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