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

eason for moderate removal efficiency could be because of the refractory nature of the
leachate.
Improvement in COD
Removal
30%
25%
20%
15%
10%
5%
0%
Biokinetic
Study
16h HRT
Figure 4.27 Expected and Actual Improvement in COD Removal with Ammonia Stripping
in the YMBR and BMBR Systems
The average BOD removal efficiency of the 16 and 24 h HRT in both the reactors is
given in Figure 4.30. At 16 h HRT, BOD in the bacterial reactor was about 202 mg/L and
that of yeast reactor was 84 mg/L. At 24 h HRT, BOD of yeast effluent was within the
wastewater discharge standards (30 mg/L) and bacterial effluent slightly exceeded the
discharge standards (55 mg/L).
As the BOD removal was high, the BOD/COD drastically reduced. The influent
BOD/COD concentration was 0.4. As shown in Figure 4.31, the BOD/COD ratio reduced
significantly from 0.4 to 0.1 in the BMBR and 0.01-0.03 in the YMBR.
The achieved low BOD/COD ratio indicated that both YMBR and BMBR effluents
contains a high refractory organic substances which might be due to the contribution of the
slowly biodegradable organics and non-biodegradable organics contained in the raw
leachate.
100
24h HRT
BMBR
YMBR