Tom Stanley, chief technology officer at GE Water and Process Technologies, said: “We can help turn wastewater treatment plants from energy consumers into energy producers.”
According to Stanley, part of the equation is finding new ways to reduce their energy consumption. One area inside wastewater treatment plants that is energy intensive is aeration, a process that brings oxygen into the sludge and helps bacteria break down the organic matter. The average water treatment facility spends as much as much 60% of its energy on aeration.
Stanley’s solution revolves around a technology called membrane aerated bio film reactor (MABR). Rather than just pumping oxygen into the water, the reactor sends it through bundles of hollow fibres to grow a bio-film. The fibres transfer the oxygen more efficiently to the bio-film and help it neutralise the wastewater pollutants.
It is claimed that the design is so effective that a plant can reduce energy needed for wastewater treatment aeration four-fold. “A great thing about using a MABR is that you don’t have to shut down a facility to achieve this upgrade,” Stanley said. “You can retrofit within the plant’s existing footprint by inserting a MABR into the existing biology tank.”
Once energy consumption has been addressed, the solids caught inside the plant can be used to produce energy. The GE design feeds them into an anaerobic digester where another set of bacteria turns them into biogas. The water treatment plant then uses the biogas to fuel a power-generating gas engine or sends it to other users through a pipeline.
Stanley says that all countries could benefit from the solution, regardless of their GDP. In the US alone, wastewater treatment plants use enough energy to power 2 million homes, and the demand will likely grow following population increase and more stringent regulations.
The technology could be even more effective in developing countries, where electricity as well as clean water is often scarce.
