IMPROVED INDUSTRIAL WASTEWATER TREATMENT
THROUGH PARTICLE SIZE MANAGEMENT USING LEACHATE
TREATMENT AS A CASE STUDY
Audrey D. Levine, Research Engineer
George Tchobanoglous, Professor
Department of Civil Engineering
University of California, Davis
Davis, California 95616
William M. Copa, Director of Research
Gary Garzonetti, Product Manager
Environmental and Energy Systems
Zimpro, Inc.
Rothschild, Wisconsin 54474
INTRODUCTION
Industrial wastes are typically characterized by nonspecific measurements such as COD, SS, etc.
However, the chemical nature and treatability of the contaminants cannot be assessed directly from
analysis of such lumped parameters. It is impractical to evaluate wastewaters for each of the multitude
of chemical compounds that may be present. As an alternative, particle size measurements can be
used for identification of the size ranges of contaminants.
Treatment of industrial wastewater can be improved by effective characterization of the size distributions of wastewater contaminants. For each wastewater treatment operation and process, an
optimal size range exists over which effective treatment can occur [I]. Therefore, size characterization
of waste contaminants can be used to facilitate the selection and design of appropriate cost-effective
treatment technologies for the treatment of industrial wastes.
PARTICLE SIZE MANAGEMENT IN INDUSTRIAL WASTE TREATMENT
Particle size management is a systematic approach to waste treatment. The elements of particle
size management are as follows: First, the constituents of the waste are characterized by particle size.
Recommended techniques for size characterization are discussed in the following section. The next
step is to assess the biological or physical/chemical treatability of the constituents of each size range.
Based on these data, appropriate operations and processes are selected and designed for treatment
of specific size ranges of contaminants. Finally, a cost-effective analysis is performed to select alternatives.
To illustrate the application of particle size management in industrial waste treatment, the treatment of landfill leachates will be used as a case study. Characterization of leachate is particularly
challenging because the composition of leachate varies not only from site to site but also over time
and space within a particular site [2,3,4]. Moreover, the treatment of leachate is of importance due
to the increasing need to mitigate the harmful effects of leachate migration into groundwater.
GENERAL CHARACTERISTICS OF LANDFILL LEACHATES
Leachate is the liquid that accumulates in and percolates out of the bottom of landfills. In addition
to water, leachates collected from the bottom of landfills contain a complex mixture of dissolved
and suspended organic and inorganic compounds, and microorganisms [4-8]. Generation of leachate
is dependent on many factors including precipitation patterns, landfill moisture, physical and chem-
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