Hand leaf thinning for improvement of fruit coloration and quality is one of the most labor-consuming works in Korean apple cultivation. The study was aimed at investigating whether foliar application of two chelate compounds (Cu-EDTA, Fe-EDTA) could defoliate effectively ‘Hongro’/M.9 apple leaves and enhance fruit coloration and quality. At 30 days before harvest, foliar spray with two chelate compounds defoliated significantly the apple leaves. Chelate treatments did not affect the leaf chlorophyll content. High concentration of chelates decreased drastically photosynthetic rate of true leaves, and then it stayed in low levels, whereas low levels of chelates reduced sharply the photosynthetic rate but it was gradually restored over time. Cu-EDTA regardless of its concentration triggered higher defoliation compared to Fe-EDTA. Consequently, higher defoliation improved light interception of fruits and accumulated more anthocyanin. Particularly, Cu-EDTA could target mainly fruit cluster leaves which affect directly light interception of the fruits, i.e. more selective defoliants compared to Fe-EDTA. However, 3% Cu-EDTA rather defoliated excessively, accompanying with reduction of fruit weight and soluble solids. Therefore, our results suggest that 1% Cu-EDTA which defoliates properly the fruit cluster leaves could improve coloration and quality of ‘Hongro’/M.9 apple fruits.

Several experiments have done to investigate the removal of hydrogen sulfide(H2S) synthetic gas from biogas streams by means of chemical absorption and chemical reaction with 0.1 M – 1 M Fe/EDTA solution. The hydrogen sulfide of biogas was bubbled through an gas-lift column with Fe/EDTA resulting in the formation of sulfur particles. Wide range of optimal operating conditions were tested for both Fe/EDTA solution and the biogas, and the optimal ratio of Fe/EDTA concentration for efficient removal of hydrogen sulfide was found. The roles of Fe/EDTA were studied to enhance the removal efficiency of hydrogen sulfide because of oxidizing by Fe+3/EDTA. The motivation of this investigation is first to explore the feasibility of enhancing the toxic gas treatment in the biogas facility. The biogas purification strategy affords many advantages. For instance, the process can be performed under mild environmental conditions and at low temperature, and it removes hydrogen sulfide selectively. The end product of separation is elemental sulfur, which is a stable material that can be easily disposed of with minor potential for further pollution. The process to address over 90% removal efficiency of hydrogen sulfide does offer considerable advantages unrealized.

The present study was performed to develop the removal system of the offensive gases, including hydrogen sulfide of acid gas, ammonia or amine of base gas, from the nightsoil treatment plant. In order to remove the offensive gases, the Fe-EDTA system liquid phase catalytic oxidation method with the bubble lift column reactor was employed. From the results obtained it was confirmed that the offensive gases can be deodorized simultaneously and also hydrogen sulfide of acid gas, ammonia of base gas completely removed at pH 6.45. In addition, as input gases feed rate the efficiency of acid gas did not change but the efficiency of base gases decreased to approximately 90% at pH 6.0. From the result of particle size analyzer, it was found that the particle sizes including sulfur and other impurites grew up to 21μm over 72hour reaction time.