NUTRIENT REQUIREMENTS FOR AEROBIC BIOSTABILIZATION
OF LANDFILL LEACHATE
E. P. Temoin, Head
Municipal Section
Waste Management Branch
Ministry of Environment
Prince George, British Columbia, Canada
D. S. Mavinic, Associate Professor
Department of Civil Engineering
The University of British Columbia
Vancouver, British Columbia, Canada
When solid wastes are disposed of in a sanitary landfill, contaminated seepage, known
as leachate, can become a problem. Some leachates contain a high concentration of organic
matter and inorganic ions, including metals [ 1). Several cases of polluted groundwater,
caused by municipal landfills, have been documented [2,3).
In an attempt to control groundwater or receiving water degradation, the leachate should
be collected and treated. Since the leachate can have a much higher concentration of organics and metals than domestic sewage, it has been questioned whether conventional
treatment systems could handle the wastewater effectively. Aerobic biological treatment
of organic wastes is affected by the interplay of three factors: nutrients, microorganisms,
and substrate. One factor which may be limiting in the overall mechanism of bio-oxidation
is the rate at which nutrients enter the cell. Sufficient quantities of available nutrients must
be present in a wastewater undergoing treatment, such that the micro-organisms may grow
and be active.
The object of this study was to determine the nitrogen and phosphorus requirements of
aerobic micro-organisms treating a high-strength, landfill leachate, both by itself and in
combination with domestic sewage. Special emphasis was placed on determining the efficiency of metal removal, as a function of nutrient loading.
SYSTEM DESIGN
Physical Design
A single-stage, bench scale system was used in this research. The reactors were made
from large glass bottles. Each reactor was fitted with a coarse-bubble air diffuser and a
mechanical mixer. The air flow rates and speed of mixing were adjusted to maintain a
well mixed, aerobic condition, while minimizing foaming. Based on the work of Uloth [4),
a retention time of 20 days was used in all experiments. The clarification operation involved
two and one half hours of settling.
Leachate and Sewage Characteristics
The leachate used in this research [5] was obtained from one of the landfill lysimeters
used in a leaching study at the University of British Columbia [6]. The sewage sample was
collected weekly from the Annacis Island Sewage Treatment Plant.
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