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Environmental Impact of Concrete Waste Leachates Study

Investigating ecotoxicity effects of concrete waste leachates on aquatic plants and organisms. Analyzing samples from virgin and recycled concrete to assess toxicity levels. Results show varying toxic effects and pH dynamics.

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Environmental Impact of Concrete Waste Leachates Study

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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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