Ammonium Removal and Electricity Generation by Using Microbial Desalination Cells
Table 6. Scenarios tested in MDC stage No
Desalination chamber
1
H_Salt 1.5 g/L
2
H_Salt 2.5 g/L
3
H_Salt 2.5 g/L
4
H_Salt 5 g/L
5
H_Salt 15 g/L
6
Filtrated supernatant
7
Filtrated supernatant
8
Filtrated influent wastewater
9
H_Salt 15 g/L
10
H_Salt 15 g/L
Process description Test the removal degree as well as electricity generation under 48 hours. Test the NH4+ removal degree as well as electricity generation under 22 hours. Test the NH4+ removal degree as well as electricity generation under 45 hours. Test the NH4+ removal degree as well as electricity generation under 67 hours. Under the high NH4+ concentration condition, test NH4+ removal degree as well as electricity generation under 24 hours. Test the filtrated supernatant sample in 21 hours. Sample was taken from Hammarby Sjöstadsverk. Test the filtrated supernatant sample as comparison in 71 hours. Sample was taken from Hammarby Sjöstadsverk. Test the filtrated influent wastewater sample under 24 hours. Sample was taken from Hammarby Sjöstadsverk. Under the high NH4+ concentration condition, add the KMnO4 to the former catholyte, test the electricity generation performance under 24 hours. Under the high NH4+ concentration condition, add the KMnO4 to the former catholyte, test the electricity generation performance under 92 hours. NH4+
The MFC of FOOD 2 produced maximum voltage of 13.4 mV and OCV of 233.5 mV under 400 ohm resistance condition. In the MFC stage, the MFC of FOOD 1 performed generally better than the MFC of FOOD 2 (Table 11 in the appendix). While it is admitted that due to lack of operation experience and monitoring video, the biofilm formation time can only be roughly estimated, ~50 hours. Compared to many other researches, this result does not even reach the average power production level (ranging from 200 mV to 600 mV). However it is still reasonable due to the container size, lack of stirrer and centrifuge, oxygen diffusion from cathode chamber to anode chamber, which will be discussed in 5.2.11.
5.2. MDC stage 5.2.1. Scenario 1 During the 48 hours, the MDC produced maximum voltage of 26.3 mV, maximum power of 0.00157 mW, maximum power density of 1.45 mW/m2 (based on 10.8 cm2 electrode area) and 46.73 mW/m3 (based on 33.6 mL volume) under 440 ohm condition (Table 13 and Table 12). The time for MDC to reach maximum voltage is 27 hours (Figure 23). However, as the curve rises slowly after 2.03 h, it is possible to use 2.03 as the “arrival time”. It is necessary to state that, the voltage data measured by multimeter was lost during 2011/08/02 14:15 to 2011/08/03 10:00.due to the laptop
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