Encyclopedia of Environmental Science and Engineering, Volume I and II

PCBs AND ASSOCIATED AROMATICS 929

W out  Mass emission rate of the incoming compound

past the incineration zone.

Water and carbon dioxide are the main products of

combustion for organic material. However, incineration

equipment does not always produce complete combustion

and the effluent or residues can contain organic material of

varying complexity which is derived from either incomplete

combustion or thermal synthesis. A better understanding

and acceptance of the pyrolysis data accumulated over the

last few years has given rise to the concepts of Principal

Organic Hazardous Constituents (POHCs) and Products of

Incomplete Combustion (PlCs).

POHCs can be any incoming hazardous waste stream

but in the particular case of refractory organic compounds

such as PCBs, TCBzs and other halogenated compounds, the

pyrolysis chemistry is complex and can lead to the genera-

tion of PlCs which are much more toxic than the original

POHC. There is a wide variety of equipment available for

the incineration of waste organic materials, but the suitabil-

ity of the incinerator for refractory compounds such as PCBs

is restricted to those which allow the use of high tempera-

tures and a suitably long residence time to achieve a DRE

of 99.9999%.

A rotary kiln is usually large and expensive to operate

but does fulfill the required conditions. Such kilns are used

by Energy Systems Corporation in El Dorado, Arkansas and

SCA/Chemical Waste Management in Chicago, Illinois.

The kiln consists of a refractory lined cylinder with its axis

slightly inclined to produce a tumbling action which mixes

the wastes. The advantage of the design lies in the wide

range of wastes which can be accommodated because the

residence time can be controlled to the extent necessary for

complete combustion. Combustion temperatures range from

870°C to 1650°C.

Halogenerated wastes can be used to fire cement kilns. This

has been done by the St. Lawrence Cement Co. in Mississauga,

Ontario, and the Peerless Cement Co. in Detroit, Michigan.

The calcium oxide of the cement apparently reacts with the

chlorine in the PCB to form calcium chloride. The resulting

cement is not contaminated by organic material because the

kiln operates at about 1500°C. The process has the advantage

that some amount of chloride imparts beneficial mechanical

properties to the cement.

Hazardous waste has been used as a supplemental fuel

in a lime kiln located near Manitowoc, Wisconsin in a

research program run by Monsanto Research Corp. for the

EPA. The DRE for each POHC has been measured together

with the chlorine and trace metals pyrolysis products. The

concentration of stack gas pollutants under baseline and

waste fuel test burn conditions were found to be similar

and the DREs exceeded RCRA regulations for incineration.

Perhaps a disadvantage of both rotary kilns and cement

kilns is that they are operated on fixed land sites so that

the PCB wastes must be transported to them through the

surrounding communities. The siting of hazardous waste

disposal facilities is, in general, complicated by the “not in

my back yard” (NIMBY) syndrome. The result has been

that companies have attempted to mobilize their disposal

technology. Offshore incineration has been proposed. Bayer

AG in Germany and Solvay Cie in Belgium began using a

converted tanker, the 984 ton Matthias I, in 1969. After five

years, the ship was replaced with the 3,445 ton tanker the

Matthias II. Bayer, Solvay and Westab GMBH are also cur-

rently using the Vesta, a 1,356 ton incinerator ship which

was converted in 1979.

Oceanic Combustion Services, a chemical waste man-

agement company, has used a converted chemical tanker

fitted with two large incinerators. This ship, the Vulcanus,

was the first to be used in US coastal waters. It sailed from

the Mobile-Chickasaw port facility in Alabama to an EPA

designated incineration site in the Gulf of Mexico. At-Sea

Incineration Co. of Greenwich, Connecticut, also presented

a plan to burn PCBs on an incinerator ship operating out of

Port Newark, New Jersey. The $74.5 million program was

aimed at the construction of two ships, each of which was to

be capable of burning 1.3 million gal. of hazardous wastes

at each sailing. The disposal rate of liquid wastes through

each of the two onboard 170 ton incinerators was expected

to be 70 gal./min.

The construction of large scale facilities for the land-

based support of ocean incineration was an unresolved issue

which contributed to the demise of ocean incineration. Instead,

mobile incinerators are being tested which can be used onsite.

The EPA has built and tested a reactor built onto a series of

four flatbed trailers. A 4.9 meter long, 1.2 meter diameter kiln

is mounted on the first trailer and operates at 1000°C with a

nominal solids retention time of up to 60 minutes. A second-

ary combustion chamber operating at 1300°C is housed on

the second trailer and provides a secondary retention time

of 2 to 3 seconds. The third trailer houses a water quench-

ing apparatus, a wet electrostatic precipitator and an alkaline

scrubber for off-gas treatment. The fourth trailer is used for

monitoring instruments and controls. The unit was developed

at a cost of $10 million and subsequent units are projected to

cost $5 million each.

The operating parameters of such equipment must typi-

cally provide very high temperatures to make up for the

restriction on size which limits residence time. The unit has

TABLE 53

Area ratios for standard samples remain constant but vary for the

samples in question

Area rations relative to Rt  7.75 min

Sample 4.27 min 6.28 min 7.52 min 8.04 min 11.4 min

EPA 0.34 0.40 1 0.50 0.43

Standard 0.34 0.39 1 0.46 0.36

Oil (1) 0.33 0.40 1 0.44 0.34

Oil (2) 20.6 8.67 1 1.48 0.20

Oil (3) 0.39 0.41 1 0.43 0.36

Oil (4) 45.7 8.71 1 1.64 N.D.

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