Bioremediation of polychlorinated-p-dioxins/dibenzofurans contaminated soil using simulated compost-amended landfill reactors under hypoxic conditions.

Compost-amended landfill reactors were developed to reduce polychlorinated-p-dioxins and dibenzofurans (PCDD/Fs) in contaminated soils. By periodically recirculating leachate and suppling oxygen, the online monitoring of the oxidation reduction potential confirmed that the reactors were maintained under hypoxic conditions, with redox levels constantly fluctuating between -400 and +80mV. The subsequent reactor operation demonstrated that PCDD/F degradation in soil could be facilitated by amending compost originating from the cow manure and waste sludge and that the degradation might be affected by the availability of easily degradable substrates in the soil and compost.

Pyrosequencing analysis reveals high population dynamics of the soil microcosm degrading octachlorodibenzofuran.

A deeper understanding of the microbial community structure is very important in bioremediation for polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs). However, this has been insufficiently addressed in previous studies. To obtain more information, we pyrosequenced the V4/V5 regions of the 16S rRNA genes of bacterial communities transited from polluted soil to batch microcosms that rapidly degraded high concentrations of octachlorodibenzofuran (OCDF).

Bioremediation potential of soil contaminated with highly substituted polychlorinated dibenzo-p-dioxins and dibenzofurans: microcosm study and microbial community analysis.

Highly chlorinated dibenzo-p-dioxins/dibenzofurans (DD/Fs) are main hazardous dioxins, and ubiquitously distributed in the environment. To study the feasibility of bioremediation for remedying contamination of highly chlorinated dioxins, closed microcosms were constructed with soil from a chronological site under oxygen-stimulated conditions. The results showed that high levels of near-fully and fully chlorinated DD/Fs, particularly octachlorodibenzofuran were effectually reduced without accumulation of less substituted congeners.

Effects of sintering atmosphere on cement clinkers produced from chromium-bearing sludge.

The purpose of this study was to investigate the effects of sintering atmosphere (oxidizing and reducing) on the polymorphs of dicalcium silicates (Ca2SiO4, C2S) and on the chromium leaching of the belite-rich clinkers made from a chromium-bearing sludge. This sludge was generated in an electroplating factory, and in addition to chromium, it contained nickel, copper and zinc. In the clinker production, air was used as the oxidizing atmosphere, and carbon monoxide, which was produced by burning graphite with an insufficient amount of oxygen, was employed as the reducing atmosphere.

Stabilization of residues obtained from the treatment of laboratory waste: Part 2--transformation of plasma vitrified slag into composites.

The Sustainable Environment Research Center of National Cheng Kung University in Taiwan has set up a treatment plant to dispose of laboratory waste. In the treatment process, the residue from the incineration system and the physical and chemical system is vitrified by a plasma melting system. Part 1 of this study described the treatment path of metals during vitrification.

Hydration and leaching characteristics of cement pastes made from electroplating sludge.

The purpose of this study was to investigate the hydration and leaching characteristics of the pastes of belite-rich cements made from electroplating sludge. The compressive strength of the pastes cured for 1, 3, 7, 28, and 90 days was determined, and the condensation of silicate anions in hydrates was examined with the (29)Si nuclear magnetic resonance (NMR) technology. The leachabilities of the electroplating sludge and the hardened pastes were studied with the multiple toxicity characteristic leaching procedure (MTCLP) and the tank leaching test (NEN 7345), respectively.

Reusing pretreated desulfurization slag to improve clinkerization and clinker grindability for energy conservation in cement manufacture.

The purpose of this study was to combine the physical pretreatments of grinding, sieving, and magnetic-separation processes to reclaim iron-rich materials from the desulfurization slag, and to use the remainder for cement clinker production. The iron-rich materials can be separated out efficiently by grinding for 30 min and sieving with a 0.3 mm mesh.

Stabilization of residues obtained from the treatment of laboratory waste. Part 1--Treatment path of metals in a plasma melting system.

The objective of this study is to investigate the treatment path of metals during the plasma vitrification of fly ash, bottom ash, sludge, and activated carbon collected from a laboratory waste treatment plant. Sampling, digestion, and analysis procedures that followed the standard methods of the Taiwan Environmental Protection Administration were used to determine the composition of the input and output materials. The microstructure was qualitatively examined using a scanning electron microscope.

Synthesis of nanosize-controllable copper and its alloys in carbon shells.

Nanosize-controllable Cu, Ag, Pd, Ni, CuPd alloy and Cu-Ag bimetal encapsulated in inert carbon shells can be synthesized by carbonization of metal-cyclodextrin complexes with a remarkable capability of experimentally determining the size-dependent melting temperature depression of many metal or alloy nanoparticles.

The influence of heavy metals on the polymorphs of dicalcium silicate in the belite-rich clinkers produced from electroplating sludge.

The purpose of this study is to utilize an electroplating sludge for belite-rich clinker production and to observe the influence of heavy metals on the polymorphs of dicalcium silicate (C(2)S). Belite-rich clinkers prepared with 0.5-2% of NiO, ZnO, CuO, and Cr(2)O(3) were used to investigate the individual effects of the heavy metals in question.

Inactivation of bacteria by a mixed argon and oxygen micro-plasma as a function of exposure time.

Purpose: A radio-frequency dielectric barrier discharge (DBD) was applied as a micro-plasma device for the inactivation of bacteria, e.g., Escherichia coli.

Vitrification for reclaiming spent alkaline batteries.

The object of this study is to stabilize spent alkaline batteries and to recover useful metals. A blend of dolomite, limestone, and cullet was added to act as a reductant and a glass matrix former in vitrification. Specimens were vitrified using an electrical heating furnace at 1400 degrees C and the output products included slag, ingot, flue gas, and fly ash.

Photocatalytic degradation of spill oils on TiO(2) nanotube thin films.

The nitrogen-doped TiO(2) nanotube (N-TNT) thin films were synthesized using ZnO nanorods as the template and doped with urea at 623K. Under ultraviolet (UV) and visible light irradiation, the efficiencies for photocatalytic degradation of methylene blue is as high as 30%. About 10% of toluene (representing aromatics in the spill oils) in sea water can be photocatalytically degraded under visible light radiation for 120 min.

An alternative approach for reusing slags from a plasma vitrification process.

Vitrification is widely applied to transform hazardous materials into inert slags. Raising the value of the recycled slag is an important issue from an economic point of view. In this study, an alternative approach for mixing a plasma slag with unsaturated polyester resin for making the dough-like molding composites is proposed.

Stabilization of copper sludge by high-temperature CuFe2O4 synthesis process.

Copper sludge was stabilized by high-temperature CuFe(2)O(4) ferritization technique with different sintering temperature, isothermal time and Fe(3+)/M(2+) molar ratio. Copper is stabilized by inserting the copper ion into the stable CuFe(2)O(4) structure by ferritization. The result indicates that sintering temperature above 800 degrees C would be proper temperature range for CuFe(2)O(4) synthesis.

Emission of polycyclic aromatic hydrocarbons (PAHs) from the liquid injection incineration of petrochemical industrial wastewater.

This study investigated the emission of polycyclic aromatic hydrocarbons (PAHs) from stack flue gas and air pollution control device (APCD) effluent of the liquid injection incinerator (LII) disposing the petrochemical industrial wastewater, and PAH removal efficiencies of wet electrostatic precipitator (WESP) and wet scrubber (WSB). The PAH carcinogenic potency were investigated with the benzo(a)pyrene equivalent concentration (BaP(eq)). The remarkably high total-BaP(eq) concentration (220 microgNm(-3)) in the stack flue gas was much higher than those of several published emission sources, and indicated the possible influence on its surrounding environment.

Effects of CH4 and CO on the reduction of nitric oxide to nitrogen in a discharge reactor.

Additives are often added to enhance the efficiency of NO removal. This study uses a radio frequency (rf) discharge to consider the effect of added CH4 and CO to simulated NO/N2/O2/H2O mixtures on the elevation of NO conversion and the reduction of NO into N2. The enhancement levels of NO conversion when using various additives were found to be in this order: +CH4 > +CO > no additive.

Influence of start-up on PCDD/F emission of incinerators.

This study aims to evaluate the influence of start-up on polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) concentration in the stack flue gas of incinerators and its contributing PCDD/F emission. The PCDD/F emission of the first sample among three consecutive stack flue gas samples of five intermittent incinerators, which sampled at a stable combustion condition after start-up, is 2-3 times higher than the mean of the others. For verifying the PCDD/F characteristics of incinerators during start-up, one continuous MSWI was investigated for two years.

Tracking of copper species in incineration fly ashes.

Speciation of copper in the incineration waste heat boiler (HB) and the down stream electrostatic precipitator (EP) fly ashes during the flue gas cooling down (1123-->473 K) has been studied by X-ray absorption near edge structural (XANES) spectroscopy in the present work. Copper species such as Cu(OH)(2) (59-67%), CuCl(2) (5-12%), CuO (24-26%), and a small amount of CuS (3-4%) in fly ashes were determined by semi-quantitative analyses of the XANES spectra. In the toxicity characteristics leaching procedure (TCLP) tests, about 83 and 20% of copper were leached from the EP and HB fly ashes, respectively.

Comparisons of levels of polychlorinated dibenzo-p-dioxins/dibenzofurans in the surrounding environment and workplace of two municipal solid waste incinerators.

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the surrounding environment (outdoor) and workplace air of two municipal solid waste incinerators (MSWIs, T and M) were characterized and compared. T and M represented two typical municipal solid waste incinerators in the north of Taiwan, which have different processes for controlling the PCDD/F emissions. The results of this study are summarized as follows.

Leaching behavior and chemical stability of copper butyl xanthate complex under acidic conditions.

Although xanthate addition can be used for treating copper-containing wastewater, a better understanding of the leaching toxicity and the stability characteristics of the copper xanthate complexes formed is essential. This work was undertaken to evaluate the leaching behavior of copper xanthate complex precipitates by means of toxicity characteristics leaching procedure (TCLP) and semi-dynamic leaching test (SDLT) using 1 N acetic acid solution as the leachant. Also, the chemical stability of the copper xanthate complex during extraction has been examined with the studying of variation of chemical structure using UV-vis, Fourier transform infrared and X-ray photoelectron spectroscopies (XPS).

Leaching behavior and ESEM characterization of water-sensitive mudstone in southwestern Taiwan.

This investigation attempts to understand the critical soluble salts in natural mudstone and the leaching, microstructural, and microchemical characteristics in soaked mudstone using scanning electron microscopy (SEM)/energy-dispersive X-ray analysis (EDAX), X-ray fluorescence spectrometry (XRF), X-ray diffractometry (XRD), conductivity measurement, ion chromatography (IC), and environmental scanning electron microscopy (ESEM)/EDAX techniques. Natural mudstone probably includes soluble salts such as Na2SO4, NaCl, NaCO3, and CaCO3. The dissolution of Na2SO4 controls water-sensitive mudstone very susceptible to slaking and dispersion.

Effects of leaching parameters on swelling behaviors of compacted mudstone used in landfill liner.

This study attempt to determine the swelling deformation of compacted mudstone using the free swell test, and the leaching parameters using a pH meter, a conductivity meter, and ion chromatography (IC) techniques. Closely examining chemical characteristics indicated that natural mudstone is saline-alkali soil. The maximum swelling deformation obtained from the free swell test is about 15.

Integrated copper-containing wastewater treatment using xanthate process.

Although, the xanthate process has been shown to be an effective method for heavy metal removal from contaminated water, a heavy metal contaminated residual sludge is produced by the treatment process and the metal-xanthate sludge must be handled in accordance with the Taiwan EPA's waste disposal requirements. This work employed potassium ethyl xanthate (KEX) to remove copper ions from wastewater. The toxicity characteristic leaching procedure (TCLP) and semi-dynamic leaching test (SDLT) were used to determine the leaching potential and stability characteristics of the residual copper xanthate (Cu-EX) complexes.

Speciation of copper in the incineration fly ash of a municipal solid waste.

The speciation of copper and zinc in the incineration fly ash of a municipal solid waste in Taiwan was investigated in the present work. By the least-squares fitted X-ray absorption near edge structural (XANES) spectroscopy, we found that CuCO3, CuOH2, and CuO (fractions of 0.09, 0.