Improved Performance Of Microbial Fuel Cell And Treatment Of Antibiotic Wastewater

Nowadays, energy shortage and environmental pollution have become more and more serious. As microbial fuel cell (MFC) is a device that transforms chemical energy stored in organic matters into electricity via electrochemical reactions for energy recovery, it is considered to be a promising bio-electrochemical power source for directly recovering electrical energy from organic. It can also play an important role in achieving sustainable human development. At present, the power problem is the bottleneck of the development of MFC, and the main reason for no enterring the utility field is also due to the low power output. Improvement of the power output has become a very important issue in the field of microbial fuel cells.In this study, we have worked from two aspects, namely, electricity generation and wastewater treatment, aimed to explore feasibiliaty of improving electricity generation performance of MFC with addition of surfactants, and investigate the removal efficiency and power production of antibiotics wastewater in the MFC using antibiotic wastewater as substrate.Firstly, an air-cathode single chamber MFC with carbon felt-anode was successfully demonstrated using glucose as substrate, aiming to study the effect of surfactant on the performance of MFC. Two non-toxic surfactants was used as the addition, one is non-ionic surfactant Tween 80, the other is bio-surfactant rhamnolipid. We aimed to investigate the influence of addition of surfactant on voltage, power output, and electrode polization of the MFC, and the feasibility of improving the performance of MFC with surfactant addition.Results demonstrated that (1) for an air-cathode MFC operating on 1 g L-1 glucose, when the addition of Tween 80 increased from 0 to 80 mg L"1, the maximum power density increased 770% from 21.5 to 187 W m-3 (0.6 to 5.2 W m-2), and the corresponding open circuit voltage increased from 0.483 to 0.606 V. Electrochemical impedance spectroscopy (EIS) analysis suggested that the resistance of MFC decreased from 27.0 to 5.7Ω. The anode discharge increased from 0.78 A m-2 to 1.26 A m-2. (2) For an air-cathode MFC operating on 1 g L"1 glucose with different addition of rhamnolipid from 0 to 80 mg L"1, the open circuit voltage (OCV) was 1.8-fold increased from 483 to 878 mV, the maximum power density was 12.5-fold increased from 22 to 275 W m-3 (0.6 to 7.6 W m-2). EIS analysis suggested that the resistance of MFC decreased from 27 to 5.3Ω. Anode discharge analysis increased from 0.78 to 1.47 A m-2. The improved performance of MFC achieved here might be due to the increase of permeability of cell membranes by addition of surfactant (Tween 80 or rhamnolipid), which reduced the electron transfer resistance through the cell membrane and promoted the electron transfer rate and number, consequently enhanced the current and power output. A promising way of utilizing bio-surfactant to improve energy generation of MFC was demonstrated.Secondly, an air-cathode single chamber MFC was constructed to study the feasibility of wastewater treatment and electricity generation at the same time in the MFC as using antibiotics wastewater as substrate. Results showed that, (1) penicillin can be degraded and produce electricity simultaneously. These glucose-penicillin mixtures played an active role in production of electricity. The maximum power density for 1000 mg L"1 glucose+50 mg L" penicillin (101.2 W m-3) was 6-fold higher than the sum of that for 1000 mg L-1 glucose (14.7 W m-3) and 50 mg L-1 penicillin (2.1 W m-3) as the sole fuel. Moreover, penicillin degradation rate reached 98% within 24 h using MFC. (2) A single chamber microbial fuel cell (MFC) with an air-cathode is successfully demonstrated using glucose-ceftriaxone sodium mixtures or ceftriaxone sodium as fuel. The ceftriaxone sodium can be biodegraded and produce electricity simultaneously. Interestingly, these ceftriaxone sodium-glucose mixtures play an active role in production of electricity. The maximum power density is increased in comparison to 1000 mg L-1 glucose (19 W m"3) by 495% for 50 mg L-1 ceftriaxone sodium+1000 mg L-1 glucose (113 W m-3), while the maximum power density is 11 W m-3 using 50 mg L"1 ceftriaxone sodium as the sole fuel. Moreover, ceftriaxone sodium biodegradation rate reaches 91% within 24 h using the MFC in comparison with 51% using the traditional anaerobic reactor.Results suggested thatβ-Lactam antibiotics (penicillin or ceftriaxone sodium) can be degraded and generate electricity at the same time. The presence ofβ-Lactam antibiotics can facilitate the power output and wastewater treatment. According to the fact that allβ-Lactam antibiotics work by inhibiting the formation of peptidoglycan cross-links in the cell walls of bacteria, the addition of ceftriaxone sodium (0-50 mg L-1) in the MFC might destroy the integrity of the cell walls, so the electrons transferred more easily through the cells with the weak restrictions of the cell walls, which led to the increase of the electrons transfer ability from microorganism to anode, resulting in an increase of power output. These results indicated that some toxic and bio-refractory organic matter such as antibiotic wastewater might be suitable resources for electricity generation using the MFC technology. This study also provided a new methode to treatment antibiotics wastewater.