Membrane Bioreactors: A Key Technology in Wastewater Treatment

March 1, 2025

MBR technology revolutionizes wastewater treatment by combining biological processes with ultrafiltration, enabling water reuse, reducing space needs, and improving effluent quality. With high contaminant removal efficiency and modular design, it suits municipal, industrial, and specialized applications.

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Traditional biological wastewater treatment, consisting of primary treatment followed by an activated sludge process and a secondary clarifier with sludge recirculation, is an economical and efficient solution for treating effluents destined for discharge into sewer systems or natural water bodies.

However, the implementation of MBR technology has brought significant advancements by enabling water reuse, reducing potable water consumption, and minimizing the space required for wastewater treatment plant (WWTP) installations.

What is MBR Technology?
Membrane bioreactors (MBR) emerged in the late 1960s as a combination of a biological reactor and an ultrafiltration (UF) membrane system. Initially, adoption was limited due to high membrane costs, high energy consumption, and maintenance expenses. However, in the 1990s, the introduction of MBR systems with submerged membranes significantly reduced operational costs. This, along with the growing demand for wastewater reuse in irrigation and industrial processes, fueled the expansion of this technology. Today, MBR systems are one of the best solutions for advanced wastewater treatment, particularly in applications requiring high-quality effluent or where space constraints exist.

An MBR system consists of two key stages:

Biological treatment, where aerobic bacteria break down organic matter in the wastewater.
Membrane filtration, utilizing ultrafiltration (UF) modules—flat-sheet, tubular, or hollow fiber membranes—that can operate either submerged or externally as a complementary system.

Membrane filtration removes a significant amount of suspended solids (SS), organic matter (OM), and biological contaminants, producing high-quality treated effluent. Additionally, MBR systems achieve much higher biomass concentrations in the reactor than conventional systems, with values ranging between 6,000 and 12,000 mg/L.

Advantages of MBR Systems
MBR technology replaces traditional secondary clarification and tertiary treatment, offering multiple benefits:

Reduced footprint: Its compact design minimizes the need for civil works.
High contaminant removal efficiency: With a filtration cutoff of 0.1 - 0.01 µm, it expands the possibilities for effluent reuse in service water and even process water in some industries.
Operational flexibility: UF membranes are modular, allowing easy adaptation to different applications.
Lower sludge production: Due to extended solids retention time in the system.

Applications of MBR Systems
MBR technology is highly versatile and can be used to treat wastewater from various sources, including:

Municipal wastewater
Industrial wastewater
Agricultural wastewater
Mining wastewater
Remote locations and camps.
Hospital wastewater
Hotel and resorts wastewater
Shopping mall wastewater

Conclusion
Wastewater treatment is essential for environmental protection, and MBR technology stands out as one of the most advanced and efficient solutions. By combining biological processes with membrane filtration, MBR systems produce high-quality effluent, optimize space usage, and reduce environmental impact.

Despite operational challenges such as membrane fouling, its benefits in effluent quality, sustainability, and water reuse have made membrane bioreactors an increasingly preferred solution for wastewater treatment.