Min-Koo Kang

Evaluation of struvite obtained from semiconductor wastewater as a fertilizer in cultivating Chinese cabbage.

The present work evaluated the fertilizing value of struvite deposit recovered from semiconductor wastewater in cultivating Chinese cabbage. The fertilizing effect of struvite deposit was compared with that of commercial fertilizers: complex, organic and compost. Laboratory pot test results clearly showed that the growth of Chinese cabbage was better promoted when the struvite deposit was used than with organic and compost fertilizers even though complex fertilizer was the most effective in growing Chinese cabbage. It was revealed that potassium (K) was a key element in the determination of growth rate of Chinese cabbage. Also, the abundant nutrients such as nitrogen (N), phosphorus (P), K, calcium (Ca) and magnesium (Mg) were observed in the vegetable tissue of struvite pot. Specifically, P was the most-founded component in the vegetable tissue of struvite pot. Meanwhile, the utilization of struvite as a fertilizer led to the lowest accumulation of copper (Cu) and no detection of cadmium (Cd), arsenic (As), lead (Pb) and nickel (Ni) in the Chinese cabbage. It was found that the optimum struvite dosage for the cultivation of Chinese cabbage was 1.6 g struvite/kg soil. Based on these findings, it was concluded that the struvite deposits recovered from semiconductor wastewater were effective as a multi-nutrient fertilizer for Chinese cabbage cultivation.

Fluoride Removal Using Ready-Mixed Concrete Sludge

The purpose of this study was performed to investigate the optimum conditions of pH, concrete sludge, seed dosage, mixing intensity, operation time in treating fluoride-containing wastewater as CaF2 using the ready-mixed concrete sludge. Considering fluoride removal, water content, that pH 6, concrete sludge dosage of 10 g/L, Seed dosage (CaF2) of 2 g/L, mixing intensity of 100 rpm and operation time of 60 min were found to be optimum. Correspondingly, removal of fluoride and water content was about 85% and 64%, respectively. Increase in amount of seed dosage did not affect fluoride removal efficiency. but the result that the water content is decreased was shown up in occuring the solid-liquid separation well.

The Performance of the Lanthanum-Zeolite Composite for the Eutrophication Prevention

Nutrients such as phosphorus and nitrogen have been widely known as important source of algal appearance in eutrophic water. In order to prevent lake eutrophication, it is required to remove these nutrients not only presented in the lake water, but also released from the sediment. In order to solve this problem this study, the trivalent lanthanum ions and ammonia Nitrogen (NH4-N) for the adsorption capacity of a zeolite support as it combines the lake water has dissolved in the nutrient removal, as well as deposits in the eluted in the continuously adsorbing the complex to develop and study was to inhibit the growth of algae. In experimental results, lanthanum complexes when the adsorption characteristics were evaluated PO4-P and the NH4-N removal was confirmed that has an excellent ability, when it applied lake water the time of Chl-a and the turbidity decreased. In this study, these results suggest that the lanthanum complexes produced inhibitory effects on algae in the lake water is determined to excellent. Further, when applied to a complex of lanthanum in lake water to a standard 48 hours Acute Toxicity Method of toxicity were measured, and the results for the toxic effect was not observed.