The microbial fuel cells can be operated as {TAIL ~ monitors}, {HEAD ~ filtration devices}, and sensors 
The microbial fuel cells can be operated as { TAIL ~ monitors } , { HEAD ~ filtration devices } , and sensors
OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH