Exergy saving and exergy production in municipal wastewater ...

Exergy saving and exergy production in municipal wastewater treatment
Table 4 Performance comparison of hydrogen production of
three different process (Wang et al, 2011).
Dark
fermentation
process MFC-
MEC
Fermentation
Yield
14.3 mmol
cellulose
10.1 mmol
cellulose
Combination of 9.8 mmol
two MFCs with COD
one large MEC
In MEC in the 33.2 mmol
combination of COD
two MFCs with
one large MEC
Production rate, Q
(((m 3 H 2)/m 3 )/d)
Energy efficiency,
cellulose (%)
0.24 23 ------
Energy
efficiency
, COD
(%)
0.24 16 -------
0.28 -------- 19
0.48 -------- 64
1.35. MFC for electricity production
If MFC is put to series and parallel configuration the electricity produced
can be increased and using convertor it can be changed into AC
electricity. Connecting MFCs in series leads to increase in voltage
production and their parallel connection leads to increase in the current
production. Consequently in both configurations the power production
will increase. However, the efficiency of the MEC will be higher as the
input voltage increases therefore the serial shape will be more effective
when it is used with the MEC. In combined configurations, the electron
produced from the anode in a MFC will not be used in the cathode of
that MFC but it goes to the cathode in the next MFC (Sun et al, 2009).
However, real world application of this device is limited because of the
low power density level of several thousand MW/m 2 .
Fig. 8. MEC with two MFCs A) in series B) in parallel (Sun et
al, 2009).
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