Northeast Utility Manhole Contact Water


The treatment system for manhole contact water that is contaminated with oil and grease, suspended solids, gasoline/fuels and PCBs. Periodically the water needs to be pumped out of the manholes so inspections and maintenance can be conducted. The goal of the system is to treat the contaminants so the water can be discharged to a POTW collection system. The discharge limit is 2 ppb for PCBs. About 1800L to 3780L of contact water is processed each month.


The environmental firm designed a system that includes an oil/water separator followed by three filter stages in series (25-micron, 10-micron and 1-micron), a MYCELX MX-4 with MYCELX PCB cartridges and a final polisher vessel.

The system has been in operation since October 2002.


The system has never failed to meet the discharge limit of 2 ppb for PCBs. The detection limit is 0.118 ppb. In one sampling event the influent to the MX-4 was 1000 ppb. The effluent was 1 ppb. That is a 99.9% single pass efficiency for the four MYCELX PCB cartridges.