An Indian reservation in the Sierra Nevada mountain region in California was experiencing septic system failure that posed severe environmental and health risks for the tribe and local businesses. More than 30% of the region’s septic tank and drainfield systems had failed and an additional 30% was predicted to fail in the near future. The tribe’s failure rate significantly exceeded the U.S. Environmental Protection Agency’s reported national average of 10% to 20%.
A remote Caribbean island resort owned by a global corporation faced myriad challenges related to its existing sequencing batch reactor (SBR). It needed a new solution for water treatment that would save money and reduce corporate risk. The wastewater from a temporary destination location can be a challenge to effectively treat due to transient visitors who can swell the resort population from a few to a few thousand in a short period of time.
In Canton, Ohio, a few weeks after ringing in 2014, four contractors submitted bids to update an aging extended aeration wastewater treatment plant (WWTP). Based on bid numbers, it will cost about $80 million to upgrade the 42-million-gal-per-day (mgd) plant to a membrane bioreactor (MBR), or less than $2 per gallon of water treated.
A historic change in how membrane bioreactor (MBR) wastewater treatment plants are designed, built and operated is on display at the Pembroke, Mass., Wastewater Treatment Facility (WWTF). Serving several commercial establishments, this innovative WWTF incorporates simultaneous nitrification denitrification, high mixed liquor suspended solids (MLSS) (20,000 mg/L) and concentrated oxygen all in a single-stage process designed to produce reuse-quality effluent with a total nitrogen (TN) concentration of less than 7 mg/L.
The Frackville Area Municipal Authority (FAMA) Wastewater Treatment Facility (WWTF) in Frackville, Pa., currently operates an Ovivo Airbeam cover aerobic digestion system that was commissioned in October 2010.
FAMA was seeking to upgrade and improve its aerobic digestion system, so it contacted Entech Eng. to design a new system that would reduce the amount of solids that needed to be disposed for land application.
Aerobic Digestion System Design
Long considered the best available technology, membrane bioreactors (MBR) have historically been more expensive and energy-intensive than conventional wastewater treatment technologies. Improved approaches to MBR system design and operation, however, have negated these issues and leveled the playing field.
The challenge now is to utilize better evaluation methods and to properly incentivize energy-efficient operations to make the best available technology more accessible to more projects.
Ask most engineers—at least those actively engaged in the design of wastewater treatment plants (WWTPs)—when membrane bioreactor (MBR) technology makes sense and you will probably get the following response: “MBR technology should be considered when the site footprint is small and when you are trying to produce high-quality effluent.” Both are great reasons to think MBR, but the sentiment is lagging behind the facts and a growing trend.
Union Rome Wastewater Treatment Plant (WWTP) in Union Rome, Ohio, currently operates a membrane bioreactor (MBR) activated sludge system followed by an Ovivo pre-thickened aerobic digestion process using a Kubota P.A.D.-K flat plate membrane thickener process that was commissioned in December 2009.
The Rio Del Oro Wastewater Treatment Plant, located in Los Lunas, N.M., is owned and operated by private utility New Mexico Water Services Co. In 2005, New Mexico Water began the upgrade of the 100,000-gal-per-day (gpd), single-train conventional activated sludge (CAS) system with an Enviroquip membrane bioreactor (MBR) system to meet Class 1A effluent for reuse.
Membrane bioreactors (MBRs) may have a reputation for being costly, but they do not have to be. A survey of 137 MBRs on the U.S. mainland shows that an MBR using flat-plate (FP) technology typically is half to three-quarters the capital expenditure (CapEx) of hollow-fiber (HF) systems.
Nestled in a valley between the Pukalani Country Club’s golf course and a surrounding residential community is the Pukalani MBR Water Reuse Facility. It is a state-of-the-art membrane bioreactor system (MBR) producing R-1 water that is reused to irrigate the award-winning golf course. Prior to its startup in October 2010, the Pukalani STP was in a state of serious disrepair. The concentric circular steel tank was in such poor condition that the design and construction of the MBR was fast-tracked to ensure treatment was not interrupted.