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CONVERSION OF DREDGING SEDIMENTS TO GROWING MEDIA BY MEANS OF CO-COMPOSTING

Explore the potential of co-composting to convert dredged sediments into artificial soil, offering a sustainable solution for sediment reuse in various applications. Investigate the process, benefits, and outcomes of this innovative approach.

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CONVERSION OF DREDGING SEDIMENTS TO GROWING MEDIA BY MEANS OF CO-COMPOSTING

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  1. CONVERSION OF DREDGING SEDIMENTS TO GROWING MEDIA BY MEANS OF CO-COMPOSTING Paola Mattei Giancarlo Renella

  2. DREDGED SEDIMENTS Dredged sediments: minerals and organic materials accumulated in the bottom of water bodies and removed by dredging. • Maintenance dredging: safety and efficiency of shipping and port operations • Environmental dredging: containment of aquatic ecosystem pollution and consequent risks WHY DREDGE? • …HUGE AMOUNT OF DREDGED SEDIMENTS: • ≈ 200 million m3/y in Europe • 5 – 6 million m3/y in Italy POLLUTED SEDIMENTS HOW CAN WE TREAT AND REUSE DREDGED SEDIMENTS?

  3. MENEGMENT OF DREDGED SEDIMENTS Sediments are generally menaged as wastes… INTERNATIONAL CONVENTIONS: Oslo Convention (1972) Convention of London (1972) Paris Convention (1974) OSPAR Convention (1992) Convention of Barcelona (1995) RECOVERY and REUSE instead LANDFILLING Reuse without treatments DREDGED SEDIMENTS Pollutants analyses Landfilling Reuse Treatment

  4. POTENTIAL RECOVERY TREATMENTS AND REUSE REUSES “Beneficial use” (USACE, 1986) TREATMENTS Aim: reduce volume or hazardous nature of sediments, facilitate its handling or enhance recovery (Dir. 1999/31 / EC) (Dutch-German Exchange on Dredged Material, 2002) Environmental restoration Bricks Urban parcks Beaches nourishment Strip mine reclamation Artificial soil Nursery, horticulture

  5. REUSE OF DREDGEDSEDIMENTS TO PRODUCE ARTIFICIALSOILPreviousexperiences • AGRIPORT (ECO/08/239065/S12.532262): sediments reclamation by phytoremediation • Reuse of phytoremediated harbor sediments as in vessel growing medium for Photina x fraseri • Reuse of phytoremediated river sediments as in vessel growing medium for aromatic plants • CLEANSED project (LIFE-ENV-12-E-000652, http://www.lifecleansed.com/it/): reuse of phytoremediated river sediments as growing medium in open field for ornamental plants

  6. REUSE OF DREDGEDSEDIMENTS TO PRODUCE ARTIFICIALSOILPreviousexperiences Basil Rosemary Mint Soil Soil + sediments Sage Lavander PHYTOREMEDIATION: It works! But…

  7. Limits of Phytoremediation: • Long process (3 – 6 years) • Need for large treatment areas • Scarceability to modifysedimentsphysicalcharacteristics Aim of myresearch: an alternative to phytoremediation Evaluate co-composting as bio-treatment aimed at conversion of dredged sediments in artificial soil Advantages and potential of co-composting: • Minimum Input and Minimum inpact • Use of waste materials • Use of existing infrastructures • Custom chemical-physical characteristics to meet plants and environment needs

  8. Production of an artificial soil by co-composting of dredged sediments and pruning residues Working hypothesis: Dredged sediments Pruning residues Artificial soil CO-COMPOSTING fromWASTEto RESORCE

  9. Production of an artificial soil by co-composting of dredged sediments and pruning residues Sediments co-composting Biological treatment where sediments and organic materials are subjected to aerobic digestion by microorganisms • Aim: enrich sediments of nutrients, improve their physical property (structure, porosity, water retention) and degrade organic pollutants • Applicability: sewage sludge, soil and sediment contaminated by biodegradable pollutants • Contaminants: Pentachlorophenol, pesticides, explosives, polycyclic aromatic hydrocarbons, ethylene glycol, diols.

  10. Production of an artificial soil by co-composting of dredged sediments and pruning residues Materials used: Sediments: Sediments dredged in March 2014, From Navicelli canal (Pisa, Italy). Organic compaund: Pruning residues from Florence urban green (Quadrifoglio s.p.a., Florence). Composters: wire mesh and nonwoven fabric; volume: 0.196m3 ZERO INPUT!

  11. Production of an artificial soil by co-composting of dredged sediments and pruning residuesExperimental design: 2 treatments e 2 controls, three replicates : • TR1:1 = 40Kg sed. + 40Kg p.r. • TR3:1 = 60 Kg sed. + 20Kg p.r. • PR = only p.r. (control 1) • SED = only sed. (control 2) • Analyses: • Temperature • pH • EC • TC, TOC, N, C/N • Humic substances • PAH • Heavy metals • Eco-toxicity (BioToxTM Flash Test) • Manual turning: end of September, mid-April

  12. TEMPERATURE TREND PR, Tr1:1 35.5°C COLD COMPOSTING PROCESS: experimental conditions did not allow the achievement of the thermophilic phase of composting (minimum volume for the accumulation of heat: 1m3)

  13. ECOTOXICITYBioToxTM Flash Test - ISO STANDARD 21338 Ecotoxicity determination by BioToxTMFlash Test (Aboatox Oy, Turku, Finland): standardized method based on inhibition of the bioluminescence of Vibrio fischeri(ISO STANDARD 21338) Further investigation needed to identify compound responsible for the toxicity of treatments containing pruning residues: probably secondary metabolites?

  14. LEACHATE pH AND CONDUCTIVITY pH and conductivity were determined on leachate as it is, by, respectively, pH-meter GLP 22 CRISON, conductivity meter COND400 Eutech Instruments.

  15. CARBON AND NITROGEN CONTENT • TOC and TN content are measured in accordance with ISO 10694 (Official Method VII.1), by elemental analyzer CHN-S Flash E1112 (Thermofinnigan). • Initial C/N: optimum in Tr 1:1, acceptablein Tr3:1 • TOC: slightreductionduring the process in all the treatment • No losses of N

  16. POLYCYCLIC AROMATIC HYDROCARBONS 0.6% -26.2% -56.8% -24.4% • Quantification of 18 PAH regulate by D.Lgs152/2006 • PAHs determination by Gas chromatography-mass spectrometry (GC-MS) GC, using Agilent 6890N inert series/MSD 5973 with DB-35ms column (J&W Scientific, Folsom, CA, USA). • Initial contamination (Law 152/2006) by benzopyrene, and indenopirenebenzoperilene in all treatments containing sediment; • Reduction of indenopirene concentration in Tr1:1 to value below the law limit after 6 months of treatment; • PR: No hydrocarbon contamination in pruning residues. • Reduction of PAHsconcentration of 26.2% in Tr3: 1 and 56.8% in Tr1: 1

  17. HEAVY METALS

  18. Ongoinganalyses: • Microbial community study: extraction of DNA and RNA and analysis by PCR-DGGE Humic substances content Analyses on the end-product: • Physico-chemical characterization (C, N, humic substances, pollutants, water retention, porosity ...) • Further eco-toxicitytests: germination test withSorghumsaccharatum, Lepidiumsativumand Sinapis alba; Tetrahymenathermophila, Daphniamagna, Selenastrumcapricornutum • Small-scale in vessel experiment CO-COMPOSTING PRODUCTS WILL BE EVALUATED AS GROWTHSUBSTRATES IN A SUBSEQUENT TRIAL: planting of ornamental plants in urban settings.

  19. Small-scale in vessel experiment • 2 ornamentalspecies: Photinia x fraseri, Viburnumtinus • Treatments: Tr1:1, Tr3:1, PR, SED (threereplicates) • Control: peat-pumice mix (threereplicates) • Fertilization with OsmocoteTopdressN/P/K 23-5-10 • 30 plants in 1l pots • Analyses: • Growth monitoring • Initial and final dry weight • Chlorophyll content • Evaluation of the state of oxidative stress (malondialdehyde assay) • Quantification of metals content in plant tissues

  20. Conclusions: • Dredged sediments could be converted to fertile artificial soils after appropriate treatments • Co-composting has the potential to be an efficient and sustainable treatment to convert sediments to artificial soil, degrading organic pollutants and improving chemical and physical characteristic of the raw material with minimal input and impact on the environment • Despite the thermophilic phase has not been reached, the experiment in progress shows the efficiency of co-composting to degrade PAHs, expecially in the treatment Tr1:1.

  21. Thanks for your attention!

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