Thesis - faculty.ait.ac.th - Asian Institute of Technology

(2) Biomass
The growth of biomass is important for the treatment of the leachate. Sufficient
MLSS should be obtained in order to get a good COD removal efficiency. The change in
the biomass for the bacterial and the yeast culture when stepwise COD load was increased
is illustrated in the Figure 4.3 and 4.4. The initial MLSS of the yeast reactor was around
3,750 mg/L, while the bacterial initial sludge MLSS was 2,620 mg/L. The final MLSS of
yeast and bacteria after acclimatization were 11,700 and 6,420 mg/L, respectively. The
MLSS concentration maintained throughout the membrane bioreactor experiment was
about 10,000 mg/L for the yeast reactor and 5, 000 mg/L for the bacterial reactor. The final
MLSS in the yeast system was about 3.12 times the initial MLSS concentration which
shows a 21 % increase in the biomass. In the bacterial system, the final MLSS was 2.5
times initial biomass, which shows an increase of 14.5% in the biomass. Once the cultures
have been acclimatized with a final leachate concentration having COD of 7,300 mg/L
(approximately the initial concentration to be used in the bioreactors), the cultures was
used for the experimental studies.
MLSS (mg/L)
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0
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Time (Days)
Figure 4.3 Increase in Biomass during Acclimatization of the Bacterial Sludge
70
MLSS
Influent COD
9000
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7000
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Influent COD (mg/L) .