Reduction of toxicity of antimicrobial compounds by degradation processes using activated sludge, gamma radiation, and UV.

The occurrence and persistence of pharmacologically active compounds in the environment has been an increasingly important issue. The objectives of this study were to investigate the decomposition of aqueous antimicrobial compounds using activated sludge, γ-irradiation, and UV treatment, and to evaluate the toxicity towards green algae, Pseudokirchneriella subcapitata, before and after treatment. Tetracycline (TCN), lincomycin (LMC) and sulfamethazine (SMZ) were used as target compounds.

Degradation and toxicity assessment of sulfamethoxazole and chlortetracycline using electron beam, ozone and UV.

Recently, the occurrence of antibiotics in sewage treatment plant effluent, as well as drinking water, has raised concern about their potential impacts on the environment and public health. Antibiotics are found in surface and ground waters, which indicate their ineffective removal by conventional wastewater treatment processes. Therefore, advanced oxidation processes (AOPs) have received considerable attention for the removal of antibiotics.

Combination of ion exchange system and biological reactors for simultaneous removal of ammonia and organics.

A novel process for a simultaneous removal of ammonia and organics was developed on the basis of ion exchange and biological reactions. From batch experiments, it was found out that NH(4)(+) could be removed effectively by combining cation exchange and biological nitrification showing 0.98 mg N/m(2) ∙ s of a maximum flux.

Carbon source recovery from waste activated sludge by alkaline hydrolysis and gamma-ray irradiation for biological denitrification.

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.

Simultaneous nitrification and denitrification in a CEM (cation exchange membrane)-bounded two chamber system.

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.

TiO2 photocatalytic oxidation mechanism of As(III).

There has been a controversy over the TiO2 photocatalytic oxidation (PCO) mechanism of As(III) for the last several years. The key argument has been whether superoxide (HO2*/O2(-)*) is the main oxidant of As(III) in the UV/TiO2 system. Previously we and other groups have refuted the claim that superoxide plays the main role in the TiO2 PCO of As(III).

Decomposition and mineralization of cefaclor by ionizing radiation: kinetics and effects of the radical scavengers.

There has been recent growing interest in the presence of antibiotics in different environmental sectors. One considerable concern is the potential development of antibiotic-resistant bacteria in the environment, even at low concentrations. Cefaclor, one of the beta-lactam antibiotics, is widely used as an antibiotic.

Decomposition of 2,4,6-trinitrotoluene (TNT) by gamma irradiation.

The purpose of this study was to evaluate the potential of gamma irradiation to decompose 2,4,6-trinitrotoluene (TNT) in an aqueous solution; the concentration range of the TNT solution was 0.11-0.44 mmol/L.

Comparative study of H(2)O(2) and O3 effects on radiation treatment of TCE and PCE.

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.

EPR investigation on the efficiency of hydroxyl radical production of gamma-irradiated anatase and bentonite.

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.

Effect of dissolved metal ions on PCE decomposition by gamma-rays.

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.