By Ken Pantuck
In addition to being the largest facility of its kind in the U.S., the Blue Plains Advanced Wastewater Treatment Plant, in Washington D.C. is also now the first in the nation constructing power-producing Cambi units to treat sludge.
After the water we use in our homes and businesses gets sent down the drain, it goes to wastewater treatment plants, like Blue Plains, where processes remove large debris, settle out dirt and grit, consume organic matter, and disinfect the water before it gets discharged. But these processes leave behind leftover solids or sludge, which is where the Cambi units come in.
The units act like a giant pressure cooker, where the combination of pressure and heat speeds up the sludge digestion process. In addition to processing sludge at a faster pace, it also produces Class A biosolids, which can be safely sold to the public for use on lawns and gardens.
The innovative features of this new technology, currently used successfully in Europe, go beyond just treatment. While conventional wastewater treatment plants use mega-quantities of energy, these units will actually provide a source of energy for the plant, generating enough methane to run three gas combustion turbines that will supply about 40 percent of electricity needed to run the plant.
When operational, the Cambi units will also reduce odors, as well as sludge transportation costs and related pollution.
A few weeks ago, some of my colleagues and I toured the stainless steel reactors and associated digesters as they were going up, as part of DC Water’s $900 million improvements at the Blue Plains plant.
Saving energy and costs, reducing sludge volume and odors, while creating biosolids which we can use on lawns and gardens, makes me think this type of technology may have the potential for broader applications at wastewater treatment plants across the U.S.