CONVERSION OF DREDGING SEDIMENTS TO GROWING MEDIA BY

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

DREDGED SEDIMENTS Dredged sediments: minerals and organic materials accumulated in the bottom of water bodies and removed by dredging. WHY DREDGE? o Maintenance dredging: safety and efficiency of shipping and port operations o Environmental dredging: containment of aquatic ecosystem pollution and consequent risks …HUGE AMOUNT OF DREDGED SEDIMENTS: • ≈ 200 million m 3/y in Europe • 5 – 6 million m 3/y in Italy POLLUTED SEDIMENTS HOW CAN WE TREAT AND REUSE DREDGED SEDIMENTS?

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 SEDIMENT S Pollutants analyses Landfilling Treatment Reuse

POTENTIAL RECOVERY TREATMENTS AND REUSES “Beneficial use” TREATMENTS Aim: reduce volume or hazardous nature of sediments, facilitate its handling or enhance recovery (Dir. 1999/31 / EC) PRINCIPLE Separation of less contaminated dredged materials fractions Environmental restoration Bricks TREATMENT Classification Sorting Beaches Urban parcks nourishment Evaporation Dewatering Contaminant separation Contaminant destruction Contaminant immobilisation Mechanical dewatering Chemical extraction Thermal desorption Biological reduction Chemical oxidation Thermal oxidation Strip mine reclamation Artificial soil Thermal immobilisation Chemical immobilisation (Dutch-German Exchange on Dredged Material, 2002) Nursery, horticulture (USACE, 1986)

REUSE OF DREDGED SEDIMENTS TO PRODUCE ARTIFICIAL SOIL Previous experiences AGRIPORT (ECO/08/239065/S 12. 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

REUSE OF DREDGED SEDIMENTS TO PRODUCE ARTIFICIAL SOIL Previous experiences Basil Rosemary Mint Soil Sage Soil + sediments Lavander PHYTOREMEDIATION: It works! But…

Limits of Phytoremediation: Long process (3 – 6 years) Need for large treatment areas Scarce ability to modify sediments physical characteristics Aim of my research: 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

Production of an artificial soil by co-composting of dredged sediments and pruning residues Working hypothesis: Dredged sediments Pruning residues Artificial soil CO-COMPOSTING from WASTE to RESORCE

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.

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). LEACHING TEST Sediments Law limit (DM 05. 02. 98) PCB mg/Kg SS 0. 005 0. 01 PAH mg/Kg SS 1. 36 Heavy metals Sediments 1 Law limit (Col. A; D. Lgs. 152/2006) Be ms/Kg ss 2. 23 2 Composters: wire mesh and nonwoven fabric; volume: 0. 196 m 3 ZERO INPUT! Organic compaund: Pruning residues from Florence urban green (Quadrifoglio s. p. a. , Florence).

Production of an artificial soil by co-composting of dredged sediments and pruning residues Experimental design: 2 treatments e 2 controls, three replicates : TR 1: 1 = 40 Kg sed. + 40 Kg p. r. TR 3: 1 = 60 Kg sed. + 20 Kg p. r. PR = only p. r. (control 1) SED = only sed. (control 2) Analyses: • Temperature • p. H • EC • TC, TOC, N, C/N • Humic substances • PAH • Heavy metals • Eco-toxicity (Bio. Tox. TM Flash Test) Manual turning: end of September, mid-April

TEMPERATURE TREND PR, Tr 1: 1 35. 5°C COLD COMPOSTING PROCESS: experimental conditions did not allow the achievement of thermophilic phase of composting (minimum volume for the accumulation of heat: 1 m 3)

ECOTOXICITY Bio. Tox. TM Flash Test - ISO STANDARD 21338 Ecotoxicity determination by Bio. Tox. TM Flash 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?

LEACHATE p. H AND CONDUCTIVITY p. H and conductivity were determined on leachate as it is, by, respectively, p. H-meter GLP 22 CRISON, conductivity meter COND 400 Eutech Instruments.

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 E 1112 (Thermofinnigan). • Initial C/N: optimum in Tr 1: 1, acceptable in Tr 3: 1 • TOC: slight reduction during the process in all the treatment • No losses of N

POLYCYCLIC AROMATIC HYDROCARBONS 0. 6% -26. 2% -56. 8% -24. 4% • Quantification of 18 PAH regulate by D. Lgs 152/2006 • PAHs determination by Gas chromatography-mass spectrometry (GC-MS) GC, using Agilent 6890 N inert series/MSD 5973 with DB-35 ms column (J&W Scientific, Folsom, CA, USA). • Initial contamination (Law 152/2006) by benzopyrene, and indenopirene benzoperilene in all treatments containing sediment; • Reduction of indenopirene concentration in Tr 1: 1 to value below the law limit after 6 months of treatment; • PR: No hydrocarbon contamination in pruning residues. • Reduction of PAHs concentration of 26. 2% in Tr 3: 1 and 56. 8% in Tr 1: 1

HEAVY METALS

Ongoing analyses: 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-toxicity tests: germination test with Sorghum saccharatum, Lepidium sativum and Sinapis alba; Tetrahymena thermophila, Daphnia magna, Selenastrum capricornutum Small-scale in vessel experiment CO-COMPOSTING PRODUCTS WILL BE EVALUATED AS GROWTH SUBSTRATES IN A SUBSEQUENT TRIAL: planting of ornamental plants in urban settings.

Small-scale in vessel experiment o o o 2 ornamental species: Photinia x fraseri, Viburnum tinus Treatments: Tr 1: 1, Tr 3: 1, PR, SED (three replicates) Control: peat-pumice mix (three replicates) Fertilization with Osmocote Topdress N/P/K 23 -5 -10 30 plants in 1 l 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

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 thermophilic phase has not been reached, the experiment in progress shows the efficiency of co-composting to degrade PAHs, expecially in the treatment Tr 1: 1.

Thanks for your attention!