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Department of Environmental Chemistry , UCT Prague , Klara.Mocova @ vscht.cz

Department of Environmental Chemistry , UCT Prague , Klara.Mocova @ vscht.cz. Klára A. MOCOVÁ , Lyndon N.A. SACKEY, Pavla RENKEROVÁ. Environmental Impact of Concrete and Concrete - based Construction Waste Leachates. Introduction : Ecotoxicity.

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Department of Environmental Chemistry , UCT Prague , Klara.Mocova @ vscht.cz

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  1. Department ofEnvironmentalChemistry, UCT Prague, Klara.Mocova@vscht.cz Klára A. MOCOVÁ, Lyndon N.A. SACKEY, Pavla RENKEROVÁ EnvironmentalImpactofConcreteandConcrete-basedConstructionWasteLeachates

  2. Introduction: Ecotoxicity • Studies concerning environmental impact of construction materials based on realecotoxicologicalbiotests are very rare up to date Ecotoxicitybiotest: • control (H2O + nutrients) • sample (original / adjusted pH) • test organism (plants, animals...) Observedeffects: • no effect ( sample ≈ control) • lethaleffect (sample = zerogrowth) • growthinhibition (0-100 % ofcontrol) • growthstimulation ( sample ˃ controlgrowth) 1191

  3. MaterialsandMethods Samples - C1, C2 - virginconcrete (fromcompetitivecompanies) W – recycledconcrete solid sample homogenization leachates (100 g solid/ 1000 mL H2O; 5 RPM; 24 h) pH, conductivity, metal analysis ecotoxicityassays: algae, aquaticplant, daphniadifferentleachatestreatment (pH ≈ 7.0; nutrientsadd) 1. sample treatment 2. physical + chemicalproperties 3. aquaticecotoxicity 1191

  4. EcotoxicologicalBiotests DaphniaFreshwateralgaeAquaticplant (duckweed) Immobilisation GR (cells/mL) GR (leaves), chlorophyll 1191

  5. PlantGrowthDetermination Totalleaf area measured by digital image analysis (sw NIS Elements 4.2):1. digital image – 2. binary image – 3. calibration – 4. measurement (mm2) 1191

  6. ToxicEffects in AquaticPlants No toxicity: normalgrowthLethaleffect: necrosisToxiceffect: chlorosis 1191

  7. Results – UndilutedLeachates Values in theTab: Inhibition / Stimulation (%) nontoxic (0 -10 %) orstimulation ( ˂-10 %) low toxicity ( 10 - 30 %) L - lethaleffect (100 %) high toxicity (30 - 90 %) 1191

  8. Results: DaphniaandAlgae(Dilution) Daphnia sensitive to alkaline pH andhighconductivityAlgaerelativelyresistant Legend:originalsamplesdilutedwithcontrol media (darkcolours – C1, C2, W)samplesadjusted to pH 7.0 andenrichedwithnutrients (lightcolours – tC1, tC2, tW) 1191

  9. Results: DilutedSamples:PlantGrowthandChlorophyll No treatmentofleachatesanddilutiondifferencesamongsamplesToxicity: W ≈ C1 ˂ C2 1191

  10. Results – pH Dynamics, Conductivity C2: highest toxicity Conductivityoforiginal 100% leachates: C1: middle toxicity W: lowest toxicity 1191

  11. ChemicalAnalysisof Solid Samples No significantinorganicelements in leachatesexceptof Ca, Na major metals: minor metals: no highlytoxicelementsno significantdifferencesamongsampleshighestamount in concretewaste W 1191

  12. Conclusions • Toxicity ofconcreteleachates: - Highconductivity - High pH persistence underdilutionandtime - Chemicalcomposition (?) • Furtherresearch:ecotoxicityofrecycledconcretes, no homogenizing, various leaching patterns... 1191

  13. Klára A. Mocová Klara.Mocova@vscht.cz 1191

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