Ultimate Disposal of Liquid Wastes by Chemical Fixation
JESSE R. CONNER, President
CHEMFIX, Inc.
Division of Environmental Sciences, Inc.
Pittsburgh, Pennsylvania 15226
INTRODUCTION
In the last decade, concern over the environment has led to rapid development and use
of water and air pollution control equipment and processes. Along with such control
techniques, however, has come a new problem: the disposal of concentrated residues from
equipment and processes which discharge purified air and water to the environment. As a
result, a new segment of the environmental industry is developing which is perhaps best
described by the words "Ultimate Disposal." It is new only in the sense that the problem has
become more intense and, therefore, better recognized, although it has always existed.
"Ultimate Disposal" means the final disposition of waste which, for either technical or
economic reasons, may not be recycled or further reduced in volume by conventional
treatment processes. For example, non-combustible solids such as metal compounds,
which have insufficient economic value at present to allow their recycling, eventually result
from certain wastewater treatment processes regardless of what techniques are used.
Having removed them from the air we breathe or the water we drink, we have already made
the choice to dispose of them on the land we live on, or in the depths of our oceans.
The necessity for dealing with these wastes — in fact even the existence of any problem
— was ignored for many years, probably because no easy solution was in sight. Difficulties
were both chemical and physical, and the huge volume was frightening to anyone tackling
the problem. Almost all of the available information from the literature, from universities,
and from practical experience was based on results and experience dealing with municipal
sewage. A number of processes were developed for "disposing of" such wastes: incineration
(or other oxidation methods), reduction to dry fertilizer or soil conditioner, or most
frequently, simply dumping. Little or no thought was given to the minor toxic constituents
in the waste, and the problem was considered to be primarily a biological one.
METHODS OF ULTIMATE DISPOSAL
Some of the methods which have been used for ultimate disposal (1, 2, 3,4) are shown
in Table I. When we consider the chemical and physical nature of many of these wastes
(Table II) and the economic climate surrounding their potential re-use, it is obvious that
disposal must be on or in the land. This, of course, is not surprising since we now dispose of
almost all of garbage, refuse, construction debris, and other so called "solid wastes" by
landfill. Two problems always encountered in using land disposal methods have been
availability of land and the effect of the disposal method on the surrounding environment.
Where suitable land is attainable, sanitary landfill of solid waste is often adequate and
undoubtedly will be continued as the primary disposal method in the near future, regardless
of developments in recycling and energy utilization. However, the problem with liquid or
semi-liquid ultimate wastes is more complex and difficult to solve. Typically, these wastes
contain dissolved or soluble constituents which can contaminate ground and surface water
supplies or which might be toxic to plants or animals. Their physical form is such that they
tend to remain in the liquid or semi-liquid state under ambient conditions, thereby
eliminating other use of the land in that area as well as posing potential hazards.
906