BACKGROUND: The large Itaya zeolite deposit in Yonezawa, Japan produces good quality, natural zeolite. Its properties as an adsorbent and a functional carrier were assessed and the ion exchange characteristics examined. Natural zeolite has a useful high cation exchange capacity, but has a disadvantage in scattering of the powder. In this study a nonwoven fabric containing zeolite was tested for the removal of cesium. RESULTS:The X-ray diffraction (XRD) peak pattern confirmed that Itaya zeolite is mainly clinoptilolite and contains some mordenite. Ion exchange selectivity of the natural zeolite was Ag + > Pb 2+ > Cu 2+ > Zn 2+ > Cd 2+ > Cr 3+ > Ni 2+ with almost 100% removal of Ag + and Pb 2+ ions.The cation exchange capacity (CEC) of Itaya zeolite was 131 cmol kg -1 . Low concentrations of Cs + were removed effectively from the solution with natural zeolite. Cesium ions were removed by ion exchange with potassium and sodium. Cs + was desorbed from the zeolite with ammonium salt solutions. Elution of Cs + was influenced by the coordination ability of counter anions. CONCLUSION: Satisfactory results were obtained using zeolite-containing nonwoven fabric for the removal of cesium ions.

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The concentration variations of dissolved metal ions and their buffering effect in an acidified river were investigated by analyzing the data collected through a long-term field investigation and an intensive field investigation. The field investigations targeted Matsukawa River in Japan, which is acidified by the inflow of acid mine drainage. In periods of rainfall and snowmelt, Al, Mn, Fe, Cu, and Zn ions exhibited different decreasing trends than did alkali and alkaline earth metal ions and sulfate. These findings suggested that the decreases in Al, Mn, Fe, Cu, and Zn ion concentration were attributable not only to dilution by the inflow of rainwater and snowmelt but also to the hydrolysis of Al. Additionally, the mineral phases of Al in this acidified river were analyzed by using the geochemical modeling software (PHREEQC). From the results, dissolved Al ions acted as a buffer from pH 4 to 6, and the basaluminite (Al 4 (SO 4 )(OH) 10 ) as the dominant chemical species, mainly controlled the solubility of Al from pH 4 to 6.

This study was carried out to develop a technique for treatments of acidified river water using waste concrete aggregates for sustainable protection of the water environment. In this study, the water quality in the Matsukawa River, Japan, which receives acidic mine drainage, were investigated as a model field of an acidic water environment. Additionally, chemical component analyses of the waste concrete aggregates and neutralization testing in batch mode were carried out to use of waste concrete aggregates to neutralize acidified rivers. The results of the field investigation suggested that dissolved Al acts as a buffer substance, inhibiting rises in pH in acidified water environments. The results of the neutralization tests confirmed that it was possible to neutralize acidified river water by using concrete aggregates; dissolved Al in the acidified river water was settling removed effectively by these neutralization treatments. Additionally, increases in pH could be accelerated by adding aeration to the neutralization process. Aeration decreased the requirement for neutralization aggregates by approximately 30%. These results suggested that use of waste concrete aggregates effectively neutralizes water that has been acidified by high concentrations of Al acting as a buffer inhibiting pH rise.

Boron is widely used in industry, and is regulated by the effluent standard (10 mg/L) in Japan. The standard azomethine H absorptiometric method for determining boron concentration requires long time; therefore, we have developed a simple, rapid azomethine H method for the management of the wastewater treatment equipment. The amount of boron was determined by measuring the absorbance of the boron-azomethine H complex after 5 min by using a simple spectrophotometer with a photodiode (370 -600 nm) and a light-emitting diode (470 nm). Phosphate buffer with ammonium chloride was used, because the ammonium salt accelerated the formation of the boron complex. The effect of a large amount of calcium ions in the wastewater, which originated from calcium hydroxide, was eliminated by adding an excess of the buffer reagents. A combination of powdered azomethine H, L-ascorbic acid, EDTA, potassium dihydrogenphosphate, disodium hydrogenphosphate, and ammonium chloride was appropriate for the simple, rapid on-site determination of boron using a portable spectrophotometer.