Environmental Engineering Reference
In-Depth Information
along with any planktonic organisms was collected by dislodging the cells from the
electrode with a needle, followed by withdrawal of the liquid sample from the anode
exit. The original inoculum for the MFC was from a Municipal wastewater treat-
ment anaerobic digestor reactor. The anode biocatalyst for the MFC in this study
was established using a synthetic wastewater containing minerals and a mixture of
carbon source containing glucose and lactate. A preliminary test with the Mayfield
wastewater as the carbon source indicated slow growth, as evidenced by negligible
current production over a period of 8 days. A glucose and lactate mixture was used
as the substrate for biocatalyst growth over a period of 5 days. After this period,
the defined medium was replaced with wastewater. Acclimation of the biocatalyst
to the wastewater was carried out by starting with 25% wastewater (balance being
defined medium with no amended carbon source). This was followed by operation
with 100% wastewater as the liquid phase. The MFC system used in the study is
shown in Fig. 5.1.
Fig. 5.1
Schematic of the
MFC and the recirculation set
up
Nitrogen
sparging
Pump
Diffusive
air cathode
Substrate
In
Pt/C
Carbon
felt
5.2.4 Wastewater Collection and Use
The wastewater was collected from a local milk dairy plant operated by Mayfield
Dairy Farms in Athens, TN. The plant generates about 190,000 gallons of wastew-
ater per day with an average BOD of 2250 mg/L. The wastewater is released into
the sewer to be treated by the municipal wastewater treatment plant. The wastewa-
ter was collected from the discharge pipe of the plant and stored at 4
◦
C until use.
The solids were allowed to settle to the bottom and the supernatant was used as the
substrate for the MFC.
5.2.5 Electrical and Analytical Measurements
The voltage output from the MFCs was measured using a Hewlett Packard HP
3468B multimeter. The data were continuously collected using a 4-port DATAQ DI-
158 USB data acquisition device. This was interfaced via USB cable into a computer
