Effects of adding slags on strength and leaching properties of soft soil

Journal of Material Cycles and Waste Management - Dredged soils are typically mixed with additives to improve their mechanical properties and reduce the risks of leaching toxic elements. An...     

Degradation characteristics of methyl ethyl ketone by Pseudomonas sp. KT-3 in liquid culture and biofilter

With ketone pollution forming an ever-growing problem, it is important to identify a ketone-degrading microorganism and establish its effect. Here, a methyl ethyl ketone (MEK)-degrading bacterium, Pseudomonas sp. KT-3, was isolated and its MEK degradation characteristics were examined in liquid cultures and a polyurethane-packed biofilter. In liquid cultures, strain KT-3 could degrade other ketone solvents, including diethyl ketone (DK), methyl propyl ketone (MPK), methyl isopropyl ketone (MIPK), methyl isobutyl ketone (MIBK), methyl butyl ketone (MBK) and methyl isoamyl ketone (MIAK). The maximum specific growth rate (mumax) of the isolate was 0.136 h(-1) in MEK medium supplemented with MEK as a sole carbon source, and kinetically, the maximum removal rate (Vm) and saturation constant (Km) for MEK were 12.28 mM g(-1)DCW h(-1) (DCW: dry cell weight) and 1.64 mM, respectively. MEK biodegradation by KT-3 was suppressed by the addition of MIBK or acetone, but not by toluene. In the tested biofilter, KT-3 exhibited a>90% removal efficiency for MEK inlet concentrations of around 500 ppmv at a space velocity (SV) of 150 h(-1). The elimination capacity of MEK was more influenced by SV than by the inlet concentration. Kinetic analysis showed that the maximum MEK removal rate (Vm) was 690 g m(-3) h(-1) and the saturation constant (Km) was 490 ppmv. Collectively, these results indicate the polyurethane sequencing batch biofilter with Pseudomonas sp. KT-3 will provide an excellent performance in the removal of gaseous MEK.     

Comparison of fenton and photo-fenton processes for livestock wastewater treatment

In this study, the photochemical degradation of livestock wastewater was carried out by the Fenton and Photo-Fenton processes. The effects of pH, reaction time, the molar ratio of Fe(2 +)/H(2)O(2), and the Fe(2 +) dose were studied. The optimal conditions for the Fenton and Photo-Fenton processes were found to be at a pH of 4 and 5, an Fe(2 +) dose of 0.066 M and 0.01 M, a concentration of hydrogen peroxide of 0.2 M and 0.1 M, and a molar ratio (Fe(2 +)/H(2)O(2)) of 0.33 and 0.1, respectively. The optimal reaction times in the Fenton and Photo-Fenton processes were 60 min and 80 min, respectively. Under the optimal conditions of the Fenton and Photo-Fenton processes, the chemical oxygen demand (COD), color, and fecal coliform removal efficiencies were approximately 70--79, 70--85 and 96.0--99.4%, respectively.     

Sorption and reduction of tetrachloroethylene with zero valent iron and amphiphilic molecules

Effects of surfactants and natural organic matter (NOM) on the sorption and reduction of tetrachloroethylene (PCE) with zero valent iron (ZVI) were examined in this study. PCE reduction by ZVI depended on the ionic type of the surfactants. The removal of PCE and production of TCE with non-ionic Triton X-100 and cationic hexadecyltrimethyl-ammonium (HDTMA) at one-half and two times the critical micelle concentration (CMC) were 1.2-1.8 times higher than without surfactants because of the enhanced PCE partitioning and surface concentration by the sorbed surfactants. When anionic sodium dodecyl benzene sulfonate (SDDBS) at one-half and two times CMC and NOM at 20 mg l(-1) and 50 mg l(-1) concentrations were used, the removal of PCE doubled and TCE production decreased. In the presence of SDDBS, TCE production by ZVI was lower than with HDTMA and Triton X-100 while PCE removal was higher than with the other surfactants.