Comparison between membrane bioreactor and hybrid membrane bioreactor (IFAS MBR) systems: A pilot scale study

Abstract

With the increasing global demand for water treatment, there has been rising interest in innovative treatment methods that offer compact designs, cost-effectiveness, and high-quality water output. Membrane technologies have emerged as a leading solution in this domain and are increasingly being adopted in place of conventional systems, especially in domestic wastewater treatment facilities. Membrane Bioreactor (MBR) systems, due to their economic feasibility and ease of operation, have become a key focus of research in the field. Membrane Bioreactor (MBR) systems are a cutting-edge process that integrates biological wastewater treatment with advanced membrane filtration, offering a highly efficient solution for both domestic and industrial wastewater treatment. In MBR systems, biological degradation of organic matter occurs through the activated sludge process, while solid-liquid separation is achieved using a membrane. This obviates the need for secondary settling tanks, which are a standard component of traditional wastewater treatment facilities. Fine pores of membrane, typically in the microfiltration or ultrafiltration range, allow for high-quality effluent with low turbidity and nearly complete removal of suspended solids and pathogens. MBR systems are particularly valued for their ability to operate with higher biomass concentrations, resulting in smaller footprint requirements and improved treatment performance. Today, it has become necessary to revise conventional wastewater treatment plants to ensure nitrogen and phosphorus removal and to achieve treatment efficiency levels that allow for wastewater reuse in water-intensive industries. To meet these demands, new technologies must be employed, and wherever possible, local resources should be utilized in the design of facilities and selection of equipment. In doing so, the environmental sector can reduce dependency on foreign technologies. The Integrated Fixed Film Activated Sludge (IFAS) system represents a relatively recent advancement in wastewater treatment technology, providing several benefits compared to conventional activated sludge systems. In IFAS systems, a growth medium is introduced into the activated sludge tank to facilitate biomass development and enhance the overall treatment process. This medium can either be fixed or free-moving. The technology is relatively recent and can be implemented either as an upgrade to existing facilities or as part of new construction projects. IFAS integrates advantages of traditional activated sludge and biofilm technologies within a single reactor, providing performance improvements of up to 40% without requiring additional aeration tanks. The media in IFAS system provides an increased surface area to support greater biomass accumulation and enhances microbial growth, increasing sludge retention time and treatment efficiency. This thesis presents a comparative analysis of the operational performance of two wastewater treatment systems: a Membrane Bioreactor (MBR) and a Hybrid Membrane Bioreactor known as the Integrated Fixed Film Activated Sludge Membrane Bioreactor (IFAS MBR). The two systems were operated simultaneously parallel under identical conditions using real wastewater from the Istanbul Technical University's Ayazaga Campus. The aim of the study was to assess the treatment efficiencies, operational stability, and membrane fouling behaviors of both systems in handling municipal wastewater at SRT 5 days.