MBR is the wastewater treatment method that combines membrane technology with biological treatment. Unlike conventional biological treatments that employ a clarifier for gravity settling, this approach uses microfiltration or ultrafiltration to separate the sludge generated by biological treatments. MBR has several advantages over traditional activated sludge processing. While the hydraulic retention time in MBR is less than in the CAS process, the solid retention period in MBR is longer than in CAS.
Furthermore, in the case of MBR, sludge separation is more effective. Because MBR’s effluent quality is superior in terms of suspended particles, turbidity, and biochemical oxygen demand, it may be used for water reclamation and takes up less area. In addition to CAS, MBR may be utilized in anaerobic treatments by substituting traditional anaerobic digestion with an anaerobic baffled tank reactor, enlarged granular sludge bed, or up-flow anaerobic sludge blanket. By regulating the biomass content, the anaerobic MBR membrane bioreactor may create high-quality effluent with a lower chemical oxygen requirement than the traditional method.
Dorr-Oliver Inc. originally launched the MBR method in 1969. Unfortunately, because to the high costs of membrane material and energy, the first discoveries could not be converted into widespread industrial uses. For its use in commercial applications, more advancements in membrane designs, materials, and process parameters have been developed since then. Since MBR’s initial use in the treatment of municipal and industrial wastewater, its commercial development has accelerated.
With a compound annual growth rate of 7.6%, the global MBR market, currently valued at USD 3.35 billion, is projected to reach USD 8.78 billion by 2022. Many middle-scale to super-large-scale plants have been put into service during the 1990s, thanks to advancements in submerged configuration and extremely efficient membrane materials. Globally, more than 5000 wastewater treatment facilities use MBR technology. In China, MBR’s commercial uses have grown at the fastest rate. Despite being a tested technology with marketable uses, there is still room for improvement in terms of its low-cost and sustainable applications.
Many operational factors, such as the membrane material, pretreatment, F/M ratio, permeate flow, temperature, aeration, SRT, HRT, cleaning procedure, etc., affect the efficacy of MBR wastewater treatment. It is necessary to tune these process parameters in order to achieve effective therapy. The high energy consumption, membrane fouling, and membrane material expense of MBR are key drawbacks.
To make it more popular than traditional wastewater treatment methods, these issues need to be resolved. Precautions may be taken to reduce membrane fouling, a serious issue for MBRs that require energy-efficient operation. Membrane fouling is contingent upon the kind of membrane, influent, and process parameters. The energy consumption of the conventional CAS in conjunction with a tertiary treatment plant is comparable to that of the MBR process.
This paper provides an overview of the evolution of MBR technology and evaluates its potential for sustainable industrial applications. Information on the most current developments in MBR has not been well-organized, despite the abundance of studies and publications on the subject. We offer a succinct overview of the developments in MBR technology to address the obstacles that accompany it. Recent developments in MBR technology have helped to lessen the challenges and provide a long-term solution for the treatment of industrial wastewater.
One of the more promising techniques for treating industrial and municipal wastewater is MBR. It combines a biological treatment process from the secondary stage with the microfiltration or ultrafiltration of the advanced treatment stage. Compact MBR membrane bioreactors are capable of eliminating bacteria, viruses, and suspended and soluble materials from wastewater while producing high-quality effluent. It does away with the need for supplementary clarifiers and the time needed for them.
In the 1960s, the first linked activated sludge and membrane technology was created. Since then, MBR technology has evolved into a more effective choice for areas with scarce water supplies. In that time, wastewater at the General Motors Plant was treated using a side-stream setup with an external membrane. In 1998, the submerged membrane arrangement full-scale MBR plant was first launched in North America. Hinada is one among the several MBR technology vendors in the globe at the moment.
A mechanical screen, anoxic, aerobic, and anaerobic tanks for biological treatments, an air blower for aeration, sludge recirculation, and the chemical dosing system, a cleaning tank for backwash, and other components are often used in an MBR plant.
Transmembrane pressure and permeability are essential for membrane function. Permeate flow divided by TMP represents permeability, which measures the effectiveness of filtration across the membrane. TMP is the driving force behind filtration. The MBR has two modes of operation.
The way a membrane operates is greatly influenced by its surface characteristics. The water affinity of the components that make up the membrane has a significant impact on its performance. Consequently, a composite membrane that combines a thin layer of hydrophilic material with a hydrophobic membrane coating has been the favored method in recent times to balance the fouling problem and material strength. The size of the membrane pores is also a crucial design factor.