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

Figure 4.39 Molecular Weight Cut-off of Raw Leachate, Stripped Leachate, Bacterial
and Yeast Effluents
COD
COD (mg/L)
8000
7000
6000
5000
4000
3000
2000
1000
0
Raw
Leachate
Stripped
Leachate
Figure 4.40 Percent Contribution of Various Molecular Weight Compounds to the
Total
The compounds greater than 50 k molecular weight contributed almost 80% of the
raw leachate COD. It could be found that some portion of the > 50 k compounds is broken
down into < 5 k after ammonia stripping. This is indicated by the increase of < 5 k
compounds. The > 5 k fraction in the raw leachate after stripping increased from 0 to 17%,
while the > 50 k fraction reduced from 87 to 65%. The 10-50 k and 5-10 k fraction did not
increase significantly. The increase in 10-50 k and 5-10 k fractions was from 5 to 6% and 8
to 11%, respectively. Yoon, et al. (1998) showed that about 72-89% of the organics greater
than MW 500 could be removed and 42% of the organics with less than MW 500 could be
removed from the leachate using Fenton’s process. However, it was noticed that Fenton’s
process was not effective in removing organics less than MW of 500.
The MWCO after MBR treatment indicated notable reduction in > 50 k fraction. The
> 50 k fraction reduced to 3% in the yeast effluent and 7% in the bacterial system. The
lower molecular weight compounds with MW 10-50 k, 5-10 k and >5 k in the yeast
effluent increased by 3 to 9%, 7 to 19% and 18 to 65%, respectively. These fractions
increased from 6 to 12%, 11 to 31% and 18 to 69%, respectively in the bacterial system.
Using the aerated lagoon for the treatment of leachate, it was found that only 19-28% of
the total leachate organics was composed of organics less than MW 500 in the effluent
111
Yeast
Effleunt
Bacterial
Effluent
MW>50k MW 10k-50k MW 5k-10k MW