Spray Irrigation of Wastes from the
Manufacture of Hardboard
WARD C. PARSONS, Chief Utilities Engineer
Masonite Corporation
Chicago, Illinois
INTRODUCTION
I believe it only fair to preface my remarks with a qualifying statement as to
their contents. The reason is that they will be clearly "state of the art" rather
than purely technical. Spray irrigation disposal of wastes is somewhat of an enigma
as it has been both praised and condemned over the years.
The disposal of organic wastes by irrigation and natural filtration was pioneered at Seabrook Farms in New Jersey in the 1950's under the direction of Dr.
C. W. Thornthwaite. This initial installation was successful. Some of the popular
technical magazines then began to liken this installation to a gigantic sand filter,
thus implying that the water purification was accomplished by straining through
the upper layers of the soil. These implications were, and are, false as the actual
purification is biological. Unfortunately, this misconception has persisted over
the years.
Along with this popular misconception came the preconceived notion that
agricultural irrigation was applicable to the use of industrial waste water. In our
case, it was not.
Purification of waste water by irrigation and natural filtration is the direct
result of two basic natural phenomena -- that of natural biological reduction and
adsorption (not absorption). By the process of adsorption, molecules of suspended
and dissolved impurities are removed from solution by attaching themselves to
particles of soil, clay, vegetation, and humus at or near the soil surface. This
process is closely related to the cation exchange capacity of a soil colloid whereby negatively charged colloidal particles attract and hold molecules of plant
nutrients in fertilizing.
The effluent is attacked by a variety of micro-organisms which inhabit the
vegetation and the soil, and is biologically reduced to an inert humus. It naturally
follows that the greater the surface area for this adsorption, the greater the disposal potential.
The efficiency of a system continues to increase as the vegetation develops
and the vegetative litter accumulates. Its improvement is accelerated when the
area is kept constantly moist so that micro-organisms do not become desiccated
during the intervals between applications of water. The system efficiency will
continue to improve for a period of approximately three years. At this stage, the
system is then considered to be "mature" and the accumulated vegetation will
then be decomposing at approximately the same rate that it is resupplied.
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