식생토 활용을 위한 준설토의 식물생장 특성

Abstract

At present, most dredged soil is dumped simply in large dumping areas and buried. Dumping and burying dredged soil has diverse effects, for example, damaging the coastal environment, devastating fishing spots, and destroying sandbars. Also, because heavy metals in the dredged soil can cause secondary pollution, it is necessary to positively recycle the dredged soil. To positively respond to the international regulations for the marine environment, for example, the London Convention(1972) and the Kyoto Protocol(1996), it is also necessary to secure technology for recycling dredged soil. The technology for recycling dredged soil can contribute to preventing environmental pollution and saving national budgets. The method for making the Goonsan Saemangeum reclaimed land is to bury dredged soil, make embankments covered with mountain soil as thick as 30 cm and create a vegetation base in the area of approximately 40,000 ha. However, heavy equipment is used to excavate, transport and lay the mountain soil to cause environmental issues and expenses. The ‘Master Plan for Conservation of Topsoil’ announced by the MOE(Ministry Of Environment) in 2012 aims to positively conserve soil, making it difficult to excavate mountain soil.

Therefore, the objectives of this study are described below.

Collect a typical type of dredged soil in Goonsan, Incheon and Gwangyang to analyze the physical and physico-chemical properties thereof, and evaluate the effect of physico-chemical improvement depending on improvers (Bio, AC (amino acid), sawdust fertilizer, and coffee sludge) through laboratory experiments. Mix the collected dredged soil with typical improvers (Bio, AC, sawdust fertilizer) in given ratios to sow, and then analyze the germination rate of areas treated and not treated with the improvers {(the maximum number of germinated seeds) / (the number of initial sowed seeds) × 100} and the growth rate (the maximum weight of plants), and the economic efficiency of the typical improvers. Mix coffee sludge with typical improvers (AC, sawdust fertilizer) in a given ratio and then sow in the mixture. Analyze the germination rate of areas treated and not treated with the improvers, and the optimized mixing ratio of coffee sludge. Apply the seed spray technique for the in-situ experiment in Goonsan Saemangeum (about 284㎡ of total area, in which there are two sites of a planar area 10 m × 10 m, and the slope is L21 m × H4 m, Select a 1:1 slope to carry out in-situ experiment) to make a biological environment material that can be used for stabilizing slopes in the civil engineering sites and developing marine spaces as a vegetation base treated at the site with improvers and planted with seeds. The aim is to evaluate the effect of the dredged soil treated with improvers for a vegetation base.

The analysis of physical properties about the exemplary dredged soil samples taken from Goonsan, Incheon and Gwangyang reveals that the Goonsan soil is SM sample, the Incheon soil is CL-ML sample, and the Gwangyang soil is ML sample in the USCS(Unified Soil Classification System classification). The analysis of physicochemical properties following treatment with improvers reveals that the SM sample which allows easy water sprinkling demonstrates high improvement. Therefore, this suggests that the most effective technique is water sprinkling for the SM sample. The laboratory test for improving dredged soil as vegetation soil reveals the highest growth rate is shown in 6% of bio improver and 6% of sawdust fertilizer. This suggests that the sawdust fertilizer is a good improver for improving dredged soil as vegetation soil. The sawdust fertilizer costs about 40 times less in terms of economy. The test of adding the improver of coffee sludge which is general waste reveals weak acidity and porosity of coffee sludge contributes to lowering pH. Because of rich organic matters in the coffee sludge, the highest germination rate is obtained in sawdust fertilizer 6% and coffee sludge 8% to improve dredged soil as vegetation soil. The in-situ test by spraying was carried out. In the fourth measurement (180th day), the covering ratio by no treatment was 65%, and at least 95% by treatment with coffee sludge for slopes. This suggests that coffee sludge used in the field is an effective soil improver for improving dredged soil as vegetation soil physically and physicochemically.