Membrane filtration is the most recent development in water treatment technologies. It ensures physical barrier and almost complete removal of suspended and dissolved particles from the water source. This removal process depends primarily on the pore size of the membrane material. Application of these materials either in single or in combination provides complete solution for various requirements, based on their sizes and configuration.

Types of Products

¤ Micro-filtration
To produce high quality treated water, hollow fiber membranes are used. The size of pores are very fine, around 0.1 micron, which ensures complete removal of bacteria, silt, colloids, cyst such as Cryptospordium and Giardia upto log 6. At the same time, it collects the removed particles for further processing or disposal. Triveni provides Memcor Microfiltration. It covers the largest market share in membrane filtration for RO pretreatment and drinking water technology across the world. The patented air scour process is the key to the efficient operation of this unit. It is used at regular intervals to remove the concentrated particles from the fibers. The backwash air is introduced within the membrane bundles and scours the surface of the membranes with a scrubbing action that is not achievable with external air scour techniques.

Microfiltration membranes are also applied to mixed liquor for the separation of treated biological effluent from the mixed liquor in MBR process. The sub-module membranes are made of thousands of hollow fibers surrounded by a protective plastic screen. It is sealed with polyurethane "pots" at both ends. The filtered water is passed through the top pot from the hollow inner core, or lumen, of the membrane fibers to the filtrate manifold. The ends of the fibers are sealed by the bottom pot. It allows low pressure process air to pass through a series of holes to the outside surface of the membranes within the fiber bundle during backwash.

At first sub-modules are connected to groups of four via a sub-manifold. The sub-manifolds are connected through a stainless steel manifold to form a module rack of sub-manifolds. Backwash airflow is connected via a central tube over the bottom sub-manifolds while the filtrate connection is via each top sub-manifold.

The Memcor system works on the principle of an unique OUTSIDE IN concept. The water molecules travel from outer surface of the fiber to inner surface and are accumulated through the capillary of individual fiber. During this process, suspended impurities are removed and these impurities remain at the outer shell of each fiber. The fibers can be easily loosen by even low pressure air scour action and thus it complete removal by back washing through water flowing at higher flux. It ensures complete removal of colloidal as well as suspended impurities, thus making it fit for drinking application as well as RO pretreatment application.

During this operation, screened feed water is fed into the bottom of the CMF-S filter tank and then passed over and around the microporous hollow fiber membranes. Through the membrane wall clean water is drawn by suction pressure into the center of each membrane fiber. Filtrate flow passes from the top of each module rack to the filtrate manifold. Backwash operation in the MF system is carried out by Filtrate pump and the complete operation is PLC based.

¤ Ultrafiltration
Ultrafiltration technology uses hollow fiber membrane. However apart from water pretreatment, its main use is in pigment separation, dye extraction, oil removal, dairy application, beverages, pharma etc. Since it is a finer membrane it also needs some pretreatment like media filtration for its smoother operation. Like microfiltration it also ensures complete removal of colloidal and suspended impurities as well as bacteria. Thus it makes water suitable for drinking applications as well as for RO pretreatment.

Ultrafiltration is capable of accumulating bacteria, some dyes, some proteins and constituents that have a larger molecular weight of greater than 10,000 daltons. This process is more concerned with the size of the particle and not much dependent upon the charge of the particle. Normally system is PLC based, however, this system require separate pumps to carry out the backwash operations.

¤ Nanofiltration
Nanofiltration membranes are similar to reverse osmosis membranes in several respects except the degree of removal of monovalent ions such as chlorides etc. Reverse osmosis membranes provide 90 to 99% removal of ions while nanofiltration membrane are used for the selective removal of ions from 50 % to 90 %. It depends upon the material and manufacturing of the membrane.

Nanofiltration is a membrane liquid separation technology, positioned between reverse osmosis and Ultrafiltration. It can remove the molecules falling in between the range. Essentially it is a lower-pressure version of reverse osmosis where the purity of product water is not very critical. The level of dissolved solids to be removed is less than what is typically encountered in brackish water or seawater. Nanofiltration is especially suited to treatment of water from many surface supplies like wells, rivers or lakes. The system operations are normally governed by PLC.

¤ Reverse Osmosis
Reverse osmosis is the most efficient filtration process known. This process is capable of removing particles as small as ions from a solution. It is used to purify water and remove salts and other impurities in order thus improving the color, taste and other properties of the fluid. Its most common use is in purifying drinking water. It produces water of very high purity that meets the most demanding specifications.


A semi-permeable membrane is used, which allows the water to pass through it. It rejects the minerals and impurities present in the water. Usually the reverse osmosis technology uses a process known as cross flow. It continually clean the membrane itself. As some of the water passes through the membrane the rest continues downstream, removing the rejected species away from the membrane. Reverse osmosis requires a driving force or a high pressure pump to push the water through the membrane. The higher the minerals or dissolved solids present in the water, the larger the driving force or pressure requirement.

Reverse osmosis is capable of removal of up to 99.5 % salt rejection. It uses the finest membrane available so it is very much prone for fouling with various contaminants like heavy metals, colloids, oil & grease etc. These membranes are not able to tolerate the chlorine. Therefore while designing a RO system, precautions must be taken into consideration for avoiding all this. That's why in recent times Microfiltration is getting popularity world wide.

RO systems are also preferably PLC based so that all safety features and limiting conditions can be taken care off.

¤ Membrane Bio Reactor
It is the most advanced development in the field of biological treatment providing treated wastewater for recycling in smaller footprint and under stringent discharge norms.


Hollow fiber membranes are used to mixed liquor to separate treated effluent from mixed liquor. The membrane is the absolute physical barriers that ensures complete removal of suspended impurities. MBR applications include even constituents of existing systems as well as installation of new systems, for both meeting the most stringent discharge norms and reuse. The treated wastewater can be even reused for cooling tower make-up. It is used to generate high purity water through reverse osmosis and other non-potable applications. The MBR process helps in the protection of environment by treating wastewater. It makes the water suitable for variety of application and thus conserve precious drinking water. Biological system designed for MBR process operates at higher MLVSS concentration. It works with higher sludge retention time thus produces a low quantum of biological sludge thus reducing the sludge de watering cost.

Triveni offers MBR process in exclusive association with Memcor Australia, a part of US Filter of U.S.A., leader in total water management systems.

Memcor's MBR technology combines the skills of Memcor's membrane specialists and the biological treatment engineers at JetTech (another element of US Filter's global expertise) to deliver integrated treatment solutions with firm process guarantees such as BOD and TSS less than 5 mg/l and also removal of nutrient (nitrogen & phosphorous) coliforms.


Biological process fluid (mixed liquor) is pumped to the Membrane Operating System ("MOS"). The mixed liquor is introduced to membrane, along with air, evenly across the bottom of the tank through a unique two-phase jet system. This mixed liquor fills the membrane tank and flows upward through the membrane submodules, creating cross-flow dynamics across the membrane surface. This cross-flow continuously scours the membrane surface and prevent solids dehydration at the membrane surface. Applying a low-pressure vacuum to the inside of the membrane fiber pulls water through the membranes and pumps the filtered water to the next process step. Solids, including organics, bacteria, and most viruses, are rejected by the membrane system and retained in the mixed liquor, which overflows the MOS back to the aeration tank.

Send Online Enquiry