Section 2.    LAND DISPOSAL
BIOGR AD ABILITY SCREENING OF INDUSTRIAL
WASTE SLUDGES FOR LAND TREATMENT
Don F. Kincannon, Professor
Enos L. Stover, Associate Professor
David Crosby, Graduate Student
Bioenvironmental and Water Resources Engineering
School of Civil Engineering
Oklahoma State University
Stillwater, Oklahoma 74078
INTRODUCTION
The objective of industrial waste land treatment technology is to dispose of the waste in an
environmentally safe manner by designing and operating the system to utilize the natural biological,
chemical, and physical processes in the soil for the purpose of assimilating those wastes receiving such
treatment. Assimulation of the waste by a land treatment system is a function of the waste and soil
characteristics, environmental conditions, and operation. Methodology currently used to define the
assimilative capacity of a land treatment system is not standardized. Parameters usually considered
are: hydraulic loading, nutrient availability, oil and grease, known organics, acids-bases-salts, ionic
constituents, and heavy metals. However, no standard procedure has been developed for determining
the biodegradation potential of the industrial waste.
The biochemical reactions resulting in the oxidation of complex organics are catalyzed by enzyme
systems that are generally specific to particular chemical structure. Microorganisms must have or
develop suitable enzyme systems if they are to metabolize particular organic compounds. The development of a reliable biodegradability screening test procedure for specific organic compounds or
complex industrial wastes requires an understanding of the microbiology and biochemistry of these
biochemical stabilization reactions. Certain heavy metals and organic compounds are known to be
toxic or inhibitory to microorganisms, and inhibitatory levels have been documented in the literature.
Microbial adaption to inhibitatory substances consistently present in higher concentrations than those
that cause toxicity on slug discharges has also been established. These aspects of biodegradability
screening must also be evaluated in an acceptable biodegradability screening test procedure.
Biodegradability and inhibition or toxicity have been traditionally measured by empirical bioassay
procedures. Methodologies for use of bacterial cultures in bioassay measurements have been insufficiently developed or misused in the past due to the difficulty of quantifying an easily measurable
response of the bacteria. Biological activity responses that have received the most attention include
oxygen uptake, carbon dioxide evaluation, adenosine triphosphate (ATP), and dehydrogenase.
Biodegradability screening procedures consisting of quantitative assessment of inorganic and
organic compounds known to possibly cause inhibition or toxicity problems is time consuming, very
expensive and can lead to erroneous conclusions. Procedures for biodegradability screening of wastes
for determination of applicability to land treatment have typically consisted of pilot soil column
testing or respirometry type testing relative to measurement of C02 production. These test procedures
have several disadvantages due to the limited information developed, accuracy and repeatability of
test results, and length of time required to develop the information.
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