CONTAMINANT DESTRUCTION USING THERMAL PROCESSES

ERDC TN-DOER-T2

December 2000

Electrochemical remediation

Soil washing

Solidification/stabilization

CONTAMINANT DESTRUCTION USING THERMAL PROCESSES

Blended Cement. The Cement-Lock Technology is marketed by ENDESCO Services, Inc.,

Des Plaines, IL. Cement-Lock is an advanced thermochemical manufacturing process for

decontaminating wastes including dredged sediments, soils, and sludges, and producing a

marketable resource. Using this technology, dredged sediment can be transformed into

construction-grade cement that meets ASTM standards (i.e., a dry cementlike product, not a

concretelike matrix). During the process, organic contaminants are destroyed with destruction

efficiencies greater than 99 percent. Heavy metals are immobilized in the cement matrix thus

limiting their mobility and allowing for meeting Toxicity Characteristic Leaching Procedure

(TCLP) regulatory criteria.

In operation, the water content of the dredged sediment (or other waste) is reduced using waste heat

from the thermal process. The sediment is then transferred into a proprietary kiln identified as an

ECOMELTTM Generator where fuel, air, and modifiers are introduced. A clinker-type material,

produced in the ECOMELTTM Quench Unit, is transferred to a pulverizer/mixer where additional

additives are introduced and mixed resulting in the Cement-Lock product. Modifiers and additives

used in the process are formulated based on the chemical and physical characteristics of the sediment

(or other waste) feed stream. Off-gas from the kiln is treated in a secondary combustion chamber;

heat from the gas is recovered for use in drying the feed stream; and the gas stream is passed through

a final cleanup process prior to discharge.

Building Bricks. Bricks for building are manufactured from contaminated dredged sediment by

Hanseaten-Stein Ziegelei GmbH in Hamburg, Germany. Using this technology, dewatered

contaminated sediments from the Port of Hamburg are used in the production of regular bricks

suitable for use in the building industry. During the drying and ceramization process, organic

contaminants are oxidized and metal contaminants are converted to stable immobile compounds or

are volatilized.

In operation, the fine-grained portion of dewatered dredge sediments is used as the raw material for

the bricks. The sediments dredged from the Port of Hamburg are dewatered and segregated in a

system operated by the port prior to being transported to the Hanseaten-Stein facility. Analytical

data indicate that a large percentage of the contaminants are associated with the fine-grained fraction

(less than 63 m) of the sediment. At the manufacturing facility, the sediment is mixed with natural

clay and ground brick in a pan mill. The mixture is dried from 30 percent moisture to below 2 percent

moisture content using a steam dryer. The water removed (in the form of vapor) is condensed and

treated using an activated carbon system. The mixture from the steam dryer is dry-pressed to form

the bricks, which are then placed in a kiln. The bricks are dried at a temperature of 600 C (1,112 F).

The temperature is then increased to 1,066 C (1,950 F) for the ceramization process. The bricks

are cooled and prepared for shipment. Flue gas from the process is treated with calcium hydroxide

and activated carbon, and passed through a fabric filter prior to discharge.