Teijiro Miyata

Treatment of waste water by a combined technique of radiation and conventional method

Abstract Treatment of waste water by radiation in combination with a conventional method such as biological oxidation, coagulation with Fe 2 (SO 4 ) 3 , and ozonation has been studied for reducing necessary dose. Ethylene glycol ethers, polyoxyethylene n -nonyl phenyl ether (NPE), polyvinyl alcohol (PVA), ethylene glycol, phenol, and oxalic acid were used as a model pollutant. The combined use of radiation and biological oxidation markedly improved the removal of TOC in aqueous oxygenated solution of ethylene glycol ethers. The combined use of radiation and coagulation has remarkable effects on the reduction of TOC in aqueous deoxygenated solution of NPE or PVA. The simultaneous use of radiation and ozone gave a synergistic effect on oxidative degradation of organic pollutants. The synergistic effect was suggested to arise from chain reactions having a powerful oxidizing agent (OH radical). The rate of TOC removal by the process depended on dose rate. Aqueous solution of 150 mg/l oxalic acid was treated by the combined use of electron beams and ozone using a new type of irradiation vessel to reduce TOC with G(-TOC) of 87 at 2.3 × 10 7 rad/h. The simultaneous use of radiation and ozone is superior to the removal of TOC by other combined methods and can be applied irrespective of the type of organic matter.

Decoloration and degradation of an anthraquinone dye aqueous solution in flow system using an electron accelerator

Abstract A study on the decoloration and degradation of a commercial anthraquinone dye (Acid Blue 40) was carried out by electron-beam irradiation. Experiments were done in a flow system using a five-stage, dual-tube bubbling column reactor. The oxygen contents of the gas bubbled into the inner tubes of the columns were varied from 0 to 100%. The inlet dye concentration, the solution feed rate and the dose rate were also varied from 50 to 100 ppm, 1.5 to 101/min and 0.1 to 0.15 Mrad/s, respectively. The degree of decoloration and degradation of aromatic rings increased with the oxygen content and became close to those for pure oxygen bubbling system at about 25% of oxygen content. The amount of degraded aromatic rings was proportional to that of consumed oxygen. The rate expression of the decoloration and degradation of the dye and the oxygen consumption were derived according to a reaction scheme.

The degradation of an azo dye in aqueous solutions by high-intensity electron-beam irradiation

Abstract A study of the degradation of Acid Red 265 (azo dye) in aqueous solutions by high-intensity electron- irradiation was carried out in a flow system. For the oxygen-saturated solutions (oxygen bubbled during irradiation), the change of absorption spectra, the degree of decoloration at 542 nm, the reduction in optical density at 230 nm, the change of pH, and the amount of dissolved oxygen were measured as functions of dose under various conditions (dye concentration, dose rate, solution flow rate, and oxygen flow rate). The decoloration scheme in the flow system by electron beam irradiation was similar to that in the batch system by gamma radiation. Oxygen was not necessary for the destruction of the chromophore but was absolutely essential for the destruction of substituted aromatic rings in the dye molecule. For the purpose of the destruction of the skeleton of the Acid Red 265 molecules, it was necessary to keep the concentration of dissolved oxygen above at about 30 ppm (in mass) in the case of the 60 ppm dye solution.

Radiation-induced decomposition of phenol in flow system

Abstract The radiation-induced decomposition of phenol in aqueous solution was studied in flow system. The reactor used was a five-stage, dual-tube bubbling-column-type and an electron accelerator was used as a radiation source. Products in the oxygenated solution were hydroxy-hydroquinone (1,2,4 - trihydroxybenzene), hydroquinone (1,4 - dihydroxybenzene), pyrocatechol (1,2 - dihydroxybenzene), and trace amounts of phloroglucinol (1,3,5 - trihydroxybenzene) and resorcinol (1,3 - dihydroxybenzene). On the other hand, hydroquinone, pyrocatechol, and small amounts of resorcinol and hydroxyhydroquinone were detected in the deaerated solution. A significant amount of suspended solid was also observed in the deaerated solution. The G -value for phenol reduction in the deaerated solution was 2.6 and was 5–6 times larger than that obtained in the deaerated solution using 60 Co as a radiation source. Calculations were done on the concentration of phenol and products according to the reaction scheme obtained from the batch experiments using 60 Co. The results agreed well with the experimental values of the flow system.

Radiation-induced decoloration and sedimentation of colloidal disperse dyes in water

Abstract The aqueous solutions of disperse dyes can not be easily decolored and sedimented by γ radiation. The change of pH after irradiation into acidic conditions made sedimentation occur effectively. In oxygen-saturated solutions, absorption band, change of pH and total organic carbon decreased markedly, while in nitrogen-saturated solutions a smooth decrease was seen. Sedimentation was also induced by addition of various electrolytes. The mechanism of the sedimentation was also discussed.

Pilot-scale test for electron beam purification of flue gas from a municipal waste incinerator with slaked-lime

Abstract The flue gas treatment by electron beam irradiation with the blowing of slaked-lime powder was tested in the pilot plant built at a municipal waste incinerator. The flue gas containing NO x , SO 2 and HCl was irradiated by electron beam with slaked-lime powder(Ca(OH) 2 ). Approximately 70 % ofNO x , and 100 % of SO 2 and HCl in the flue gas were removed by the irradiation at a dose of 10 kGy at 150°C with two stoichiometric amount of slaked-lime powder. Lower irradiation temperature and increased amounts of the powder resulted in higher removal rates of NO X .

Pilot-plant for NOx, SO2 and HC⪋ removal from flue-gas of municipal waste incinerator by electron beam irradiation

Abstract According to the basic research performed using a small size reactor at TRCRE of JAERI, the electron beam irradiation process was proved to be very effective for NOx, SO2 and HC⪋ removals from flue-gas of municipal waste incinerators. Based on this result, a pilot-plant was constructed for the demonstration of NOx, SO2 and HC⪋ removal performance using electron accelerator of maximum energy 0.95 MeV and maximum power 15kW. The pilot-plant was constructed at Matsudo City waste Disposal Center. The flue-gas of 1,000 Nm3/hr is guided from the waste incinerator flue-gas line of 30,000Nm3/hr to the pilot-plant to be processed by spraying Ca(OH)2 slurry or powder and irradiation with high-energy electron beam of the accelerator. NOx, SO2 and HC⪋ are removed simultaneously from the flue-gas by the enhanced reaction with Ca (OH)2 under irradiation. A brief explanation of the pilot-plant and preliminary results of the experiments are introduced in this paper.

Pilot-scale test on electron beam treatment of municipal solid waste flue gas with spraying slaked-lime slurry

Abstract Simultaneous removal of NO x , SO 2 and HCl in flue gas of a municipal solid waste incinerator was studied by using electron beam irradiation technology. The flue gas around of 1000 Nm 3 /h was led to a spray-dryer-type reactor from an inlet of ESP of the municipal waste incinerator by spraying slaked-lime slurry with one or more stoichiometic amount of the pollutants, concentrations of HCl (400 ppm) and SO 2 (50 ppm) decreased almost completely, while concentrations of NO x (100 ppm) were markedly decreased to about 20 ppm by electron beam irradiation with a dose of 10 kGy at 150°C under spraying slaked-time slurry of two stoichiometric amounts. The removal of NO x was improved by increasing the dose and the amount of spraying slaked-time slurry, and by lowering the irradiation temperature.

Inhibition of trihalomethane formation in city water by radiation-ozone treatment and rapid composting of radiation disinfected sewage sludge

Abstract Humic acid and Fulvic acid in natural water are precursors of carcinogenic THM which is formed during chlorine disinfection in city water processing. The radiation-oxidation process in the presence of ozone is effective to remove the precursors. The THM formation was reduced more than the decrease in TOC by the combination treatment. This is mainly due to a change in the chemical structure of the oxidation products. A composting of radiation disinfected sludge cake for agricultural reuse could be achieved within 3 days primary fermentation in a sewage plant. The rapid fermentation with use of radiation is effective to scale down of a fermentor of composting plant and the process reduces a health risk from the workers as well as final users.

Effect of 60Coγ-Ray Irradiation on Dilute Aqueous Solution of Phthalate

フタル酸ジメチルの希薄水溶液を酸素あるいは窒素飽和下において60Coγ線で照射し, その分解過程を紫外および赤外吸収スペクトルの変化, 添加物効果ならびにガスクロマトグラフ法による分解生成物の分析結果から検討した。その結果, 以下の諸事実が明らかになった, 分解は主としてOHラジカルのベンゼン環への攻撃によって開始されるが, 水和電子は分解には直接寄与しない。分解のG値は酸素飽和 (2.3) のほうが窒素飽和 (1.6) より高い。酸素飽和の状態で照射した場合, 窒素飽和で困難なペンゼン環の開裂と置換基の脱離反応が容易に起こりメタノールが生成する。フタル酸ジメチルは最終的にシュウ酸あるいはギ酸を経て二酸化炭素にまで完全に分解される。