New Membrane Bioreactor It cuts energy costs and boosts throughput Chemical Engineering©

GE Power & Water (Trevose, Penn.; ge.com) has introduced an improved membrane bioreactor (mbr) technology whose productivity is said to be 15% higher than that of its predecessor for wastewater treatment plants. The new system, called LEAPmbr, was derived from innovations to GE’s ZeeWeed 500 mbr.

Glenn Vicevic, senior manager, Engineered Systems, says the system has been tested on a commercial scale at three of its customers’ plants and has demonstrated several improvements in addition to higher productivity. These include a 30% reduction in membrane energy costs, a 50% reduction in membrane aeration equipment and controls, and a 20% smaller footprint.

The system consists of rectangular cassettes of PVDF hollow-fiber membranes, immersed in a bioreactor in which bacteria break down pollutants. A pump draws treated water through the membranes, while solids, bacteria and colloidal material are retained in the tank.

An improved aeration method for cleaning the membranes was the key element in lowering energy costs, says Vicevic. “The conventional wisdom is that there should be a continuous air scour of the membranes,” he says, “but over the last decade, we experimented with bubble-size-diffuser design and frequency of air release. From that we determined that large bubbles delivered intermittently was the most effective.” He adds that the improved productivity was obtained by optimizing the manufacturing techniques, while the smaller footprint was achieved by increasing the surface area of the membrane.