Bieby Voijant T., PhD

Technologies of

Remediation

Bieby Voijant T., PhD

Jurusan Teknik Lingkungan FTSP - ITS

Type of technologies

Thermal

• _{Thermal Treatment,}

In Situ

• _{Hot Gas}

Decontamination, Ex Situ

• _{Incineration, Ex Situ} • _{Pyrolysis, Ex Situ}

• _{Thermal Desorption,}

Ex Situ

Physical/

Chemical

• _{Chemical Oxidation,}

In Situ

• _{Electrokinetic} Separation, In Situ

• _{Fracturing, In and Ex}

Situ

• _{Soil Flushing, In Situ} • _{Soil Vapor}

Extraction, In Situ

• _{Solidifcation/}

Stabilization, In and Ex Situ

• _{Chemical Extraction,}

Ex Situ

• _{Chemical Reduction/} Oxidation, Ex Situ

• _{Dehalogenation, Ex}

Situ

• _{Separation, Ex Situ} • _{Soil Washing, Ex Situ}

Biological

• _{Bioventing, In Situ} • _Enhanced

Bioremediation, In Situ

• _{Phytoremediation, In}

Situ

Introduction

Hot gas decontamination is essentially a low temperature

thermal desorption process. The process raises the

temperature of the contaminated soil to approximately 260

°C for a specifed period of time by exposing it to hot gases (i.e.

heated air), volatilizing the contaminants, and destroying them

in an afterburner.

Advantage

v      can be

used to

decontaminate equipment

and structures that have

been contaminated with

explosive residues

v     

Contaminants

are

completely destroyed

Disadvantage

v      The largest concern is

atmospheric emissions

from

the thermal oxidizer

v      The furnace design must

take into consideration

possible

explosions

v      The

cost

of this method is

higher than open burning

Thermal Treatment

Thermal Treatment

HOT GAS DECONTAMINATION, EX SITU

Technology Applicability

v For decontamination of explosives-contaminated masonry, TNT or metallic structures. 

v Mines & shells

v Scrap material contaminated with explosives

v Buildings associated with ammunition plants & arsenals

THERMAL TREATMENT – HOT AIR INJECTION, IN SITU

Introduction - Hot Air Injection

Air at about 700°F was introduced into three injection

wells, two of which were slanted to address

contamination beneath a building. Two vapor

extraction wells eventually extracted a

hydrocarbon-contaminated air stream at about 200°F through a

thermal oxidizer, which operated at 1400°F to break

down the petroleum hydrocarbons.

Suitable for homogenous granular soil with a high

permeability and hydraulic conductivity

Advantage

v creating an expanded

in situ bioreactor. Given adequate oxygen, the volatilized hydrocarbons will biodegrade in these surrounding

uncontaminated soils, increasing the fraction of contaminants biodegraded compared with an air

extraction confguration. v can also be used in

conjuction with other thermal enhancement

technologies

Disadvantage

v has limited

applicability to dioxins,

furans and PCBs

v Requires a high pressure multi-stage compression

v Overheating and burning may occur

Types of In

Situ Thermal

Treatment

1. Electrical Resistance Heating

2. Radio Frequency / Electromagnetic Heating 3. Hot Air Injection

4. Steam Injection 5. Conductive Heating

Thermal Treatment

THERMAL TREATMENT – HOT AIR INJECTION, IN SITU

Technolog

y

Applicabili

ty

remove of

volatile

and semi-volatile

organic

compounds

(solvents, certain

pesticides, and

certain petroleum

hydrocarbons)

present

in

the

Physical/Chemical

Treatment

Introduction

Water, or water containing an additive

to enhance contaminant

solubility, is

applied

to the soil or

injected

into

the ground water to

raise the water table into the

contaminated soil zone

.

Contaminants

are

leached

into the ground water, which is

then

extracted and

treated

.

Advantage

v when performed under ideal conditions, can lead to a volume reduction of approximately 90%

of the originally contaminated soil v the large volume of soil that is not contaminated after

washing can be reused as backfll at the site

v pH level and temperature of the soil being treated can be

controlled and closely monitored

v saves money and time and generally the process can be run at a very high rate of around 100 cubic yards per day

Disadvantage

v Flushing additives may leave small

residuals in the soil or groundwater, and they should be evaluated on a site-specifc basis. v Additives must be recovered from the

underlying aquifer and, when possible, should be recycled.

v Treatment of the recovered fuids forms

residual sludges that must be treated or

disposed.

v Recovered groundwater may need treatment to meet appropriate discharge standards.

v If used to extract volatile organic

compounds (VOCs), air emissions should be treated.

v Low permeability soils, such as clays, are

difcult to treat with this method.

v Surfactants may reduce soil porosity, and therefore they should only be used on a case-by-case basis.

Physical/Chemical

Treatment

SOIL FLUSHING, IN SITU

Technology Applicability

Physical/Chemical

Treatment

Introduction

Solidifcation/stabilization (S/S) treatment is

used to treat

hazardous wastes

for disposal and in the remediation/site restoration of contaminated

land

. S/S is also an increasingly popular technology for brownfelds (industrial

property) redevelopment, since treated wastes can often be left on-site and to

improve the soil for subsequent construction.

Though S/S are used both in situ and ex situ, but their ex situ is most common

Advantage

v Low cost because the

reagents are widely

available and inexpensive

v Can be used on a large variety of contaminants

v Can be applied to

diferent types of soils

v Equipment is widely available and simple

v High throughput rates

Disadvantage

v Contaminants are still in the soil, not destroyed or removed

v Volume of the treated wastes usually increases

signifcantly

v Volatile organic compounds and some particulates may come out during treatment process

v Delivering reagents deep into the wastes and

mixing them evenly is difcult

v In situ S/S site may not be redeveloped

v Long-term efciency of S/S is still uncertain

Physical/Chemical

Treatment

SOLIDIFICATION/STABILIZATION, IN SITU AND EX SITU

Physical/Chemical

Treatment

SOLIDIFICATION/STABILIZATION, IN SITU AND EX SITU

Introduction

remediation technology that

uses

microorganisms

to

biodegrade organic

constituents

adsorbed on soils

in the unsaturated zone

.

Bioventing

enhances

the

activity

of

indigenous bacteria

and

simulates

the

natural

in

situ

biodegradation

of hydrocarbons in soil

by inducing ai

r or

oxygen fow

into

the

unsaturated zone

and,

if necessary

, by

adding nutrients

.

Advantage

v Uses readily available equipment;

easy to install.

v Creates minimal disturbance to site operations. Can be used to address inaccessible areas (e.g., under buildings). v Requires short treatment times: usually 6 months to 2 years under optimal conditions.

v Is cost competitive: $45-140/ton of contaminated soil.

v Easily combinable with other technologies (e.g., air sparging, groundwater extraction).

v May not require costly ofgas

treatment.

Disadvantage

v High constituent concentrations may initially be toxic to microorganisms.

v Not applicable for certain site

conditions (e.g., low soil permeabilities, high clay content, insufcient delineation of subsurface conditions).

v Cannot always achieve very low cleanup standards.

v Permits generally required for nutrient injection wells (if used). (A few states also require permits for air injection.)

BIOVENTING, IN SITU

Biological Treatment

BIOVENTING, IN SITU

Technology Applicability

remediates soils contaminated with fuel, non-chlorinated

solvents, some pesticides, wood preservatives, and other

Introduction

Slurry phase biological treatment comprises of the treatment of excavated soil in a bioreactor.

The soil is initially processed to separate out any stones and rubble that may be present. The soil is then mixed with water to a predetermined concentration depending on the concentration of the contaminants present, the rate of biodegradation, and the physical nature of the soils. Some processes pre-wash the soil to concentrate the contaminants. Clean sand can then be discharged; thus leaving just contaminated fnes and washwater that requires treating. Normally, a slurry contains 10 to 30% solids by weight.

Advantage

v

Good temperature

control.

v

Good heat

recovery.

v

Constant

overall

catalytic

activity

maintained easily by

addition of small amount of catalyst.

v

Useful

for

catalysts

that can't

be pelletized.

v

Large heat capacity of

reactor

acts as a safety feature

against explosions.

Disadvantage

v

Reactor

may

plug up

.

v

Uncertainties

in

design

process

.

v

Finding suitable liquids

may be

difcult

.

v

ratio

of

liquid

to catalyst

than in other reactors.

Biological Treatment

Biological Treatment

SLURRY PHASE, EX SITU

Technology Applicability

used mainly to treat non-halogenated SVOCs and VOCs in excavated soils or dredged sediments. Sequential anaerobic/aerobic slurry-phase bioreactors are exploited to treat

PCBs, halogenated SVOCs, pesticides, and ordnance compounds.

Bioreactors are preferred over in situ biological techniques for low permeability soils - areas where underlying ground water may be hard to capture, or when faster

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