Description

TABLE D-1-Continued

of sorbent depends upon several factors including the surface area per
unit volume (or weight) of the sorbent and the intensity of the attrac-
tive forces. Activated carbon has been historically used to remove
organic and other contaminants from water.

6. Ammonia can be readily removed from alkaline aqueous wastes by
stripping with steam at atmospheric pressure. The waste stream, at or
near its boiling point, is introduced at the top of a packed or bubble
cap tray type column and contacted concurrently with steam. Due to its
high partial pressure over alkaline solutions, ammonia is condensed
and reclaimed for sale, and liquid effluents from a properly designed
steam stripping column will be essentially ammonia free.

7. This process involves the physical removal of the solid constitutes
from the aqueous waste stream. A slurry is forced against a filter
medium. The pores of the medium are small enough to prevent the
passage of some of the solid particles; others impinge on the fiber of
the medium. Consequently, a cake builds up on the filter and after the
initial deposition, the cake itself serves as the barrier. The capacity of
this process is governed by the rate of the fluid filtrate through the
bed formed by the solid particles.

8. This process is used to separate aqueous waste streams from the
particles suspended in them. The suspension is placed in a tank, and
the particles are allowed to settle out; the fluid can then be removed
from above the solid bed. The final state is that of a packed bed re-
sembling a filter cake if the process is allowed to continue long enough.
9. This process is used when fine particles in a waste stream are dif-
ficult to separate from the medium in which they are suspended. These
waste constitutes are in the low and fractional micron-range of sizes;
they settle too slowly for economic sedimentation and they are often
difficult to filter. Thus, this process is applied to gather these particles
together as flocculates which allows them to settle much faster and the
resulting sediment is less dense and is often mobile. The particles also
filter more readily into a cake which is permeable and does not clog.

Waste Handling Capability

organic wastes from water. Those which have low removal by carbon
include short carbon chain polar substances such as methanol, formic
acid, and perhaps acetone. This process is being utilized to treat herbi-
cide plant wastes. Also, full scale carbon sorption units have been
successfully used for petroleum and petrochemical wastes.

6. This process is quite useful in the treatment of ammonia bearing
wastes. However, it can also be used to remove various volatile and
organic contaminants from waste streams.

7.

Most of the aqueous hazardous waste streams which contain solid constituents will be treated by this process.

8. Sedimentation is widely used throughout industry for treatment of
waste streams for which there is a need for separation of precipitated
solids from the liquid phase.

9.

Flocculation is also widely used throughout industry for treatment
of waste streams for which there is a need for separation of precipitated
solids from the liquid phase.

TABLE D-1-Continued

1.

Description

The reversible interchange of ions between a solid and a liquid
phase in which there is no permanent change in the structure of the
solid. It is a method of collecting and concentrating undesirable ma-
terials from waste streams. The mechanism of ion exchange is chemical,
utilizing resins that react with either cations or anions.

2. This method is utilized to prevent excessively acid or alkaline
wastes from being discharged in plant effluents. Some of the methods
utilized to neutralize such wastes are: (a) mixing wastes such that the
net effect is a near-neutral pH; (b) passing acid wastes through beds
of limestone; (c) mixing acid with lime slurries; (d) adding proper
proportions of concentrated solutions of caustic soda (NaOH) or soda
ash to acid waste waters; (e) blowing waste boiler-flue gas through
alkaline wastes; (f) adding compressed CO2 to alkaline waste; and
(h) adding sulfuric acid to alkaline wastes.

3. This is a process by which waste streams containing reductants are
converted to a less hazardous state. Oxidation may be achieved with
chlorine, hypochlorites, ozone, peroxide, and other common oxidizing
agents. The method most commonly applied on a large scale is oxida-
tion by chlorine.

4. This is a process whereby streams containing oxidants are treated
with sulfur dioxide to reduce the oxidants to less noxious materials.
Other reductants which can be used are sulfite salts and ferrous sulfate
depending on the availability and cost of these materials.

5. The process of separating solid constituents from an aqueous waste
stream by chemical changes. In this process, the waste stream is con-
verted from one with soluble constituents to one with insoluble con-
stituents.

6. The process of heating a waste material to a high temperature but
without fusing in order to effect useful changes, such as oxidation or
pulverization.

Waste Handling Capability

1. lon exchange technology has been available and has been em-
ployed for many years for removing objectionable traces of metals and
even cyanides from the various waste streams of the metal process in-
dustries. Objectionable levels of fluorides, nitrates, and manganese
have also been removed from drinking water sources by means of ion
exchange. Technology has been developed to the extent that the con-
taminants that are removed can either be recycled or readily trans-
formed into a harmless state or safely disposed.

2.

Neutralization is utilized in the precipitation of heavy metal hy-
droxides or hydrous oxides and calcium sulfate.

3. Ths process is used in the treating of cyanides and other re-
ductants.

This process is used to treat chromium-6 and other oxidants.

5. This process is applicable to the treatment of waste streams con-
taining heavy metals.

6.

Calcination is commonly applied in the processing of high-level radioactive wastes.

TABLE D-1-Continued

Thermal Treatment Processes

1.

Description

A controlled process to convert a waste to a less bulky, less toxic, or less noxious material. Most incineration systems contain four basic components: namely, a waste storage facility, a burner and combustion chamber, an effluent purification device when warranted, and a vent or a stack. The (11) basic types of incineration units are: open pit, open burning, multiple hearth, rotary kiln, fluidized bed, liquid combustors, catalytic combustors, after burners, gas combustors, and stack flares. 2. The thermal decompisition of a compound. Wastes are subjected to temperatures of about 1200°F, (648°C), plus or minus 300°F (148°C), depending upon the nature of the wastes, in an essentially oxygen-free atmosphere. Without oxygen, the wastes cannot burn and are broken down (pyrolyzed) into steam, carbon oxides, volatile vapors and charcoal.

Waste Handling Capability

1. The type of waste for which each of these incineration units is best suited is detailed diagrammatically in Figure D-1.

2.

Most municipal and industrial wastes which are basically organic
in nature can be converted to coke or activated charcoal and gaseous
mixtures which may approach natural gas in heating values through the
utilization of pyrolysis.

TABLE D-1-Continued

Description

1. The activated sludge process may be defined as a system in which
biologically active growths are continuously circulated and contacted
with organic waste in the presence of oxygen. Normally, oxygen is sup-
plied to the system in the form of fine air bubbles under turbulent
conditions. The activated sludge is composed of the biologically active
growths and contains microorganisms which feed on the organic waste.
Oxygen is required to sustain the growth of the microorganisms. In the
conventional activated sludge process incoming waste water is mixed
with recycled activated sludge and the mixture is aerated for several
hours in an aeration tank. During this period, adsorption, flocculation,
and various oxidation reactions take place which are responsible for
removing much of the organic matter from the waste water. The effluent
from the aeration tank is passed to a sedimentation tank where the
flocculated microorganisms or sludge settles out. A portion of this
sludge is recycled as seed to the influent waste water.

2. A basin of significant depth (usually 6 to 17 feet or 1.83 to 5.19
meters), in which organic waste stabilization is accomplished by a dis-
peresed biological growth system, and where oxygenation is provided by
mechanical or diffused aeration equipment.

3. Trickling filters are artificial beds of rocks or other porous media
through which the liquid from settled organic waste is percolated. In
the process the waste is brought into contact with air and biological
growths. Settled liquid is applied intermittently or continuously over
the top surface of the filter by means of a distributor. The filtered
liquid is collected and discharged at the bottom. The primary removal
of organic material is not accomplished through filtering or straining
action. Removal is the result of an adsorption process similar to acti-
vated sludge which occurs at the surfaces of the biological growths or
slimes covering the filter media.

4.

Waste Stabilization Ponds are large shallow basins (usually 2 to 4
feet or 0.61 to 1.22 meters deep) used for the purposes of purifying
waste water by storage under climatic conditions that favor the growth
of algae. The conversion of organics to inorganics or stabilization in
such ponds results from the combined metabolic activity of bacteria by
the algae and by surface aeration. Waste stabilization ponds have been
widely used where land is plentiful and climatic conditions are favorable.

1.

Waste Handling Capability

The activated sludge process has been applied very extensively in
the treatment of refinery, petrochemical, and biodegradable organic
waste waters.

2.

Aerated lagoons have been used successfully as an economical
means to treat industrial wastes where high quality effluents are not
required.

3. Trickling filters have been used extensively in the treatment of
industrial wastes such as: acetaldehyde, acetic acid, acetone, acrolein,
alcohols, benzene, butadiene, chlorinated hydrocarbons, cyanides,
epichlorohydrin, formaldehyde, formic acid, ketones, monoethanola-
mines, phenolics, proplylenedichloride, terpenes, ammonia, ammonium
nitrate, nylon and nylon chemical intermediates, resins, and rocket
fuels.

4. They have been used extensively in treating industrial wastewaters
when a high degree of purification is not required. More recently,
stabilization ponds have proven to be successful in treating steel mill
wastes.