30    ANAEROBIC SEQUENCING BATCH REACTOR TREATMENT
OF LANDFILL LEACHATE
Jake A. Hollopeter, Staff Engineer
Gray & Osborne, Inc.
Yakima, Washington 98901
Richard R. Dague, Professor of Environmental Engineering
Department of Civil Engineering
Iowa State University
Ames, Iowa 50011
INTRODUCTION
Sanitary landfills have been the primary dumping ground for municipal solid waste for many years.
Even today, when concerns over environmental protection are at the forefront of world politics,
recent studies indicate that the majority of municipal solid waste generated in the U.S. is still ultimately disposed of in the sanitary landfill.1 Landfill disposal of municipal solid wastes has continued
to be popular because it is one of the simplest and most economical disposal methods available. The
use of the sanitary landfill also minimizes adverse environmental effects and other risks and inconveniences, and allows waste to decompose under controlled conditions until its eventual transformation
into relatively inert, stabilized material.2
Although the sanitary landfill is the most popular method of solid waste disposal, there are certain
environmental hazards associated with landfilling that must be controlled. One of the major hazards
is the possible contamination of neighboring surface and/or groundwaters by migrating leachate. In
order to prevent the migration of leachate, leachate collection systems, including impermeable liners
and drainage pipes, have been developed by the U. S. Environmental Protection Agency and are
implemented in today's landfill designs. However, even though it is possible to prevent leachate
migration, it is impossible to prevent leachate production, and all of the leachate that is produced at a
landfill site must be treated in a safe and effective manner.
Leachates are liquid wastes produced at all landfill sites as water percolates through the refuse and
leaches out an assortment of organic and inorganic constituents. The characteristics of the leachate
produced from a sanitary landfill can vary widely in quantity and composition from site to site and
seasonally at each landfill. The factors controlling the composition of the leachate include the degree
of compaction and composition of the solid waste, particle size, the hydrology of the site, the climate,
and the age of the landfill.3 The possibility of substantial concentrations of organic materials and
various soluble metals, as well as the high level of volume and strength variability, make the treatment
of most leachates much more difficult than the treatment of municipal wastewater.
Treatment technologies for landfill leachate are relatively young. Evaluation of various leachate
treatment processes was first conducted by Boyle and Ham4 in 1974. This research provided a
foundation for further development in the area of leachate treatment. Since those initial studies, the
methods available for the treatment of leachates have expanded dramatically. Table 1 classifies a
variety of alternatives available for the partial or total treatment of landfill leachates.2
Landfill leachates are generally well suited to anaerobic treatment due to the amount of volatile
fatty acids found in them. It is these readily degradable acids that account for the bulk of the chemical
oxygen demand of many leachates which make them amenable to anaerobic treatment.5 However, the
variability of the leachate from site to site can create problems in selecting an adequate treatment
method. What may be a successful treatment method at one site may not work well at another
location. Extensive testing must be conducted to ensure that the best treatment method is selected for
each particular leachate.
This research was conducted in two phases and focused on treating municipal landfill leachate using
the ASBR at a constant temperature of 35°C. The ASBR is a new high-rate anaerobic treatment
49th Purdue Industrial Waste Conference Proceedings, 1994 Lewis Publishers, Chelsea, Michigan 48118. Printed in
U.S.A.
277