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

cake used on the top of the membrane usually acts as a secondary membrane which retains
protein aggregates, reducing protein fouling of the primary membrane (Guell, et al., 1999).
These could be the reasons for lower membrane fouling in the yeast membrane.
The protein and carbohydrates form the main component of the EPS; because of
these the EPS components were also measured. It is also interesting to note that the protein
to carbohydrate ratio in the bound EPS was higher in yeast reactor than the bacterial
reactor and the protein to carbohydrate ratio in the soluble EPS was higher in the bacterial
reactor than the yeast reactor. This may suggest that higher protein to carbohydrate ratio
plays a more important role in membrane fouling, if present in the soluble EPS rather than
that of the bound EPS.
4.5.5 Conductivity and TDS
As the TDS and conductivity are also important parameters for determining leachate
quality, the TDS and conductivity was monitored for a short period. The average
conductivity and TDS of raw leachate were found to be 29,213 µS/cm and 14,603 mg/L,
respectively. After stripping, the leachate contained an average conductivity of 42,255
µS/cm and average TDS of 21,128 mg/L. For YMBR and BMBR systems, the
conductivity and TDS concentration were not different (Table 4.19). The TDS and the
conductivity exceeded the effluent discharge standards.
Table 4.19 Conductivity and TDS Concentrations in Leachate and Effluents
Conductivity (µS/cm)
Sample Raw Stripped YMBR BMBR YMBR BMBR
Leachate Leachate Effluent Effluent Reactor Reactor
1 30,060 43,140 40,980 40,830 36,690 37,530
2 29,640 42,360 36,090 35,760 36,990 38,130
3 29,040 41,310 38,940 41,400 37,650 39,180
4 28,110 42,210 36,930 36,600 35,940 35,010
Average 29,213 42,255 38,235 38,648 36,818 37,463
TDS (mg/L)
Sample Raw Stripped YMBR BMBR YMBR BMBR
Leachate Leachate Effluent Effluent Reactor Reactor
1 15,030 21,570 20,490 20,400 18,360 18,750
2 14,820 21,180 18,060 17,880 18,480 19,050
3 14,520 20,640 19,470 20,670 18,840 19,590
4 14,040 21,120 18,450 18,300 17,970 17,520
Average 14,603 21,128 19,118 19,313 18,413 18,728
4.5.6 Cost Analysis for Operation
To further compare the overall performance of the bacterial and yeast membrane
bioreactor, the cost analysis of the two systems was done. Table 4.20 gives the cost of
chemicals used for pH adjustment. Table 4.21 gives the overall treatment cost for each
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