitation was used to facilitate the washing of the soil using the biosurfactant anaerobic compost tea. More than 85 and 95% of total removal efficiencies were achieved for moderately and highly contaminated soils after 6 and 10 washing cycles, respectively, under ambient temperature, a soil/liquid ratio 1:2.5, 700 rpm, and over a relatively short duration. These results were achieved through the collision and penetration effects of this combined treatment as well as PCDD/F partitioning between the particles and anaerobic compost tea. This study represents the first to report the use of anaerobic compost tea solvent to wash soil highly contaminated by dioxin. It was concluded that anaerobic compost tea, rich in non-toxic bio-surfactants (e.g., alcohols, humic acids), can be used to improve bioavailability and bioactivity of the soil making bio-attenuation and full remediation more efficient.

Efficacy of Indigenously Prepared Sugarcane and Pineapple Wine Solvents for Washing Highly Dioxin-Contaminated Field Soils

“…The details of sample analysis can be viewed in our previous studies [1,2]. Technically, extraction was performed using a method recommended by the United States Environmental Protection Agency [29].…”

“…The details of soil sample preparation were described in our previous publications [1,2]. Briefly, a soil screening standard of the American Society for Testing and Materials [25] was employed for soil sample preparation.…”

“…It should be noted that the other particle sizes, even the finest ones, could be economically treated by the current treatment method employed at the contaminated site (incineration) considering that the amount of these particles is somewhat small. The dioxin TEQs of the other particle sizes can be viewed from our previous publication [1].…”

“…Because target compounds were unknown, USEPA method 8260B was adopted for the qualification and quantification of VOCs [34]. In order to clarify the mechanism of the high removal efficiencies of the wine solvents, we spiked them (10 µ L each) into a 40 mL deionized water vial [1,2]. Then, using a purge and trap system combined with 6890-5973 GC-MSD for this analysis [34], we compared the peaks we found with those established in the NIST mass spectra library [35].…”

“…Dioxins, polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) negatively affect the environment and human health [1,2]. They are considered nonvolatile chemicals and because of their characteristics of hydrophobicity and lipophilicity, their water-solubility is considerably low, meaning that they are often attached to soil and sediments [3].…”