Membrane Bioreactor System

Membrane Bio-reactor (MBR) is a process that combines a membrane ultra / micro filtration process and activated sludge process. (The MBR process is used in place of the secondary sedimentation tank and sand filter used for tertiary treatment in the conventional activated sludge process.)

Aqua-Tech Membrane Sewage Treatment Plant provides features such as space saving, easy operation and high quality treated water which is reusable. In addition, advanced treatment of nitrogen and phosphorus removal can be achieved by anoxic / aerobic treatment.

In the MBR process, raw sewage from equalization or holding tank first passes through fine screens to remove substances that may clog or scratch the membrane before going into the MBR facilities.

In order to meet more stringent reuse requirement, which is beyond what can be accomplished by conventional sewage treatment plant; a tertiary treatment (filtration) are incorporated when requested, to further polish the secondary treated water.

The membrane bioreactor facility consists of aerobic tank and anoxic tank. Membrane modules are immersed inside the aerobic tank where organic contents (BOD) in the sewage will be biologically degraded by activated sludge. The MLSS (Mixed Liquor Suspended Solid) concentration in the MBR System is 10 to 20 g/L compared to 3 to 4 g/L in conventional activated sludge systems, thus the retention time required is only 30% of conventional system. The membranes also separate suspended solids from liquid through the filtration process. Because the pore size of the membrane is 0.1 micron, not only suspended solids but also bacteria such as coliform bacteria are also removed. The immersed membrane filtration process also eliminates the requirement for gravity sedimentation tank or clarifier required by conventional activated sludge systems. Through recirculation of MLSS from aerobic tank to anoxic tank, nitrate content is removed. Additional coagulant and flocculant dosing also can be incorporated for phosphorous removal.

Hitachi MBR Modules

Aqua-Tech Engineering and Supplies Pte Ltd used high quality membranes manufactured by Hitachi Plant Technologies, Ltd. Compared with membranes from other suppliers, the Hitachi MBR modules have the following advantages.

• Simple and high-performance PVDF flat sheet type membrane
• Maximum 3 stages of modules in vertical formation
• Air is constantly diffused from beneath the bottom of membrane module

According to customer requirements and site conditions, Aqua-Tech offers two types of MBR Plants to customers. One is the Hitachi Compact MBR Plant, which consists of major components installed in pre-fabricated steel tanks (aerobic tank with or without anoxic tank depending on requirement). The advantages of Hitachi Compact MBR Plant also includes:

• Movable unit
• Easy installation
• Minimize site construction works
• Modular design

Another type is site constructed concrete tanks. This type of plant reduces shipment cost by construction concrete tanks on-site and also makes customerization easier to suit site conditions.