Development & Material for Red Tide Control Using Dredged Sediment It's Application

A study on the decontamination of dredged coastal sediment and its utilization for red-tide control were performed. The organic matter contained in the sediment could be stabilized aerobically, but the performance was affected by the content of soluble and degradable organics. For the sediment with high organic content of 2000 mg SCOD/L, the SCOD could be decreased to 400mg/L in the aerobic stabilization reactor with 5days HRT after the acclimation of 60days. In the case of the sediment with lower organic content (100-400mg SCOD/L), the stabilization efficiency was relatively lower than the sediment with higher SCOD. However, the stabilization of organic matter in the sediment could be enhanced by some pretreatments, such as alkaline (NaOH) treatment or ultrasonication, increasing the degradability of the organic matter. The heavy metals contained in sediment could be detoxified by the metal-phosphate immobilization with an ultrasonication, and the immobilization performance was affected by both the equivalent ratio of metal and phosphate and the ultrasonication (intensity, radiation time). The stabilized sediment was quite effective for the red-tide control in near shore coastal sea. When the sediment (diluted to proper concentration) was sprayed on the sea water surface, the sediment particles were quickly settled down to the bottom. During the settling, the tiny particles of the sediment was attached on the surface of the red-tide organisms, and swept out from the sea water. The effectiveness of sediment on the red-tide organisms could be described by a surface adsorption, a control failure of the osmotic pressure and an expansion and rupture of the cell wall, and the removal from the settling. It was concluded that the dredged sediment could be used as a good material for the red-tide control in coastal sea, if the pollutants including degradable organics and heavy metals were stabilized.목 차 ⅰ List of Tables ⅲ List of Figures ⅳ Abstract ⅶ 제 1장 서론 1 제 2장 문헌연구 3 2.1 적조의 원인 및 피해 현황 3 2.2 우리나라의 적조방제 체제 7 2.3 적조 구제 기술현황 10 2.4 준설 퇴적물의 처리기술 12 제 3장 실험 15 3.1 실험재료 15 3.2 시료의 전처리 17 3.2.1 준설토 체분리 17 3.2.2 유기물 분해 17 3.3 인산염과 초음파를 이용한 중금속의 무해화 20 3.3.1 중금속 고정화 20 3.4 준설토의 적조제거 성능평가 21 3.4.1 적조구제물질의 효능 및 제거기작 21 3.4.2 적조구제물질의 해수 중 거동 23 3.5 준설토 적조구제물질의 현장 효능 검증 24 3.5.1 현장살포장치 연구 24 3.5.2 현장조건 하에서 적조구제물질의 효능검증 24 제 4장 결과 및 고찰 26 4.1 시료의 전처리 26 4.1.1 유기오염물의 안정화를 위한 운전 연구 26 4.1.2 유기물 안정화 효율에 대한 물리화학적 처리의 영향 32 4.2 인산염과 초음파를 이용한 중금속의 무해화 37 4.2.1 인화합물을 이용한 중금속 고정화 37 4.2.2 초음파조사에 의한 금속인산염 고정화 성능향상 42 4.3 준설토의 적조제거 성능평가 43 4.3.1 적조구제물질의 효능 및 제거기작 43 4.3.2 적조구제물질의 해수 중 거동 47 4.4 준설토 적조구제물질의 현장 효능 검증 50 4.4.1 현장살포장치 연구 50 4.4.2 현장 조건하에서 적조구제물질의 효능검증 52 제 5장 결 론 61 참고문헌 63 List of Tables Table 2.1 Fisheries to be affected by harmful algae 6 Table 2.2 Forecasting criteria for red tide occurrence 9 Table 2.3 Technologies for red tide control 11 Table 3.1 Chemical characteristics of active sludge and dredged soil 16 Table 3.2 Contents of heavy metals in the dredged soil concern levels in soil 16 Table 3.3 Metal concentrations before and after phosphorous addition in the dredged soil 20 Table 3.4 Ingredients of f/2 stock solution(Guillard and Ryther 1962) 21 Table 4.1 Removal of heavy metals by addition of phosphorous 42 Table 4.2 Influence of TSS concentration on various height in the sedimentation 48 Table 4.3 Change of sea water quality after application of the sedi- ment slurry (Velocity=700m/h. Spray area=100 m2) 54 Table 4.4 Change of TS, VS, nutrient and Chlorophyll a concentration after the sediment spray in the field 55 Table 4.5 Removal of red tide after the sediment spray in the field 57 List of Figures Fig. 2.1 Harmful algae in fisheries in Korea. Coclodinium polykrikoides (A), Heterosigma akashiwo(B), Gymnodinium mikimotoi(C), Gyrodinium(D) sp 3 Fig. 2.2 Coastal area affected red tide blooming in Korea 4 Fig. 3.1 Aerobic stabilization system dredged soil 18 Fig. 3.2 Test procedure for red tide remediation material (A: f/2 medium, B: C.ploykrikoides addition, C: s praying of sediment or soil, D: sample collection and storage) 22 Fig. 3.3 Sedimentation tests of red tide remediation materials 23 Fig. 4.1 TCOD variation of the reactor depending on HRT 27 Fig. 4.2 SCOD variation of the reactor depending on HRT 27 Fig. 4.3 TSS variation of the reactor depending on HRT 28 Fig. 4.4 VSS variation of the reactor depending on HRT 28 Fig. 4.5 TKN variation of the reactor depending on HRT 29 Fig. 4.6 NH4+-N variation of the reactor depending on HRT 30 Fig. 4.7 NO3--N variation of the reactor depending on HRT 31 Fig. 4.8 NO2--N variation of the reactor depending on HRT 31 Fig. 4.9 Effect of alkali pretreatment on COD in the reactor 32 Fig. 4.10 Effect of alkali pretreatment on SCOD in the reactor 33 Fig. 4.11 Effect of alkali pretreatment on SCOD in the reactor 34 Fig. 4.12 Effect of NaOH and ultrasound treatment on TCOD in the reactor 35 Fig. 4.13 SEffect of on NaOH and ultrasound treatment SCOD in the reactor 35 Fig. 4.14 Effect of on NaOH and ultrasound treatment on TSS in the reactor 36 Fig. 4.15 Effect of on NaOH and ultrasound treatment on VSS in the reactor 37 Fig. 4.16 Effect of phosphorus addition on the removal of lead(Pb) in the sediment 38 Fig. 4.17 Effect of phosphorus addition on the removal of nickel (Ni) in the sediment 38 Fig. 4.18 Effect of phosphorus addition on the removal of copper (Cu) in the sediment 39 Fig. 4.19 Effect of phosphorus addition on the removal of zinc (Zn) in the sediment 40 Fig. 4.20 Effect of phosphorus addition on the removal of cadmium (Cd) in the sediment 41 Fig. 4.21 Effect of phosphorus addition on the removal of chromium (Cr) in the sediment 41 Fig. 4.22 Removal efficiency of C.polykrikoides by addition of the treated sediment (up) and soil (down) 44 Fig. 4.23 Effect of the sediment treatment on the morphological change of red tide (Cochlodinium sp.) 46 Fig. 4.24 Electron microscopy of Cochlodinium sp. (A: Four chain forming cells with an exocellular fibrillar matrix (arrow) Scale bar = 20 &microm, B: A higher resolution image of the exocellular matrix) 46 Fig. 4.25 Electron microscopy of the (A) sediment and (B) loess used in this study 47 Fig. 4.26 Effect of sedimentation time on the TSS concentration in the column 49 Fig. 4.27 Dilution unit for the sediment slurry used to control red tide 50 Fig. 4.28 Design of the used to spray the sediment slurry (left) schematic diagram, (right) the product 51 Fig. 4.29 Photograph of nozzle application in the field 51 Fig. 4.30 Field remediation process of the red tide using the sediment slurry 53 Fig. 4.31 Effect of initial density of the red tide on their removal 58 Fig. 4.32 Effect of amount of spray volume on the red tide removal 59 Fig. 4.33 Effect of the sediment slurry spray on the red tide removal over time 6