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Management of municipal solid waste towards a recycling-based society in Japan Dr. Jiro ETOH Institute of Environmental Systems, Kyushu University, Japan.

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Presentation on theme: "Management of municipal solid waste towards a recycling-based society in Japan Dr. Jiro ETOH Institute of Environmental Systems, Kyushu University, Japan."— Presentation transcript:

1 Management of municipal solid waste towards a recycling-based society in Japan Dr. Jiro ETOH Institute of Environmental Systems, Kyushu University, Japan

2 Final landfill 53 Food consumption 124 Energy consumption 404 Return to nature 84 Total material input 2138 Exploitation of natural Resources 1926 Import of resources Import of processed Products 64 Recycling 212 Additions to Stock 1124 Emission Spraying, volatilization 239 Exploitation of domestic resources Export 123 1169 692 Material Balance (2001) (unit :million tons) Source: the Ministry of Environment MSW 9.95 Industrial Waste 43

3 Discharged MSW 4,394 4,205 4,345 5,044 5,069 5,236 5,210 1,105 1,120 986 1,032 1,033 1,132 1,124 2,500 3,000 3,500 4,000 4,500 5,000 5,500 197519801985199019952000 900 1,000 1,100 1,200 1,300 1,400 1,500 Total discharge amounts of MSW Daily discharge amount of MSW per capita Source: the Ministry of Environment Total discharge amount of waste Discharge amount of waste/capita/day g/capita/day10,000 ton/day Year

4 Treatment of MSW (2001) Collected amounts in group 2.84 Direct recycle 2.29 (4.4%) Discharge amounts 52.10 Final disposal 9.95 (19.1%) Recycled amounts after treated 3.12 (6.0%) Final disposal after treated 7.20 (13.9%) Reduced amounts 36.60 (70.4%) Intermediate treatment 46.92 (90.3%) Direct final disposal 2.75 ( 5.3% ) Total amounts of recycle 8.25 (15.4%) Self treatment 0.25 Unit : million tons Treated residue 10.32 ( 19.9% ) Designed treatment 51.84 ( 100% )

5 Burner method Melting Methods Plasma melting

6 Interlocking block Aggregate for pavement Concrete blockBackfill Use of Molten Slag In 2002 Generation: 276,505 t (100%) Reuse: 132,722 t (48%)

7 Aggregate for Construction Materials Bottom ash Ferrous Treated bottom ash (<13mm)

8 Use as Base Course of Parking Lot

9 10 mm SEM photo of bottom ash particle Core Minute particles The cross section of bottom ash particles solidified in the resin was photographed by SEM. Bottom ash with core The core, which was surrounded by minute particles, existed in a bottom ash particle.

10 Classification of bottom ash particles Bottom ash particles With core Without core Others Metal Stone Ceramic Glass Complex melted material Simplex melted material Materials of core in bottom ash Materials of core

11 Heavy metal contents in bottom ash and the elution test (Japan Leaching Test for soil; JLT46) Chemical properties Result of 10 samples Lead concentration in leachates tends to exceed the environmental standard for soil (<0.01 mg/l). Heavy metal contentElution test (mg/kg)(mg/l) Cd < 11.7 < 0.01 Pb294 - 3330 < 3.03 Ce< 0.1< 0.01 T-Cr73.7-546- Cr 6+ -< 0.05 As < 13.5 < 0.01 Zn1310-7330- Hg < 3.91 < 0.0005 pH- 8.8-12.6 Elements

12 (1) Clear difference was observed between core and minute particle. (2) Minute particle partially showed high concentration of Ca, Cl, and Fe. (3) Distribution of Pb was not uniform. Surface analysis of particles cross sections by EPMA With core Without core Distribution of elements in bottom ash particles

13 Cation in a solution reacts with dissolved carbon dioxide and transforms into a carbonate. Example: PbCl 2 (Soluble) PbCO 3 (Insoluble) (1) Mechanism of carbonation Carbonation treatment

14 Experimental procedures 6 kg of dried bottom ash was loaded into a mixer and distilled water was added. Exhaust gas from MSWI plant was reused. Flow rate of exhaust gas: 400 L/min Temperature of exhaust gas: 30 ˚C Leaching test (JLT46) for bottom ash carbonation Carbonation experiments at the incineration plant

15 System of the carbonation equipment Flow of exhaust gas and bottom ash

16 Carbonation mixer for bottom ash

17 11.0 11.5 12.0 12.5 13.0 0102030405060 pH in leachate (-) 10 15 5 Elapsed time (minute) Percentage of additional water (%) Changing of Pb Concentration in leachate with time Changing of pH in leachate with time Effect of Pb immobilization by carbonation

18 Recyclable Landfill Recyclable Landfill Eluviation of chloride in incineration residues by infiltrated rainfall Landfill disposal site : Wash out + Storage Excavation of landfilled incineration residues Regeneration of landfill space (Recycle-based landfill) Cement plant (Raw material for cement) Construction material (Cement) Municipal solid waste Incineration plant Incineration residues Recyclable Landfill Recyclable Landfill Concept of recyclable landfill

19 Total Chloride Soluble Chloride (NaCl, KCl etc.) It is dissolved out in a landfill. Insoluble Chloride (Friedel’s salt etc.) It is hard to be dissolved out in a landfill. Removed easily Solubilization is required to remove Insoluble chloride; Friedel’s salt Friedel’s salt: 3CaO Al 2 O 3 CaCl 2 10H 2 O It is briefly formed by the hydration reaction.

20 Solubilization of insoluble chloride by CO 2 The experiment was conducted to confirm the solubilization of insoluble chloride in bottom ash by CO 2 gas passing. Experimental procedure Water content of bottom ash was adjusted. The columns were filled with the bottom ash, and CO 2 5% or CO 2 0% gas was passed. Chloride, pH, and X-ray diffraction were analyzed for collected samples.

21 Solubilization of the insoluble chloride by CO 2 *: Insoluble chloride = Total chloride – Soluble chloride Time (hour) pH (-) Time (hour) Insoluble chloride * (%) In case of CO 2 5%, insoluble chloride decreased from about 0.4% to 0.1% for 6 hours CO 2 passing. And pH decreased from 12 to 8 for the same period.

22 Decrease of Friedel’s salt by CO 2 2θ (deg) Intensity (cps) 0h6h12h24h Main peak of Friedel’s salt (CO 2 5 %) In case of CO 2 5%, Friedel’s salt decreased with duration time of CO 2 passing

23 Tasks for Beneficial Reuse of MSWI Residues Beneficial reuse of MSWI residues Reuse - Monitoring system - Disclosure of information - Feedback to pretreatment - Elution characteristic of hazardous substance (2) Quality (1) Safety Prevention of diffusion of hazardous substance to natural environment - Condition of recycling - LCA - Competition with other construction materials - Law establishment of suitable for recycle - Pretreatment technology of low energy - Quality of MSW - Control of incineration (3) Market New utilization method of MSWI residues

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