GE Technology Reduces Energy Use, Increases Productivity of Marco Island, southwest Florida, Wastewater Treatment Plant

GE and Marco Island, southwest Florida, officials have announced that data from an ongoing, nearly two-year demonstration project in Marco Island proves the capability of GE's new LEAPmbr membrane bioreactor wastewater-treatment technology to reduce energy costs and increase productivity, among other key benefits.

GE's LEAPmbr system, introduced in July 2011, is the result of a multi-year development effort. It was driven by GE's product innovation and development capabilities and more than 25 years of experience with proven, highly reliable MBR technology in diverse applications around the world. Data from Marco Island demonstrates the cost and efficiency savings of the GE LEAPmbr system compared to existing GE MBR technologies resulting in:

• a minimum 30 per cent reduction in energy costs
• a 15 per cent improvement in productivity (greater water-treatment capacity)
• a 50 per cent reduction in membrane aeration equipment and controls, leading to a simpler design with lower construction, installation and maintenance costs
• a 20 per cent reduction in physical footprint leading to further reduced construction and installation costs as well as lower ongoing consumption of cleaning chemicals.

These results were announced at WEFTEC 2011, the 84th Annual Water Environment Federation Technical Exhibition and Conference.

'The number one cost here at our water and wastewater plants is energy,' said Jeff Poteet, general manager of the water and sewer department of Marco Island. 'If we can reduce those costs by 30 per cent, which is what the LEAPmbr system is going to do for us, it won’t just make my staff look good, it will demonstrate the real value our water utilities are providing to consumers.'

The city of Marco Island is a resort community whose wastewater volumes have increased driven by development and by a gradual phase out of septic systems. Additional space for expansion was unavailable, and large seasonal population fluctuations meant project timing would be critical as well. Thus, in a series of phases beginning in 2003, the city evolved its wastewater operations from a 3.5-million-gallon-per-day conventional treatment facility into a 5-mgd GE MBR system, in the same physical footprint. The treated water at Marco Island is used for irrigation at an elementary school, condominiums and hotels and golf courses, thereby conserving freshwater supplies.

The MBR system at Marco Island consists of five GE MBR process trains, each with six cassettes of GE ZeeWeed* 500D modules. GE and Marco Island have collaborated over the past two years to demonstrate various technology innovations that are part of the new LEAPmbr system. In its most recent demonstration beginning in May 2010, GE replaced a ZeeWeed 500D cassette in one of the working trains with a ZeeWeed 500D LEAPmbr cassette, side-by-side. A dedicated air blower was provided for the LEAPmbr cassette, which was instrumented for data collection and put into use in real-world, varying conditions.

Blower operating data revealed the 30 percent reduction in energy use for membrane air scour, which is the result of LEAPmbr technology's more efficient membrane air scour system. Fewer valves, equipment and controls and an overall simpler design drive the lower maintenance requirements. Based on projections by GE, if implemented throughout the entire MBR system at the Marco Island facility, LEAPmbr technology would reduce annual energy use by an amount equivalent to the average annual energy use of 25 to 30 homes, based on US energy consumption data.

GE's MBR technology consists of a suspended-growth biological reactor integrated with GE's high-performance, rugged ZeeWeed hollow-fibre ultrafiltration membranes. The ZeeWeed membranes are immersed in a membrane tank, in direct contact with the water to be treated, which is known as mixed liquor. Through the use of a permeate pump, a vacuum is applied to a header connected to the membranes. The vacuum draws the water through the ZeeWeed membranes, which filter out solids, along with bacteria and viruses. The filtered water, or permeate, then can be further treated, reused or discharged as needed.

Nearly 1,000 plants worldwide use this technology to meet or exceed stringent wastewater treatment and water reuse standards.