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Decomposition of PCBs in commercially used transformer oil used for more than 30 years has been carried out at normal temperature and pressure without any additives using an electron beam accelerator. The experiments were carried out in two ways: batch and continuous pilot plant with 1.5 MeV of energy, a 50 mA current, and 75 kW of power in a commercial scale accelerator. The electron beam irradiation seemed to transform large molecular weight compounds into lower ones, but the impact was considered too small on the physical properties of oil. Residual concentrations of PCBs after irradiation depend on the absorption dose of the electron beam energy, but aliphatic chloride compounds were produced at higher doses of irradiation. As the results from FT-NMR, chloride ions decomposed from the PCBs are likely to react with aliphatic hydro carbon compounds rather than existing as free radical ions in the transformer oil. Since this is a dry process, treated oil can be used as cutting oil or machine oil for heavy equipment without any additional treatments.

The object of this study was to improve pre-concentration techniques using hollow fibre protected-liquid phase micro-extraction (LPME) for its application on biotic samples and limited environmental samples provided in small volumes. Five parameters, including extraction time, type of solvent, extents of agitation, fibre length and salt content of HF-LPME were optimised for the yeast two-hybrid assay and gas chromatography-mass spectrometer (GC/MS) chemical analysis. The results of chemical analysis were compared to the results of a bioassay using the yeast two-hybrid system to analyse endocrine-disrupting chemicals (EDCs). For the yeast two-hybrid assay, the optimised parameters comprised of an extraction time of 40 min, toluene as the extraction solvent, a stirring rate of 500 rpm, a fibre length of 2.0 cm and a salt concentration of 20% (w/v). For GC/MS analysis, HF-LPME conditions were optimised with an extraction time of 40 min, toluene: dichloromethane at a ratio of 1 : 1 (v : v) as the extraction s...

This study was conducted to investigate the effects of gamma ray irradiation on the solubilization of waste sewage sludge. The recovery of an organic carbon source from sewage sludge by gamma ray irradiation was also studied. The gamma ray irradiation showed effective sludge solubilization efficiencies. Both soluble chemical oxygen demand (SCOD) and biochemical oxygen demand (BOD5) increased by gamma ray irradiation. The feasibility of the solubilized sludge carbon source for a biological nitrogen removal was also investigated. A modified continuous bioreactor (MLE process) for a denitrification was operated for 20 days by using synthetic wastewater. It can be concluded that the gamma ray irradiation was useful for the solubilization of sludge and the recovery of carbon source from the waste sewage sludge for biological nitrogen removal.

The oxidation of ammonia coupled with the reduction of iron is a unique pathway mostly reported in soils and sediments. An anaerobic sludge from a piggery wastewater treatment plant had been acclimated to an NH+/Fe3+-rich environment to secure an enrichment culture and investigate an anaerobic ammonia oxidation coupled with an iron reduction. The enrichment culture showed an average pH of 6.8 and the concentration of mixed liquor volatile suspended solid was measured as 1,120 mg/L. The mol ratio of oxidized NH4 + and reduced Fe3+ was 0.33 mol NH4 +/mol Fe3+. It was suggested that the culture acclimated to NH4 +/Fe3+ contained the anaerobic ammonia oxidizing bacteria as well and thus NH4 + was fully oxidized to NO3 − by the bacterial consortia. In a batch experiment using the culture, the oxidation of NH4 + was increased as the initial concentration increased. However, it was suspected from the experimental results that other iron reducing bacteria had grown under the environment applied for the enrichment culture. As a result, it was observed that heterotrophic and autotrophic iron reducers were competing for Fe3+.

As the result of a conventional wastewater treatment such as activated sludge process, an excess sludge is produced and must be disposed of safely. Recently, increased attention has been given to a minimization of waste sludge in a wastewater treatment process. In this study, hydrogen peroxide oxidation was applied for an excess activated sludge reduction and an alkaline pretreatment method was used to enhance the efficiency of hydrogen peroxide oxidation of sludge. Sludge particle disintegration by hydrogen peroxide oxidation was confirmed through the evaluations of total solid concentration and particle size distribution. The solubility (SCOD/TCOD) of sludge was increased, while the viscosity was decreased with hydrogen peroxide oxidation and alkaline hydrolysis. The settleability of sludge was improved. When alkaline hydrolysis was applied as a pretreatment for hydrogen peroxide oxidation, the sludge particle disintegration, viscosity decrease, and settleability improvement were accelerated. From the results of this experiment, it can be concluded that hydrogen peroxide oxidation combined with alkaline pretreatment was useful for an excess sludge reduction.

A novel process was developed to induce a simultaneous oxidation of ammonia and denitrification in a single system consisting of two chambers separated by a cation exchange membrane. One was an anoxic chamber and the other was an aerobic chamber. The maximum mass flux via the membrane was calculated as 0.83mg NH(4)(+)-N/m(2)s in a batch test when the initial concentration of NH(4)(+) was 700 mg N/L. And it was observed that NO(3)(-) and NO(2)(-) moved via the membrane in a reverse direction when NH(4)(+) was transported. When the system was operated in a continuous mode by feeding a wastewater containing glucose and NH(4)(+), it was observed that soluble chemical oxygen demand and NH(4)(+) were simultaneously removed showing 99% and 71 approximately 86% of efficiency, respectively. Denitrification occurred in the anoxic chamber and nitrification was carried out in the aerobic chamber.

This study was conducted to investigate the decomposition of three γ-irradiated antibiotics (e.g., tetracycline, sulfamethazine, and lincomycin) and to compare the toxic effects on Daphnia magna, Vibrio fischeri, and Pseudokirchneriella subcapitata. The median cell growth inhibition concentrations (IC50) of tetracycline, lincomycin, and sulfamethazine for P. subcapitata dramatically increased (e.g., toxicity decreased) after radiolysis. The results demonstrated that γ-radiation treatment was efficient to decompose antibiotics and thereby their toxicity on P. subcaptitata remarkably decreased due to reduced parent compounds.

Electron beam was studied to enhance the biodegradability of sewage sludge. Changes in physicochemical characteristics of the sludge were examined with various irradiation doses, sludge thicknesses and exposure times. Irradiation thickness was suggested as the key factor affecting the efficiency of solublization of solid organic matter, whereas exposure time would be the most critical parameter in inducing cell lysis in sewage sludge. In addition, biogas production was improved as much as 22% when the sludge thickness was 0.5 cm with a dose of 7 kGy.

Textile wastewater generally contains various pollutants, which can cause problems during biological treatment. Electron beam radiation technology was applied to enhance the biodegradability of textile wastewater for an activated sludge process. The biodegradability (BOD5/COD) increased at a 1.0 kGy dose. The biorefractory organic compounds were converted into more easily biodegradable compounds such as organic acids having lower molecular weights. In spite of the short hydraulic retention time (HRT) of the activated sludge process, not only high organic removal efficiencies, but also high microbial activities were achieved. In conclusion, textile wastewater was effectively treated by the combined process of electron beam radiation and an activated sludge process.

Radiation treatment using gamma-rays was investigated in order to reclaim the secondary effluent from a sewage treatment plant. The radiation treatment reduced BOD by 85% irrespective of absorbed dose, and the removals of COD, TOC and color were up to 64%, 34% and 88%, respectively, at a dose of 15 kGy. Gamma-rays effectively disinfected microorganisms and completely removed them at a dose of 0.3 kGy. The combination of gamma-rays and titanium dioxide significantly improved the treatment process. The increases of COD, TOC and color removals were 40%, 10% and 20%, respectively. As confirmed by EPR and the spin-trapping method, this increase was partly caused by the increase of hydroxyl radicals in the presence of titanium dioxide.

This study investigates the effect of initial tetrachloroethylene (PCE) concentration, irradiation dose and dissolved metal ions such as Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+ and Zn2+ on removal of PCE by gamma irradiation. The amount of removed PCE decreased with increase in initial PCE concentration and increased with increase in irradiation dose. PCE removal reached a maximum in the presence of Fe3+, while Cu2+ strongly hindered PCE decomposition. Except for Cu2+, the amount of removed PCE in the presence of metal ions was linearly dependent on the standard reduction potential of the metal ions. The extraordinary inhibition of Cu2+ in PCE removal was caused by the action of Cu2+ as a strong OH scavenger, that was directly confirmed by electron paramagnetic resonance spectroscopy.

Multigenerational exposure of Daphnia magna to tetracycline was carried out through four consecutive generations. The effects of tetracycline on the survival, reproduction and growth of D. magna were assessed over a period of 21 days per generation. The evaluated endpoints were overall fecundity (total mean neonates per female over 21 days), time to first reproduction, longevity, molting number and somatic growth, such as body weight and body length. Using the results obtained for reproduction and survival rates, the intrinsic population growth rate (PGR) was calculated and compared throughout the generations. Reproductive impairment was observed in all generations and magnified with increasing generation number. The value of no observed effect concentration on D. magna also markedly decreased with increasing generation number. This subsequently resulted in a reduction of the PGR value. In addition, the PGR value was decreased with increasing exposure concentration, decreasing by about 30 and 60% at 0.1 and 5.0 mg/L tetracycline, respectively. On the other hands, somatic growth increased with increasing generation number, because the remaining input energy from the reduced reproduction was mainly used for body maintenance. As a result, the somatic growth and reproduction showed reversed trends on continuous exposure of tetracycline to four generations. In conclusion, multigenerational exposure of tetracycline can induce overall responses on reproduction and the somatic growth of D. magna. Moreover, the PGR value of D. magna exposed to tetracycline was reduced with increasing generation number; thereby, inhibiting the long term propagation of D. magna.

The recovery of an organic carbon source from a waste activated sludge by using alkaline hydrolysis and radiation treatment was studied, and the feasibility of the solubilized sludge carbon source for a biological denitrification was also investigated. The effects of an alkaline treatment and gamma-ray irradiation on a biodegradability enhancement of the sludge were also studied. A modified continuous bioreactor for a denitrification (MLE reactor) was operated by using a synthetic wastewater for 47 days. Alkaline treatment of pH 10 and gamma-ray irradiation of 20 kGy were found to be the optimum carbon source recovery conditions. COD removal of 84% and T-N removal of 51% could be obtained by using the solubilized sludge carbon source through the MLE denitrification process. It can be concluded that the carbon source recovered from the waste activated sludge was successfully employed as an alternative carbon source for a biological denitrification.

Toxicity changes in copper and diazinon were investigated in the presence of food, clay, and their mixture by using Daphnia magna. In sorption equilibrium experiments, copper was significantly attracted (>34% sorbed) to food, clay, and food-clay mixture due to their negative zeta potential, while diazinon was less sorbed (

The effects of H(2)O(2) and O(3) on the decomposition of trichloroethylene (TCE) and perchloroethylene (PCE) by gamma-rays (gamma-rays) were investigated in this work. The combined gamma-rays/O(3) process showed a synergistic effect and enhanced the removal of TCE and PCE compared with gamma-rays alone, but, the gamma-rays/H(2)O(2) process did not increase the removal. This interesting result was successfully identified by an electron paramagnetic resonance spectroscopy/spin-trapping method that can quantify hydroxyl radicals, which is directly related to the efficiency of TCE and PCE decomposition. For gamma-rays/H(2)O(2) system, there was no difference of hydroxyl radical production between gamma-rays alone and gamma-rays/H(2)O(2). This indicates gamma-rays cannot activate H(2)O(2) to produce hydroxyl radicals and this causes no increase of TCE and PCE removals. To the contrary, the production of hydroxyl radicals was obviously increased in the case of gamma-rays/O(3) process. This suggests additional hydroxyl radicals are produced from the reaction of O(3) with the irradiation products of water such as hydrated electrons, hydrogen atoms, etc. and this accelerates the removal of TCE and PCE.

Anatase and bentonite were treated by gamma rays in various conditions, and the change of the catalysts was characterized by electron paramagnetic resonance spectroscopy. Anatase gave four peaks with g(parallel) = 1.951 g(perpendicular) = 1.973, g = 1.992 and 2.005. The height of the four peaks was directly proportional to the efficiency of hydroxyl radical production, and anatase treated by gamma rays in alkaline condition showed the most efficient production. Bentonite gave a peak with g = 2.005. In contrast to anatase, the peak height was inversely proportional to the efficiency of hydroxyl radical production, and non-treated bentonite was the most efficient catalyst. Furthermore, the efficiency of hydroxyl radical production of the catalysts significantly influenced the decomposition of trichloroethylene and perchloroethylene by gamma rays.

In the decomposition of perchloroethylene (PCE) by gamma-rays, clay from tidal flat sediments showed an efficient catalytic activity. Moreover, the clay thermally treated at 700°C in air enhanced the PCE removal efficiency better than that of the well known catalyst Degussa P-25 TiO2. The change of the clay by the thermal treatment was identified by electron paramagnetic resonance (EPR) spectroscopy. The intensity of the signal that arises from the natural radiation defect was decreased with increasing thermal treatment temperature, and inversely dependent on the PCE removal efficiency.

When t-butanol in aqueous system was decomposed by simultaneous application of γ-rays and ozone treatment, the addition of the cupric ion (Cu2+) drastically improved the efficiency of the removal of organic substances from water. The major reason for the remarkable decrement of total organic substances is the positive catalytic effect of Cu2+ on the oxidation of carboxylic acids.