SPECIFIC CONDUCTANCE AS A MEASURE OF TREATABILITY
OF LANDFILL LEACHATE EN ALGAL LAGOONS
Paul A. Walker, Environmental Engineer
Hollingsworth & Vose Company
East Walpole, Massachusetts 02032
Donald D. Adrian, Professor
Civil Engineering Department
University of Massachusetts
Amherst, Massachusetts 01003
INTRODUCTION
Recently, leachate generated at sanitary landfills has been recognized as a carrier of high
concentrations of pollutants. Under pressure from state and federal regulatory agencies the
solid waste industry has been searching for low-cost leachate treatment methods. Field observations by University of Massachusetts environmental engineers of algal blooms in dilute
leachate pools prompted the authors to study leachate treatment using algal lagoons. A
modified version of the Algal Assay Procedure Bottle Test (AAPBT) [ 1 ] was adapted to
study the effects of sanitary landfill leachate on algal growth.
MATERIALS AND METHODS
Unialgal cultures of the green alga Scenedesmus dimorphous were used in this study.
These cultures were maintained in 3.78-liter (1 -gal) glass culture vessels containing AAPBT
synthetic algal nutrient medium. Because several recommended nutrients were unavailable,
the following substitutions were made:   12.170 mg/1 MgCl2-6H20 for 5.700 mg/1 MgCl2,
415.543 /ig/1 MnCl2 -4H2O for 264.264 pg/1 MnCl2, 1.429 Mg/1 CoCl2 6H20 for 0.780 /ig/1
CoCl2, and 0.01073 /ig/1 CuCl2-2H20 for 0.009 Mg/1 CuCl2. Cultures were incubated in a
constant-temperature control room at a temperature of 24 ± 2 C. Illumination was provided
by two ceiling lamps, each equipped with two 48-in. cool white fluorescent bulbs.  Light intensity adjacent to the vessels at liquid level was approximately 400 foot-candles, as recommended by Trainor [2]. The light cycle was 14 hr of light and 10 hr of darkness, as suggested
by Myers and Graham [3]. Culture vessels were rotated daily in an attempt to correct for
any local differences in light intensity. All other test procedures are outlined in the Algal
Assay Procedure Bottle Test.  Samples of sanitary landfill leachate were taken from the
Barre, Massachusetts landfill site. A test vessel was made up for each of four dilutions of
leachate. Three controls were prepared in a manner similar to that used for the test vessels
except that no leachate was added.
A complete physical-chemical analysis of the leachate was made immediately before the
test period. Two-liter volumes of each of the test vessels, together with the control vessels,
were inoculated with an appropriate volume of Scenedesmus dimorphous cells to result in
a starting concentration of 1 x 104 cells/ml. All vessels were incubated in a climate control
room under test conditions described above. To permit adequate gas exchange, each of the
vessels was hand swirled twice daily, 20 times in the morning and 20 times in the evening.
Growth of algae was monitored over a 2-week test period. The Sedgewick-Rafter counting
procedure was adapted from Standard Methods [4]. Counts were obtained at a magnification of 100X using a 10X ocular and a 10X objective and a Whipple disc placed in the eyepiece. Algal cells were counted in 10 or more random fields of the Whipple grid, as recommended by Moore [5]. For selecting locations of fields to be counted, a procedure similar
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