O’Brien Water Reclamation Plant tests SUEZ technology to improve treatment performance and reduce energy costs
Help MWRD become energy neutral
Faced with the need to find a solution to meet a new permit limit for phosphorus removal, the Metropolitan Reclamation District of Greater Chicago set the goal to become an energy neutral wastewater treatment leader by 2023 while protecting water quality.
Energy neutrality is the ability to reduce energy consumption while increasing energy production to the point that a facility produces as much or more energy than it consumes, which is increasingly important since water and wastewater treatment typically accounts for 35 percent of a municipality’s energy budget.
To meet their goals, they turned to SUEZ to provide a solution to meet more stringent water quality requirements in the existing plant footprint while reducing energy consumption.
Improve treatment performance and reduce energy costs
Implementing an innovative solution
MWRD decided to demonstrate a new, innovative membrane-aerated biofilm reactor (MABR) technology at the O’Brien Water Reclamation Plant (OWRP) to prove the technology works – an important first step before the district considers whether to install the technology in the full-scale plant.
A full-scale ZeeLung cassette was deployed in June 2015 to run for a year. The nominal capacity of the demonstration equipment is 0.5 MGD. The goal of the project is to determine and optimize the nitrification rate, oxygen transfer rate, and aeration efficiency of the MABR technology.
Results from this work will be used to project the design and performance of a full-scale configuration.
The MABR process employs a gas transfer membrane to deliver oxygen to a biofilm that grows on the surface of the ZeeLung membrane, The technology is being evaluated for its potential to increase existing treatment capacity by providing nitrification in a smaller tank volume that that required for conventional treatment, effectively expanding the capacity of the existing treatment plant to enable enhanced biological phosphorus removal to meet future effluent phosphorus limits, without the needs to construct additional infrastructure.
The MABR process has the added benefits of improving performance for TSS and ammonia removal during stressed conditions (specifically cold temperature peak flow periods). A significant potential to reduce the energy consumption required for aeration by up to 40% compared to the current conventional treatment process.
Modeling has shown that at full scale, ZeeLung has the potential to help the MWRD improve the O’Brien facility’s performance under stressed conditions, specifically cold temperature peak events.
Other benefits of ZeeLung MABR technology for the Metropolitan Water Reclamation District are:
- Simple – ZeeLung membranes are installed directly into the existing bioreactor tanks, reducing the impact on plant hydraulics and operations. The MABR solution also avoids the need to build new concrete tanks to add coagulant for chemical phosphorus removal.
- Small Footprint – Nutrient removal and capacity expansion in existing bioreactor volumes avoids the need to construct new bioreactor tanks. Given the space constraints at the OWRP, and the cost considerations, MWRD prefers to improve treatment performance within their existing footprint.
- Low Energy – Oxygen is delivered at an efficiency up to 4x greater than fine bubble aeration, resulting in significant energy savings. Since OWRP treats nearly 250 million gallons of wastewater per day and up to 450 million gallons a day during wet weather and peak events, reductions in energy have a significant impact and cost savings. Reducing the electricity usage also provides the added benefit of a reduction in greenhouse gases generated in the production of that electricity.
- Nutrient Removal – Increasing biomass inventory by supplementing a suspended growth system with attached growth enables biological nutrient removal in the existing tank footprint, by implementing biological phosphorus removal, MWRD can save money associated with coagulant supply and solids handling that would be required for a chemical treatment technology.