Project GREEN SITE

“Supercritical fluid technologies for

river and sea dredge sediment

remediation”

Ing. Ruggero Corazza – ALLES S.p.A.

remediation”

– LIFE 10 ENV/IT/343 –

Definition:

Super-critical state: in conditions over theircritical temperature and pressure, fluids andtheir behaviours become partly like liquids(p.e. density) and partly like gas (p.e.propagation).Water and Carbon dioxide, in supercritical

What’s a supercritical fluid

Water and Carbon dioxide, in supercriticalconditions, are able to dissolve organiccompounds.

Sub-critical state: in conditions of temperatureand/or pressure a little below its critical ones,only some properties of a supercritical fluidhave been acquired.

Inlet: Polluted sediment, H2O, CO2

Outlet: H2O, CO2 , pollutants and

cleaned sediment

Process Temperature 250°C

Process Pressure 300 bar

1st Phase: Extraction of the pollutants

using supercritical CO2 and subcritical H2O

Process Pressure 300 bar

CO2 has Tcritical 31°C, Pcritical71 bar

H2O has Tcritical 374°C, Pcritical220 bar

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Inlet: H2O + Pollutants extracted

in Phase 1, air 300 bar

Outlet: CO2, H2O and salts, heat

Process Temperature 800°C

2nd Phase: Supercritical Oxidation of the pollutants

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Process Temperature 800°C

Process Pressure 300 bar

Extraction Reactor (left), Oxidation Reactor (right)

• Over 90% abatement of organic solvents.

• Over 95% abatement of washing liquor.

• Extraction times for the target compounds: 60’ – 90’ (max 5kg)

Oxidation times of 1 l of the target compounds: 1’ – 5’

• Absence of any residual solvents and micro-organisms in the dredged

Project targets

• Absence of any residual solvents and micro-organisms in the dredged

sediments.

Layout of the plant (Extraction + Oxidation)

Green Site’s plant front view

Green Site’s plant back and side view

Extraction layout during a test

Fase di Estrazione: Esecuzione

During the testing activity 2 kinds of samples have been used with 2 differentconcentration levels of contaminants: one with 50mg/kg and one with100mg/kg.

For each test about 2 kg of sediments have been treated.

Carbon Dioxide, used for extraction, has been re-used every time, while the

Extraction phase: test running

Carbon Dioxide, used for extraction, has been re-used every time, while the

liquid phase exiting from the separators has been collected and analized.

Oxidation layout during a test

Oxidation tests have been carried out introducing, at first, a liquid mixture ofwater and isopropyl alcohol to bring the reactor to the optimum processconditions; then, the first mixture has been replaced by a mixture of waterand hydrocarbons (polluttants)

Oxidation phase: inlets

For the oxidation tests we’ve used a mixture of water and aboput 7% ofhydrocarbons, in fact we wanted to verify the oxidation reaction using as fule,only hydrocarbons. So, we needed to concentrate the liquid phase obtainedfrom the extraction tests separing some cleaned water from the moreconcentrated mixture. In case of an industrial scale plant, for thisconcentration, we are thinking about a system based on a union of floatingsystems and filtration on membrane.

The performed oxidation tests have shown the ignition of an hydrotermal

Oxidation phase: test running

The performed oxidation tests have shown the ignition of an hydrotermalflame at the expected conditions (400°C and 300 bar) and its stablemaintenance (about at 800°C and 300 bar) both with the water and isopropylalcohol mixture and with the water and hydrocarbons mixture.

THANK YOU FOR YOUR

KIND ATTENTIONFor other informations:

www.green-site.netwww.alles.it

e-mail info@alles.it