Effects of serial passage on the characteristics and chondrogenic differentiation of canine umbilical cord matrix derived mesenchymal stem cells.

Mesenchymal stem cells (MSCs) are often known to have a therapeutic potential in the cell-mediated repair for fatal or incurable diseases. In this study, canine umbilical cord MSCs (cUC-MSCs) were isolated from umbilical cord matrix (n = 3) and subjected to proliferative culture for 5 consecutive passages. The cells at each passage were characterized for multipotent MSC properties such as proliferation kinetics, expression patterns of MSC surface markers and self-renewal associated markers, and chondrogenic differentiation. In results, the proliferation of the cells as determined by the cumulative population doubling level was observed at its peak on passage 3 and stopped after passage 5, whereas cell doubling time dramatically increased after passage 4. Expression of MSC surface markers (CD44, CD54, CD61, CD80, CD90 and Flk-1), molecule (HMGA2) and pluripotent markers (sox2, nanog) associated with self-renewal was negatively correlated with the number of passages. However, MSC surface marker (CD105) and pluripotent marker (Oct3/4) decreased with increasing the number of subpassage. cUC-MSCs at passage 1 to 5 underwent chondrogenesis under specific culture conditions, but percentage of chondrogenic differentiation decreased with increasing the number of subpassage. Collectively, the present study suggested that sequential subpassage could affect multipotent properties of cUC-MSCs and needs to be addressed before clinical applications.

Removal of heavy metals in an abandoned mine drainage via ozone oxidation: a pilot-scale operation.

The objective of this study was to evaluate the ozone oxidation of dissolved heavy metals in an abandoned mine drainage (AMD) by conducting a pilot-scale operation at two different ozone doses of 7.5 and 24.0 g O(3)/h into an ozone reactor. A portion of the abandoned mine drainage near the Jungam Mine in Samchuck, Korea was pumped into this pilot-scale plant and used as an influent for the ozone oxidation. Some possible precipitates of metal oxides and hydroxides that resulted from the pilot-scale ozone oxidation of the dissolved Fe and Mn ions in the AMD (with a hydraulic retention time of 106 seconds in the ozone reactor) were effectively removed via sand filtration. A six-hour ozone oxidation with an ozone dose of 24.0 g O(3)/h and subsequent sand filtration, before backwashing the sand filter bed, can meet Korean drinking water quality standards (less than 0.3 mg/L) for Fe and Mn in the sand filter effluent under the operating conditions that were used in this study. The SO(4)(-2) concentrations and alkalinities of the influents were not affected by the ozone oxidation. The pH values of the influents were neutral or slightly alkaline, and after the six-hour oxidation, increased very slightly. These experiment results show that the ozone oxidation of dissolved heavy metals and the subsequent sand filtration of metal precipitates are desirable alternatives to removing heavy metals in an abandoned mine drainage.

Degradation of diethyl phthalate in treated effluents from an MBR via advanced oxidation processes: effects of nitrate on oxidation and a pilot-scale AOP operation.

The major objective of this study was to delineate the oxidation of diethyl phthalate (DEP) in water, using bench-scale UV/H2O2 and O3/H2O2 processes, and to determine the effects of nitrate (NO(3-)-N, 5 mg L(-1)) on this oxidation. The oxidation of DEP was also investigated through a pilot-scale advanced oxidation process (AOP), into which a portion of the effluent from a pilot-scale membrane bioreactor (MBR) plant was pumped. The bench-scale operation showed that DEP could be oxidized via solely UV oxidation or O3 oxidation. The adverse effect of nitrate on the DEP oxidation was remarkable in the UV/H2O2 process, and the nitrate clearly reduced its oxidation. The adverse effect of nitrate on O3 oxidation was also observed. It was noted, however, that the nitrate clearly enhanced the DEP oxidation in the O3/H2O2 process. A series of pilot-scale AOP operations indicated that the addition of H2O2 enhanced DEP oxidation in both the UV/H2O2 and O3/H2O2 processes. No noticeable adverse effect of nitrate was observed in the NO(3-)-N concentration of about 6.0 mg L(-1), which was naturally contained in the treatment stream. About 52% and 61% of the DEP were oxidized by each of these two oxidation processes in this pilot-scale operation. Both the UV/H2O2 and O3/H2O2 processes appeared to be desirable alternatives for DEP oxidation in treatment effluent streams.

Advanced H2O2 oxidation for diethyl phthalate degradation in treated effluents: effect of nitrate on oxidation and a pilot-scale AOP operation.

One of the objectives of this study was to delineate the effect of nitrate on diethyl phthalate (DEP) oxidation by conducting a bench-scale ultraviolet (UV)/H2O2 and O3/H2O2 operations as suggested in a previous study. We also aim to investigate DEP oxidation at various UV doses and H2O2 concentrations by performing a pilot-scale advanced oxidation processes (AOP) system, into which a portion of the effluent from a pilot-scale membrane bioreactor (MBR) plant was pumped. In the bench-scale AOP operation, the O3 oxidation alone as well as the UV irradiation without H2O2 addition could be among the desirable alternatives for the efficient removal of DEP dissolved in aqueous solutions at a low DEP concentration range of 85+/-15 microg/L. The adverse effect in the UV/H2O2 process was significantly greater than that in the UV oxidation alone, and its oxidation was almost halved by the nitrate. However, the nitrate clearly enhanced the DEP oxidation in the O3 oxidation and O3/H2O2 process. Especially, the addition of nitrate almost doubled the DEP oxidation efficiency in the O3/H2O2 process. The series of pilot-scale AOP operations confirmed that about 30-50% of DEP dissolved in the treated MBR effluent streams was, at least, oxidized by the O3 oxidation alone as well as the UV irradiation without H2O2 addition. The UV photolysis of H2O2 was most effective for DEP degradation with an H2O2 concentration of 40 mg/L at a UV dose of 500 mJ/cm2.

Effects of nitrate on the UV photolysis of H2O2 for VOCs degradation in an aqueous solution.

The major objective of this study was to delineate the effect of nitrate on the UV oxidation of benzene and toluene, dissolved in less than 100 microg l(-1), by conducting a bench-scale operation at various reaction times and with various initial concentrations of H2O2 and NO3-. The oxidation of benzene and toluene can be expected to be only about 10% and 18%, respectively, through the photolysis of H2O2 (initial conc. of 50 mg l(-1)), where the reactor was operated at a reaction time of 2 min, with an initial NO(3-)-N concentration of 5 mg l(-1). Nitrate clearly hindered UV oxidation when the initial H2O2 concentration in the reactor was less than 50 mg l(-1). Even if approximately 40% removal could be achieved under the conditions mentioned above (an initial H2O2 concentration of 200 mg l(-1) at a reaction time of 9 min, with a high UV dose), the operating conditions for the 40% removal might be beyond the practical limits applied for effluents discharged from wastewater treatment plants. The results of the experiment also indicate that benzene and toluene can be oxidized in very limited amounts through direct photolysis, without additional oxidation by hydroxyl radicals.

Biological nutrient removal using an IACOD process: determining the combined effects of low temperature and long solids retention time.

This study was undertaken using an intermittently aerated cylindrical oxidation ditch (IACOD) process for biological nutrient removal. The kinetic aspects of nitrification, denitrification, and phosphorus release/uptake were investigated by conducting a pilot-scale operation under various contact times for the aerobic/anoxic reactor, SRTs, and HRTs. The effects of temperature were also evaluated. The results of the study revealed that a cycle time of 180 min. (i.e., the aerobic contact time of 60 mim. followed by the anoxic contact time of 120 min.) enhanced the biological nutrient removal at an aerobic SRT of 8.3 days and an HRT of 24 hours in the aerobic/anoxic reactor. Even during the winter months with mixed liquor temperatures between 9.6 degrees C and 12 degrees C at an aerobic SRT of 10 days, the IACOD process was capable of almost completely nitrifying the influent NH4- -N. The IACOD process was also capable of denitrifying the NO3- -N in the aerobic/anoxic reactor, yielding effluent NO3- -N concentrations of less than 2.0 mg l(-1) N. Furthermore, the release and abundant uptake of phosphorus successfully occurred at this low temperature range. The enhanced biological phosphorus removal rates increased steadily as the temperature increased from 9.6 degrees C to 22 degrees C. However, an inhibition of phosphorus release was observed at a temperature range of 18 degrees C to 20 degrees C. This inhibition might have been caused by the sudden increase in the NO3- -N concentration of the return sludge, which was induced by the rapid nitrification of the influent NH4+ -N at a relatively elevated temperature. The inhibition was not prolonged due to the subsequent increase in the denitrification rate as the temperature increased further to 20 degrees C and above.

Denitrification and phosphorus release under anoxic conditions in an anoxic-anaerobic-aerobic BNR process.

An anoxic-anaerobic-aerobic biologial nutrient removal process was used in this study. The kinetic aspects of denitrification and phosphorus release under anoxic conditions were investigated by conducting a pilot-scale plant operation under various SRTs (solids retention times), HRTs (hydraulic retention times) and internal recycle ratios. The process was capable of completely denitrifying the NOx- -N (the sum of NO2- -N and NO3- -N) in the nitrified recycle, resulting in an NOx- -N concentration of less than 1.0 mg l(-1) N in the anoxic zones. Denitrification and phosphorus release were accomplished due to abundant organic substrates in the anoxic zone at the head end of the process and achieved approximately equivalent rates with respect to influent SCOD loading in the zone. Phosphorus release continued without any nitrate inhibition due to low NOx- -N concentrations of less than 2.0 mg l(-1) N in the anaerobic zone.

Wastewater screening method for evaluating applicability of zero-valent iron to industrial wastewater.

This study presents a screening protocol to evaluate the applicability of the ZVI pretreatment to various industrial wastewaters of which major constituents are not identified. The screening protocol consisted of a sequential analysis of UV-vis spectrophotometry, high-performance liquid chromatograph (HPLC), and bioassay. The UV-vis and HPLC analyses represented the potential reductive transformation of unknown constituents in wastewater by the ZVI. The UV-vis and HPLC results were quantified using principal component analysis (PCA) and Euclidian distance (ED). The short-term bioassay was used to assess the increased biodegradability of wastewater constituents after ZVI treatment. The screening protocol was applied to seven different types of real industrial wastewaters. After identifying one wastewater as the best candidate for the ZVI treatment, the benefit of ZVI pretreatment was verified through continuous operation of an integrated iron-sequencing batch reactor (SBR) resulting in the increased organic removal efficiency compared to the control. The iron pretreatment was suggested as an economical option to modify some costly physico-chemical processes in the existing wastewater treatment facility. The screening protocol could be used as a robust strategy to estimate the applicability of ZVI pretreatment to a certain wastewater with unknown composition.

Zero-valent iron pretreatment for detoxifying iodine in liquid crystal display (LCD) manufacturing wastewater.

This study investigated reductive transformation of iodine by zero-valent iron (ZVI), and the subsequent detoxification of iodine-laden wastewater. ZVI completely reduced aqueous iodine to non-toxic iodide. Respirometric bioassay illustrated that the presence of iodine increase the lag phase before the onset of oxygen consumption. The length of lag phase was proportional to increasing iodine dosage. The reduction products of iodine by ZVI did not exhibit any inhibitory effect on the biodegradation. The cumulative biological oxidation associated with iodine toxicity was closely fitted to Gompertz model. When iodine-laden wastewater was continuously fed to a bench-scale activated sludge unit, chemical oxygen demand (COD) removal efficiencies decreased from above 90% to below 80% along with a marked decrease in biomass concentration. On the other hand, the COD removal efficiency and biomass concentration remained constant in the integrated ZVI-activated sludge system. Respirometric bioassay with real iodine-laden LCD manufacturing wastewater demonstrated that ZVI was effective for detoxifying iodine and consequently enhancing biodegradability of wastewater. This result suggested that ZVI pretreatment may be a feasible option for the removal of iodine in LCD processing wastewater, instead of more costly processes such as adsorption and chemical oxidation, which are commonly in the iodine-laden LCD wastewater treatment facility.