The Evolution of MBR Design to Minimize Capital Cost and Optimize Energy Efficiency

Abstract

Since the development of immersed membrane bioreactors (MBRs) in the mid 1990s, MBR acceptance and application has steadily increased. The technology has now reached a level of maturity such that there is industry consensus on MBR design. The evolution of MBR design to reduce capital costs and optimize energy efficiency -two of the major hurdles to widespread application -is examined by comparing seven MBR designs performed over the past decade. Two primary drivers for reduced MBR costs are (1) design improvements that are now the industry standard and (2) innovative whole-plant process designs that maximize the benefits of MBR systems while minimizing their limitations. This paper discusses the benefits of innovative MBR applications for addressing peak flow treatment, waste active sludge reduction, control system automation and nutrient removal. The evolution of MBR design approaches toward the industry standard is also discussed. KEYWORDSMembrane bioreactor, procurement, design, capital cost INTRODUCTIONSince the development of immersed membrane bioreactors (MBRs) in the mid 1990s, MBR technology has steadily increased in acceptance and application. Five generations of MBR design philosophies have evolved during this time, with each evolution helping to decrease the capital and operating costs of the technology (Crawford et al, 2000;Crawford et al, 2001;Boe et al, 2006). First generation MBRs replaced conventional activated sludge (CAS) systems in small, package plant applications. Second and third generation MBRs incorporated nutrient removal and decreased the design solids concentrations and solids retention times (SRTs) to improve flux and oxygen transfer efficiency. These advances in MBR technology widened the scope of MBR application toward limit of technology nutrient removal and larger installations were possible as the technology became cost competitive. Increased understanding of MBR design created a fourth generation of larger, more complex MBRs with owners and consultants taking greater responsibility for the overall treatment process design. Fifth generation MBRs incorporate full reliability and redundancy features for large-scale, end-of-pipe systems in addition to applying advanced, fully redundant control systems for optimized MBR operation and control. MBR can now be cost competitive with CAS when a high degree of nutrient removal or exceptional effluent quality is required .

Membrane Processes

“…A review was conducted on the use of submerged hollow fiber membranes in MBR applications (Chang, 2011 A comparison of seven MBR designs over the past decade was conducted to demonstrate the evolution in applications of MBR technology in order to minimize capital cost while optimizing energy usage (Menniti et al, 2011). Five generations of approach to MBR design are identified with the latest demonstrating comparable costs with conventional treatment with similar treatment objectives, while achieving advanced treatment quality and incorporating increasingly complex levels of control and system redundancy.…”

Neoteric approach for mitigation of fouling in membrane bioreactor utilizing green composites

“…Impending limitations in conventional water treatment processes have stimulated the need for efficient processes proficient at removing high values of biochemical oxygen demand (BOD), turbidity, suspended solids, phosphorus, nitrogen and bacteria (Hai et al 2014;Zhang et al 2006). The membrane bioreactor (MBR) has evolved as the well-organized cost-effective technology for municipal as well as industrial wastewater treatment (Sutton et al 2002;Togna and Sutton 2003;Chen and LaPara 2006;Menniti et al 2011;Hosseinzadeh et al 2013;Ahmed et al 2007;Kimura et al 2005;Xing et al 2000;Huang et al 2001;Shimizu et al 1996;Wang et al 2008;Shin and Kang 2003).…”