Restoration of contaminated Elbe River floodplain soils by phytoremediation

Transcription

1 Restoration of contaminated Elbe River floodplain soils by phytoremediation R. Meissner, S. Bolze, H. Rupp- Helmholtz Centre for Environmental Research - UFZ C. Baum, D. Zimmer, P. Leinweber University of Rostock M. Grau, U.Klee, F. Tetzlaff, P. Pickel University of Halle-Wittenberg

2 Topics - Introduction - Status quo of floodplain contamination - Research strategy - Preliminary results and discussion -- Plant uptake of contaminants -- Hydrological regime and behaviour of contaminants -- Using the biomass for the production of energy - Conclusions - Acknowledgement Page 2

3 Hamburg Berlin Magdeburg Elbe Elbe River catchment area km 2 Germany: km 2 Labe Rhein Page 3

4 Page 4 Flood damages in Germany, August 2002

5 Industrial pollutants Municipial and agricultural pollutants Sediments in a floodplain of the Elbe River after a flood event (floodplain area: about ha) Page 5

6 Sketch of a floodplain at the Elbe River relic floodplain dike agricultural use recent floodplain succession Page 6 Foto: R. Schwartz groyne-field Elbe River

7 Transport of pollutants in a floodplain BBodSchV aah Page 7 am BBodSchV: German soil protection act (1999), differs in: Precaution Examining Action values

8 Contamination of top-soils in floodplains of the river Elbe with As and significant heavy metals (until Aug. 2002) As Cd Cr Cu Hg Ni Pb Zn Amount (µg/g) (µg/g) (µg/g) (µg/g) (µg/g) (µg/g) (µg/g) (µg/g) Minimum % % Median Average % % Maximum Grassland Action value ; 200 for Sheep The action value of the BBodSchV for As, Cu, und Hg are frequently exceeded (for Hg > 70 per cent of all investigated sites). Page 8

9 Contamination of grassland vegetation in floodplains of the river Elbe with As and significant heavy metals (until 2002) As Cd Cr Cu Hg Ni Pb Zn Amount (µg/g) (µg/g) (µg/g) (µg/g) (µg/g) (µg/g) (µg/g) (µg/g) Minimum % % Median Average % % Maximum Maximum value acc.to Animal Feed Reg Contamination values of grassland vegetation do not reflect the soil contamination Page 9

10 Summary status quo of floodplain contamination and research goals Floodplains retention areas for floods and sediments Sediments loaded with pollutants (i.e. heavy metals and As, organic pollutants) due to anthropogenic activities Contamination hot spots (bayou hollows in the floodplain exceeding of limits and precaution values of BBodSchV) Highly dynamic hydrological regime - the behavior of heavy metals, As, and organic pollutants regarding mobilization, immobilization, plant uptake etc. is unknown Main research question: Is it possible to restore the contaminated floodplain soils by phytoremediation and can we use the biomass to produce energy? Page 10

11 Research strategy of the phytoremediation project - promoted by the German duration: 04/2007 until 03/2010 Phytoremediation of contaminated floodplain soils Sub-project 1 Bio-technology of phytoremediation & special analytics (Univ. Rostock) Sub-project 2 Hydrology of floodplain sites & mechanisms of heavy metal release (UFZ- coordinator) Sub-project 3 Process engineering of thermal utilization & economic fundamentals (Univ. of Halle) Page 11

12 Step 1: Biotechnology Increased biomass Stimulating the uptake of heavy metals by willows and poplars by selection and inoculation with siteadapted Ectomycorrhiza fungi... and higher metal concentrations 500 mg Zn kg mg Zn kg -1 Ectomycorrhiza Pot experiments with floodplain soils and Salix x dasyclados (willow species) without (Ctr) and with inoculation with two species of Ectomycorrhiza-fungi (GÜL, FRA) Page 12

13 Essential results of a pot experiment with dual inoculated willows (fungi and bacteria) in comparison to a non-inoculated control - Total Cd and Zn accumulation increased up to 62 % due to higher biomass production in the inoculated willows - Decrease of theoretical remediation time for Cd and Zn from 70 (control) to 45 years Page 13

14 Step 2: Design of an experimental field trial in the Elbe River floodplain near Schoenberg Hamburg Elbe Berlin Data logger Vacuum system for suction cups Field site Schönberg Deich (ELBE km 435) Rhein Labe Willows control vs. inoculated Reference gauge Suction cups GWgauge FDR PT /1 40/1 20/1 20/5 40/5 60/5 Redox probes 3 m Poplars Tensiometer control vs. inoculated In situ remediation site 16 m Field plot Page 14

15 Results of the in situ experiments Changing of the As concentrations in pore water at the three depths during inundation periods As15 As45 As85 ElbeGauge As [µg/l] Date Water level [cm asl.] As partly exceeded the precaution value for the path soil groundwater (BBodSchV, 1999) Page 15

16 Results of the in situ experiments Changing of the Zn- concentrations in pore water at three depths during inundation periods Zn [µg L -1 ] Zn15 Zn45 Zn85 Elbe Elbe River Gauge [cm asl.] Zn partly exceeded the precaution value for the path soil groundwater (BBodSchV, 1999) Date Page 16

17 Lysimeter experiments Populus/ Salix 0,7 m 0,1 m 0,2 m Soil monolith Probes (soil moisture, redox, temperature) GW-Level variation, flooding / 0.2 m / 0.4 m Device for GW-level regulation and reference probe for redox measurement - soil monoliths, diameter 0.3 m, depth 0.9 m 0,3 m - cont. measurement of soil moisture, redox, temperature - suction cups, seepage sampling - e.g. HM-analysis - variation of GW-level - drying and rewetting cycles - soil acidification Page 17

18 Results of the lysimeter experiments Redox and As- concentration in a depth of 10 cm and GW-level inside the lysimeter same behavior as monitored in situ As [µg*l -1 ] 8 6 Eh [mv] Eh GW-Level As GW-Level [cm b.s.] Date Page

19 Results of the lysimeter experiments Redox and Zn- concentration in a depth of 10 cm and GW-level inside the lysimeter same behavior as monitored in situ Zn [µg L -1 ] Eh [mv] Eh GW-Level Zn GW-Level [cm b.s.] Mai 9 Jun 23 Jun 7 Jul 21 Jul 4 Aug 2009 Page 19

20 Preliminary results of the in-situ field experiment Heavy metal per m 2 Cd Cu Ni Pb Zn HM mass (mg ) for removal from soil HM mass (mg) input with sediment Dual inoculated willows annual HM removal by willow shoots (mg) years for remediation Non inoculated willows annual HM removal by willow shoots (mg) years for remediation HM Heavy metals Depth of soil: 0.1 m Flood channel: loamy to clay texture, ph < 6 Page 20

21 Step 3: Production of bioenergy Page 21

22 Page 22 Teaching-, research- and demonstration pilot plant at the Martin-Luther-University of Halle-Wittenberg System for the usage of bio energy

23 Harvest and preparation of the contaminated wooden material before thermo-chemical gasification Harvesting the willow resp. poplar plantation in the floodplain with a self-propelled harvester Humidity of the wooden material after harvest: >50%; shredding to a chip size of about 30x30mm (G30) Technical drying of the chips to a moisture content of approximately 35% (optimum for gasification process) with hot air from the gasification facility Page 23

24 Flow chart of energy during the thermo-chemical gasification process K. Purr, adapted: M. Grau 194 kw input power of biomass (40 kg wooden material per h = 4,9 kwh/kg) and production of a fuel gas with an energy content of about 144 kw bound in chemical compounds (CO, H2, CH4 and other gaseous hydrocarbons) cold gas efficiency = 74% Page 24

25 Conclusions Phytoremediation of contaminated floodplain soils is possible, but needs a lot of time it is better to call it phytomanagement Inoculation with ectomycorrhizal fungi improved the amount of heavy metal transfer from soil to plant; in floodplains willows are more suitable than poplars The field investigations showed that due to inundation an appreciable mobilization resp. immobilization of heavy metals and As occurred The sustainable use of contaminated wood for the production of energy seems to be possible Further research is necessary to explain the mechanisms of heavy metal transfer into the inoculated willows during flooding events, to develop site adapted strategies to increase the uptake of pollutants and to calculate the economic benefits of this remediation measure Page 25

26 Thanks for your attention and the for funding the project! Restoration of contaminated Elbe River floodplain soils by phytoremediation Contact: